lock.c File Reference

#include "postgres.h"
#include <signal.h>
#include <unistd.h>
#include "access/transam.h"
#include "access/twophase.h"
#include "access/twophase_rmgr.h"
#include "access/xlog.h"
#include "access/xlogutils.h"
#include "miscadmin.h"
#include "pg_trace.h"
#include "storage/lmgr.h"
#include "storage/proc.h"
#include "storage/procarray.h"
#include "storage/spin.h"
#include "storage/standby.h"
#include "utils/memutils.h"
#include "utils/ps_status.h"
#include "utils/resowner.h"

Include dependency graph for lock.c:

Go to the source code of this file.

Data Structures
struct	TwoPhaseLockRecord
struct	FastPathStrongRelationLockData

Macros
#define	NLOCKENTS()    mul_size(max_locks_per_xact, add_size(MaxBackends, max_prepared_xacts))
#define	FAST_PATH_REL_GROUP(rel)    (((uint64) (rel) * 49157) & (FastPathLockGroupsPerBackend - 1))
#define	FAST_PATH_SLOT(group, index)
#define	FAST_PATH_GROUP(index)
#define	FAST_PATH_INDEX(index)
#define	FAST_PATH_BITS_PER_SLOT   3
#define	FAST_PATH_LOCKNUMBER_OFFSET   1
#define	FAST_PATH_MASK   ((1 << FAST_PATH_BITS_PER_SLOT) - 1)
#define	FAST_PATH_BITS(proc, n)   (proc)->fpLockBits[FAST_PATH_GROUP(n)]
#define	FAST_PATH_GET_BITS(proc, n)    ((FAST_PATH_BITS(proc, n) >> (FAST_PATH_BITS_PER_SLOT * FAST_PATH_INDEX(n))) & FAST_PATH_MASK)
#define	FAST_PATH_BIT_POSITION(n, l)
#define	FAST_PATH_SET_LOCKMODE(proc, n, l)    FAST_PATH_BITS(proc, n) |= UINT64CONST(1) << FAST_PATH_BIT_POSITION(n, l)
#define	FAST_PATH_CLEAR_LOCKMODE(proc, n, l)    FAST_PATH_BITS(proc, n) &= ~(UINT64CONST(1) << FAST_PATH_BIT_POSITION(n, l))
#define	FAST_PATH_CHECK_LOCKMODE(proc, n, l)    (FAST_PATH_BITS(proc, n) & (UINT64CONST(1) << FAST_PATH_BIT_POSITION(n, l)))
#define	EligibleForRelationFastPath(locktag, mode)
#define	ConflictsWithRelationFastPath(locktag, mode)
#define	FAST_PATH_STRONG_LOCK_HASH_BITS   10
#define	FAST_PATH_STRONG_LOCK_HASH_PARTITIONS    (1 << FAST_PATH_STRONG_LOCK_HASH_BITS)
#define	FastPathStrongLockHashPartition(hashcode)    ((hashcode) % FAST_PATH_STRONG_LOCK_HASH_PARTITIONS)
#define	LOCK_PRINT(where, lock, type)   ((void) 0)
#define	PROCLOCK_PRINT(where, proclockP)   ((void) 0)

Typedefs
typedef struct TwoPhaseLockRecord	TwoPhaseLockRecord

Functions
static bool	FastPathGrantRelationLock (Oid relid, LOCKMODE lockmode)
static bool	FastPathUnGrantRelationLock (Oid relid, LOCKMODE lockmode)
static bool	FastPathTransferRelationLocks (LockMethod lockMethodTable, const LOCKTAG *locktag, uint32 hashcode)
static PROCLOCK *	FastPathGetRelationLockEntry (LOCALLOCK *locallock)
static uint32	proclock_hash (const void *key, Size keysize)
static void	RemoveLocalLock (LOCALLOCK *locallock)
static PROCLOCK *	SetupLockInTable (LockMethod lockMethodTable, PGPROC *proc, const LOCKTAG *locktag, uint32 hashcode, LOCKMODE lockmode)
static void	GrantLockLocal (LOCALLOCK *locallock, ResourceOwner owner)
static void	BeginStrongLockAcquire (LOCALLOCK *locallock, uint32 fasthashcode)
static void	FinishStrongLockAcquire (void)
static ProcWaitStatus	WaitOnLock (LOCALLOCK *locallock, ResourceOwner owner)
static void	waitonlock_error_callback (void *arg)
static void	ReleaseLockIfHeld (LOCALLOCK *locallock, bool sessionLock)
static void	LockReassignOwner (LOCALLOCK *locallock, ResourceOwner parent)
static bool	UnGrantLock (LOCK *lock, LOCKMODE lockmode, PROCLOCK *proclock, LockMethod lockMethodTable)
static void	CleanUpLock (LOCK *lock, PROCLOCK *proclock, LockMethod lockMethodTable, uint32 hashcode, bool wakeupNeeded)
static void	LockRefindAndRelease (LockMethod lockMethodTable, PGPROC *proc, LOCKTAG *locktag, LOCKMODE lockmode, bool decrement_strong_lock_count)
static void	GetSingleProcBlockerStatusData (PGPROC *blocked_proc, BlockedProcsData *data)
void	LockManagerShmemInit (void)
void	InitLockManagerAccess (void)
LockMethod	GetLocksMethodTable (const LOCK *lock)
LockMethod	GetLockTagsMethodTable (const LOCKTAG *locktag)
uint32	LockTagHashCode (const LOCKTAG *locktag)
static uint32	ProcLockHashCode (const PROCLOCKTAG *proclocktag, uint32 hashcode)
bool	DoLockModesConflict (LOCKMODE mode1, LOCKMODE mode2)
bool	LockHeldByMe (const LOCKTAG *locktag, LOCKMODE lockmode, bool orstronger)
bool	LockHasWaiters (const LOCKTAG *locktag, LOCKMODE lockmode, bool sessionLock)
LockAcquireResult	LockAcquire (const LOCKTAG *locktag, LOCKMODE lockmode, bool sessionLock, bool dontWait)
LockAcquireResult	LockAcquireExtended (const LOCKTAG *locktag, LOCKMODE lockmode, bool sessionLock, bool dontWait, bool reportMemoryError, LOCALLOCK **locallockp, bool logLockFailure)
static void	CheckAndSetLockHeld (LOCALLOCK *locallock, bool acquired)
bool	LockCheckConflicts (LockMethod lockMethodTable, LOCKMODE lockmode, LOCK *lock, PROCLOCK *proclock)
void	GrantLock (LOCK *lock, PROCLOCK *proclock, LOCKMODE lockmode)
void	AbortStrongLockAcquire (void)
void	GrantAwaitedLock (void)
LOCALLOCK *	GetAwaitedLock (void)
void	ResetAwaitedLock (void)
void	MarkLockClear (LOCALLOCK *locallock)
void	RemoveFromWaitQueue (PGPROC *proc, uint32 hashcode)
bool	LockRelease (const LOCKTAG *locktag, LOCKMODE lockmode, bool sessionLock)
void	LockReleaseAll (LOCKMETHODID lockmethodid, bool allLocks)
void	LockReleaseSession (LOCKMETHODID lockmethodid)
void	LockReleaseCurrentOwner (LOCALLOCK **locallocks, int nlocks)
void	LockReassignCurrentOwner (LOCALLOCK **locallocks, int nlocks)
VirtualTransactionId *	GetLockConflicts (const LOCKTAG *locktag, LOCKMODE lockmode, int *countp)
static void	CheckForSessionAndXactLocks (void)
void	AtPrepare_Locks (void)
void	PostPrepare_Locks (FullTransactionId fxid)
Size	LockManagerShmemSize (void)
LockData *	GetLockStatusData (void)
BlockedProcsData *	GetBlockerStatusData (int blocked_pid)
xl_standby_lock *	GetRunningTransactionLocks (int *nlocks)
const char *	GetLockmodeName (LOCKMETHODID lockmethodid, LOCKMODE mode)
void	lock_twophase_recover (FullTransactionId fxid, uint16 info, void *recdata, uint32 len)
void	lock_twophase_standby_recover (FullTransactionId fxid, uint16 info, void *recdata, uint32 len)
void	lock_twophase_postcommit (FullTransactionId fxid, uint16 info, void *recdata, uint32 len)
void	lock_twophase_postabort (FullTransactionId fxid, uint16 info, void *recdata, uint32 len)
void	VirtualXactLockTableInsert (VirtualTransactionId vxid)
void	VirtualXactLockTableCleanup (void)
static bool	XactLockForVirtualXact (VirtualTransactionId vxid, TransactionId xid, bool wait)
bool	VirtualXactLock (VirtualTransactionId vxid, bool wait)
int	LockWaiterCount (const LOCKTAG *locktag)

Variables
int	max_locks_per_xact
bool	log_lock_failures = false
static const LOCKMASK	LockConflicts []
static const char *const	lock_mode_names []
static bool	Dummy_trace = false
static const LockMethodData	default_lockmethod
static const LockMethodData	user_lockmethod
static const LockMethod	LockMethods []
static int	FastPathLocalUseCounts [FP_LOCK_GROUPS_PER_BACKEND_MAX]
static bool IsRelationExtensionLockHeld	PG_USED_FOR_ASSERTS_ONLY = false
int	FastPathLockGroupsPerBackend = 0
static volatile FastPathStrongRelationLockData *	FastPathStrongRelationLocks
static HTAB *	LockMethodLockHash
static HTAB *	LockMethodProcLockHash
static HTAB *	LockMethodLocalHash
static LOCALLOCK *	StrongLockInProgress
static LOCALLOCK *	awaitedLock
static ResourceOwner	awaitedOwner

Macro Definition Documentation

ConflictsWithRelationFastPath

#define ConflictsWithRelationFastPath	(		locktag,
			mode
	)

Value:

    ((locktag)->locktag_lockmethodid == DEFAULT_LOCKMETHOD && \
    (locktag)->locktag_type == LOCKTAG_RELATION && \
    (locktag)->locktag_field1 != InvalidOid && \
    (mode) > ShareUpdateExclusiveLock)

Definition at line 273 of file lock.c.

EligibleForRelationFastPath

#define EligibleForRelationFastPath	(		locktag,
			mode
	)

Value:

    ((locktag)->locktag_lockmethodid == DEFAULT_LOCKMETHOD && \
    (locktag)->locktag_type == LOCKTAG_RELATION && \
    (locktag)->locktag_field1 == MyDatabaseId && \
    MyDatabaseId != InvalidOid && \
    (mode) < ShareUpdateExclusiveLock)

Definition at line 267 of file lock.c.

FAST_PATH_BIT_POSITION

#define FAST_PATH_BIT_POSITION	(		n,
			l
	)

Value:

    (AssertMacro((l) >= FAST_PATH_LOCKNUMBER_OFFSET), \
     AssertMacro((l) < FAST_PATH_BITS_PER_SLOT+FAST_PATH_LOCKNUMBER_OFFSET), \
     AssertMacro((n) < FastPathLockSlotsPerBackend()), \
     ((l) - FAST_PATH_LOCKNUMBER_OFFSET + FAST_PATH_BITS_PER_SLOT * (FAST_PATH_INDEX(n))))

Definition at line 247 of file lock.c.

FAST_PATH_BITS

#define FAST_PATH_BITS	(		proc,
			n
	)		(proc)->fpLockBits[FAST_PATH_GROUP(n)]

Definition at line 244 of file lock.c.

FAST_PATH_BITS_PER_SLOT

#define FAST_PATH_BITS_PER_SLOT   3

Definition at line 241 of file lock.c.

FAST_PATH_CHECK_LOCKMODE

#define FAST_PATH_CHECK_LOCKMODE	(		proc,
			n,
			l
	)		(FAST_PATH_BITS(proc, n) & (UINT64CONST(1) << FAST_PATH_BIT_POSITION(n, l)))

Definition at line 256 of file lock.c.

FAST_PATH_CLEAR_LOCKMODE

#define FAST_PATH_CLEAR_LOCKMODE	(		proc,
			n,
			l
	)		FAST_PATH_BITS(proc, n) &= ~(UINT64CONST(1) << FAST_PATH_BIT_POSITION(n, l))

Definition at line 254 of file lock.c.

FAST_PATH_GET_BITS

#define FAST_PATH_GET_BITS	(		proc,
			n
	)		((FAST_PATH_BITS(proc, n) >> (FAST_PATH_BITS_PER_SLOT * FAST_PATH_INDEX(n))) & FAST_PATH_MASK)

Definition at line 245 of file lock.c.

FAST_PATH_GROUP

#define FAST_PATH_GROUP

(

index

)

Value:

    (AssertMacro((uint32) (index) < FastPathLockSlotsPerBackend()), \
     ((index) / FP_LOCK_SLOTS_PER_GROUP))

Definition at line 233 of file lock.c.

FAST_PATH_INDEX

#define FAST_PATH_INDEX

(

index

)

Value:

    (AssertMacro((uint32) (index) < FastPathLockSlotsPerBackend()), \
     ((index) % FP_LOCK_SLOTS_PER_GROUP))

Definition at line 236 of file lock.c.

FAST_PATH_LOCKNUMBER_OFFSET

#define FAST_PATH_LOCKNUMBER_OFFSET   1

Definition at line 242 of file lock.c.

FAST_PATH_MASK

#define FAST_PATH_MASK   ((1 << FAST_PATH_BITS_PER_SLOT) - 1)

Definition at line 243 of file lock.c.

FAST_PATH_REL_GROUP

#define FAST_PATH_REL_GROUP

(

rel

)

(((uint64) (rel) * 49157) & (FastPathLockGroupsPerBackend - 1))

Definition at line 217 of file lock.c.

FAST_PATH_SET_LOCKMODE

#define FAST_PATH_SET_LOCKMODE	(		proc,
			n,
			l
	)		FAST_PATH_BITS(proc, n) |= UINT64CONST(1) << FAST_PATH_BIT_POSITION(n, l)

Definition at line 252 of file lock.c.

FAST_PATH_SLOT

#define FAST_PATH_SLOT	(		group,
			index
	)

Value:

    (AssertMacro((uint32) (group) < FastPathLockGroupsPerBackend), \
     AssertMacro((uint32) (index) < FP_LOCK_SLOTS_PER_GROUP), \
     ((group) * FP_LOCK_SLOTS_PER_GROUP + (index)))

Definition at line 224 of file lock.c.

FAST_PATH_STRONG_LOCK_HASH_BITS

#define FAST_PATH_STRONG_LOCK_HASH_BITS   10

Definition at line 300 of file lock.c.

FAST_PATH_STRONG_LOCK_HASH_PARTITIONS

#define FAST_PATH_STRONG_LOCK_HASH_PARTITIONS    (1 << FAST_PATH_STRONG_LOCK_HASH_BITS)

Definition at line 301 of file lock.c.

FastPathStrongLockHashPartition

#define FastPathStrongLockHashPartition

(

hashcode

)

((hashcode) % FAST_PATH_STRONG_LOCK_HASH_PARTITIONS)

Definition at line 303 of file lock.c.

LOCK_PRINT

#define LOCK_PRINT	(		where,
			lock,
			type
	)		((void) 0)

Definition at line 405 of file lock.c.

NLOCKENTS

#define NLOCKENTS

(

)

mul_size(max_locks_per_xact, add_size(MaxBackends, max_prepared_xacts))

Definition at line 56 of file lock.c.

PROCLOCK_PRINT

#define PROCLOCK_PRINT	(		where,
			proclockP
	)		((void) 0)

Definition at line 406 of file lock.c.

Typedef Documentation

TwoPhaseLockRecord

typedef struct TwoPhaseLockRecord TwoPhaseLockRecord

Function Documentation

AbortStrongLockAcquire()

void AbortStrongLockAcquire

(

void

)

Definition at line 1860 of file lock.c.

{
    uint32      fasthashcode;
    LOCALLOCK  *locallock = StrongLockInProgress;
 
    if (locallock == NULL)
        return;
 
    fasthashcode = FastPathStrongLockHashPartition(locallock->hashcode);
    Assert(locallock->holdsStrongLockCount == true);
    SpinLockAcquire(&FastPathStrongRelationLocks->mutex);
    Assert(FastPathStrongRelationLocks->count[fasthashcode] > 0);
    FastPathStrongRelationLocks->count[fasthashcode]--;
    locallock->holdsStrongLockCount = false;
    StrongLockInProgress = NULL;
    SpinLockRelease(&FastPathStrongRelationLocks->mutex);
}

References Assert(), FastPathStrongRelationLockData::count, FastPathStrongLockHashPartition, FastPathStrongRelationLocks, LOCALLOCK::hashcode, LOCALLOCK::holdsStrongLockCount, FastPathStrongRelationLockData::mutex, SpinLockAcquire, SpinLockRelease, and StrongLockInProgress.

Referenced by LockAcquireExtended(), and LockErrorCleanup().

AtPrepare_Locks()

void AtPrepare_Locks

(

void

)

Definition at line 3478 of file lock.c.

{
    HASH_SEQ_STATUS status;
    LOCALLOCK  *locallock;
 
    /* First, verify there aren't locks of both xact and session level */
    CheckForSessionAndXactLocks();
 
    /* Now do the per-locallock cleanup work */
    hash_seq_init(&status, LockMethodLocalHash);
 
    while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
    {
        TwoPhaseLockRecord record;
        LOCALLOCKOWNER *lockOwners = locallock->lockOwners;
        bool        haveSessionLock;
        bool        haveXactLock;
        int         i;
 
        /*
         * Ignore VXID locks.  We don't want those to be held by prepared
         * transactions, since they aren't meaningful after a restart.
         */
        if (locallock->tag.lock.locktag_type == LOCKTAG_VIRTUALTRANSACTION)
            continue;
 
        /* Ignore it if we don't actually hold the lock */
        if (locallock->nLocks <= 0)
            continue;
 
        /* Scan to see whether we hold it at session or transaction level */
        haveSessionLock = haveXactLock = false;
        for (i = locallock->numLockOwners - 1; i >= 0; i--)
        {
            if (lockOwners[i].owner == NULL)
                haveSessionLock = true;
            else
                haveXactLock = true;
        }
 
        /* Ignore it if we have only session lock */
        if (!haveXactLock)
            continue;
 
        /* This can't happen, because we already checked it */
        if (haveSessionLock)
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("cannot PREPARE while holding both session-level and transaction-level locks on the same object")));
 
        /*
         * If the local lock was taken via the fast-path, we need to move it
         * to the primary lock table, or just get a pointer to the existing
         * primary lock table entry if by chance it's already been
         * transferred.
         */
        if (locallock->proclock == NULL)
        {
            locallock->proclock = FastPathGetRelationLockEntry(locallock);
            locallock->lock = locallock->proclock->tag.myLock;
        }
 
        /*
         * Arrange to not release any strong lock count held by this lock
         * entry.  We must retain the count until the prepared transaction is
         * committed or rolled back.
         */
        locallock->holdsStrongLockCount = false;
 
        /*
         * Create a 2PC record.
         */
        memcpy(&(record.locktag), &(locallock->tag.lock), sizeof(LOCKTAG));
        record.lockmode = locallock->tag.mode;
 
        RegisterTwoPhaseRecord(TWOPHASE_RM_LOCK_ID, 0,
                               &record, sizeof(TwoPhaseLockRecord));
    }
}

References CheckForSessionAndXactLocks(), ereport, errcode(), errmsg(), ERROR, FastPathGetRelationLockEntry(), hash_seq_init(), hash_seq_search(), LOCALLOCK::holdsStrongLockCount, i, LOCALLOCKTAG::lock, LOCALLOCK::lock, LockMethodLocalHash, TwoPhaseLockRecord::lockmode, LOCALLOCK::lockOwners, TwoPhaseLockRecord::locktag, LOCKTAG::locktag_type, LOCKTAG_VIRTUALTRANSACTION, LOCALLOCKTAG::mode, PROCLOCKTAG::myLock, LOCALLOCK::nLocks, LOCALLOCK::numLockOwners, LOCALLOCK::proclock, RegisterTwoPhaseRecord(), PROCLOCK::tag, LOCALLOCK::tag, and TWOPHASE_RM_LOCK_ID.

Referenced by PrepareTransaction().

BeginStrongLockAcquire()

static void BeginStrongLockAcquire ( LOCALLOCK *  locallock, uint32  fasthashcode  )

static

Definition at line 1824 of file lock.c.

{
    Assert(StrongLockInProgress == NULL);
    Assert(locallock->holdsStrongLockCount == false);
 
    /*
     * Adding to a memory location is not atomic, so we take a spinlock to
     * ensure we don't collide with someone else trying to bump the count at
     * the same time.
     *
     * XXX: It might be worth considering using an atomic fetch-and-add
     * instruction here, on architectures where that is supported.
     */
 
    SpinLockAcquire(&FastPathStrongRelationLocks->mutex);
    FastPathStrongRelationLocks->count[fasthashcode]++;
    locallock->holdsStrongLockCount = true;
    StrongLockInProgress = locallock;
    SpinLockRelease(&FastPathStrongRelationLocks->mutex);
}

References Assert(), FastPathStrongRelationLockData::count, FastPathStrongRelationLocks, LOCALLOCK::holdsStrongLockCount, FastPathStrongRelationLockData::mutex, SpinLockAcquire, SpinLockRelease, and StrongLockInProgress.

Referenced by LockAcquireExtended().

CheckAndSetLockHeld()

static void CheckAndSetLockHeld ( LOCALLOCK *  locallock, bool  acquired  )

inlinestatic

Definition at line 1464 of file lock.c.

{
#ifdef USE_ASSERT_CHECKING
    if (LOCALLOCK_LOCKTAG(*locallock) == LOCKTAG_RELATION_EXTEND)
        IsRelationExtensionLockHeld = acquired;
#endif
}

References LOCALLOCK_LOCKTAG, and LOCKTAG_RELATION_EXTEND.

Referenced by GrantLockLocal(), and RemoveLocalLock().

CheckForSessionAndXactLocks()

static void CheckForSessionAndXactLocks ( void  )

static

Definition at line 3390 of file lock.c.

{
    typedef struct
    {
        LOCKTAG     lock;       /* identifies the lockable object */
        bool        sessLock;   /* is any lockmode held at session level? */
        bool        xactLock;   /* is any lockmode held at xact level? */
    } PerLockTagEntry;
 
    HASHCTL     hash_ctl;
    HTAB       *lockhtab;
    HASH_SEQ_STATUS status;
    LOCALLOCK  *locallock;
 
    /* Create a local hash table keyed by LOCKTAG only */
    hash_ctl.keysize = sizeof(LOCKTAG);
    hash_ctl.entrysize = sizeof(PerLockTagEntry);
    hash_ctl.hcxt = CurrentMemoryContext;
 
    lockhtab = hash_create("CheckForSessionAndXactLocks table",
                           256, /* arbitrary initial size */
                           &hash_ctl,
                           HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
 
    /* Scan local lock table to find entries for each LOCKTAG */
    hash_seq_init(&status, LockMethodLocalHash);
 
    while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
    {
        LOCALLOCKOWNER *lockOwners = locallock->lockOwners;
        PerLockTagEntry *hentry;
        bool        found;
        int         i;
 
        /*
         * Ignore VXID locks.  We don't want those to be held by prepared
         * transactions, since they aren't meaningful after a restart.
         */
        if (locallock->tag.lock.locktag_type == LOCKTAG_VIRTUALTRANSACTION)
            continue;
 
        /* Ignore it if we don't actually hold the lock */
        if (locallock->nLocks <= 0)
            continue;
 
        /* Otherwise, find or make an entry in lockhtab */
        hentry = (PerLockTagEntry *) hash_search(lockhtab,
                                                 &locallock->tag.lock,
                                                 HASH_ENTER, &found);
        if (!found)             /* initialize, if newly created */
            hentry->sessLock = hentry->xactLock = false;
 
        /* Scan to see if we hold lock at session or xact level or both */
        for (i = locallock->numLockOwners - 1; i >= 0; i--)
        {
            if (lockOwners[i].owner == NULL)
                hentry->sessLock = true;
            else
                hentry->xactLock = true;
        }
 
        /*
         * We can throw error immediately when we see both types of locks; no
         * need to wait around to see if there are more violations.
         */
        if (hentry->sessLock && hentry->xactLock)
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("cannot PREPARE while holding both session-level and transaction-level locks on the same object")));
    }
 
    /* Success, so clean up */
    hash_destroy(lockhtab);
}

References CurrentMemoryContext, HASHCTL::entrysize, ereport, errcode(), errmsg(), ERROR, HASH_BLOBS, HASH_CONTEXT, hash_create(), hash_destroy(), HASH_ELEM, HASH_ENTER, hash_search(), hash_seq_init(), hash_seq_search(), HASHCTL::hcxt, i, HASHCTL::keysize, LOCALLOCKTAG::lock, LockMethodLocalHash, LOCALLOCK::lockOwners, LOCKTAG::locktag_type, LOCKTAG_VIRTUALTRANSACTION, LOCALLOCK::nLocks, LOCALLOCK::numLockOwners, and LOCALLOCK::tag.

Referenced by AtPrepare_Locks().

CleanUpLock()

static void CleanUpLock ( LOCK *  lock, PROCLOCK *  proclock, LockMethod  lockMethodTable, uint32  hashcode, bool  wakeupNeeded  )

static

Definition at line 1738 of file lock.c.

{
    /*
     * If this was my last hold on this lock, delete my entry in the proclock
     * table.
     */
    if (proclock->holdMask == 0)
    {
        uint32      proclock_hashcode;
 
        PROCLOCK_PRINT("CleanUpLock: deleting", proclock);
        dlist_delete(&proclock->lockLink);
        dlist_delete(&proclock->procLink);
        proclock_hashcode = ProcLockHashCode(&proclock->tag, hashcode);
        if (!hash_search_with_hash_value(LockMethodProcLockHash,
                                         &(proclock->tag),
                                         proclock_hashcode,
                                         HASH_REMOVE,
                                         NULL))
            elog(PANIC, "proclock table corrupted");
    }
 
    if (lock->nRequested == 0)
    {
        /*
         * The caller just released the last lock, so garbage-collect the lock
         * object.
         */
        LOCK_PRINT("CleanUpLock: deleting", lock, 0);
        Assert(dlist_is_empty(&lock->procLocks));
        if (!hash_search_with_hash_value(LockMethodLockHash,
                                         &(lock->tag),
                                         hashcode,
                                         HASH_REMOVE,
                                         NULL))
            elog(PANIC, "lock table corrupted");
    }
    else if (wakeupNeeded)
    {
        /* There are waiters on this lock, so wake them up. */
        ProcLockWakeup(lockMethodTable, lock);
    }
}

References Assert(), dlist_delete(), dlist_is_empty(), elog, HASH_REMOVE, hash_search_with_hash_value(), PROCLOCK::holdMask, LOCK_PRINT, PROCLOCK::lockLink, LockMethodLockHash, LockMethodProcLockHash, LOCK::nRequested, PANIC, PROCLOCK::procLink, PROCLOCK_PRINT, ProcLockHashCode(), LOCK::procLocks, ProcLockWakeup(), LOCK::tag, and PROCLOCK::tag.

Referenced by LockRefindAndRelease(), LockRelease(), LockReleaseAll(), and RemoveFromWaitQueue().

DoLockModesConflict()

bool DoLockModesConflict	(	LOCKMODE	mode1,
		LOCKMODE	mode2
	)

Definition at line 623 of file lock.c.

{
    LockMethod  lockMethodTable = LockMethods[DEFAULT_LOCKMETHOD];
 
    if (lockMethodTable->conflictTab[mode1] & LOCKBIT_ON(mode2))
        return true;
 
    return false;
}

References LockMethodData::conflictTab, DEFAULT_LOCKMETHOD, LOCKBIT_ON, and LockMethods.

Referenced by Do_MultiXactIdWait(), DoesMultiXactIdConflict(), initialize_reloptions(), and test_lockmode_for_conflict().

FastPathGetRelationLockEntry()

static PROCLOCK * FastPathGetRelationLockEntry ( LOCALLOCK *  locallock )

static

Definition at line 2958 of file lock.c.

{
    LockMethod  lockMethodTable = LockMethods[DEFAULT_LOCKMETHOD];
    LOCKTAG    *locktag = &locallock->tag.lock;
    PROCLOCK   *proclock = NULL;
    LWLock     *partitionLock = LockHashPartitionLock(locallock->hashcode);
    Oid         relid = locktag->locktag_field2;
    uint32      i,
                group;
 
    /* fast-path group the lock belongs to */
    group = FAST_PATH_REL_GROUP(relid);
 
    LWLockAcquire(&MyProc->fpInfoLock, LW_EXCLUSIVE);
 
    for (i = 0; i < FP_LOCK_SLOTS_PER_GROUP; i++)
    {
        uint32      lockmode;
 
        /* index into the whole per-backend array */
        uint32      f = FAST_PATH_SLOT(group, i);
 
        /* Look for an allocated slot matching the given relid. */
        if (relid != MyProc->fpRelId[f] || FAST_PATH_GET_BITS(MyProc, f) == 0)
            continue;
 
        /* If we don't have a lock of the given mode, forget it! */
        lockmode = locallock->tag.mode;
        if (!FAST_PATH_CHECK_LOCKMODE(MyProc, f, lockmode))
            break;
 
        /* Find or create lock object. */
        LWLockAcquire(partitionLock, LW_EXCLUSIVE);
 
        proclock = SetupLockInTable(lockMethodTable, MyProc, locktag,
                                    locallock->hashcode, lockmode);
        if (!proclock)
        {
            LWLockRelease(partitionLock);
            LWLockRelease(&MyProc->fpInfoLock);
            ereport(ERROR,
                    (errcode(ERRCODE_OUT_OF_MEMORY),
                     errmsg("out of shared memory"),
                     errhint("You might need to increase \"%s\".", "max_locks_per_transaction")));
        }
        GrantLock(proclock->tag.myLock, proclock, lockmode);
        FAST_PATH_CLEAR_LOCKMODE(MyProc, f, lockmode);
 
        LWLockRelease(partitionLock);
 
        /* No need to examine remaining slots. */
        break;
    }
 
    LWLockRelease(&MyProc->fpInfoLock);
 
    /* Lock may have already been transferred by some other backend. */
    if (proclock == NULL)
    {
        LOCK       *lock;
        PROCLOCKTAG proclocktag;
        uint32      proclock_hashcode;
 
        LWLockAcquire(partitionLock, LW_SHARED);
 
        lock = (LOCK *) hash_search_with_hash_value(LockMethodLockHash,
                                                    locktag,
                                                    locallock->hashcode,
                                                    HASH_FIND,
                                                    NULL);
        if (!lock)
            elog(ERROR, "failed to re-find shared lock object");
 
        proclocktag.myLock = lock;
        proclocktag.myProc = MyProc;
 
        proclock_hashcode = ProcLockHashCode(&proclocktag, locallock->hashcode);
        proclock = (PROCLOCK *)
            hash_search_with_hash_value(LockMethodProcLockHash,
                                        &proclocktag,
                                        proclock_hashcode,
                                        HASH_FIND,
                                        NULL);
        if (!proclock)
            elog(ERROR, "failed to re-find shared proclock object");
        LWLockRelease(partitionLock);
    }
 
    return proclock;
}

References DEFAULT_LOCKMETHOD, elog, ereport, errcode(), errhint(), errmsg(), ERROR, FAST_PATH_CHECK_LOCKMODE, FAST_PATH_CLEAR_LOCKMODE, FAST_PATH_GET_BITS, FAST_PATH_REL_GROUP, FAST_PATH_SLOT, FP_LOCK_SLOTS_PER_GROUP, PGPROC::fpInfoLock, PGPROC::fpRelId, GrantLock(), HASH_FIND, hash_search_with_hash_value(), LOCALLOCK::hashcode, i, LOCALLOCKTAG::lock, LockHashPartitionLock, LockMethodLockHash, LockMethodProcLockHash, LockMethods, LOCKTAG::locktag_field2, LW_EXCLUSIVE, LW_SHARED, LWLockAcquire(), LWLockRelease(), LOCALLOCKTAG::mode, PROCLOCKTAG::myLock, MyProc, PROCLOCKTAG::myProc, ProcLockHashCode(), SetupLockInTable(), PROCLOCK::tag, and LOCALLOCK::tag.

Referenced by AtPrepare_Locks().

FastPathGrantRelationLock()

static bool FastPathGrantRelationLock ( Oid  relid, LOCKMODE  lockmode  )

static

Definition at line 2782 of file lock.c.

{
    uint32      i;
    uint32      unused_slot = FastPathLockSlotsPerBackend();
 
    /* fast-path group the lock belongs to */
    uint32      group = FAST_PATH_REL_GROUP(relid);
 
    /* Scan for existing entry for this relid, remembering empty slot. */
    for (i = 0; i < FP_LOCK_SLOTS_PER_GROUP; i++)
    {
        /* index into the whole per-backend array */
        uint32      f = FAST_PATH_SLOT(group, i);
 
        if (FAST_PATH_GET_BITS(MyProc, f) == 0)
            unused_slot = f;
        else if (MyProc->fpRelId[f] == relid)
        {
            Assert(!FAST_PATH_CHECK_LOCKMODE(MyProc, f, lockmode));
            FAST_PATH_SET_LOCKMODE(MyProc, f, lockmode);
            return true;
        }
    }
 
    /* If no existing entry, use any empty slot. */
    if (unused_slot < FastPathLockSlotsPerBackend())
    {
        MyProc->fpRelId[unused_slot] = relid;
        FAST_PATH_SET_LOCKMODE(MyProc, unused_slot, lockmode);
        ++FastPathLocalUseCounts[group];
        return true;
    }
 
    /* No existing entry, and no empty slot. */
    return false;
}

References Assert(), FAST_PATH_CHECK_LOCKMODE, FAST_PATH_GET_BITS, FAST_PATH_REL_GROUP, FAST_PATH_SET_LOCKMODE, FAST_PATH_SLOT, FastPathLocalUseCounts, FastPathLockSlotsPerBackend, FP_LOCK_SLOTS_PER_GROUP, PGPROC::fpRelId, i, and MyProc.

Referenced by LockAcquireExtended().

FastPathTransferRelationLocks()

static bool FastPathTransferRelationLocks ( LockMethod  lockMethodTable, const LOCKTAG *  locktag, uint32  hashcode  )

static

Definition at line 2861 of file lock.c.

{
    LWLock     *partitionLock = LockHashPartitionLock(hashcode);
    Oid         relid = locktag->locktag_field2;
    uint32      i;
 
    /* fast-path group the lock belongs to */
    uint32      group = FAST_PATH_REL_GROUP(relid);
 
    /*
     * Every PGPROC that can potentially hold a fast-path lock is present in
     * ProcGlobal->allProcs.  Prepared transactions are not, but any
     * outstanding fast-path locks held by prepared transactions are
     * transferred to the main lock table.
     */
    for (i = 0; i < ProcGlobal->allProcCount; i++)
    {
        PGPROC     *proc = &ProcGlobal->allProcs[i];
        uint32      j;
 
        LWLockAcquire(&proc->fpInfoLock, LW_EXCLUSIVE);
 
        /*
         * If the target backend isn't referencing the same database as the
         * lock, then we needn't examine the individual relation IDs at all;
         * none of them can be relevant.
         *
         * proc->databaseId is set at backend startup time and never changes
         * thereafter, so it might be safe to perform this test before
         * acquiring &proc->fpInfoLock.  In particular, it's certainly safe to
         * assume that if the target backend holds any fast-path locks, it
         * must have performed a memory-fencing operation (in particular, an
         * LWLock acquisition) since setting proc->databaseId.  However, it's
         * less clear that our backend is certain to have performed a memory
         * fencing operation since the other backend set proc->databaseId.  So
         * for now, we test it after acquiring the LWLock just to be safe.
         *
         * Also skip groups without any registered fast-path locks.
         */
        if (proc->databaseId != locktag->locktag_field1 ||
            proc->fpLockBits[group] == 0)
        {
            LWLockRelease(&proc->fpInfoLock);
            continue;
        }
 
        for (j = 0; j < FP_LOCK_SLOTS_PER_GROUP; j++)
        {
            uint32      lockmode;
 
            /* index into the whole per-backend array */
            uint32      f = FAST_PATH_SLOT(group, j);
 
            /* Look for an allocated slot matching the given relid. */
            if (relid != proc->fpRelId[f] || FAST_PATH_GET_BITS(proc, f) == 0)
                continue;
 
            /* Find or create lock object. */
            LWLockAcquire(partitionLock, LW_EXCLUSIVE);
            for (lockmode = FAST_PATH_LOCKNUMBER_OFFSET;
                 lockmode < FAST_PATH_LOCKNUMBER_OFFSET + FAST_PATH_BITS_PER_SLOT;
                 ++lockmode)
            {
                PROCLOCK   *proclock;
 
                if (!FAST_PATH_CHECK_LOCKMODE(proc, f, lockmode))
                    continue;
                proclock = SetupLockInTable(lockMethodTable, proc, locktag,
                                            hashcode, lockmode);
                if (!proclock)
                {
                    LWLockRelease(partitionLock);
                    LWLockRelease(&proc->fpInfoLock);
                    return false;
                }
                GrantLock(proclock->tag.myLock, proclock, lockmode);
                FAST_PATH_CLEAR_LOCKMODE(proc, f, lockmode);
            }
            LWLockRelease(partitionLock);
 
            /* No need to examine remaining slots. */
            break;
        }
        LWLockRelease(&proc->fpInfoLock);
    }
    return true;
}

References PROC_HDR::allProcCount, PROC_HDR::allProcs, PGPROC::databaseId, FAST_PATH_BITS_PER_SLOT, FAST_PATH_CHECK_LOCKMODE, FAST_PATH_CLEAR_LOCKMODE, FAST_PATH_GET_BITS, FAST_PATH_LOCKNUMBER_OFFSET, FAST_PATH_REL_GROUP, FAST_PATH_SLOT, FP_LOCK_SLOTS_PER_GROUP, PGPROC::fpInfoLock, PGPROC::fpLockBits, PGPROC::fpRelId, GrantLock(), i, j, LockHashPartitionLock, LOCKTAG::locktag_field1, LOCKTAG::locktag_field2, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), PROCLOCKTAG::myLock, ProcGlobal, SetupLockInTable(), and PROCLOCK::tag.

Referenced by LockAcquireExtended().

FastPathUnGrantRelationLock()

static bool FastPathUnGrantRelationLock ( Oid  relid, LOCKMODE  lockmode  )

static

Definition at line 2825 of file lock.c.

{
    uint32      i;
    bool        result = false;
 
    /* fast-path group the lock belongs to */
    uint32      group = FAST_PATH_REL_GROUP(relid);
 
    FastPathLocalUseCounts[group] = 0;
    for (i = 0; i < FP_LOCK_SLOTS_PER_GROUP; i++)
    {
        /* index into the whole per-backend array */
        uint32      f = FAST_PATH_SLOT(group, i);
 
        if (MyProc->fpRelId[f] == relid
            && FAST_PATH_CHECK_LOCKMODE(MyProc, f, lockmode))
        {
            Assert(!result);
            FAST_PATH_CLEAR_LOCKMODE(MyProc, f, lockmode);
            result = true;
            /* we continue iterating so as to update FastPathLocalUseCount */
        }
        if (FAST_PATH_GET_BITS(MyProc, f) != 0)
            ++FastPathLocalUseCounts[group];
    }
    return result;
}

References Assert(), FAST_PATH_CHECK_LOCKMODE, FAST_PATH_CLEAR_LOCKMODE, FAST_PATH_GET_BITS, FAST_PATH_REL_GROUP, FAST_PATH_SLOT, FastPathLocalUseCounts, FP_LOCK_SLOTS_PER_GROUP, PGPROC::fpRelId, i, and MyProc.

Referenced by LockRelease(), and LockReleaseAll().

FinishStrongLockAcquire()

static void FinishStrongLockAcquire ( void  )

static

Definition at line 1850 of file lock.c.

{
    StrongLockInProgress = NULL;
}

References StrongLockInProgress.

Referenced by LockAcquireExtended().

GetAwaitedLock()

LOCALLOCK * GetAwaitedLock

(

void

)

Definition at line 1898 of file lock.c.

{
    return awaitedLock;
}

References awaitedLock.

Referenced by LockErrorCleanup(), ProcessRecoveryConflictInterrupt(), and ProcSleep().

GetBlockerStatusData()

BlockedProcsData * GetBlockerStatusData

(

int

blocked_pid

)

Definition at line 3998 of file lock.c.

{
    BlockedProcsData *data;
    PGPROC     *proc;
    int         i;
 
    data = (BlockedProcsData *) palloc(sizeof(BlockedProcsData));
 
    /*
     * Guess how much space we'll need, and preallocate.  Most of the time
     * this will avoid needing to do repalloc while holding the LWLocks.  (We
     * assume, but check with an Assert, that MaxBackends is enough entries
     * for the procs[] array; the other two could need enlargement, though.)
     */
    data->nprocs = data->nlocks = data->npids = 0;
    data->maxprocs = data->maxlocks = data->maxpids = MaxBackends;
    data->procs = (BlockedProcData *) palloc(sizeof(BlockedProcData) * data->maxprocs);
    data->locks = (LockInstanceData *) palloc(sizeof(LockInstanceData) * data->maxlocks);
    data->waiter_pids = (int *) palloc(sizeof(int) * data->maxpids);
 
    /*
     * In order to search the ProcArray for blocked_pid and assume that that
     * entry won't immediately disappear under us, we must hold ProcArrayLock.
     * In addition, to examine the lock grouping fields of any other backend,
     * we must hold all the hash partition locks.  (Only one of those locks is
     * actually relevant for any one lock group, but we can't know which one
     * ahead of time.)  It's fairly annoying to hold all those locks
     * throughout this, but it's no worse than GetLockStatusData(), and it
     * does have the advantage that we're guaranteed to return a
     * self-consistent instantaneous state.
     */
    LWLockAcquire(ProcArrayLock, LW_SHARED);
 
    proc = BackendPidGetProcWithLock(blocked_pid);
 
    /* Nothing to do if it's gone */
    if (proc != NULL)
    {
        /*
         * Acquire lock on the entire shared lock data structure.  See notes
         * in GetLockStatusData().
         */
        for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
            LWLockAcquire(LockHashPartitionLockByIndex(i), LW_SHARED);
 
        if (proc->lockGroupLeader == NULL)
        {
            /* Easy case, proc is not a lock group member */
            GetSingleProcBlockerStatusData(proc, data);
        }
        else
        {
            /* Examine all procs in proc's lock group */
            dlist_iter  iter;
 
            dlist_foreach(iter, &proc->lockGroupLeader->lockGroupMembers)
            {
                PGPROC     *memberProc;
 
                memberProc = dlist_container(PGPROC, lockGroupLink, iter.cur);
                GetSingleProcBlockerStatusData(memberProc, data);
            }
        }
 
        /*
         * And release locks.  See notes in GetLockStatusData().
         */
        for (i = NUM_LOCK_PARTITIONS; --i >= 0;)
            LWLockRelease(LockHashPartitionLockByIndex(i));
 
        Assert(data->nprocs <= data->maxprocs);
    }
 
    LWLockRelease(ProcArrayLock);
 
    return data;
}

References Assert(), BackendPidGetProcWithLock(), dlist_iter::cur, data, dlist_container, dlist_foreach, GetSingleProcBlockerStatusData(), i, PGPROC::lockGroupLeader, PGPROC::lockGroupMembers, LockHashPartitionLockByIndex, LW_SHARED, LWLockAcquire(), LWLockRelease(), MaxBackends, NUM_LOCK_PARTITIONS, and palloc().

Referenced by pg_blocking_pids().

GetLockConflicts()

VirtualTransactionId * GetLockConflicts	(	const LOCKTAG *	locktag,
		LOCKMODE	lockmode,
		int *	countp
	)

Definition at line 3069 of file lock.c.

{
    static VirtualTransactionId *vxids;
    LOCKMETHODID lockmethodid = locktag->locktag_lockmethodid;
    LockMethod  lockMethodTable;
    LOCK       *lock;
    LOCKMASK    conflictMask;
    dlist_iter  proclock_iter;
    PROCLOCK   *proclock;
    uint32      hashcode;
    LWLock     *partitionLock;
    int         count = 0;
    int         fast_count = 0;
 
    if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
        elog(ERROR, "unrecognized lock method: %d", lockmethodid);
    lockMethodTable = LockMethods[lockmethodid];
    if (lockmode <= 0 || lockmode > lockMethodTable->numLockModes)
        elog(ERROR, "unrecognized lock mode: %d", lockmode);
 
    /*
     * Allocate memory to store results, and fill with InvalidVXID.  We only
     * need enough space for MaxBackends + max_prepared_xacts + a terminator.
     * InHotStandby allocate once in TopMemoryContext.
     */
    if (InHotStandby)
    {
        if (vxids == NULL)
            vxids = (VirtualTransactionId *)
                MemoryContextAlloc(TopMemoryContext,
                                   sizeof(VirtualTransactionId) *
                                   (MaxBackends + max_prepared_xacts + 1));
    }
    else
        vxids = (VirtualTransactionId *)
            palloc0(sizeof(VirtualTransactionId) *
                    (MaxBackends + max_prepared_xacts + 1));
 
    /* Compute hash code and partition lock, and look up conflicting modes. */
    hashcode = LockTagHashCode(locktag);
    partitionLock = LockHashPartitionLock(hashcode);
    conflictMask = lockMethodTable->conflictTab[lockmode];
 
    /*
     * Fast path locks might not have been entered in the primary lock table.
     * If the lock we're dealing with could conflict with such a lock, we must
     * examine each backend's fast-path array for conflicts.
     */
    if (ConflictsWithRelationFastPath(locktag, lockmode))
    {
        int         i;
        Oid         relid = locktag->locktag_field2;
        VirtualTransactionId vxid;
 
        /* fast-path group the lock belongs to */
        uint32      group = FAST_PATH_REL_GROUP(relid);
 
        /*
         * Iterate over relevant PGPROCs.  Anything held by a prepared
         * transaction will have been transferred to the primary lock table,
         * so we need not worry about those.  This is all a bit fuzzy, because
         * new locks could be taken after we've visited a particular
         * partition, but the callers had better be prepared to deal with that
         * anyway, since the locks could equally well be taken between the
         * time we return the value and the time the caller does something
         * with it.
         */
        for (i = 0; i < ProcGlobal->allProcCount; i++)
        {
            PGPROC     *proc = &ProcGlobal->allProcs[i];
            uint32      j;
 
            /* A backend never blocks itself */
            if (proc == MyProc)
                continue;
 
            LWLockAcquire(&proc->fpInfoLock, LW_SHARED);
 
            /*
             * If the target backend isn't referencing the same database as
             * the lock, then we needn't examine the individual relation IDs
             * at all; none of them can be relevant.
             *
             * See FastPathTransferRelationLocks() for discussion of why we do
             * this test after acquiring the lock.
             *
             * Also skip groups without any registered fast-path locks.
             */
            if (proc->databaseId != locktag->locktag_field1 ||
                proc->fpLockBits[group] == 0)
            {
                LWLockRelease(&proc->fpInfoLock);
                continue;
            }
 
            for (j = 0; j < FP_LOCK_SLOTS_PER_GROUP; j++)
            {
                uint32      lockmask;
 
                /* index into the whole per-backend array */
                uint32      f = FAST_PATH_SLOT(group, j);
 
                /* Look for an allocated slot matching the given relid. */
                if (relid != proc->fpRelId[f])
                    continue;
                lockmask = FAST_PATH_GET_BITS(proc, f);
                if (!lockmask)
                    continue;
                lockmask <<= FAST_PATH_LOCKNUMBER_OFFSET;
 
                /*
                 * There can only be one entry per relation, so if we found it
                 * and it doesn't conflict, we can skip the rest of the slots.
                 */
                if ((lockmask & conflictMask) == 0)
                    break;
 
                /* Conflict! */
                GET_VXID_FROM_PGPROC(vxid, *proc);
 
                if (VirtualTransactionIdIsValid(vxid))
                    vxids[count++] = vxid;
                /* else, xact already committed or aborted */
 
                /* No need to examine remaining slots. */
                break;
            }
 
            LWLockRelease(&proc->fpInfoLock);
        }
    }
 
    /* Remember how many fast-path conflicts we found. */
    fast_count = count;
 
    /*
     * Look up the lock object matching the tag.
     */
    LWLockAcquire(partitionLock, LW_SHARED);
 
    lock = (LOCK *) hash_search_with_hash_value(LockMethodLockHash,
                                                locktag,
                                                hashcode,
                                                HASH_FIND,
                                                NULL);
    if (!lock)
    {
        /*
         * If the lock object doesn't exist, there is nothing holding a lock
         * on this lockable object.
         */
        LWLockRelease(partitionLock);
        vxids[count].procNumber = INVALID_PROC_NUMBER;
        vxids[count].localTransactionId = InvalidLocalTransactionId;
        if (countp)
            *countp = count;
        return vxids;
    }
 
    /*
     * Examine each existing holder (or awaiter) of the lock.
     */
    dlist_foreach(proclock_iter, &lock->procLocks)
    {
        proclock = dlist_container(PROCLOCK, lockLink, proclock_iter.cur);
 
        if (conflictMask & proclock->holdMask)
        {
            PGPROC     *proc = proclock->tag.myProc;
 
            /* A backend never blocks itself */
            if (proc != MyProc)
            {
                VirtualTransactionId vxid;
 
                GET_VXID_FROM_PGPROC(vxid, *proc);
 
                if (VirtualTransactionIdIsValid(vxid))
                {
                    int         i;
 
                    /* Avoid duplicate entries. */
                    for (i = 0; i < fast_count; ++i)
                        if (VirtualTransactionIdEquals(vxids[i], vxid))
                            break;
                    if (i >= fast_count)
                        vxids[count++] = vxid;
                }
                /* else, xact already committed or aborted */
            }
        }
    }
 
    LWLockRelease(partitionLock);
 
    if (count > MaxBackends + max_prepared_xacts)   /* should never happen */
        elog(PANIC, "too many conflicting locks found");
 
    vxids[count].procNumber = INVALID_PROC_NUMBER;
    vxids[count].localTransactionId = InvalidLocalTransactionId;
    if (countp)
        *countp = count;
    return vxids;
}

References PROC_HDR::allProcCount, PROC_HDR::allProcs, ConflictsWithRelationFastPath, LockMethodData::conflictTab, dlist_iter::cur, PGPROC::databaseId, dlist_container, dlist_foreach, elog, ERROR, FAST_PATH_GET_BITS, FAST_PATH_LOCKNUMBER_OFFSET, FAST_PATH_REL_GROUP, FAST_PATH_SLOT, FP_LOCK_SLOTS_PER_GROUP, PGPROC::fpInfoLock, PGPROC::fpLockBits, PGPROC::fpRelId, GET_VXID_FROM_PGPROC, HASH_FIND, hash_search_with_hash_value(), PROCLOCK::holdMask, i, InHotStandby, INVALID_PROC_NUMBER, InvalidLocalTransactionId, j, lengthof, VirtualTransactionId::localTransactionId, LockHashPartitionLock, LockMethodLockHash, LockMethods, LOCKTAG::locktag_field1, LOCKTAG::locktag_field2, LOCKTAG::locktag_lockmethodid, LockTagHashCode(), LW_SHARED, LWLockAcquire(), LWLockRelease(), max_prepared_xacts, MaxBackends, MemoryContextAlloc(), MyProc, PROCLOCKTAG::myProc, LockMethodData::numLockModes, palloc0(), PANIC, ProcGlobal, LOCK::procLocks, VirtualTransactionId::procNumber, PROCLOCK::tag, TopMemoryContext, VirtualTransactionIdEquals, and VirtualTransactionIdIsValid.

Referenced by ProcSleep(), ResolveRecoveryConflictWithLock(), and WaitForLockersMultiple().

GetLockmodeName()

const char * GetLockmodeName	(	LOCKMETHODID	lockmethodid,
		LOCKMODE	mode
	)

Definition at line 4255 of file lock.c.

{
    Assert(lockmethodid > 0 && lockmethodid < lengthof(LockMethods));
    Assert(mode > 0 && mode <= LockMethods[lockmethodid]->numLockModes);
    return LockMethods[lockmethodid]->lockModeNames[mode];
}

References Assert(), lengthof, LockMethods, LockMethodData::lockModeNames, and mode.

Referenced by DeadLockReport(), LockAcquireExtended(), overexplain_range_table(), pg_lock_status(), ProcSleep(), and waitonlock_error_callback().

GetLocksMethodTable()

LockMethod GetLocksMethodTable

(

const LOCK *

lock

)

Definition at line 527 of file lock.c.

{
    LOCKMETHODID lockmethodid = LOCK_LOCKMETHOD(*lock);
 
    Assert(0 < lockmethodid && lockmethodid < lengthof(LockMethods));
    return LockMethods[lockmethodid];
}

References Assert(), lengthof, LOCK_LOCKMETHOD, and LockMethods.

Referenced by DeadLockCheck(), and FindLockCycleRecurseMember().

GetLockStatusData()

LockData * GetLockStatusData

(

void

)

Definition at line 3795 of file lock.c.

{
    LockData   *data;
    PROCLOCK   *proclock;
    HASH_SEQ_STATUS seqstat;
    int         els;
    int         el;
    int         i;
 
    data = (LockData *) palloc(sizeof(LockData));
 
    /* Guess how much space we'll need. */
    els = MaxBackends;
    el = 0;
    data->locks = (LockInstanceData *) palloc(sizeof(LockInstanceData) * els);
 
    /*
     * First, we iterate through the per-backend fast-path arrays, locking
     * them one at a time.  This might produce an inconsistent picture of the
     * system state, but taking all of those LWLocks at the same time seems
     * impractical (in particular, note MAX_SIMUL_LWLOCKS).  It shouldn't
     * matter too much, because none of these locks can be involved in lock
     * conflicts anyway - anything that might must be present in the main lock
     * table.  (For the same reason, we don't sweat about making leaderPid
     * completely valid.  We cannot safely dereference another backend's
     * lockGroupLeader field without holding all lock partition locks, and
     * it's not worth that.)
     */
    for (i = 0; i < ProcGlobal->allProcCount; ++i)
    {
        PGPROC     *proc = &ProcGlobal->allProcs[i];
 
        /* Skip backends with pid=0, as they don't hold fast-path locks */
        if (proc->pid == 0)
            continue;
 
        LWLockAcquire(&proc->fpInfoLock, LW_SHARED);
 
        for (uint32 g = 0; g < FastPathLockGroupsPerBackend; g++)
        {
            /* Skip groups without registered fast-path locks */
            if (proc->fpLockBits[g] == 0)
                continue;
 
            for (int j = 0; j < FP_LOCK_SLOTS_PER_GROUP; j++)
            {
                LockInstanceData *instance;
                uint32      f = FAST_PATH_SLOT(g, j);
                uint32      lockbits = FAST_PATH_GET_BITS(proc, f);
 
                /* Skip unallocated slots */
                if (!lockbits)
                    continue;
 
                if (el >= els)
                {
                    els += MaxBackends;
                    data->locks = (LockInstanceData *)
                        repalloc(data->locks, sizeof(LockInstanceData) * els);
                }
 
                instance = &data->locks[el];
                SET_LOCKTAG_RELATION(instance->locktag, proc->databaseId,
                                     proc->fpRelId[f]);
                instance->holdMask = lockbits << FAST_PATH_LOCKNUMBER_OFFSET;
                instance->waitLockMode = NoLock;
                instance->vxid.procNumber = proc->vxid.procNumber;
                instance->vxid.localTransactionId = proc->vxid.lxid;
                instance->pid = proc->pid;
                instance->leaderPid = proc->pid;
                instance->fastpath = true;
 
                /*
                 * Successfully taking fast path lock means there were no
                 * conflicting locks.
                 */
                instance->waitStart = 0;
 
                el++;
            }
        }
 
        if (proc->fpVXIDLock)
        {
            VirtualTransactionId vxid;
            LockInstanceData *instance;
 
            if (el >= els)
            {
                els += MaxBackends;
                data->locks = (LockInstanceData *)
                    repalloc(data->locks, sizeof(LockInstanceData) * els);
            }
 
            vxid.procNumber = proc->vxid.procNumber;
            vxid.localTransactionId = proc->fpLocalTransactionId;
 
            instance = &data->locks[el];
            SET_LOCKTAG_VIRTUALTRANSACTION(instance->locktag, vxid);
            instance->holdMask = LOCKBIT_ON(ExclusiveLock);
            instance->waitLockMode = NoLock;
            instance->vxid.procNumber = proc->vxid.procNumber;
            instance->vxid.localTransactionId = proc->vxid.lxid;
            instance->pid = proc->pid;
            instance->leaderPid = proc->pid;
            instance->fastpath = true;
            instance->waitStart = 0;
 
            el++;
        }
 
        LWLockRelease(&proc->fpInfoLock);
    }
 
    /*
     * Next, acquire lock on the entire shared lock data structure.  We do
     * this so that, at least for locks in the primary lock table, the state
     * will be self-consistent.
     *
     * Since this is a read-only operation, we take shared instead of
     * exclusive lock.  There's not a whole lot of point to this, because all
     * the normal operations require exclusive lock, but it doesn't hurt
     * anything either. It will at least allow two backends to do
     * GetLockStatusData in parallel.
     *
     * Must grab LWLocks in partition-number order to avoid LWLock deadlock.
     */
    for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
        LWLockAcquire(LockHashPartitionLockByIndex(i), LW_SHARED);
 
    /* Now we can safely count the number of proclocks */
    data->nelements = el + hash_get_num_entries(LockMethodProcLockHash);
    if (data->nelements > els)
    {
        els = data->nelements;
        data->locks = (LockInstanceData *)
            repalloc(data->locks, sizeof(LockInstanceData) * els);
    }
 
    /* Now scan the tables to copy the data */
    hash_seq_init(&seqstat, LockMethodProcLockHash);
 
    while ((proclock = (PROCLOCK *) hash_seq_search(&seqstat)))
    {
        PGPROC     *proc = proclock->tag.myProc;
        LOCK       *lock = proclock->tag.myLock;
        LockInstanceData *instance = &data->locks[el];
 
        memcpy(&instance->locktag, &lock->tag, sizeof(LOCKTAG));
        instance->holdMask = proclock->holdMask;
        if (proc->waitLock == proclock->tag.myLock)
            instance->waitLockMode = proc->waitLockMode;
        else
            instance->waitLockMode = NoLock;
        instance->vxid.procNumber = proc->vxid.procNumber;
        instance->vxid.localTransactionId = proc->vxid.lxid;
        instance->pid = proc->pid;
        instance->leaderPid = proclock->groupLeader->pid;
        instance->fastpath = false;
        instance->waitStart = (TimestampTz) pg_atomic_read_u64(&proc->waitStart);
 
        el++;
    }
 
    /*
     * And release locks.  We do this in reverse order for two reasons: (1)
     * Anyone else who needs more than one of the locks will be trying to lock
     * them in increasing order; we don't want to release the other process
     * until it can get all the locks it needs. (2) This avoids O(N^2)
     * behavior inside LWLockRelease.
     */
    for (i = NUM_LOCK_PARTITIONS; --i >= 0;)
        LWLockRelease(LockHashPartitionLockByIndex(i));
 
    Assert(el == data->nelements);
 
    return data;
}

References PROC_HDR::allProcCount, PROC_HDR::allProcs, Assert(), data, PGPROC::databaseId, ExclusiveLock, FAST_PATH_GET_BITS, FAST_PATH_LOCKNUMBER_OFFSET, FAST_PATH_SLOT, LockInstanceData::fastpath, FastPathLockGroupsPerBackend, FP_LOCK_SLOTS_PER_GROUP, PGPROC::fpInfoLock, PGPROC::fpLocalTransactionId, PGPROC::fpLockBits, PGPROC::fpRelId, PGPROC::fpVXIDLock, PROCLOCK::groupLeader, hash_get_num_entries(), hash_seq_init(), hash_seq_search(), PROCLOCK::holdMask, LockInstanceData::holdMask, i, j, LockInstanceData::leaderPid, VirtualTransactionId::localTransactionId, LOCKBIT_ON, LockHashPartitionLockByIndex, LockMethodProcLockHash, LockInstanceData::locktag, LW_SHARED, LWLockAcquire(), LWLockRelease(), PGPROC::lxid, MaxBackends, PROCLOCKTAG::myLock, PROCLOCKTAG::myProc, NoLock, NUM_LOCK_PARTITIONS, palloc(), pg_atomic_read_u64(), LockInstanceData::pid, PGPROC::pid, ProcGlobal, VirtualTransactionId::procNumber, PGPROC::procNumber, repalloc(), SET_LOCKTAG_RELATION, SET_LOCKTAG_VIRTUALTRANSACTION, LOCK::tag, PROCLOCK::tag, LockInstanceData::vxid, PGPROC::vxid, PGPROC::waitLock, LockInstanceData::waitLockMode, PGPROC::waitLockMode, LockInstanceData::waitStart, and PGPROC::waitStart.

Referenced by pg_lock_status().

GetLockTagsMethodTable()

LockMethod GetLockTagsMethodTable

(

const LOCKTAG *

locktag

)

Definition at line 539 of file lock.c.

{
    LOCKMETHODID lockmethodid = (LOCKMETHODID) locktag->locktag_lockmethodid;
 
    Assert(0 < lockmethodid && lockmethodid < lengthof(LockMethods));
    return LockMethods[lockmethodid];
}

References Assert(), lengthof, LockMethods, and LOCKTAG::locktag_lockmethodid.

Referenced by pg_blocking_pids().

GetRunningTransactionLocks()

xl_standby_lock * GetRunningTransactionLocks

(

int *

nlocks

)

Definition at line 4173 of file lock.c.

{
    xl_standby_lock *accessExclusiveLocks;
    PROCLOCK   *proclock;
    HASH_SEQ_STATUS seqstat;
    int         i;
    int         index;
    int         els;
 
    /*
     * Acquire lock on the entire shared lock data structure.
     *
     * Must grab LWLocks in partition-number order to avoid LWLock deadlock.
     */
    for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
        LWLockAcquire(LockHashPartitionLockByIndex(i), LW_SHARED);
 
    /* Now we can safely count the number of proclocks */
    els = hash_get_num_entries(LockMethodProcLockHash);
 
    /*
     * Allocating enough space for all locks in the lock table is overkill,
     * but it's more convenient and faster than having to enlarge the array.
     */
    accessExclusiveLocks = palloc(els * sizeof(xl_standby_lock));
 
    /* Now scan the tables to copy the data */
    hash_seq_init(&seqstat, LockMethodProcLockHash);
 
    /*
     * If lock is a currently granted AccessExclusiveLock then it will have
     * just one proclock holder, so locks are never accessed twice in this
     * particular case. Don't copy this code for use elsewhere because in the
     * general case this will give you duplicate locks when looking at
     * non-exclusive lock types.
     */
    index = 0;
    while ((proclock = (PROCLOCK *) hash_seq_search(&seqstat)))
    {
        /* make sure this definition matches the one used in LockAcquire */
        if ((proclock->holdMask & LOCKBIT_ON(AccessExclusiveLock)) &&
            proclock->tag.myLock->tag.locktag_type == LOCKTAG_RELATION)
        {
            PGPROC     *proc = proclock->tag.myProc;
            LOCK       *lock = proclock->tag.myLock;
            TransactionId xid = proc->xid;
 
            /*
             * Don't record locks for transactions if we know they have
             * already issued their WAL record for commit but not yet released
             * lock. It is still possible that we see locks held by already
             * complete transactions, if they haven't yet zeroed their xids.
             */
            if (!TransactionIdIsValid(xid))
                continue;
 
            accessExclusiveLocks[index].xid = xid;
            accessExclusiveLocks[index].dbOid = lock->tag.locktag_field1;
            accessExclusiveLocks[index].relOid = lock->tag.locktag_field2;
 
            index++;
        }
    }
 
    Assert(index <= els);
 
    /*
     * And release locks.  We do this in reverse order for two reasons: (1)
     * Anyone else who needs more than one of the locks will be trying to lock
     * them in increasing order; we don't want to release the other process
     * until it can get all the locks it needs. (2) This avoids O(N^2)
     * behavior inside LWLockRelease.
     */
    for (i = NUM_LOCK_PARTITIONS; --i >= 0;)
        LWLockRelease(LockHashPartitionLockByIndex(i));
 
    *nlocks = index;
    return accessExclusiveLocks;
}

References AccessExclusiveLock, Assert(), xl_standby_lock::dbOid, hash_get_num_entries(), hash_seq_init(), hash_seq_search(), PROCLOCK::holdMask, i, LOCKBIT_ON, LockHashPartitionLockByIndex, LockMethodProcLockHash, LOCKTAG::locktag_field1, LOCKTAG::locktag_field2, LOCKTAG_RELATION, LOCKTAG::locktag_type, LW_SHARED, LWLockAcquire(), LWLockRelease(), PROCLOCKTAG::myLock, PROCLOCKTAG::myProc, NUM_LOCK_PARTITIONS, palloc(), xl_standby_lock::relOid, LOCK::tag, PROCLOCK::tag, TransactionIdIsValid, xl_standby_lock::xid, and PGPROC::xid.

Referenced by LogStandbySnapshot().

GetSingleProcBlockerStatusData()

static void GetSingleProcBlockerStatusData ( PGPROC *  blocked_proc, BlockedProcsData *  data  )

static

Definition at line 4078 of file lock.c.

{
    LOCK       *theLock = blocked_proc->waitLock;
    BlockedProcData *bproc;
    dlist_iter  proclock_iter;
    dlist_iter  proc_iter;
    dclist_head *waitQueue;
    int         queue_size;
 
    /* Nothing to do if this proc is not blocked */
    if (theLock == NULL)
        return;
 
    /* Set up a procs[] element */
    bproc = &data->procs[data->nprocs++];
    bproc->pid = blocked_proc->pid;
    bproc->first_lock = data->nlocks;
    bproc->first_waiter = data->npids;
 
    /*
     * We may ignore the proc's fast-path arrays, since nothing in those could
     * be related to a contended lock.
     */
 
    /* Collect all PROCLOCKs associated with theLock */
    dlist_foreach(proclock_iter, &theLock->procLocks)
    {
        PROCLOCK   *proclock =
            dlist_container(PROCLOCK, lockLink, proclock_iter.cur);
        PGPROC     *proc = proclock->tag.myProc;
        LOCK       *lock = proclock->tag.myLock;
        LockInstanceData *instance;
 
        if (data->nlocks >= data->maxlocks)
        {
            data->maxlocks += MaxBackends;
            data->locks = (LockInstanceData *)
                repalloc(data->locks, sizeof(LockInstanceData) * data->maxlocks);
        }
 
        instance = &data->locks[data->nlocks];
        memcpy(&instance->locktag, &lock->tag, sizeof(LOCKTAG));
        instance->holdMask = proclock->holdMask;
        if (proc->waitLock == lock)
            instance->waitLockMode = proc->waitLockMode;
        else
            instance->waitLockMode = NoLock;
        instance->vxid.procNumber = proc->vxid.procNumber;
        instance->vxid.localTransactionId = proc->vxid.lxid;
        instance->pid = proc->pid;
        instance->leaderPid = proclock->groupLeader->pid;
        instance->fastpath = false;
        data->nlocks++;
    }
 
    /* Enlarge waiter_pids[] if it's too small to hold all wait queue PIDs */
    waitQueue = &(theLock->waitProcs);
    queue_size = dclist_count(waitQueue);
 
    if (queue_size > data->maxpids - data->npids)
    {
        data->maxpids = Max(data->maxpids + MaxBackends,
                            data->npids + queue_size);
        data->waiter_pids = (int *) repalloc(data->waiter_pids,
                                             sizeof(int) * data->maxpids);
    }
 
    /* Collect PIDs from the lock's wait queue, stopping at blocked_proc */
    dclist_foreach(proc_iter, waitQueue)
    {
        PGPROC     *queued_proc = dlist_container(PGPROC, links, proc_iter.cur);
 
        if (queued_proc == blocked_proc)
            break;
        data->waiter_pids[data->npids++] = queued_proc->pid;
        queued_proc = (PGPROC *) queued_proc->links.next;
    }
 
    bproc->num_locks = data->nlocks - bproc->first_lock;
    bproc->num_waiters = data->npids - bproc->first_waiter;
}

References dlist_iter::cur, data, dclist_count(), dclist_foreach, dlist_container, dlist_foreach, LockInstanceData::fastpath, BlockedProcData::first_lock, BlockedProcData::first_waiter, PROCLOCK::groupLeader, PROCLOCK::holdMask, LockInstanceData::holdMask, LockInstanceData::leaderPid, PGPROC::links, links, VirtualTransactionId::localTransactionId, LockInstanceData::locktag, PGPROC::lxid, Max, MaxBackends, PROCLOCKTAG::myLock, PROCLOCKTAG::myProc, dlist_node::next, NoLock, BlockedProcData::num_locks, BlockedProcData::num_waiters, LockInstanceData::pid, BlockedProcData::pid, PGPROC::pid, LOCK::procLocks, VirtualTransactionId::procNumber, PGPROC::procNumber, repalloc(), LOCK::tag, PROCLOCK::tag, LockInstanceData::vxid, PGPROC::vxid, PGPROC::waitLock, LockInstanceData::waitLockMode, PGPROC::waitLockMode, and LOCK::waitProcs.

Referenced by GetBlockerStatusData().

GrantAwaitedLock()

void GrantAwaitedLock

(

void

)

Definition at line 1889 of file lock.c.

{
    GrantLockLocal(awaitedLock, awaitedOwner);
}

References awaitedLock, awaitedOwner, and GrantLockLocal().

Referenced by LockErrorCleanup().

GrantLock()

void GrantLock	(	LOCK *	lock,
		PROCLOCK *	proclock,
		LOCKMODE	lockmode
	)

Definition at line 1658 of file lock.c.

{
    lock->nGranted++;
    lock->granted[lockmode]++;
    lock->grantMask |= LOCKBIT_ON(lockmode);
    if (lock->granted[lockmode] == lock->requested[lockmode])
        lock->waitMask &= LOCKBIT_OFF(lockmode);
    proclock->holdMask |= LOCKBIT_ON(lockmode);
    LOCK_PRINT("GrantLock", lock, lockmode);
    Assert((lock->nGranted > 0) && (lock->granted[lockmode] > 0));
    Assert(lock->nGranted <= lock->nRequested);
}

References Assert(), LOCK::granted, LOCK::grantMask, PROCLOCK::holdMask, LOCK_PRINT, LOCKBIT_OFF, LOCKBIT_ON, LOCK::nGranted, LOCK::nRequested, LOCK::requested, and LOCK::waitMask.

Referenced by FastPathGetRelationLockEntry(), FastPathTransferRelationLocks(), JoinWaitQueue(), lock_twophase_recover(), LockAcquireExtended(), ProcLockWakeup(), and VirtualXactLock().

GrantLockLocal()

static void GrantLockLocal ( LOCALLOCK *  locallock, ResourceOwner  owner  )

static

Definition at line 1792 of file lock.c.

{
    LOCALLOCKOWNER *lockOwners = locallock->lockOwners;
    int         i;
 
    Assert(locallock->numLockOwners < locallock->maxLockOwners);
    /* Count the total */
    locallock->nLocks++;
    /* Count the per-owner lock */
    for (i = 0; i < locallock->numLockOwners; i++)
    {
        if (lockOwners[i].owner == owner)
        {
            lockOwners[i].nLocks++;
            return;
        }
    }
    lockOwners[i].owner = owner;
    lockOwners[i].nLocks = 1;
    locallock->numLockOwners++;
    if (owner != NULL)
        ResourceOwnerRememberLock(owner, locallock);
 
    /* Indicate that the lock is acquired for certain types of locks. */
    CheckAndSetLockHeld(locallock, true);
}

References Assert(), CheckAndSetLockHeld(), i, LOCALLOCK::lockOwners, LOCALLOCK::maxLockOwners, LOCALLOCKOWNER::nLocks, LOCALLOCK::nLocks, LOCALLOCK::numLockOwners, LOCALLOCKOWNER::owner, and ResourceOwnerRememberLock().

Referenced by GrantAwaitedLock(), and LockAcquireExtended().

InitLockManagerAccess()

void InitLockManagerAccess

(

void

)

Definition at line 505 of file lock.c.

{
    /*
     * Allocate non-shared hash table for LOCALLOCK structs.  This stores lock
     * counts and resource owner information.
     */
    HASHCTL     info;
 
    info.keysize = sizeof(LOCALLOCKTAG);
    info.entrysize = sizeof(LOCALLOCK);
 
    LockMethodLocalHash = hash_create("LOCALLOCK hash",
                                      16,
                                      &info,
                                      HASH_ELEM | HASH_BLOBS);
}

References HASHCTL::entrysize, HASH_BLOBS, hash_create(), HASH_ELEM, HASHCTL::keysize, and LockMethodLocalHash.

Referenced by BaseInit().

lock_twophase_postabort()

void lock_twophase_postabort	(	FullTransactionId	fxid,
		uint16	info,
		void *	recdata,
		uint32	len
	)

Definition at line 4598 of file lock.c.

{
    lock_twophase_postcommit(fxid, info, recdata, len);
}

References len, and lock_twophase_postcommit().

lock_twophase_postcommit()

void lock_twophase_postcommit	(	FullTransactionId	fxid,
		uint16	info,
		void *	recdata,
		uint32	len
	)

Definition at line 4572 of file lock.c.

{
    TwoPhaseLockRecord *rec = (TwoPhaseLockRecord *) recdata;
    PGPROC     *proc = TwoPhaseGetDummyProc(fxid, true);
    LOCKTAG    *locktag;
    LOCKMETHODID lockmethodid;
    LockMethod  lockMethodTable;
 
    Assert(len == sizeof(TwoPhaseLockRecord));
    locktag = &rec->locktag;
    lockmethodid = locktag->locktag_lockmethodid;
 
    if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
        elog(ERROR, "unrecognized lock method: %d", lockmethodid);
    lockMethodTable = LockMethods[lockmethodid];
 
    LockRefindAndRelease(lockMethodTable, proc, locktag, rec->lockmode, true);
}

References Assert(), elog, ERROR, len, lengthof, LockMethods, TwoPhaseLockRecord::lockmode, LockRefindAndRelease(), TwoPhaseLockRecord::locktag, LOCKTAG::locktag_lockmethodid, and TwoPhaseGetDummyProc().

Referenced by lock_twophase_postabort().

lock_twophase_recover()

void lock_twophase_recover	(	FullTransactionId	fxid,
		uint16	info,
		void *	recdata,
		uint32	len
	)

Definition at line 4359 of file lock.c.

{
    TwoPhaseLockRecord *rec = (TwoPhaseLockRecord *) recdata;
    PGPROC     *proc = TwoPhaseGetDummyProc(fxid, false);
    LOCKTAG    *locktag;
    LOCKMODE    lockmode;
    LOCKMETHODID lockmethodid;
    LOCK       *lock;
    PROCLOCK   *proclock;
    PROCLOCKTAG proclocktag;
    bool        found;
    uint32      hashcode;
    uint32      proclock_hashcode;
    int         partition;
    LWLock     *partitionLock;
    LockMethod  lockMethodTable;
 
    Assert(len == sizeof(TwoPhaseLockRecord));
    locktag = &rec->locktag;
    lockmode = rec->lockmode;
    lockmethodid = locktag->locktag_lockmethodid;
 
    if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
        elog(ERROR, "unrecognized lock method: %d", lockmethodid);
    lockMethodTable = LockMethods[lockmethodid];
 
    hashcode = LockTagHashCode(locktag);
    partition = LockHashPartition(hashcode);
    partitionLock = LockHashPartitionLock(hashcode);
 
    LWLockAcquire(partitionLock, LW_EXCLUSIVE);
 
    /*
     * Find or create a lock with this tag.
     */
    lock = (LOCK *) hash_search_with_hash_value(LockMethodLockHash,
                                                locktag,
                                                hashcode,
                                                HASH_ENTER_NULL,
                                                &found);
    if (!lock)
    {
        LWLockRelease(partitionLock);
        ereport(ERROR,
                (errcode(ERRCODE_OUT_OF_MEMORY),
                 errmsg("out of shared memory"),
                 errhint("You might need to increase \"%s\".", "max_locks_per_transaction")));
    }
 
    /*
     * if it's a new lock object, initialize it
     */
    if (!found)
    {
        lock->grantMask = 0;
        lock->waitMask = 0;
        dlist_init(&lock->procLocks);
        dclist_init(&lock->waitProcs);
        lock->nRequested = 0;
        lock->nGranted = 0;
        MemSet(lock->requested, 0, sizeof(int) * MAX_LOCKMODES);
        MemSet(lock->granted, 0, sizeof(int) * MAX_LOCKMODES);
        LOCK_PRINT("lock_twophase_recover: new", lock, lockmode);
    }
    else
    {
        LOCK_PRINT("lock_twophase_recover: found", lock, lockmode);
        Assert((lock->nRequested >= 0) && (lock->requested[lockmode] >= 0));
        Assert((lock->nGranted >= 0) && (lock->granted[lockmode] >= 0));
        Assert(lock->nGranted <= lock->nRequested);
    }
 
    /*
     * Create the hash key for the proclock table.
     */
    proclocktag.myLock = lock;
    proclocktag.myProc = proc;
 
    proclock_hashcode = ProcLockHashCode(&proclocktag, hashcode);
 
    /*
     * Find or create a proclock entry with this tag
     */
    proclock = (PROCLOCK *) hash_search_with_hash_value(LockMethodProcLockHash,
                                                        &proclocktag,
                                                        proclock_hashcode,
                                                        HASH_ENTER_NULL,
                                                        &found);
    if (!proclock)
    {
        /* Oops, not enough shmem for the proclock */
        if (lock->nRequested == 0)
        {
            /*
             * There are no other requestors of this lock, so garbage-collect
             * the lock object.  We *must* do this to avoid a permanent leak
             * of shared memory, because there won't be anything to cause
             * anyone to release the lock object later.
             */
            Assert(dlist_is_empty(&lock->procLocks));
            if (!hash_search_with_hash_value(LockMethodLockHash,
                                             &(lock->tag),
                                             hashcode,
                                             HASH_REMOVE,
                                             NULL))
                elog(PANIC, "lock table corrupted");
        }
        LWLockRelease(partitionLock);
        ereport(ERROR,
                (errcode(ERRCODE_OUT_OF_MEMORY),
                 errmsg("out of shared memory"),
                 errhint("You might need to increase \"%s\".", "max_locks_per_transaction")));
    }
 
    /*
     * If new, initialize the new entry
     */
    if (!found)
    {
        Assert(proc->lockGroupLeader == NULL);
        proclock->groupLeader = proc;
        proclock->holdMask = 0;
        proclock->releaseMask = 0;
        /* Add proclock to appropriate lists */
        dlist_push_tail(&lock->procLocks, &proclock->lockLink);
        dlist_push_tail(&proc->myProcLocks[partition],
                        &proclock->procLink);
        PROCLOCK_PRINT("lock_twophase_recover: new", proclock);
    }
    else
    {
        PROCLOCK_PRINT("lock_twophase_recover: found", proclock);
        Assert((proclock->holdMask & ~lock->grantMask) == 0);
    }
 
    /*
     * lock->nRequested and lock->requested[] count the total number of
     * requests, whether granted or waiting, so increment those immediately.
     */
    lock->nRequested++;
    lock->requested[lockmode]++;
    Assert((lock->nRequested > 0) && (lock->requested[lockmode] > 0));
 
    /*
     * We shouldn't already hold the desired lock.
     */
    if (proclock->holdMask & LOCKBIT_ON(lockmode))
        elog(ERROR, "lock %s on object %u/%u/%u is already held",
             lockMethodTable->lockModeNames[lockmode],
             lock->tag.locktag_field1, lock->tag.locktag_field2,
             lock->tag.locktag_field3);
 
    /*
     * We ignore any possible conflicts and just grant ourselves the lock. Not
     * only because we don't bother, but also to avoid deadlocks when
     * switching from standby to normal mode. See function comment.
     */
    GrantLock(lock, proclock, lockmode);
 
    /*
     * Bump strong lock count, to make sure any fast-path lock requests won't
     * be granted without consulting the primary lock table.
     */
    if (ConflictsWithRelationFastPath(&lock->tag, lockmode))
    {
        uint32      fasthashcode = FastPathStrongLockHashPartition(hashcode);
 
        SpinLockAcquire(&FastPathStrongRelationLocks->mutex);
        FastPathStrongRelationLocks->count[fasthashcode]++;
        SpinLockRelease(&FastPathStrongRelationLocks->mutex);
    }
 
    LWLockRelease(partitionLock);
}

References Assert(), ConflictsWithRelationFastPath, FastPathStrongRelationLockData::count, dclist_init(), dlist_init(), dlist_is_empty(), dlist_push_tail(), elog, ereport, errcode(), errhint(), errmsg(), ERROR, FastPathStrongLockHashPartition, FastPathStrongRelationLocks, LOCK::granted, GrantLock(), LOCK::grantMask, PROCLOCK::groupLeader, HASH_ENTER_NULL, HASH_REMOVE, hash_search_with_hash_value(), PROCLOCK::holdMask, len, lengthof, LOCK_PRINT, LOCKBIT_ON, PGPROC::lockGroupLeader, LockHashPartition, LockHashPartitionLock, PROCLOCK::lockLink, LockMethodLockHash, LockMethodProcLockHash, LockMethods, TwoPhaseLockRecord::lockmode, LockMethodData::lockModeNames, TwoPhaseLockRecord::locktag, LOCKTAG::locktag_field1, LOCKTAG::locktag_field2, LOCKTAG::locktag_field3, LOCKTAG::locktag_lockmethodid, LockTagHashCode(), LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), MAX_LOCKMODES, MemSet, FastPathStrongRelationLockData::mutex, PROCLOCKTAG::myLock, PROCLOCKTAG::myProc, PGPROC::myProcLocks, LOCK::nGranted, LOCK::nRequested, PANIC, PROCLOCK::procLink, PROCLOCK_PRINT, ProcLockHashCode(), LOCK::procLocks, PROCLOCK::releaseMask, LOCK::requested, SpinLockAcquire, SpinLockRelease, LOCK::tag, TwoPhaseGetDummyProc(), LOCK::waitMask, and LOCK::waitProcs.

lock_twophase_standby_recover()

void lock_twophase_standby_recover	(	FullTransactionId	fxid,
		uint16	info,
		void *	recdata,
		uint32	len
	)

Definition at line 4540 of file lock.c.

{
    TwoPhaseLockRecord *rec = (TwoPhaseLockRecord *) recdata;
    LOCKTAG    *locktag;
    LOCKMODE    lockmode;
    LOCKMETHODID lockmethodid;
 
    Assert(len == sizeof(TwoPhaseLockRecord));
    locktag = &rec->locktag;
    lockmode = rec->lockmode;
    lockmethodid = locktag->locktag_lockmethodid;
 
    if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
        elog(ERROR, "unrecognized lock method: %d", lockmethodid);
 
    if (lockmode == AccessExclusiveLock &&
        locktag->locktag_type == LOCKTAG_RELATION)
    {
        StandbyAcquireAccessExclusiveLock(XidFromFullTransactionId(fxid),
                                          locktag->locktag_field1 /* dboid */ ,
                                          locktag->locktag_field2 /* reloid */ );
    }
}

References AccessExclusiveLock, Assert(), elog, ERROR, len, lengthof, LockMethods, TwoPhaseLockRecord::lockmode, TwoPhaseLockRecord::locktag, LOCKTAG::locktag_field1, LOCKTAG::locktag_field2, LOCKTAG::locktag_lockmethodid, LOCKTAG_RELATION, LOCKTAG::locktag_type, StandbyAcquireAccessExclusiveLock(), and XidFromFullTransactionId.

LockAcquire()

LockAcquireResult LockAcquire	(	const LOCKTAG *	locktag,
		LOCKMODE	lockmode,
		bool	sessionLock,
		bool	dontWait
	)

Definition at line 809 of file lock.c.

{
    return LockAcquireExtended(locktag, lockmode, sessionLock, dontWait,
                               true, NULL, false);
}

References LockAcquireExtended().

Referenced by ConditionalLockPage(), ConditionalLockRelationForExtension(), LockApplyTransactionForSession(), LockDatabaseFrozenIds(), LockDatabaseObject(), LockPage(), LockRelationForExtension(), LockRelationIdForSession(), LockSharedObject(), LockSharedObjectForSession(), LockTuple(), pg_advisory_lock_int4(), pg_advisory_lock_int8(), pg_advisory_lock_shared_int4(), pg_advisory_lock_shared_int8(), pg_advisory_xact_lock_int4(), pg_advisory_xact_lock_int8(), pg_advisory_xact_lock_shared_int4(), pg_advisory_xact_lock_shared_int8(), pg_try_advisory_lock_int4(), pg_try_advisory_lock_int8(), pg_try_advisory_lock_shared_int4(), pg_try_advisory_lock_shared_int8(), pg_try_advisory_xact_lock_int4(), pg_try_advisory_xact_lock_int8(), pg_try_advisory_xact_lock_shared_int4(), pg_try_advisory_xact_lock_shared_int8(), SearchSysCacheLocked1(), SpeculativeInsertionLockAcquire(), SpeculativeInsertionWait(), StandbyAcquireAccessExclusiveLock(), VirtualXactLock(), XactLockForVirtualXact(), XactLockTableInsert(), and XactLockTableWait().

LockAcquireExtended()

LockAcquireResult LockAcquireExtended	(	const LOCKTAG *	locktag,
		LOCKMODE	lockmode,
		bool	sessionLock,
		bool	dontWait,
		bool	reportMemoryError,
		LOCALLOCK **	locallockp,
		bool	logLockFailure
	)

Definition at line 836 of file lock.c.

{
    LOCKMETHODID lockmethodid = locktag->locktag_lockmethodid;
    LockMethod  lockMethodTable;
    LOCALLOCKTAG localtag;
    LOCALLOCK  *locallock;
    LOCK       *lock;
    PROCLOCK   *proclock;
    bool        found;
    ResourceOwner owner;
    uint32      hashcode;
    LWLock     *partitionLock;
    bool        found_conflict;
    ProcWaitStatus waitResult;
    bool        log_lock = false;
 
    if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
        elog(ERROR, "unrecognized lock method: %d", lockmethodid);
    lockMethodTable = LockMethods[lockmethodid];
    if (lockmode <= 0 || lockmode > lockMethodTable->numLockModes)
        elog(ERROR, "unrecognized lock mode: %d", lockmode);
 
    if (RecoveryInProgress() && !InRecovery &&
        (locktag->locktag_type == LOCKTAG_OBJECT ||
         locktag->locktag_type == LOCKTAG_RELATION) &&
        lockmode > RowExclusiveLock)
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                 errmsg("cannot acquire lock mode %s on database objects while recovery is in progress",
                        lockMethodTable->lockModeNames[lockmode]),
                 errhint("Only RowExclusiveLock or less can be acquired on database objects during recovery.")));
 
#ifdef LOCK_DEBUG
    if (LOCK_DEBUG_ENABLED(locktag))
        elog(LOG, "LockAcquire: lock [%u,%u] %s",
             locktag->locktag_field1, locktag->locktag_field2,
             lockMethodTable->lockModeNames[lockmode]);
#endif
 
    /* Identify owner for lock */
    if (sessionLock)
        owner = NULL;
    else
        owner = CurrentResourceOwner;
 
    /*
     * Find or create a LOCALLOCK entry for this lock and lockmode
     */
    MemSet(&localtag, 0, sizeof(localtag)); /* must clear padding */
    localtag.lock = *locktag;
    localtag.mode = lockmode;
 
    locallock = (LOCALLOCK *) hash_search(LockMethodLocalHash,
                                          &localtag,
                                          HASH_ENTER, &found);
 
    /*
     * if it's a new locallock object, initialize it
     */
    if (!found)
    {
        locallock->lock = NULL;
        locallock->proclock = NULL;
        locallock->hashcode = LockTagHashCode(&(localtag.lock));
        locallock->nLocks = 0;
        locallock->holdsStrongLockCount = false;
        locallock->lockCleared = false;
        locallock->numLockOwners = 0;
        locallock->maxLockOwners = 8;
        locallock->lockOwners = NULL;   /* in case next line fails */
        locallock->lockOwners = (LOCALLOCKOWNER *)
            MemoryContextAlloc(TopMemoryContext,
                               locallock->maxLockOwners * sizeof(LOCALLOCKOWNER));
    }
    else
    {
        /* Make sure there will be room to remember the lock */
        if (locallock->numLockOwners >= locallock->maxLockOwners)
        {
            int         newsize = locallock->maxLockOwners * 2;
 
            locallock->lockOwners = (LOCALLOCKOWNER *)
                repalloc(locallock->lockOwners,
                         newsize * sizeof(LOCALLOCKOWNER));
            locallock->maxLockOwners = newsize;
        }
    }
    hashcode = locallock->hashcode;
 
    if (locallockp)
        *locallockp = locallock;
 
    /*
     * If we already hold the lock, we can just increase the count locally.
     *
     * If lockCleared is already set, caller need not worry about absorbing
     * sinval messages related to the lock's object.
     */
    if (locallock->nLocks > 0)
    {
        GrantLockLocal(locallock, owner);
        if (locallock->lockCleared)
            return LOCKACQUIRE_ALREADY_CLEAR;
        else
            return LOCKACQUIRE_ALREADY_HELD;
    }
 
    /*
     * We don't acquire any other heavyweight lock while holding the relation
     * extension lock.  We do allow to acquire the same relation extension
     * lock more than once but that case won't reach here.
     */
    Assert(!IsRelationExtensionLockHeld);
 
    /*
     * Prepare to emit a WAL record if acquisition of this lock needs to be
     * replayed in a standby server.
     *
     * Here we prepare to log; after lock is acquired we'll issue log record.
     * This arrangement simplifies error recovery in case the preparation step
     * fails.
     *
     * Only AccessExclusiveLocks can conflict with lock types that read-only
     * transactions can acquire in a standby server. Make sure this definition
     * matches the one in GetRunningTransactionLocks().
     */
    if (lockmode >= AccessExclusiveLock &&
        locktag->locktag_type == LOCKTAG_RELATION &&
        !RecoveryInProgress() &&
        XLogStandbyInfoActive())
    {
        LogAccessExclusiveLockPrepare();
        log_lock = true;
    }
 
    /*
     * Attempt to take lock via fast path, if eligible.  But if we remember
     * having filled up the fast path array, we don't attempt to make any
     * further use of it until we release some locks.  It's possible that some
     * other backend has transferred some of those locks to the shared hash
     * table, leaving space free, but it's not worth acquiring the LWLock just
     * to check.  It's also possible that we're acquiring a second or third
     * lock type on a relation we have already locked using the fast-path, but
     * for now we don't worry about that case either.
     */
    if (EligibleForRelationFastPath(locktag, lockmode) &&
        FastPathLocalUseCounts[FAST_PATH_REL_GROUP(locktag->locktag_field2)] < FP_LOCK_SLOTS_PER_GROUP)
    {
        uint32      fasthashcode = FastPathStrongLockHashPartition(hashcode);
        bool        acquired;
 
        /*
         * LWLockAcquire acts as a memory sequencing point, so it's safe to
         * assume that any strong locker whose increment to
         * FastPathStrongRelationLocks->counts becomes visible after we test
         * it has yet to begin to transfer fast-path locks.
         */
        LWLockAcquire(&MyProc->fpInfoLock, LW_EXCLUSIVE);
        if (FastPathStrongRelationLocks->count[fasthashcode] != 0)
            acquired = false;
        else
            acquired = FastPathGrantRelationLock(locktag->locktag_field2,
                                                 lockmode);
        LWLockRelease(&MyProc->fpInfoLock);
        if (acquired)
        {
            /*
             * The locallock might contain stale pointers to some old shared
             * objects; we MUST reset these to null before considering the
             * lock to be acquired via fast-path.
             */
            locallock->lock = NULL;
            locallock->proclock = NULL;
            GrantLockLocal(locallock, owner);
            return LOCKACQUIRE_OK;
        }
    }
 
    /*
     * If this lock could potentially have been taken via the fast-path by
     * some other backend, we must (temporarily) disable further use of the
     * fast-path for this lock tag, and migrate any locks already taken via
     * this method to the main lock table.
     */
    if (ConflictsWithRelationFastPath(locktag, lockmode))
    {
        uint32      fasthashcode = FastPathStrongLockHashPartition(hashcode);
 
        BeginStrongLockAcquire(locallock, fasthashcode);
        if (!FastPathTransferRelationLocks(lockMethodTable, locktag,
                                           hashcode))
        {
            AbortStrongLockAcquire();
            if (locallock->nLocks == 0)
                RemoveLocalLock(locallock);
            if (locallockp)
                *locallockp = NULL;
            if (reportMemoryError)
                ereport(ERROR,
                        (errcode(ERRCODE_OUT_OF_MEMORY),
                         errmsg("out of shared memory"),
                         errhint("You might need to increase \"%s\".", "max_locks_per_transaction")));
            else
                return LOCKACQUIRE_NOT_AVAIL;
        }
    }
 
    /*
     * We didn't find the lock in our LOCALLOCK table, and we didn't manage to
     * take it via the fast-path, either, so we've got to mess with the shared
     * lock table.
     */
    partitionLock = LockHashPartitionLock(hashcode);
 
    LWLockAcquire(partitionLock, LW_EXCLUSIVE);
 
    /*
     * Find or create lock and proclock entries with this tag
     *
     * Note: if the locallock object already existed, it might have a pointer
     * to the lock already ... but we should not assume that that pointer is
     * valid, since a lock object with zero hold and request counts can go
     * away anytime.  So we have to use SetupLockInTable() to recompute the
     * lock and proclock pointers, even if they're already set.
     */
    proclock = SetupLockInTable(lockMethodTable, MyProc, locktag,
                                hashcode, lockmode);
    if (!proclock)
    {
        AbortStrongLockAcquire();
        LWLockRelease(partitionLock);
        if (locallock->nLocks == 0)
            RemoveLocalLock(locallock);
        if (locallockp)
            *locallockp = NULL;
        if (reportMemoryError)
            ereport(ERROR,
                    (errcode(ERRCODE_OUT_OF_MEMORY),
                     errmsg("out of shared memory"),
                     errhint("You might need to increase \"%s\".", "max_locks_per_transaction")));
        else
            return LOCKACQUIRE_NOT_AVAIL;
    }
    locallock->proclock = proclock;
    lock = proclock->tag.myLock;
    locallock->lock = lock;
 
    /*
     * If lock requested conflicts with locks requested by waiters, must join
     * wait queue.  Otherwise, check for conflict with already-held locks.
     * (That's last because most complex check.)
     */
    if (lockMethodTable->conflictTab[lockmode] & lock->waitMask)
        found_conflict = true;
    else
        found_conflict = LockCheckConflicts(lockMethodTable, lockmode,
                                            lock, proclock);
 
    if (!found_conflict)
    {
        /* No conflict with held or previously requested locks */
        GrantLock(lock, proclock, lockmode);
        waitResult = PROC_WAIT_STATUS_OK;
    }
    else
    {
        /*
         * Join the lock's wait queue.  We call this even in the dontWait
         * case, because JoinWaitQueue() may discover that we can acquire the
         * lock immediately after all.
         */
        waitResult = JoinWaitQueue(locallock, lockMethodTable, dontWait);
    }
 
    if (waitResult == PROC_WAIT_STATUS_ERROR)
    {
        /*
         * We're not getting the lock because a deadlock was detected already
         * while trying to join the wait queue, or because we would have to
         * wait but the caller requested no blocking.
         *
         * Undo the changes to shared entries before releasing the partition
         * lock.
         */
        AbortStrongLockAcquire();
 
        if (proclock->holdMask == 0)
        {
            uint32      proclock_hashcode;
 
            proclock_hashcode = ProcLockHashCode(&proclock->tag,
                                                 hashcode);
            dlist_delete(&proclock->lockLink);
            dlist_delete(&proclock->procLink);
            if (!hash_search_with_hash_value(LockMethodProcLockHash,
                                             &(proclock->tag),
                                             proclock_hashcode,
                                             HASH_REMOVE,
                                             NULL))
                elog(PANIC, "proclock table corrupted");
        }
        else
            PROCLOCK_PRINT("LockAcquire: did not join wait queue", proclock);
        lock->nRequested--;
        lock->requested[lockmode]--;
        LOCK_PRINT("LockAcquire: did not join wait queue",
                   lock, lockmode);
        Assert((lock->nRequested > 0) &&
               (lock->requested[lockmode] >= 0));
        Assert(lock->nGranted <= lock->nRequested);
        LWLockRelease(partitionLock);
        if (locallock->nLocks == 0)
            RemoveLocalLock(locallock);
 
        if (dontWait)
        {
            /*
             * Log lock holders and waiters as a detail log message if
             * logLockFailure = true and lock acquisition fails with dontWait
             * = true
             */
            if (logLockFailure)
            {
                StringInfoData buf,
                            lock_waiters_sbuf,
                            lock_holders_sbuf;
                const char *modename;
                int         lockHoldersNum = 0;
 
                initStringInfo(&buf);
                initStringInfo(&lock_waiters_sbuf);
                initStringInfo(&lock_holders_sbuf);
 
                DescribeLockTag(&buf, &locallock->tag.lock);
                modename = GetLockmodeName(locallock->tag.lock.locktag_lockmethodid,
                                           lockmode);
 
                /* Gather a list of all lock holders and waiters */
                LWLockAcquire(partitionLock, LW_SHARED);
                GetLockHoldersAndWaiters(locallock, &lock_holders_sbuf,
                                         &lock_waiters_sbuf, &lockHoldersNum);
                LWLockRelease(partitionLock);
 
                ereport(LOG,
                        (errmsg("process %d could not obtain %s on %s",
                                MyProcPid, modename, buf.data),
                         errdetail_log_plural(
                                              "Process holding the lock: %s, Wait queue: %s.",
                                              "Processes holding the lock: %s, Wait queue: %s.",
                                              lockHoldersNum,
                                              lock_holders_sbuf.data,
                                              lock_waiters_sbuf.data)));
 
                pfree(buf.data);
                pfree(lock_holders_sbuf.data);
                pfree(lock_waiters_sbuf.data);
            }
            if (locallockp)
                *locallockp = NULL;
            return LOCKACQUIRE_NOT_AVAIL;
        }
        else
        {
            DeadLockReport();
            /* DeadLockReport() will not return */
        }
    }
 
    /*
     * We are now in the lock queue, or the lock was already granted.  If
     * queued, go to sleep.
     */
    if (waitResult == PROC_WAIT_STATUS_WAITING)
    {
        Assert(!dontWait);
        PROCLOCK_PRINT("LockAcquire: sleeping on lock", proclock);
        LOCK_PRINT("LockAcquire: sleeping on lock", lock, lockmode);
        LWLockRelease(partitionLock);
 
        waitResult = WaitOnLock(locallock, owner);
 
        /*
         * NOTE: do not do any material change of state between here and
         * return.  All required changes in locktable state must have been
         * done when the lock was granted to us --- see notes in WaitOnLock.
         */
 
        if (waitResult == PROC_WAIT_STATUS_ERROR)
        {
            /*
             * We failed as a result of a deadlock, see CheckDeadLock(). Quit
             * now.
             */
            Assert(!dontWait);
            DeadLockReport();
            /* DeadLockReport() will not return */
        }
    }
    else
        LWLockRelease(partitionLock);
    Assert(waitResult == PROC_WAIT_STATUS_OK);
 
    /* The lock was granted to us.  Update the local lock entry accordingly */
    Assert((proclock->holdMask & LOCKBIT_ON(lockmode)) != 0);
    GrantLockLocal(locallock, owner);
 
    /*
     * Lock state is fully up-to-date now; if we error out after this, no
     * special error cleanup is required.
     */
    FinishStrongLockAcquire();
 
    /*
     * Emit a WAL record if acquisition of this lock needs to be replayed in a
     * standby server.
     */
    if (log_lock)
    {
        /*
         * Decode the locktag back to the original values, to avoid sending
         * lots of empty bytes with every message.  See lock.h to check how a
         * locktag is defined for LOCKTAG_RELATION
         */
        LogAccessExclusiveLock(locktag->locktag_field1,
                               locktag->locktag_field2);
    }
 
    return LOCKACQUIRE_OK;
}

References AbortStrongLockAcquire(), AccessExclusiveLock, Assert(), BeginStrongLockAcquire(), buf, ConflictsWithRelationFastPath, LockMethodData::conflictTab, FastPathStrongRelationLockData::count, CurrentResourceOwner, StringInfoData::data, DeadLockReport(), DescribeLockTag(), dlist_delete(), EligibleForRelationFastPath, elog, ereport, errcode(), errdetail_log_plural(), errhint(), errmsg(), ERROR, FAST_PATH_REL_GROUP, FastPathGrantRelationLock(), FastPathLocalUseCounts, FastPathStrongLockHashPartition, FastPathStrongRelationLocks, FastPathTransferRelationLocks(), FinishStrongLockAcquire(), FP_LOCK_SLOTS_PER_GROUP, PGPROC::fpInfoLock, GetLockHoldersAndWaiters(), GetLockmodeName(), GrantLock(), GrantLockLocal(), HASH_ENTER, HASH_REMOVE, hash_search(), hash_search_with_hash_value(), LOCALLOCK::hashcode, PROCLOCK::holdMask, LOCALLOCK::holdsStrongLockCount, initStringInfo(), InRecovery, JoinWaitQueue(), lengthof, LOCALLOCKTAG::lock, LOCALLOCK::lock, LOCK_PRINT, LOCKACQUIRE_ALREADY_CLEAR, LOCKACQUIRE_ALREADY_HELD, LOCKACQUIRE_NOT_AVAIL, LOCKACQUIRE_OK, LOCKBIT_ON, LockCheckConflicts(), LOCALLOCK::lockCleared, LockHashPartitionLock, PROCLOCK::lockLink, LockMethodLocalHash, LockMethodProcLockHash, LockMethods, LockMethodData::lockModeNames, LOCALLOCK::lockOwners, LOCKTAG::locktag_field1, LOCKTAG::locktag_field2, LOCKTAG::locktag_lockmethodid, LOCKTAG_OBJECT, LOCKTAG_RELATION, LOCKTAG::locktag_type, LockTagHashCode(), LOG, LogAccessExclusiveLock(), LogAccessExclusiveLockPrepare(), LW_EXCLUSIVE, LW_SHARED, LWLockAcquire(), LWLockRelease(), LOCALLOCK::maxLockOwners, MemoryContextAlloc(), MemSet, LOCALLOCKTAG::mode, PROCLOCKTAG::myLock, MyProc, MyProcPid, LOCK::nGranted, LOCALLOCK::nLocks, LOCK::nRequested, LockMethodData::numLockModes, LOCALLOCK::numLockOwners, PANIC, pfree(), PROC_WAIT_STATUS_ERROR, PROC_WAIT_STATUS_OK, PROC_WAIT_STATUS_WAITING, PROCLOCK::procLink, LOCALLOCK::proclock, PROCLOCK_PRINT, ProcLockHashCode(), RecoveryInProgress(), RemoveLocalLock(), repalloc(), LOCK::requested, RowExclusiveLock, SetupLockInTable(), PROCLOCK::tag, LOCALLOCK::tag, TopMemoryContext, LOCK::waitMask, WaitOnLock(), and XLogStandbyInfoActive.

Referenced by ConditionalLockDatabaseObject(), ConditionalLockRelation(), ConditionalLockRelationOid(), ConditionalLockSharedObject(), ConditionalLockTuple(), ConditionalXactLockTableWait(), LockAcquire(), LockRelation(), LockRelationId(), and LockRelationOid().

LockCheckConflicts()

bool LockCheckConflicts	(	LockMethod	lockMethodTable,
		LOCKMODE	lockmode,
		LOCK *	lock,
		PROCLOCK *	proclock
	)

Definition at line 1529 of file lock.c.

{
    int         numLockModes = lockMethodTable->numLockModes;
    LOCKMASK    myLocks;
    int         conflictMask = lockMethodTable->conflictTab[lockmode];
    int         conflictsRemaining[MAX_LOCKMODES];
    int         totalConflictsRemaining = 0;
    dlist_iter  proclock_iter;
    int         i;
 
    /*
     * first check for global conflicts: If no locks conflict with my request,
     * then I get the lock.
     *
     * Checking for conflict: lock->grantMask represents the types of
     * currently held locks.  conflictTable[lockmode] has a bit set for each
     * type of lock that conflicts with request.   Bitwise compare tells if
     * there is a conflict.
     */
    if (!(conflictMask & lock->grantMask))
    {
        PROCLOCK_PRINT("LockCheckConflicts: no conflict", proclock);
        return false;
    }
 
    /*
     * Rats.  Something conflicts.  But it could still be my own lock, or a
     * lock held by another member of my locking group.  First, figure out how
     * many conflicts remain after subtracting out any locks I hold myself.
     */
    myLocks = proclock->holdMask;
    for (i = 1; i <= numLockModes; i++)
    {
        if ((conflictMask & LOCKBIT_ON(i)) == 0)
        {
            conflictsRemaining[i] = 0;
            continue;
        }
        conflictsRemaining[i] = lock->granted[i];
        if (myLocks & LOCKBIT_ON(i))
            --conflictsRemaining[i];
        totalConflictsRemaining += conflictsRemaining[i];
    }
 
    /* If no conflicts remain, we get the lock. */
    if (totalConflictsRemaining == 0)
    {
        PROCLOCK_PRINT("LockCheckConflicts: resolved (simple)", proclock);
        return false;
    }
 
    /* If no group locking, it's definitely a conflict. */
    if (proclock->groupLeader == MyProc && MyProc->lockGroupLeader == NULL)
    {
        Assert(proclock->tag.myProc == MyProc);
        PROCLOCK_PRINT("LockCheckConflicts: conflicting (simple)",
                       proclock);
        return true;
    }
 
    /*
     * The relation extension lock conflict even between the group members.
     */
    if (LOCK_LOCKTAG(*lock) == LOCKTAG_RELATION_EXTEND)
    {
        PROCLOCK_PRINT("LockCheckConflicts: conflicting (group)",
                       proclock);
        return true;
    }
 
    /*
     * Locks held in conflicting modes by members of our own lock group are
     * not real conflicts; we can subtract those out and see if we still have
     * a conflict.  This is O(N) in the number of processes holding or
     * awaiting locks on this object.  We could improve that by making the
     * shared memory state more complex (and larger) but it doesn't seem worth
     * it.
     */
    dlist_foreach(proclock_iter, &lock->procLocks)
    {
        PROCLOCK   *otherproclock =
            dlist_container(PROCLOCK, lockLink, proclock_iter.cur);
 
        if (proclock != otherproclock &&
            proclock->groupLeader == otherproclock->groupLeader &&
            (otherproclock->holdMask & conflictMask) != 0)
        {
            int         intersectMask = otherproclock->holdMask & conflictMask;
 
            for (i = 1; i <= numLockModes; i++)
            {
                if ((intersectMask & LOCKBIT_ON(i)) != 0)
                {
                    if (conflictsRemaining[i] <= 0)
                        elog(PANIC, "proclocks held do not match lock");
                    conflictsRemaining[i]--;
                    totalConflictsRemaining--;
                }
            }
 
            if (totalConflictsRemaining == 0)
            {
                PROCLOCK_PRINT("LockCheckConflicts: resolved (group)",
                               proclock);
                return false;
            }
        }
    }
 
    /* Nope, it's a real conflict. */
    PROCLOCK_PRINT("LockCheckConflicts: conflicting (group)", proclock);
    return true;
}

References Assert(), LockMethodData::conflictTab, dlist_iter::cur, dlist_container, dlist_foreach, elog, LOCK::granted, LOCK::grantMask, PROCLOCK::groupLeader, PROCLOCK::holdMask, i, LOCK_LOCKTAG, LOCKBIT_ON, PGPROC::lockGroupLeader, LOCKTAG_RELATION_EXTEND, MAX_LOCKMODES, MyProc, PROCLOCKTAG::myProc, LockMethodData::numLockModes, PANIC, PROCLOCK_PRINT, LOCK::procLocks, and PROCLOCK::tag.

Referenced by JoinWaitQueue(), LockAcquireExtended(), and ProcLockWakeup().

LockHasWaiters()

bool LockHasWaiters	(	const LOCKTAG *	locktag,
		LOCKMODE	lockmode,
		bool	sessionLock
	)

Definition at line 696 of file lock.c.

{
    LOCKMETHODID lockmethodid = locktag->locktag_lockmethodid;
    LockMethod  lockMethodTable;
    LOCALLOCKTAG localtag;
    LOCALLOCK  *locallock;
    LOCK       *lock;
    PROCLOCK   *proclock;
    LWLock     *partitionLock;
    bool        hasWaiters = false;
 
    if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
        elog(ERROR, "unrecognized lock method: %d", lockmethodid);
    lockMethodTable = LockMethods[lockmethodid];
    if (lockmode <= 0 || lockmode > lockMethodTable->numLockModes)
        elog(ERROR, "unrecognized lock mode: %d", lockmode);
 
#ifdef LOCK_DEBUG
    if (LOCK_DEBUG_ENABLED(locktag))
        elog(LOG, "LockHasWaiters: lock [%u,%u] %s",
             locktag->locktag_field1, locktag->locktag_field2,
             lockMethodTable->lockModeNames[lockmode]);
#endif
 
    /*
     * Find the LOCALLOCK entry for this lock and lockmode
     */
    MemSet(&localtag, 0, sizeof(localtag)); /* must clear padding */
    localtag.lock = *locktag;
    localtag.mode = lockmode;
 
    locallock = (LOCALLOCK *) hash_search(LockMethodLocalHash,
                                          &localtag,
                                          HASH_FIND, NULL);
 
    /*
     * let the caller print its own error message, too. Do not ereport(ERROR).
     */
    if (!locallock || locallock->nLocks <= 0)
    {
        elog(WARNING, "you don't own a lock of type %s",
             lockMethodTable->lockModeNames[lockmode]);
        return false;
    }
 
    /*
     * Check the shared lock table.
     */
    partitionLock = LockHashPartitionLock(locallock->hashcode);
 
    LWLockAcquire(partitionLock, LW_SHARED);
 
    /*
     * We don't need to re-find the lock or proclock, since we kept their
     * addresses in the locallock table, and they couldn't have been removed
     * while we were holding a lock on them.
     */
    lock = locallock->lock;
    LOCK_PRINT("LockHasWaiters: found", lock, lockmode);
    proclock = locallock->proclock;
    PROCLOCK_PRINT("LockHasWaiters: found", proclock);
 
    /*
     * Double-check that we are actually holding a lock of the type we want to
     * release.
     */
    if (!(proclock->holdMask & LOCKBIT_ON(lockmode)))
    {
        PROCLOCK_PRINT("LockHasWaiters: WRONGTYPE", proclock);
        LWLockRelease(partitionLock);
        elog(WARNING, "you don't own a lock of type %s",
             lockMethodTable->lockModeNames[lockmode]);
        RemoveLocalLock(locallock);
        return false;
    }
 
    /*
     * Do the checking.
     */
    if ((lockMethodTable->conflictTab[lockmode] & lock->waitMask) != 0)
        hasWaiters = true;
 
    LWLockRelease(partitionLock);
 
    return hasWaiters;
}

References LockMethodData::conflictTab, elog, ERROR, HASH_FIND, hash_search(), LOCALLOCK::hashcode, PROCLOCK::holdMask, lengthof, LOCALLOCKTAG::lock, LOCALLOCK::lock, LOCK_PRINT, LOCKBIT_ON, LockHashPartitionLock, LockMethodLocalHash, LockMethods, LockMethodData::lockModeNames, LOCKTAG::locktag_field1, LOCKTAG::locktag_field2, LOCKTAG::locktag_lockmethodid, LOG, LW_SHARED, LWLockAcquire(), LWLockRelease(), MemSet, LOCALLOCKTAG::mode, LOCALLOCK::nLocks, LockMethodData::numLockModes, LOCALLOCK::proclock, PROCLOCK_PRINT, RemoveLocalLock(), LOCK::waitMask, and WARNING.

Referenced by LockHasWaitersRelation().

LockHeldByMe()

bool LockHeldByMe	(	const LOCKTAG *	locktag,
		LOCKMODE	lockmode,
		bool	orstronger
	)

Definition at line 643 of file lock.c.

{
    LOCALLOCKTAG localtag;
    LOCALLOCK  *locallock;
 
    /*
     * See if there is a LOCALLOCK entry for this lock and lockmode
     */
    MemSet(&localtag, 0, sizeof(localtag)); /* must clear padding */
    localtag.lock = *locktag;
    localtag.mode = lockmode;
 
    locallock = (LOCALLOCK *) hash_search(LockMethodLocalHash,
                                          &localtag,
                                          HASH_FIND, NULL);
 
    if (locallock && locallock->nLocks > 0)
        return true;
 
    if (orstronger)
    {
        LOCKMODE    slockmode;
 
        for (slockmode = lockmode + 1;
             slockmode <= MaxLockMode;
             slockmode++)
        {
            if (LockHeldByMe(locktag, slockmode, false))
                return true;
        }
    }
 
    return false;
}

References HASH_FIND, hash_search(), LOCALLOCKTAG::lock, LockHeldByMe(), LockMethodLocalHash, MaxLockMode, MemSet, LOCALLOCKTAG::mode, and LOCALLOCK::nLocks.

Referenced by CheckRelationLockedByMe(), CheckRelationOidLockedByMe(), LockHeldByMe(), and UpdateSubscriptionRelState().

LockManagerShmemInit()

void LockManagerShmemInit

(

void

)

Definition at line 444 of file lock.c.

{
    HASHCTL     info;
    int64       init_table_size,
                max_table_size;
    bool        found;
 
    /*
     * Compute init/max size to request for lock hashtables.  Note these
     * calculations must agree with LockManagerShmemSize!
     */
    max_table_size = NLOCKENTS();
    init_table_size = max_table_size / 2;
 
    /*
     * Allocate hash table for LOCK structs.  This stores per-locked-object
     * information.
     */
    info.keysize = sizeof(LOCKTAG);
    info.entrysize = sizeof(LOCK);
    info.num_partitions = NUM_LOCK_PARTITIONS;
 
    LockMethodLockHash = ShmemInitHash("LOCK hash",
                                       init_table_size,
                                       max_table_size,
                                       &info,
                                       HASH_ELEM | HASH_BLOBS | HASH_PARTITION);
 
    /* Assume an average of 2 holders per lock */
    max_table_size *= 2;
    init_table_size *= 2;
 
    /*
     * Allocate hash table for PROCLOCK structs.  This stores
     * per-lock-per-holder information.
     */
    info.keysize = sizeof(PROCLOCKTAG);
    info.entrysize = sizeof(PROCLOCK);
    info.hash = proclock_hash;
    info.num_partitions = NUM_LOCK_PARTITIONS;
 
    LockMethodProcLockHash = ShmemInitHash("PROCLOCK hash",
                                           init_table_size,
                                           max_table_size,
                                           &info,
                                           HASH_ELEM | HASH_FUNCTION | HASH_PARTITION);
 
    /*
     * Allocate fast-path structures.
     */
    FastPathStrongRelationLocks =
        ShmemInitStruct("Fast Path Strong Relation Lock Data",
                        sizeof(FastPathStrongRelationLockData), &found);
    if (!found)
        SpinLockInit(&FastPathStrongRelationLocks->mutex);
}

References HASHCTL::entrysize, FastPathStrongRelationLocks, HASHCTL::hash, HASH_BLOBS, HASH_ELEM, HASH_FUNCTION, HASH_PARTITION, HASHCTL::keysize, LockMethodLockHash, LockMethodProcLockHash, FastPathStrongRelationLockData::mutex, NLOCKENTS, NUM_LOCK_PARTITIONS, HASHCTL::num_partitions, proclock_hash(), ShmemInitHash(), ShmemInitStruct(), and SpinLockInit.

Referenced by CreateOrAttachShmemStructs().

LockManagerShmemSize()

Size LockManagerShmemSize

(

void

)

Definition at line 3758 of file lock.c.

{
    Size        size = 0;
    long        max_table_size;
 
    /* lock hash table */
    max_table_size = NLOCKENTS();
    size = add_size(size, hash_estimate_size(max_table_size, sizeof(LOCK)));
 
    /* proclock hash table */
    max_table_size *= 2;
    size = add_size(size, hash_estimate_size(max_table_size, sizeof(PROCLOCK)));
 
    /*
     * Since NLOCKENTS is only an estimate, add 10% safety margin.
     */
    size = add_size(size, size / 10);
 
    return size;
}

References add_size(), hash_estimate_size(), and NLOCKENTS.

Referenced by CalculateShmemSize().

LockReassignCurrentOwner()

void LockReassignCurrentOwner	(	LOCALLOCK **	locallocks,
		int	nlocks
	)

Definition at line 2706 of file lock.c.

{
    ResourceOwner parent = ResourceOwnerGetParent(CurrentResourceOwner);
 
    Assert(parent != NULL);
 
    if (locallocks == NULL)
    {
        HASH_SEQ_STATUS status;
        LOCALLOCK  *locallock;
 
        hash_seq_init(&status, LockMethodLocalHash);
 
        while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
            LockReassignOwner(locallock, parent);
    }
    else
    {
        int         i;
 
        for (i = nlocks - 1; i >= 0; i--)
            LockReassignOwner(locallocks[i], parent);
    }
}

References Assert(), CurrentResourceOwner, hash_seq_init(), hash_seq_search(), i, LockMethodLocalHash, LockReassignOwner(), and ResourceOwnerGetParent().

Referenced by ResourceOwnerReleaseInternal().

LockReassignOwner()

static void LockReassignOwner ( LOCALLOCK *  locallock, ResourceOwner  parent  )

static

Definition at line 2736 of file lock.c.

{
    LOCALLOCKOWNER *lockOwners;
    int         i;
    int         ic = -1;
    int         ip = -1;
 
    /*
     * Scan to see if there are any locks belonging to current owner or its
     * parent
     */
    lockOwners = locallock->lockOwners;
    for (i = locallock->numLockOwners - 1; i >= 0; i--)
    {
        if (lockOwners[i].owner == CurrentResourceOwner)
            ic = i;
        else if (lockOwners[i].owner == parent)
            ip = i;
    }
 
    if (ic < 0)
        return;                 /* no current locks */
 
    if (ip < 0)
    {
        /* Parent has no slot, so just give it the child's slot */
        lockOwners[ic].owner = parent;
        ResourceOwnerRememberLock(parent, locallock);
    }
    else
    {
        /* Merge child's count with parent's */
        lockOwners[ip].nLocks += lockOwners[ic].nLocks;
        /* compact out unused slot */
        locallock->numLockOwners--;
        if (ic < locallock->numLockOwners)
            lockOwners[ic] = lockOwners[locallock->numLockOwners];
    }
    ResourceOwnerForgetLock(CurrentResourceOwner, locallock);
}

References CurrentResourceOwner, i, LOCALLOCK::lockOwners, LOCALLOCKOWNER::nLocks, LOCALLOCK::numLockOwners, LOCALLOCKOWNER::owner, ResourceOwnerForgetLock(), and ResourceOwnerRememberLock().

Referenced by LockReassignCurrentOwner().

LockRefindAndRelease()

static void LockRefindAndRelease ( LockMethod  lockMethodTable, PGPROC *  proc, LOCKTAG *  locktag, LOCKMODE  lockmode, bool  decrement_strong_lock_count  )

static

Definition at line 3286 of file lock.c.

{
    LOCK       *lock;
    PROCLOCK   *proclock;
    PROCLOCKTAG proclocktag;
    uint32      hashcode;
    uint32      proclock_hashcode;
    LWLock     *partitionLock;
    bool        wakeupNeeded;
 
    hashcode = LockTagHashCode(locktag);
    partitionLock = LockHashPartitionLock(hashcode);
 
    LWLockAcquire(partitionLock, LW_EXCLUSIVE);
 
    /*
     * Re-find the lock object (it had better be there).
     */
    lock = (LOCK *) hash_search_with_hash_value(LockMethodLockHash,
                                                locktag,
                                                hashcode,
                                                HASH_FIND,
                                                NULL);
    if (!lock)
        elog(PANIC, "failed to re-find shared lock object");
 
    /*
     * Re-find the proclock object (ditto).
     */
    proclocktag.myLock = lock;
    proclocktag.myProc = proc;
 
    proclock_hashcode = ProcLockHashCode(&proclocktag, hashcode);
 
    proclock = (PROCLOCK *) hash_search_with_hash_value(LockMethodProcLockHash,
                                                        &proclocktag,
                                                        proclock_hashcode,
                                                        HASH_FIND,
                                                        NULL);
    if (!proclock)
        elog(PANIC, "failed to re-find shared proclock object");
 
    /*
     * Double-check that we are actually holding a lock of the type we want to
     * release.
     */
    if (!(proclock->holdMask & LOCKBIT_ON(lockmode)))
    {
        PROCLOCK_PRINT("lock_twophase_postcommit: WRONGTYPE", proclock);
        LWLockRelease(partitionLock);
        elog(WARNING, "you don't own a lock of type %s",
             lockMethodTable->lockModeNames[lockmode]);
        return;
    }
 
    /*
     * Do the releasing.  CleanUpLock will waken any now-wakable waiters.
     */
    wakeupNeeded = UnGrantLock(lock, lockmode, proclock, lockMethodTable);
 
    CleanUpLock(lock, proclock,
                lockMethodTable, hashcode,
                wakeupNeeded);
 
    LWLockRelease(partitionLock);
 
    /*
     * Decrement strong lock count.  This logic is needed only for 2PC.
     */
    if (decrement_strong_lock_count
        && ConflictsWithRelationFastPath(locktag, lockmode))
    {
        uint32      fasthashcode = FastPathStrongLockHashPartition(hashcode);
 
        SpinLockAcquire(&FastPathStrongRelationLocks->mutex);
        Assert(FastPathStrongRelationLocks->count[fasthashcode] > 0);
        FastPathStrongRelationLocks->count[fasthashcode]--;
        SpinLockRelease(&FastPathStrongRelationLocks->mutex);
    }
}

References Assert(), CleanUpLock(), ConflictsWithRelationFastPath, FastPathStrongRelationLockData::count, elog, FastPathStrongLockHashPartition, FastPathStrongRelationLocks, HASH_FIND, hash_search_with_hash_value(), PROCLOCK::holdMask, LOCKBIT_ON, LockHashPartitionLock, LockMethodLockHash, LockMethodProcLockHash, LockMethodData::lockModeNames, LockTagHashCode(), LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), FastPathStrongRelationLockData::mutex, PROCLOCKTAG::myLock, PROCLOCKTAG::myProc, PANIC, PROCLOCK_PRINT, ProcLockHashCode(), SpinLockAcquire, SpinLockRelease, UnGrantLock(), and WARNING.

Referenced by lock_twophase_postcommit(), LockReleaseAll(), and VirtualXactLockTableCleanup().

LockRelease()

bool LockRelease	(	const LOCKTAG *	locktag,
		LOCKMODE	lockmode,
		bool	sessionLock
	)

Definition at line 2102 of file lock.c.

{
    LOCKMETHODID lockmethodid = locktag->locktag_lockmethodid;
    LockMethod  lockMethodTable;
    LOCALLOCKTAG localtag;
    LOCALLOCK  *locallock;
    LOCK       *lock;
    PROCLOCK   *proclock;
    LWLock     *partitionLock;
    bool        wakeupNeeded;
 
    if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
        elog(ERROR, "unrecognized lock method: %d", lockmethodid);
    lockMethodTable = LockMethods[lockmethodid];
    if (lockmode <= 0 || lockmode > lockMethodTable->numLockModes)
        elog(ERROR, "unrecognized lock mode: %d", lockmode);
 
#ifdef LOCK_DEBUG
    if (LOCK_DEBUG_ENABLED(locktag))
        elog(LOG, "LockRelease: lock [%u,%u] %s",
             locktag->locktag_field1, locktag->locktag_field2,
             lockMethodTable->lockModeNames[lockmode]);
#endif
 
    /*
     * Find the LOCALLOCK entry for this lock and lockmode
     */
    MemSet(&localtag, 0, sizeof(localtag)); /* must clear padding */
    localtag.lock = *locktag;
    localtag.mode = lockmode;
 
    locallock = (LOCALLOCK *) hash_search(LockMethodLocalHash,
                                          &localtag,
                                          HASH_FIND, NULL);
 
    /*
     * let the caller print its own error message, too. Do not ereport(ERROR).
     */
    if (!locallock || locallock->nLocks <= 0)
    {
        elog(WARNING, "you don't own a lock of type %s",
             lockMethodTable->lockModeNames[lockmode]);
        return false;
    }
 
    /*
     * Decrease the count for the resource owner.
     */
    {
        LOCALLOCKOWNER *lockOwners = locallock->lockOwners;
        ResourceOwner owner;
        int         i;
 
        /* Identify owner for lock */
        if (sessionLock)
            owner = NULL;
        else
            owner = CurrentResourceOwner;
 
        for (i = locallock->numLockOwners - 1; i >= 0; i--)
        {
            if (lockOwners[i].owner == owner)
            {
                Assert(lockOwners[i].nLocks > 0);
                if (--lockOwners[i].nLocks == 0)
                {
                    if (owner != NULL)
                        ResourceOwnerForgetLock(owner, locallock);
                    /* compact out unused slot */
                    locallock->numLockOwners--;
                    if (i < locallock->numLockOwners)
                        lockOwners[i] = lockOwners[locallock->numLockOwners];
                }
                break;
            }
        }
        if (i < 0)
        {
            /* don't release a lock belonging to another owner */
            elog(WARNING, "you don't own a lock of type %s",
                 lockMethodTable->lockModeNames[lockmode]);
            return false;
        }
    }
 
    /*
     * Decrease the total local count.  If we're still holding the lock, we're
     * done.
     */
    locallock->nLocks--;
 
    if (locallock->nLocks > 0)
        return true;
 
    /*
     * At this point we can no longer suppose we are clear of invalidation
     * messages related to this lock.  Although we'll delete the LOCALLOCK
     * object before any intentional return from this routine, it seems worth
     * the trouble to explicitly reset lockCleared right now, just in case
     * some error prevents us from deleting the LOCALLOCK.
     */
    locallock->lockCleared = false;
 
    /* Attempt fast release of any lock eligible for the fast path. */
    if (EligibleForRelationFastPath(locktag, lockmode) &&
        FastPathLocalUseCounts[FAST_PATH_REL_GROUP(locktag->locktag_field2)] > 0)
    {
        bool        released;
 
        /*
         * We might not find the lock here, even if we originally entered it
         * here.  Another backend may have moved it to the main table.
         */
        LWLockAcquire(&MyProc->fpInfoLock, LW_EXCLUSIVE);
        released = FastPathUnGrantRelationLock(locktag->locktag_field2,
                                               lockmode);
        LWLockRelease(&MyProc->fpInfoLock);
        if (released)
        {
            RemoveLocalLock(locallock);
            return true;
        }
    }
 
    /*
     * Otherwise we've got to mess with the shared lock table.
     */
    partitionLock = LockHashPartitionLock(locallock->hashcode);
 
    LWLockAcquire(partitionLock, LW_EXCLUSIVE);
 
    /*
     * Normally, we don't need to re-find the lock or proclock, since we kept
     * their addresses in the locallock table, and they couldn't have been
     * removed while we were holding a lock on them.  But it's possible that
     * the lock was taken fast-path and has since been moved to the main hash
     * table by another backend, in which case we will need to look up the
     * objects here.  We assume the lock field is NULL if so.
     */
    lock = locallock->lock;
    if (!lock)
    {
        PROCLOCKTAG proclocktag;
 
        Assert(EligibleForRelationFastPath(locktag, lockmode));
        lock = (LOCK *) hash_search_with_hash_value(LockMethodLockHash,
                                                    locktag,
                                                    locallock->hashcode,
                                                    HASH_FIND,
                                                    NULL);
        if (!lock)
            elog(ERROR, "failed to re-find shared lock object");
        locallock->lock = lock;
 
        proclocktag.myLock = lock;
        proclocktag.myProc = MyProc;
        locallock->proclock = (PROCLOCK *) hash_search(LockMethodProcLockHash,
                                                       &proclocktag,
                                                       HASH_FIND,
                                                       NULL);
        if (!locallock->proclock)
            elog(ERROR, "failed to re-find shared proclock object");
    }
    LOCK_PRINT("LockRelease: found", lock, lockmode);
    proclock = locallock->proclock;
    PROCLOCK_PRINT("LockRelease: found", proclock);
 
    /*
     * Double-check that we are actually holding a lock of the type we want to
     * release.
     */
    if (!(proclock->holdMask & LOCKBIT_ON(lockmode)))
    {
        PROCLOCK_PRINT("LockRelease: WRONGTYPE", proclock);
        LWLockRelease(partitionLock);
        elog(WARNING, "you don't own a lock of type %s",
             lockMethodTable->lockModeNames[lockmode]);
        RemoveLocalLock(locallock);
        return false;
    }
 
    /*
     * Do the releasing.  CleanUpLock will waken any now-wakable waiters.
     */
    wakeupNeeded = UnGrantLock(lock, lockmode, proclock, lockMethodTable);
 
    CleanUpLock(lock, proclock,
                lockMethodTable, locallock->hashcode,
                wakeupNeeded);
 
    LWLockRelease(partitionLock);
 
    RemoveLocalLock(locallock);
    return true;
}

References Assert(), CleanUpLock(), CurrentResourceOwner, EligibleForRelationFastPath, elog, ERROR, FAST_PATH_REL_GROUP, FastPathLocalUseCounts, FastPathUnGrantRelationLock(), PGPROC::fpInfoLock, HASH_FIND, hash_search(), hash_search_with_hash_value(), LOCALLOCK::hashcode, PROCLOCK::holdMask, i, lengthof, LOCALLOCKTAG::lock, LOCALLOCK::lock, LOCK_PRINT, LOCKBIT_ON, LOCALLOCK::lockCleared, LockHashPartitionLock, LockMethodLocalHash, LockMethodLockHash, LockMethodProcLockHash, LockMethods, LockMethodData::lockModeNames, LOCALLOCK::lockOwners, LOCKTAG::locktag_field1, LOCKTAG::locktag_field2, LOCKTAG::locktag_lockmethodid, LOG, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), MemSet, LOCALLOCKTAG::mode, PROCLOCKTAG::myLock, MyProc, PROCLOCKTAG::myProc, LOCALLOCK::nLocks, LockMethodData::numLockModes, LOCALLOCK::numLockOwners, LOCALLOCK::proclock, PROCLOCK_PRINT, RemoveLocalLock(), ResourceOwnerForgetLock(), UnGrantLock(), and WARNING.

Referenced by ConditionalXactLockTableWait(), pg_advisory_unlock_int4(), pg_advisory_unlock_int8(), pg_advisory_unlock_shared_int4(), pg_advisory_unlock_shared_int8(), ReleaseLockIfHeld(), SearchSysCacheLocked1(), SpeculativeInsertionLockRelease(), SpeculativeInsertionWait(), StandbyReleaseXidEntryLocks(), UnlockApplyTransactionForSession(), UnlockDatabaseObject(), UnlockPage(), UnlockRelation(), UnlockRelationForExtension(), UnlockRelationId(), UnlockRelationIdForSession(), UnlockRelationOid(), UnlockSharedObject(), UnlockSharedObjectForSession(), UnlockTuple(), VirtualXactLock(), XactLockForVirtualXact(), XactLockTableDelete(), and XactLockTableWait().

LockReleaseAll()

void LockReleaseAll	(	LOCKMETHODID	lockmethodid,
		bool	allLocks
	)

Definition at line 2307 of file lock.c.

{
    HASH_SEQ_STATUS status;
    LockMethod  lockMethodTable;
    int         i,
                numLockModes;
    LOCALLOCK  *locallock;
    LOCK       *lock;
    int         partition;
    bool        have_fast_path_lwlock = false;
 
    if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
        elog(ERROR, "unrecognized lock method: %d", lockmethodid);
    lockMethodTable = LockMethods[lockmethodid];
 
#ifdef LOCK_DEBUG
    if (*(lockMethodTable->trace_flag))
        elog(LOG, "LockReleaseAll: lockmethod=%d", lockmethodid);
#endif
 
    /*
     * Get rid of our fast-path VXID lock, if appropriate.  Note that this is
     * the only way that the lock we hold on our own VXID can ever get
     * released: it is always and only released when a toplevel transaction
     * ends.
     */
    if (lockmethodid == DEFAULT_LOCKMETHOD)
        VirtualXactLockTableCleanup();
 
    numLockModes = lockMethodTable->numLockModes;
 
    /*
     * First we run through the locallock table and get rid of unwanted
     * entries, then we scan the process's proclocks and get rid of those. We
     * do this separately because we may have multiple locallock entries
     * pointing to the same proclock, and we daren't end up with any dangling
     * pointers.  Fast-path locks are cleaned up during the locallock table
     * scan, though.
     */
    hash_seq_init(&status, LockMethodLocalHash);
 
    while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
    {
        /*
         * If the LOCALLOCK entry is unused, something must've gone wrong
         * while trying to acquire this lock.  Just forget the local entry.
         */
        if (locallock->nLocks == 0)
        {
            RemoveLocalLock(locallock);
            continue;
        }
 
        /* Ignore items that are not of the lockmethod to be removed */
        if (LOCALLOCK_LOCKMETHOD(*locallock) != lockmethodid)
            continue;
 
        /*
         * If we are asked to release all locks, we can just zap the entry.
         * Otherwise, must scan to see if there are session locks. We assume
         * there is at most one lockOwners entry for session locks.
         */
        if (!allLocks)
        {
            LOCALLOCKOWNER *lockOwners = locallock->lockOwners;
 
            /* If session lock is above array position 0, move it down to 0 */
            for (i = 0; i < locallock->numLockOwners; i++)
            {
                if (lockOwners[i].owner == NULL)
                    lockOwners[0] = lockOwners[i];
                else
                    ResourceOwnerForgetLock(lockOwners[i].owner, locallock);
            }
 
            if (locallock->numLockOwners > 0 &&
                lockOwners[0].owner == NULL &&
                lockOwners[0].nLocks > 0)
            {
                /* Fix the locallock to show just the session locks */
                locallock->nLocks = lockOwners[0].nLocks;
                locallock->numLockOwners = 1;
                /* We aren't deleting this locallock, so done */
                continue;
            }
            else
                locallock->numLockOwners = 0;
        }
 
#ifdef USE_ASSERT_CHECKING
 
        /*
         * Tuple locks are currently held only for short durations within a
         * transaction. Check that we didn't forget to release one.
         */
        if (LOCALLOCK_LOCKTAG(*locallock) == LOCKTAG_TUPLE && !allLocks)
            elog(WARNING, "tuple lock held at commit");
#endif
 
        /*
         * If the lock or proclock pointers are NULL, this lock was taken via
         * the relation fast-path (and is not known to have been transferred).
         */
        if (locallock->proclock == NULL || locallock->lock == NULL)
        {
            LOCKMODE    lockmode = locallock->tag.mode;
            Oid         relid;
 
            /* Verify that a fast-path lock is what we've got. */
            if (!EligibleForRelationFastPath(&locallock->tag.lock, lockmode))
                elog(PANIC, "locallock table corrupted");
 
            /*
             * If we don't currently hold the LWLock that protects our
             * fast-path data structures, we must acquire it before attempting
             * to release the lock via the fast-path.  We will continue to
             * hold the LWLock until we're done scanning the locallock table,
             * unless we hit a transferred fast-path lock.  (XXX is this
             * really such a good idea?  There could be a lot of entries ...)
             */
            if (!have_fast_path_lwlock)
            {
                LWLockAcquire(&MyProc->fpInfoLock, LW_EXCLUSIVE);
                have_fast_path_lwlock = true;
            }
 
            /* Attempt fast-path release. */
            relid = locallock->tag.lock.locktag_field2;
            if (FastPathUnGrantRelationLock(relid, lockmode))
            {
                RemoveLocalLock(locallock);
                continue;
            }
 
            /*
             * Our lock, originally taken via the fast path, has been
             * transferred to the main lock table.  That's going to require
             * some extra work, so release our fast-path lock before starting.
             */
            LWLockRelease(&MyProc->fpInfoLock);
            have_fast_path_lwlock = false;
 
            /*
             * Now dump the lock.  We haven't got a pointer to the LOCK or
             * PROCLOCK in this case, so we have to handle this a bit
             * differently than a normal lock release.  Unfortunately, this
             * requires an extra LWLock acquire-and-release cycle on the
             * partitionLock, but hopefully it shouldn't happen often.
             */
            LockRefindAndRelease(lockMethodTable, MyProc,
                                 &locallock->tag.lock, lockmode, false);
            RemoveLocalLock(locallock);
            continue;
        }
 
        /* Mark the proclock to show we need to release this lockmode */
        if (locallock->nLocks > 0)
            locallock->proclock->releaseMask |= LOCKBIT_ON(locallock->tag.mode);
 
        /* And remove the locallock hashtable entry */
        RemoveLocalLock(locallock);
    }
 
    /* Done with the fast-path data structures */
    if (have_fast_path_lwlock)
        LWLockRelease(&MyProc->fpInfoLock);
 
    /*
     * Now, scan each lock partition separately.
     */
    for (partition = 0; partition < NUM_LOCK_PARTITIONS; partition++)
    {
        LWLock     *partitionLock;
        dlist_head *procLocks = &MyProc->myProcLocks[partition];
        dlist_mutable_iter proclock_iter;
 
        partitionLock = LockHashPartitionLockByIndex(partition);
 
        /*
         * If the proclock list for this partition is empty, we can skip
         * acquiring the partition lock.  This optimization is trickier than
         * it looks, because another backend could be in process of adding
         * something to our proclock list due to promoting one of our
         * fast-path locks.  However, any such lock must be one that we
         * decided not to delete above, so it's okay to skip it again now;
         * we'd just decide not to delete it again.  We must, however, be
         * careful to re-fetch the list header once we've acquired the
         * partition lock, to be sure we have a valid, up-to-date pointer.
         * (There is probably no significant risk if pointer fetch/store is
         * atomic, but we don't wish to assume that.)
         *
         * XXX This argument assumes that the locallock table correctly
         * represents all of our fast-path locks.  While allLocks mode
         * guarantees to clean up all of our normal locks regardless of the
         * locallock situation, we lose that guarantee for fast-path locks.
         * This is not ideal.
         */
        if (dlist_is_empty(procLocks))
            continue;           /* needn't examine this partition */
 
        LWLockAcquire(partitionLock, LW_EXCLUSIVE);
 
        dlist_foreach_modify(proclock_iter, procLocks)
        {
            PROCLOCK   *proclock = dlist_container(PROCLOCK, procLink, proclock_iter.cur);
            bool        wakeupNeeded = false;
 
            Assert(proclock->tag.myProc == MyProc);
 
            lock = proclock->tag.myLock;
 
            /* Ignore items that are not of the lockmethod to be removed */
            if (LOCK_LOCKMETHOD(*lock) != lockmethodid)
                continue;
 
            /*
             * In allLocks mode, force release of all locks even if locallock
             * table had problems
             */
            if (allLocks)
                proclock->releaseMask = proclock->holdMask;
            else
                Assert((proclock->releaseMask & ~proclock->holdMask) == 0);
 
            /*
             * Ignore items that have nothing to be released, unless they have
             * holdMask == 0 and are therefore recyclable
             */
            if (proclock->releaseMask == 0 && proclock->holdMask != 0)
                continue;
 
            PROCLOCK_PRINT("LockReleaseAll", proclock);
            LOCK_PRINT("LockReleaseAll", lock, 0);
            Assert(lock->nRequested >= 0);
            Assert(lock->nGranted >= 0);
            Assert(lock->nGranted <= lock->nRequested);
            Assert((proclock->holdMask & ~lock->grantMask) == 0);
 
            /*
             * Release the previously-marked lock modes
             */
            for (i = 1; i <= numLockModes; i++)
            {
                if (proclock->releaseMask & LOCKBIT_ON(i))
                    wakeupNeeded |= UnGrantLock(lock, i, proclock,
                                                lockMethodTable);
            }
            Assert((lock->nRequested >= 0) && (lock->nGranted >= 0));
            Assert(lock->nGranted <= lock->nRequested);
            LOCK_PRINT("LockReleaseAll: updated", lock, 0);
 
            proclock->releaseMask = 0;
 
            /* CleanUpLock will wake up waiters if needed. */
            CleanUpLock(lock, proclock,
                        lockMethodTable,
                        LockTagHashCode(&lock->tag),
                        wakeupNeeded);
        }                       /* loop over PROCLOCKs within this partition */
 
        LWLockRelease(partitionLock);
    }                           /* loop over partitions */
 
#ifdef LOCK_DEBUG
    if (*(lockMethodTable->trace_flag))
        elog(LOG, "LockReleaseAll done");
#endif
}

References Assert(), CleanUpLock(), dlist_mutable_iter::cur, DEFAULT_LOCKMETHOD, dlist_container, dlist_foreach_modify, dlist_is_empty(), EligibleForRelationFastPath, elog, ERROR, FastPathUnGrantRelationLock(), PGPROC::fpInfoLock, LOCK::grantMask, hash_seq_init(), hash_seq_search(), PROCLOCK::holdMask, i, lengthof, LOCALLOCK_LOCKMETHOD, LOCALLOCK_LOCKTAG, LOCALLOCKTAG::lock, LOCALLOCK::lock, LOCK_LOCKMETHOD, LOCK_PRINT, LOCKBIT_ON, LockHashPartitionLockByIndex, LockMethodLocalHash, LockMethods, LOCALLOCK::lockOwners, LockRefindAndRelease(), LOCKTAG::locktag_field2, LOCKTAG_TUPLE, LockTagHashCode(), LOG, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), LOCALLOCKTAG::mode, PROCLOCKTAG::myLock, MyProc, PROCLOCKTAG::myProc, PGPROC::myProcLocks, LOCK::nGranted, LOCALLOCKOWNER::nLocks, LOCALLOCK::nLocks, LOCK::nRequested, NUM_LOCK_PARTITIONS, LockMethodData::numLockModes, LOCALLOCK::numLockOwners, LOCALLOCKOWNER::owner, PANIC, LOCALLOCK::proclock, PROCLOCK_PRINT, PROCLOCK::releaseMask, RemoveLocalLock(), ResourceOwnerForgetLock(), LOCK::tag, PROCLOCK::tag, LOCALLOCK::tag, LockMethodData::trace_flag, UnGrantLock(), VirtualXactLockTableCleanup(), and WARNING.

Referenced by DiscardAll(), logicalrep_worker_onexit(), ProcReleaseLocks(), and ShutdownPostgres().

LockReleaseCurrentOwner()

void LockReleaseCurrentOwner	(	LOCALLOCK **	locallocks,
		int	nlocks
	)

Definition at line 2611 of file lock.c.

{
    if (locallocks == NULL)
    {
        HASH_SEQ_STATUS status;
        LOCALLOCK  *locallock;
 
        hash_seq_init(&status, LockMethodLocalHash);
 
        while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
            ReleaseLockIfHeld(locallock, false);
    }
    else
    {
        int         i;
 
        for (i = nlocks - 1; i >= 0; i--)
            ReleaseLockIfHeld(locallocks[i], false);
    }
}

References hash_seq_init(), hash_seq_search(), i, LockMethodLocalHash, and ReleaseLockIfHeld().

Referenced by ResourceOwnerReleaseInternal().

LockReleaseSession()

void LockReleaseSession

(

LOCKMETHODID

lockmethodid

)

Definition at line 2581 of file lock.c.

{
    HASH_SEQ_STATUS status;
    LOCALLOCK  *locallock;
 
    if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
        elog(ERROR, "unrecognized lock method: %d", lockmethodid);
 
    hash_seq_init(&status, LockMethodLocalHash);
 
    while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
    {
        /* Ignore items that are not of the specified lock method */
        if (LOCALLOCK_LOCKMETHOD(*locallock) != lockmethodid)
            continue;
 
        ReleaseLockIfHeld(locallock, true);
    }
}

References elog, ERROR, hash_seq_init(), hash_seq_search(), lengthof, LOCALLOCK_LOCKMETHOD, LockMethodLocalHash, LockMethods, and ReleaseLockIfHeld().

Referenced by pg_advisory_unlock_all().

LockTagHashCode()

uint32 LockTagHashCode

(

const LOCKTAG *

locktag

)

Definition at line 557 of file lock.c.

{
    return get_hash_value(LockMethodLockHash, locktag);
}

References get_hash_value(), and LockMethodLockHash.

Referenced by CheckDeadLock(), GetLockConflicts(), lock_twophase_recover(), LockAcquireExtended(), LockRefindAndRelease(), LockReleaseAll(), LockWaiterCount(), proclock_hash(), and VirtualXactLock().

LockWaiterCount()

int LockWaiterCount

(

const LOCKTAG *

locktag

)

Definition at line 4856 of file lock.c.

{
    LOCKMETHODID lockmethodid = locktag->locktag_lockmethodid;
    LOCK       *lock;
    bool        found;
    uint32      hashcode;
    LWLock     *partitionLock;
    int         waiters = 0;
 
    if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
        elog(ERROR, "unrecognized lock method: %d", lockmethodid);
 
    hashcode = LockTagHashCode(locktag);
    partitionLock = LockHashPartitionLock(hashcode);
    LWLockAcquire(partitionLock, LW_EXCLUSIVE);
 
    lock = (LOCK *) hash_search_with_hash_value(LockMethodLockHash,
                                                locktag,
                                                hashcode,
                                                HASH_FIND,
                                                &found);
    if (found)
    {
        Assert(lock != NULL);
        waiters = lock->nRequested;
    }
    LWLockRelease(partitionLock);
 
    return waiters;
}

References Assert(), elog, ERROR, HASH_FIND, hash_search_with_hash_value(), lengthof, LockHashPartitionLock, LockMethodLockHash, LockMethods, LOCKTAG::locktag_lockmethodid, LockTagHashCode(), LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), and LOCK::nRequested.

Referenced by RelationExtensionLockWaiterCount().

MarkLockClear()

void MarkLockClear

(

LOCALLOCK *

locallock

)

Definition at line 1920 of file lock.c.

{
    Assert(locallock->nLocks > 0);
    locallock->lockCleared = true;
}

References Assert(), LOCALLOCK::lockCleared, and LOCALLOCK::nLocks.

Referenced by ConditionalLockDatabaseObject(), ConditionalLockRelation(), ConditionalLockRelationOid(), ConditionalLockSharedObject(), LockRelation(), LockRelationId(), and LockRelationOid().

PostPrepare_Locks()

void PostPrepare_Locks

(

FullTransactionId

fxid

)

Definition at line 3574 of file lock.c.

{
    PGPROC     *newproc = TwoPhaseGetDummyProc(fxid, false);
    HASH_SEQ_STATUS status;
    LOCALLOCK  *locallock;
    LOCK       *lock;
    PROCLOCK   *proclock;
    PROCLOCKTAG proclocktag;
    int         partition;
 
    /* Can't prepare a lock group follower. */
    Assert(MyProc->lockGroupLeader == NULL ||
           MyProc->lockGroupLeader == MyProc);
 
    /* This is a critical section: any error means big trouble */
    START_CRIT_SECTION();
 
    /*
     * First we run through the locallock table and get rid of unwanted
     * entries, then we scan the process's proclocks and transfer them to the
     * target proc.
     *
     * We do this separately because we may have multiple locallock entries
     * pointing to the same proclock, and we daren't end up with any dangling
     * pointers.
     */
    hash_seq_init(&status, LockMethodLocalHash);
 
    while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
    {
        LOCALLOCKOWNER *lockOwners = locallock->lockOwners;
        bool        haveSessionLock;
        bool        haveXactLock;
        int         i;
 
        if (locallock->proclock == NULL || locallock->lock == NULL)
        {
            /*
             * We must've run out of shared memory while trying to set up this
             * lock.  Just forget the local entry.
             */
            Assert(locallock->nLocks == 0);
            RemoveLocalLock(locallock);
            continue;
        }
 
        /* Ignore VXID locks */
        if (locallock->tag.lock.locktag_type == LOCKTAG_VIRTUALTRANSACTION)
            continue;
 
        /* Scan to see whether we hold it at session or transaction level */
        haveSessionLock = haveXactLock = false;
        for (i = locallock->numLockOwners - 1; i >= 0; i--)
        {
            if (lockOwners[i].owner == NULL)
                haveSessionLock = true;
            else
                haveXactLock = true;
        }
 
        /* Ignore it if we have only session lock */
        if (!haveXactLock)
            continue;
 
        /* This can't happen, because we already checked it */
        if (haveSessionLock)
            ereport(PANIC,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("cannot PREPARE while holding both session-level and transaction-level locks on the same object")));
 
        /* Mark the proclock to show we need to release this lockmode */
        if (locallock->nLocks > 0)
            locallock->proclock->releaseMask |= LOCKBIT_ON(locallock->tag.mode);
 
        /* And remove the locallock hashtable entry */
        RemoveLocalLock(locallock);
    }
 
    /*
     * Now, scan each lock partition separately.
     */
    for (partition = 0; partition < NUM_LOCK_PARTITIONS; partition++)
    {
        LWLock     *partitionLock;
        dlist_head *procLocks = &(MyProc->myProcLocks[partition]);
        dlist_mutable_iter proclock_iter;
 
        partitionLock = LockHashPartitionLockByIndex(partition);
 
        /*
         * If the proclock list for this partition is empty, we can skip
         * acquiring the partition lock.  This optimization is safer than the
         * situation in LockReleaseAll, because we got rid of any fast-path
         * locks during AtPrepare_Locks, so there cannot be any case where
         * another backend is adding something to our lists now.  For safety,
         * though, we code this the same way as in LockReleaseAll.
         */
        if (dlist_is_empty(procLocks))
            continue;           /* needn't examine this partition */
 
        LWLockAcquire(partitionLock, LW_EXCLUSIVE);
 
        dlist_foreach_modify(proclock_iter, procLocks)
        {
            proclock = dlist_container(PROCLOCK, procLink, proclock_iter.cur);
 
            Assert(proclock->tag.myProc == MyProc);
 
            lock = proclock->tag.myLock;
 
            /* Ignore VXID locks */
            if (lock->tag.locktag_type == LOCKTAG_VIRTUALTRANSACTION)
                continue;
 
            PROCLOCK_PRINT("PostPrepare_Locks", proclock);
            LOCK_PRINT("PostPrepare_Locks", lock, 0);
            Assert(lock->nRequested >= 0);
            Assert(lock->nGranted >= 0);
            Assert(lock->nGranted <= lock->nRequested);
            Assert((proclock->holdMask & ~lock->grantMask) == 0);
 
            /* Ignore it if nothing to release (must be a session lock) */
            if (proclock->releaseMask == 0)
                continue;
 
            /* Else we should be releasing all locks */
            if (proclock->releaseMask != proclock->holdMask)
                elog(PANIC, "we seem to have dropped a bit somewhere");
 
            /*
             * We cannot simply modify proclock->tag.myProc to reassign
             * ownership of the lock, because that's part of the hash key and
             * the proclock would then be in the wrong hash chain.  Instead
             * use hash_update_hash_key.  (We used to create a new hash entry,
             * but that risks out-of-memory failure if other processes are
             * busy making proclocks too.)  We must unlink the proclock from
             * our procLink chain and put it into the new proc's chain, too.
             *
             * Note: the updated proclock hash key will still belong to the
             * same hash partition, cf proclock_hash().  So the partition lock
             * we already hold is sufficient for this.
             */
            dlist_delete(&proclock->procLink);
 
            /*
             * Create the new hash key for the proclock.
             */
            proclocktag.myLock = lock;
            proclocktag.myProc = newproc;
 
            /*
             * Update groupLeader pointer to point to the new proc.  (We'd
             * better not be a member of somebody else's lock group!)
             */
            Assert(proclock->groupLeader == proclock->tag.myProc);
            proclock->groupLeader = newproc;
 
            /*
             * Update the proclock.  We should not find any existing entry for
             * the same hash key, since there can be only one entry for any
             * given lock with my own proc.
             */
            if (!hash_update_hash_key(LockMethodProcLockHash,
                                      proclock,
                                      &proclocktag))
                elog(PANIC, "duplicate entry found while reassigning a prepared transaction's locks");
 
            /* Re-link into the new proc's proclock list */
            dlist_push_tail(&newproc->myProcLocks[partition], &proclock->procLink);
 
            PROCLOCK_PRINT("PostPrepare_Locks: updated", proclock);
        }                       /* loop over PROCLOCKs within this partition */
 
        LWLockRelease(partitionLock);
    }                           /* loop over partitions */
 
    END_CRIT_SECTION();
}

References Assert(), dlist_mutable_iter::cur, dlist_container, dlist_delete(), dlist_foreach_modify, dlist_is_empty(), dlist_push_tail(), elog, END_CRIT_SECTION, ereport, errcode(), errmsg(), LOCK::grantMask, PROCLOCK::groupLeader, hash_seq_init(), hash_seq_search(), hash_update_hash_key(), PROCLOCK::holdMask, i, LOCALLOCKTAG::lock, LOCALLOCK::lock, LOCK_PRINT, LOCKBIT_ON, PGPROC::lockGroupLeader, LockHashPartitionLockByIndex, LockMethodLocalHash, LockMethodProcLockHash, LOCALLOCK::lockOwners, LOCKTAG::locktag_type, LOCKTAG_VIRTUALTRANSACTION, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), LOCALLOCKTAG::mode, PROCLOCKTAG::myLock, MyProc, PROCLOCKTAG::myProc, PGPROC::myProcLocks, LOCK::nGranted, LOCALLOCK::nLocks, LOCK::nRequested, NUM_LOCK_PARTITIONS, LOCALLOCK::numLockOwners, PANIC, PROCLOCK::procLink, LOCALLOCK::proclock, PROCLOCK_PRINT, PROCLOCK::releaseMask, RemoveLocalLock(), START_CRIT_SECTION, LOCK::tag, PROCLOCK::tag, LOCALLOCK::tag, and TwoPhaseGetDummyProc().

Referenced by PrepareTransaction().

proclock_hash()

static uint32 proclock_hash ( const void *  key, Size  keysize  )

static

Definition at line 574 of file lock.c.

{
    const PROCLOCKTAG *proclocktag = (const PROCLOCKTAG *) key;
    uint32      lockhash;
    Datum       procptr;
 
    Assert(keysize == sizeof(PROCLOCKTAG));
 
    /* Look into the associated LOCK object, and compute its hash code */
    lockhash = LockTagHashCode(&proclocktag->myLock->tag);
 
    /*
     * To make the hash code also depend on the PGPROC, we xor the proc
     * struct's address into the hash code, left-shifted so that the
     * partition-number bits don't change.  Since this is only a hash, we
     * don't care if we lose high-order bits of the address; use an
     * intermediate variable to suppress cast-pointer-to-int warnings.
     */
    procptr = PointerGetDatum(proclocktag->myProc);
    lockhash ^= DatumGetUInt32(procptr) << LOG2_NUM_LOCK_PARTITIONS;
 
    return lockhash;
}

References Assert(), DatumGetUInt32(), sort-test::key, LockTagHashCode(), LOG2_NUM_LOCK_PARTITIONS, PROCLOCKTAG::myLock, PROCLOCKTAG::myProc, PointerGetDatum(), and LOCK::tag.

Referenced by LockManagerShmemInit().

ProcLockHashCode()

static uint32 ProcLockHashCode ( const PROCLOCKTAG *  proclocktag, uint32  hashcode  )

inlinestatic

Definition at line 605 of file lock.c.

{
    uint32      lockhash = hashcode;
    Datum       procptr;
 
    /*
     * This must match proclock_hash()!
     */
    procptr = PointerGetDatum(proclocktag->myProc);
    lockhash ^= DatumGetUInt32(procptr) << LOG2_NUM_LOCK_PARTITIONS;
 
    return lockhash;
}

References DatumGetUInt32(), LOG2_NUM_LOCK_PARTITIONS, PROCLOCKTAG::myProc, and PointerGetDatum().

Referenced by CleanUpLock(), FastPathGetRelationLockEntry(), lock_twophase_recover(), LockAcquireExtended(), LockRefindAndRelease(), and SetupLockInTable().

ReleaseLockIfHeld()

static void ReleaseLockIfHeld ( LOCALLOCK *  locallock, bool  sessionLock  )

static

Definition at line 2646 of file lock.c.

{
    ResourceOwner owner;
    LOCALLOCKOWNER *lockOwners;
    int         i;
 
    /* Identify owner for lock (must match LockRelease!) */
    if (sessionLock)
        owner = NULL;
    else
        owner = CurrentResourceOwner;
 
    /* Scan to see if there are any locks belonging to the target owner */
    lockOwners = locallock->lockOwners;
    for (i = locallock->numLockOwners - 1; i >= 0; i--)
    {
        if (lockOwners[i].owner == owner)
        {
            Assert(lockOwners[i].nLocks > 0);
            if (lockOwners[i].nLocks < locallock->nLocks)
            {
                /*
                 * We will still hold this lock after forgetting this
                 * ResourceOwner.
                 */
                locallock->nLocks -= lockOwners[i].nLocks;
                /* compact out unused slot */
                locallock->numLockOwners--;
                if (owner != NULL)
                    ResourceOwnerForgetLock(owner, locallock);
                if (i < locallock->numLockOwners)
                    lockOwners[i] = lockOwners[locallock->numLockOwners];
            }
            else
            {
                Assert(lockOwners[i].nLocks == locallock->nLocks);
                /* We want to call LockRelease just once */
                lockOwners[i].nLocks = 1;
                locallock->nLocks = 1;
                if (!LockRelease(&locallock->tag.lock,
                                 locallock->tag.mode,
                                 sessionLock))
                    elog(WARNING, "ReleaseLockIfHeld: failed??");
            }
            break;
        }
    }
}

References Assert(), CurrentResourceOwner, elog, i, LOCALLOCKTAG::lock, LOCALLOCK::lockOwners, LockRelease(), LOCALLOCKTAG::mode, LOCALLOCKOWNER::nLocks, LOCALLOCK::nLocks, LOCALLOCK::numLockOwners, ResourceOwnerForgetLock(), LOCALLOCK::tag, and WARNING.

Referenced by LockReleaseCurrentOwner(), and LockReleaseSession().

RemoveFromWaitQueue()

void RemoveFromWaitQueue	(	PGPROC *	proc,
		uint32	hashcode
	)

Definition at line 2046 of file lock.c.

{
    LOCK       *waitLock = proc->waitLock;
    PROCLOCK   *proclock = proc->waitProcLock;
    LOCKMODE    lockmode = proc->waitLockMode;
    LOCKMETHODID lockmethodid = LOCK_LOCKMETHOD(*waitLock);
 
    /* Make sure proc is waiting */
    Assert(proc->waitStatus == PROC_WAIT_STATUS_WAITING);
    Assert(proc->links.next != NULL);
    Assert(waitLock);
    Assert(!dclist_is_empty(&waitLock->waitProcs));
    Assert(0 < lockmethodid && lockmethodid < lengthof(LockMethods));
 
    /* Remove proc from lock's wait queue */
    dclist_delete_from_thoroughly(&waitLock->waitProcs, &proc->links);
 
    /* Undo increments of request counts by waiting process */
    Assert(waitLock->nRequested > 0);
    Assert(waitLock->nRequested > proc->waitLock->nGranted);
    waitLock->nRequested--;
    Assert(waitLock->requested[lockmode] > 0);
    waitLock->requested[lockmode]--;
    /* don't forget to clear waitMask bit if appropriate */
    if (waitLock->granted[lockmode] == waitLock->requested[lockmode])
        waitLock->waitMask &= LOCKBIT_OFF(lockmode);
 
    /* Clean up the proc's own state, and pass it the ok/fail signal */
    proc->waitLock = NULL;
    proc->waitProcLock = NULL;
    proc->waitStatus = PROC_WAIT_STATUS_ERROR;
 
    /*
     * Delete the proclock immediately if it represents no already-held locks.
     * (This must happen now because if the owner of the lock decides to
     * release it, and the requested/granted counts then go to zero,
     * LockRelease expects there to be no remaining proclocks.) Then see if
     * any other waiters for the lock can be woken up now.
     */
    CleanUpLock(waitLock, proclock,
                LockMethods[lockmethodid], hashcode,
                true);
}

References Assert(), CleanUpLock(), dclist_delete_from_thoroughly(), dclist_is_empty(), LOCK::granted, lengthof, PGPROC::links, LOCK_LOCKMETHOD, LOCKBIT_OFF, LockMethods, dlist_node::next, LOCK::nGranted, LOCK::nRequested, PROC_WAIT_STATUS_ERROR, PROC_WAIT_STATUS_WAITING, LOCK::requested, PGPROC::waitLock, PGPROC::waitLockMode, LOCK::waitMask, PGPROC::waitProcLock, LOCK::waitProcs, and PGPROC::waitStatus.

Referenced by CheckDeadLock(), and LockErrorCleanup().

RemoveLocalLock()

static void RemoveLocalLock ( LOCALLOCK *  locallock )

static

Definition at line 1476 of file lock.c.

{
    int         i;
 
    for (i = locallock->numLockOwners - 1; i >= 0; i--)
    {
        if (locallock->lockOwners[i].owner != NULL)
            ResourceOwnerForgetLock(locallock->lockOwners[i].owner, locallock);
    }
    locallock->numLockOwners = 0;
    if (locallock->lockOwners != NULL)
        pfree(locallock->lockOwners);
    locallock->lockOwners = NULL;
 
    if (locallock->holdsStrongLockCount)
    {
        uint32      fasthashcode;
 
        fasthashcode = FastPathStrongLockHashPartition(locallock->hashcode);
 
        SpinLockAcquire(&FastPathStrongRelationLocks->mutex);
        Assert(FastPathStrongRelationLocks->count[fasthashcode] > 0);
        FastPathStrongRelationLocks->count[fasthashcode]--;
        locallock->holdsStrongLockCount = false;
        SpinLockRelease(&FastPathStrongRelationLocks->mutex);
    }
 
    if (!hash_search(LockMethodLocalHash,
                     &(locallock->tag),
                     HASH_REMOVE, NULL))
        elog(WARNING, "locallock table corrupted");
 
    /*
     * Indicate that the lock is released for certain types of locks
     */
    CheckAndSetLockHeld(locallock, false);
}

References Assert(), CheckAndSetLockHeld(), FastPathStrongRelationLockData::count, elog, FastPathStrongLockHashPartition, FastPathStrongRelationLocks, HASH_REMOVE, hash_search(), LOCALLOCK::hashcode, LOCALLOCK::holdsStrongLockCount, i, LockMethodLocalHash, LOCALLOCK::lockOwners, FastPathStrongRelationLockData::mutex, LOCALLOCK::numLockOwners, LOCALLOCKOWNER::owner, pfree(), ResourceOwnerForgetLock(), SpinLockAcquire, SpinLockRelease, LOCALLOCK::tag, and WARNING.

Referenced by LockAcquireExtended(), LockHasWaiters(), LockRelease(), LockReleaseAll(), and PostPrepare_Locks().

ResetAwaitedLock()

void ResetAwaitedLock

(

void

)

Definition at line 1907 of file lock.c.

{
    awaitedLock = NULL;
}

References awaitedLock.

Referenced by LockErrorCleanup().

SetupLockInTable()

static PROCLOCK * SetupLockInTable ( LockMethod  lockMethodTable, PGPROC *  proc, const LOCKTAG *  locktag, uint32  hashcode, LOCKMODE  lockmode  )

static

Definition at line 1283 of file lock.c.

{
    LOCK       *lock;
    PROCLOCK   *proclock;
    PROCLOCKTAG proclocktag;
    uint32      proclock_hashcode;
    bool        found;
 
    /*
     * Find or create a lock with this tag.
     */
    lock = (LOCK *) hash_search_with_hash_value(LockMethodLockHash,
                                                locktag,
                                                hashcode,
                                                HASH_ENTER_NULL,
                                                &found);
    if (!lock)
        return NULL;
 
    /*
     * if it's a new lock object, initialize it
     */
    if (!found)
    {
        lock->grantMask = 0;
        lock->waitMask = 0;
        dlist_init(&lock->procLocks);
        dclist_init(&lock->waitProcs);
        lock->nRequested = 0;
        lock->nGranted = 0;
        MemSet(lock->requested, 0, sizeof(int) * MAX_LOCKMODES);
        MemSet(lock->granted, 0, sizeof(int) * MAX_LOCKMODES);
        LOCK_PRINT("LockAcquire: new", lock, lockmode);
    }
    else
    {
        LOCK_PRINT("LockAcquire: found", lock, lockmode);
        Assert((lock->nRequested >= 0) && (lock->requested[lockmode] >= 0));
        Assert((lock->nGranted >= 0) && (lock->granted[lockmode] >= 0));
        Assert(lock->nGranted <= lock->nRequested);
    }
 
    /*
     * Create the hash key for the proclock table.
     */
    proclocktag.myLock = lock;
    proclocktag.myProc = proc;
 
    proclock_hashcode = ProcLockHashCode(&proclocktag, hashcode);
 
    /*
     * Find or create a proclock entry with this tag
     */
    proclock = (PROCLOCK *) hash_search_with_hash_value(LockMethodProcLockHash,
                                                        &proclocktag,
                                                        proclock_hashcode,
                                                        HASH_ENTER_NULL,
                                                        &found);
    if (!proclock)
    {
        /* Oops, not enough shmem for the proclock */
        if (lock->nRequested == 0)
        {
            /*
             * There are no other requestors of this lock, so garbage-collect
             * the lock object.  We *must* do this to avoid a permanent leak
             * of shared memory, because there won't be anything to cause
             * anyone to release the lock object later.
             */
            Assert(dlist_is_empty(&(lock->procLocks)));
            if (!hash_search_with_hash_value(LockMethodLockHash,
                                             &(lock->tag),
                                             hashcode,
                                             HASH_REMOVE,
                                             NULL))
                elog(PANIC, "lock table corrupted");
        }
        return NULL;
    }
 
    /*
     * If new, initialize the new entry
     */
    if (!found)
    {
        uint32      partition = LockHashPartition(hashcode);
 
        /*
         * It might seem unsafe to access proclock->groupLeader without a
         * lock, but it's not really.  Either we are initializing a proclock
         * on our own behalf, in which case our group leader isn't changing
         * because the group leader for a process can only ever be changed by
         * the process itself; or else we are transferring a fast-path lock to
         * the main lock table, in which case that process can't change its
         * lock group leader without first releasing all of its locks (and in
         * particular the one we are currently transferring).
         */
        proclock->groupLeader = proc->lockGroupLeader != NULL ?
            proc->lockGroupLeader : proc;
        proclock->holdMask = 0;
        proclock->releaseMask = 0;
        /* Add proclock to appropriate lists */
        dlist_push_tail(&lock->procLocks, &proclock->lockLink);
        dlist_push_tail(&proc->myProcLocks[partition], &proclock->procLink);
        PROCLOCK_PRINT("LockAcquire: new", proclock);
    }
    else
    {
        PROCLOCK_PRINT("LockAcquire: found", proclock);
        Assert((proclock->holdMask & ~lock->grantMask) == 0);
 
#ifdef CHECK_DEADLOCK_RISK
 
        /*
         * Issue warning if we already hold a lower-level lock on this object
         * and do not hold a lock of the requested level or higher. This
         * indicates a deadlock-prone coding practice (eg, we'd have a
         * deadlock if another backend were following the same code path at
         * about the same time).
         *
         * This is not enabled by default, because it may generate log entries
         * about user-level coding practices that are in fact safe in context.
         * It can be enabled to help find system-level problems.
         *
         * XXX Doing numeric comparison on the lockmodes is a hack; it'd be
         * better to use a table.  For now, though, this works.
         */
        {
            int         i;
 
            for (i = lockMethodTable->numLockModes; i > 0; i--)
            {
                if (proclock->holdMask & LOCKBIT_ON(i))
                {
                    if (i >= (int) lockmode)
                        break;  /* safe: we have a lock >= req level */
                    elog(LOG, "deadlock risk: raising lock level"
                         " from %s to %s on object %u/%u/%u",
                         lockMethodTable->lockModeNames[i],
                         lockMethodTable->lockModeNames[lockmode],
                         lock->tag.locktag_field1, lock->tag.locktag_field2,
                         lock->tag.locktag_field3);
                    break;
                }
            }
        }
#endif                          /* CHECK_DEADLOCK_RISK */
    }
 
    /*
     * lock->nRequested and lock->requested[] count the total number of
     * requests, whether granted or waiting, so increment those immediately.
     * The other counts don't increment till we get the lock.
     */
    lock->nRequested++;
    lock->requested[lockmode]++;
    Assert((lock->nRequested > 0) && (lock->requested[lockmode] > 0));
 
    /*
     * We shouldn't already hold the desired lock; else locallock table is
     * broken.
     */
    if (proclock->holdMask & LOCKBIT_ON(lockmode))
        elog(ERROR, "lock %s on object %u/%u/%u is already held",
             lockMethodTable->lockModeNames[lockmode],
             lock->tag.locktag_field1, lock->tag.locktag_field2,
             lock->tag.locktag_field3);
 
    return proclock;
}

References Assert(), dclist_init(), dlist_init(), dlist_is_empty(), dlist_push_tail(), elog, ERROR, LOCK::granted, LOCK::grantMask, PROCLOCK::groupLeader, HASH_ENTER_NULL, HASH_REMOVE, hash_search_with_hash_value(), PROCLOCK::holdMask, i, LOCK_PRINT, LOCKBIT_ON, PGPROC::lockGroupLeader, LockHashPartition, PROCLOCK::lockLink, LockMethodLockHash, LockMethodProcLockHash, LockMethodData::lockModeNames, LOCKTAG::locktag_field1, LOCKTAG::locktag_field2, LOCKTAG::locktag_field3, LOG, MAX_LOCKMODES, MemSet, PROCLOCKTAG::myLock, PROCLOCKTAG::myProc, PGPROC::myProcLocks, LOCK::nGranted, LOCK::nRequested, LockMethodData::numLockModes, PANIC, PROCLOCK::procLink, PROCLOCK_PRINT, ProcLockHashCode(), LOCK::procLocks, PROCLOCK::releaseMask, LOCK::requested, LOCK::tag, LOCK::waitMask, and LOCK::waitProcs.

Referenced by FastPathGetRelationLockEntry(), FastPathTransferRelationLocks(), LockAcquireExtended(), and VirtualXactLock().

UnGrantLock()

static bool UnGrantLock ( LOCK *  lock, LOCKMODE  lockmode, PROCLOCK *  proclock, LockMethod  lockMethodTable  )

static

Definition at line 1681 of file lock.c.

{
    bool        wakeupNeeded = false;
 
    Assert((lock->nRequested > 0) && (lock->requested[lockmode] > 0));
    Assert((lock->nGranted > 0) && (lock->granted[lockmode] > 0));
    Assert(lock->nGranted <= lock->nRequested);
 
    /*
     * fix the general lock stats
     */
    lock->nRequested--;
    lock->requested[lockmode]--;
    lock->nGranted--;
    lock->granted[lockmode]--;
 
    if (lock->granted[lockmode] == 0)
    {
        /* change the conflict mask.  No more of this lock type. */
        lock->grantMask &= LOCKBIT_OFF(lockmode);
    }
 
    LOCK_PRINT("UnGrantLock: updated", lock, lockmode);
 
    /*
     * We need only run ProcLockWakeup if the released lock conflicts with at
     * least one of the lock types requested by waiter(s).  Otherwise whatever
     * conflict made them wait must still exist.  NOTE: before MVCC, we could
     * skip wakeup if lock->granted[lockmode] was still positive. But that's
     * not true anymore, because the remaining granted locks might belong to
     * some waiter, who could now be awakened because he doesn't conflict with
     * his own locks.
     */
    if (lockMethodTable->conflictTab[lockmode] & lock->waitMask)
        wakeupNeeded = true;
 
    /*
     * Now fix the per-proclock state.
     */
    proclock->holdMask &= LOCKBIT_OFF(lockmode);
    PROCLOCK_PRINT("UnGrantLock: updated", proclock);
 
    return wakeupNeeded;
}

References Assert(), LockMethodData::conflictTab, LOCK::granted, LOCK::grantMask, PROCLOCK::holdMask, LOCK_PRINT, LOCKBIT_OFF, LOCK::nGranted, LOCK::nRequested, PROCLOCK_PRINT, LOCK::requested, and LOCK::waitMask.

Referenced by LockRefindAndRelease(), LockRelease(), and LockReleaseAll().

VirtualXactLock()

bool VirtualXactLock	(	VirtualTransactionId	vxid,
		bool	wait
	)

Definition at line 4745 of file lock.c.

{
    LOCKTAG     tag;
    PGPROC     *proc;
    TransactionId xid = InvalidTransactionId;
 
    Assert(VirtualTransactionIdIsValid(vxid));
 
    if (VirtualTransactionIdIsRecoveredPreparedXact(vxid))
        /* no vxid lock; localTransactionId is a normal, locked XID */
        return XactLockForVirtualXact(vxid, vxid.localTransactionId, wait);
 
    SET_LOCKTAG_VIRTUALTRANSACTION(tag, vxid);
 
    /*
     * If a lock table entry must be made, this is the PGPROC on whose behalf
     * it must be done.  Note that the transaction might end or the PGPROC
     * might be reassigned to a new backend before we get around to examining
     * it, but it doesn't matter.  If we find upon examination that the
     * relevant lxid is no longer running here, that's enough to prove that
     * it's no longer running anywhere.
     */
    proc = ProcNumberGetProc(vxid.procNumber);
    if (proc == NULL)
        return XactLockForVirtualXact(vxid, InvalidTransactionId, wait);
 
    /*
     * We must acquire this lock before checking the procNumber and lxid
     * against the ones we're waiting for.  The target backend will only set
     * or clear lxid while holding this lock.
     */
    LWLockAcquire(&proc->fpInfoLock, LW_EXCLUSIVE);
 
    if (proc->vxid.procNumber != vxid.procNumber
        || proc->fpLocalTransactionId != vxid.localTransactionId)
    {
        /* VXID ended */
        LWLockRelease(&proc->fpInfoLock);
        return XactLockForVirtualXact(vxid, InvalidTransactionId, wait);
    }
 
    /*
     * If we aren't asked to wait, there's no need to set up a lock table
     * entry.  The transaction is still in progress, so just return false.
     */
    if (!wait)
    {
        LWLockRelease(&proc->fpInfoLock);
        return false;
    }
 
    /*
     * OK, we're going to need to sleep on the VXID.  But first, we must set
     * up the primary lock table entry, if needed (ie, convert the proc's
     * fast-path lock on its VXID to a regular lock).
     */
    if (proc->fpVXIDLock)
    {
        PROCLOCK   *proclock;
        uint32      hashcode;
        LWLock     *partitionLock;
 
        hashcode = LockTagHashCode(&tag);
 
        partitionLock = LockHashPartitionLock(hashcode);
        LWLockAcquire(partitionLock, LW_EXCLUSIVE);
 
        proclock = SetupLockInTable(LockMethods[DEFAULT_LOCKMETHOD], proc,
                                    &tag, hashcode, ExclusiveLock);
        if (!proclock)
        {
            LWLockRelease(partitionLock);
            LWLockRelease(&proc->fpInfoLock);
            ereport(ERROR,
                    (errcode(ERRCODE_OUT_OF_MEMORY),
                     errmsg("out of shared memory"),
                     errhint("You might need to increase \"%s\".", "max_locks_per_transaction")));
        }
        GrantLock(proclock->tag.myLock, proclock, ExclusiveLock);
 
        LWLockRelease(partitionLock);
 
        proc->fpVXIDLock = false;
    }
 
    /*
     * If the proc has an XID now, we'll avoid a TwoPhaseGetXidByVirtualXID()
     * search.  The proc might have assigned this XID but not yet locked it,
     * in which case the proc will lock this XID before releasing the VXID.
     * The fpInfoLock critical section excludes VirtualXactLockTableCleanup(),
     * so we won't save an XID of a different VXID.  It doesn't matter whether
     * we save this before or after setting up the primary lock table entry.
     */
    xid = proc->xid;
 
    /* Done with proc->fpLockBits */
    LWLockRelease(&proc->fpInfoLock);
 
    /* Time to wait. */
    (void) LockAcquire(&tag, ShareLock, false, false);
 
    LockRelease(&tag, ShareLock, false);
    return XactLockForVirtualXact(vxid, xid, wait);
}

References Assert(), DEFAULT_LOCKMETHOD, ereport, errcode(), errhint(), errmsg(), ERROR, ExclusiveLock, PGPROC::fpInfoLock, PGPROC::fpLocalTransactionId, PGPROC::fpVXIDLock, GrantLock(), InvalidTransactionId, VirtualTransactionId::localTransactionId, LockAcquire(), LockHashPartitionLock, LockMethods, LockRelease(), LockTagHashCode(), LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), PROCLOCKTAG::myLock, VirtualTransactionId::procNumber, PGPROC::procNumber, ProcNumberGetProc(), SET_LOCKTAG_VIRTUALTRANSACTION, SetupLockInTable(), ShareLock, PROCLOCK::tag, VirtualTransactionIdIsRecoveredPreparedXact, VirtualTransactionIdIsValid, PGPROC::vxid, XactLockForVirtualXact(), and PGPROC::xid.

Referenced by ResolveRecoveryConflictWithVirtualXIDs(), WaitForLockersMultiple(), and WaitForOlderSnapshots().

VirtualXactLockTableCleanup()

void VirtualXactLockTableCleanup

(

void

)

Definition at line 4645 of file lock.c.

{
    bool        fastpath;
    LocalTransactionId lxid;
 
    Assert(MyProc->vxid.procNumber != INVALID_PROC_NUMBER);
 
    /*
     * Clean up shared memory state.
     */
    LWLockAcquire(&MyProc->fpInfoLock, LW_EXCLUSIVE);
 
    fastpath = MyProc->fpVXIDLock;
    lxid = MyProc->fpLocalTransactionId;
    MyProc->fpVXIDLock = false;
    MyProc->fpLocalTransactionId = InvalidLocalTransactionId;
 
    LWLockRelease(&MyProc->fpInfoLock);
 
    /*
     * If fpVXIDLock has been cleared without touching fpLocalTransactionId,
     * that means someone transferred the lock to the main lock table.
     */
    if (!fastpath && LocalTransactionIdIsValid(lxid))
    {
        VirtualTransactionId vxid;
        LOCKTAG     locktag;
 
        vxid.procNumber = MyProcNumber;
        vxid.localTransactionId = lxid;
        SET_LOCKTAG_VIRTUALTRANSACTION(locktag, vxid);
 
        LockRefindAndRelease(LockMethods[DEFAULT_LOCKMETHOD], MyProc,
                             &locktag, ExclusiveLock, false);
    }
}

References Assert(), DEFAULT_LOCKMETHOD, ExclusiveLock, PGPROC::fpInfoLock, PGPROC::fpLocalTransactionId, PGPROC::fpVXIDLock, INVALID_PROC_NUMBER, InvalidLocalTransactionId, VirtualTransactionId::localTransactionId, LocalTransactionIdIsValid, LockMethods, LockRefindAndRelease(), LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), MyProc, MyProcNumber, VirtualTransactionId::procNumber, PGPROC::procNumber, SET_LOCKTAG_VIRTUALTRANSACTION, and PGPROC::vxid.

Referenced by LockReleaseAll(), and ShutdownRecoveryTransactionEnvironment().

VirtualXactLockTableInsert()

void VirtualXactLockTableInsert

(

VirtualTransactionId

vxid

)

Definition at line 4622 of file lock.c.

{
    Assert(VirtualTransactionIdIsValid(vxid));
 
    LWLockAcquire(&MyProc->fpInfoLock, LW_EXCLUSIVE);
 
    Assert(MyProc->vxid.procNumber == vxid.procNumber);
    Assert(MyProc->fpLocalTransactionId == InvalidLocalTransactionId);
    Assert(MyProc->fpVXIDLock == false);
 
    MyProc->fpVXIDLock = true;
    MyProc->fpLocalTransactionId = vxid.localTransactionId;
 
    LWLockRelease(&MyProc->fpInfoLock);
}

References Assert(), PGPROC::fpInfoLock, PGPROC::fpLocalTransactionId, PGPROC::fpVXIDLock, InvalidLocalTransactionId, VirtualTransactionId::localTransactionId, LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), MyProc, VirtualTransactionId::procNumber, PGPROC::procNumber, VirtualTransactionIdIsValid, and PGPROC::vxid.

Referenced by InitRecoveryTransactionEnvironment(), and StartTransaction().

WaitOnLock()

static ProcWaitStatus WaitOnLock ( LOCALLOCK *  locallock, ResourceOwner  owner  )

static

Definition at line 1932 of file lock.c.

{
    ProcWaitStatus result;
    ErrorContextCallback waiterrcontext;
 
    TRACE_POSTGRESQL_LOCK_WAIT_START(locallock->tag.lock.locktag_field1,
                                     locallock->tag.lock.locktag_field2,
                                     locallock->tag.lock.locktag_field3,
                                     locallock->tag.lock.locktag_field4,
                                     locallock->tag.lock.locktag_type,
                                     locallock->tag.mode);
 
    /* Setup error traceback support for ereport() */
    waiterrcontext.callback = waitonlock_error_callback;
    waiterrcontext.arg = (void *) locallock;
    waiterrcontext.previous = error_context_stack;
    error_context_stack = &waiterrcontext;
 
    /* adjust the process title to indicate that it's waiting */
    set_ps_display_suffix("waiting");
 
    /*
     * Record the fact that we are waiting for a lock, so that
     * LockErrorCleanup will clean up if cancel/die happens.
     */
    awaitedLock = locallock;
    awaitedOwner = owner;
 
    /*
     * NOTE: Think not to put any shared-state cleanup after the call to
     * ProcSleep, in either the normal or failure path.  The lock state must
     * be fully set by the lock grantor, or by CheckDeadLock if we give up
     * waiting for the lock.  This is necessary because of the possibility
     * that a cancel/die interrupt will interrupt ProcSleep after someone else
     * grants us the lock, but before we've noticed it. Hence, after granting,
     * the locktable state must fully reflect the fact that we own the lock;
     * we can't do additional work on return.
     *
     * We can and do use a PG_TRY block to try to clean up after failure, but
     * this still has a major limitation: elog(FATAL) can occur while waiting
     * (eg, a "die" interrupt), and then control won't come back here. So all
     * cleanup of essential state should happen in LockErrorCleanup, not here.
     * We can use PG_TRY to clear the "waiting" status flags, since doing that
     * is unimportant if the process exits.
     */
    PG_TRY();
    {
        result = ProcSleep(locallock);
    }
    PG_CATCH();
    {
        /* In this path, awaitedLock remains set until LockErrorCleanup */
 
        /* reset ps display to remove the suffix */
        set_ps_display_remove_suffix();
 
        /* and propagate the error */
        PG_RE_THROW();
    }
    PG_END_TRY();
 
    /*
     * We no longer want LockErrorCleanup to do anything.
     */
    awaitedLock = NULL;
 
    /* reset ps display to remove the suffix */
    set_ps_display_remove_suffix();
 
    error_context_stack = waiterrcontext.previous;
 
    TRACE_POSTGRESQL_LOCK_WAIT_DONE(locallock->tag.lock.locktag_field1,
                                    locallock->tag.lock.locktag_field2,
                                    locallock->tag.lock.locktag_field3,
                                    locallock->tag.lock.locktag_field4,
                                    locallock->tag.lock.locktag_type,
                                    locallock->tag.mode);
 
    return result;
}

References ErrorContextCallback::arg, awaitedLock, awaitedOwner, ErrorContextCallback::callback, error_context_stack, LOCALLOCKTAG::lock, LOCKTAG::locktag_field1, LOCKTAG::locktag_field2, LOCKTAG::locktag_field3, LOCKTAG::locktag_field4, LOCKTAG::locktag_type, LOCALLOCKTAG::mode, PG_CATCH, PG_END_TRY, PG_RE_THROW, PG_TRY, ErrorContextCallback::previous, ProcSleep(), set_ps_display_remove_suffix(), set_ps_display_suffix(), LOCALLOCK::tag, and waitonlock_error_callback().

Referenced by LockAcquireExtended().

waitonlock_error_callback()

static void waitonlock_error_callback ( void *  arg )

static

Definition at line 2020 of file lock.c.

{
    LOCALLOCK  *locallock = (LOCALLOCK *) arg;
    const LOCKTAG *tag = &locallock->tag.lock;
    LOCKMODE    mode = locallock->tag.mode;
    StringInfoData locktagbuf;
 
    initStringInfo(&locktagbuf);
    DescribeLockTag(&locktagbuf, tag);
 
    errcontext("waiting for %s on %s",
               GetLockmodeName(tag->locktag_lockmethodid, mode),
               locktagbuf.data);
}

References arg, StringInfoData::data, DescribeLockTag(), errcontext, GetLockmodeName(), initStringInfo(), LOCALLOCKTAG::lock, LOCKTAG::locktag_lockmethodid, mode, LOCALLOCKTAG::mode, and LOCALLOCK::tag.

Referenced by WaitOnLock().

XactLockForVirtualXact()

static bool XactLockForVirtualXact ( VirtualTransactionId  vxid, TransactionId  xid, bool  wait  )

static

Definition at line 4694 of file lock.c.

{
    bool        more = false;
 
    /* There is no point to wait for 2PCs if you have no 2PCs. */
    if (max_prepared_xacts == 0)
        return true;
 
    do
    {
        LockAcquireResult lar;
        LOCKTAG     tag;
 
        /* Clear state from previous iterations. */
        if (more)
        {
            xid = InvalidTransactionId;
            more = false;
        }
 
        /* If we have no xid, try to find one. */
        if (!TransactionIdIsValid(xid))
            xid = TwoPhaseGetXidByVirtualXID(vxid, &more);
        if (!TransactionIdIsValid(xid))
        {
            Assert(!more);
            return true;
        }
 
        /* Check or wait for XID completion. */
        SET_LOCKTAG_TRANSACTION(tag, xid);
        lar = LockAcquire(&tag, ShareLock, false, !wait);
        if (lar == LOCKACQUIRE_NOT_AVAIL)
            return false;
        LockRelease(&tag, ShareLock, false);
    } while (more);
 
    return true;
}

References Assert(), InvalidTransactionId, LockAcquire(), LOCKACQUIRE_NOT_AVAIL, LockRelease(), max_prepared_xacts, SET_LOCKTAG_TRANSACTION, ShareLock, TransactionIdIsValid, and TwoPhaseGetXidByVirtualXID().

Referenced by VirtualXactLock().

Variable Documentation

awaitedLock

LOCALLOCK* awaitedLock

static

Definition at line 328 of file lock.c.

Referenced by GetAwaitedLock(), GrantAwaitedLock(), ResetAwaitedLock(), and WaitOnLock().

awaitedOwner

ResourceOwner awaitedOwner

static

Definition at line 329 of file lock.c.

Referenced by GrantAwaitedLock(), and WaitOnLock().

default_lockmethod

const LockMethodData default_lockmethod

static

Initial value:

= {
    MaxLockMode,
    LockConflicts,
    lock_mode_names,
 
 
 
    &Dummy_trace
 
}

Definition at line 125 of file lock.c.

Dummy_trace

bool Dummy_trace = false

static

Definition at line 122 of file lock.c.

FastPathLocalUseCounts

int FastPathLocalUseCounts[FP_LOCK_GROUPS_PER_BACKEND_MAX]

static

Definition at line 176 of file lock.c.

Referenced by FastPathGrantRelationLock(), FastPathUnGrantRelationLock(), LockAcquireExtended(), and LockRelease().

FastPathLockGroupsPerBackend

int FastPathLockGroupsPerBackend = 0

Definition at line 202 of file lock.c.

Referenced by FastPathLockShmemSize(), GetLockStatusData(), InitializeFastPathLocks(), and InitProcGlobal().

FastPathStrongRelationLocks

volatile FastPathStrongRelationLockData* FastPathStrongRelationLocks

static

Definition at line 312 of file lock.c.

Referenced by AbortStrongLockAcquire(), BeginStrongLockAcquire(), lock_twophase_recover(), LockAcquireExtended(), LockManagerShmemInit(), LockRefindAndRelease(), and RemoveLocalLock().

lock_mode_names

const char* const lock_mode_names[]

static

Initial value:

=
{
    "INVALID",
    "AccessShareLock",
    "RowShareLock",
    "RowExclusiveLock",
    "ShareUpdateExclusiveLock",
    "ShareLock",
    "ShareRowExclusiveLock",
    "ExclusiveLock",
    "AccessExclusiveLock"
}

Definition at line 108 of file lock.c.

LockConflicts

const LOCKMASK LockConflicts[]

static

Definition at line 65 of file lock.c.

LockMethodLocalHash

HTAB* LockMethodLocalHash

static

Definition at line 323 of file lock.c.

Referenced by AtPrepare_Locks(), CheckForSessionAndXactLocks(), InitLockManagerAccess(), LockAcquireExtended(), LockHasWaiters(), LockHeldByMe(), LockReassignCurrentOwner(), LockRelease(), LockReleaseAll(), LockReleaseCurrentOwner(), LockReleaseSession(), PostPrepare_Locks(), and RemoveLocalLock().

LockMethodLockHash

HTAB* LockMethodLockHash

static

Definition at line 321 of file lock.c.

Referenced by CleanUpLock(), FastPathGetRelationLockEntry(), GetLockConflicts(), lock_twophase_recover(), LockManagerShmemInit(), LockRefindAndRelease(), LockRelease(), LockTagHashCode(), LockWaiterCount(), and SetupLockInTable().

LockMethodProcLockHash

HTAB* LockMethodProcLockHash

static

Definition at line 322 of file lock.c.

Referenced by CleanUpLock(), FastPathGetRelationLockEntry(), GetLockStatusData(), GetRunningTransactionLocks(), lock_twophase_recover(), LockAcquireExtended(), LockManagerShmemInit(), LockRefindAndRelease(), LockRelease(), PostPrepare_Locks(), and SetupLockInTable().

LockMethods

const LockMethod LockMethods[]

static

Initial value:

= {
    NULL,
    &default_lockmethod,
    &user_lockmethod
}

Definition at line 150 of file lock.c.

Referenced by DoLockModesConflict(), FastPathGetRelationLockEntry(), GetLockConflicts(), GetLockmodeName(), GetLocksMethodTable(), GetLockTagsMethodTable(), lock_twophase_postcommit(), lock_twophase_recover(), lock_twophase_standby_recover(), LockAcquireExtended(), LockHasWaiters(), LockRelease(), LockReleaseAll(), LockReleaseSession(), LockWaiterCount(), RemoveFromWaitQueue(), VirtualXactLock(), and VirtualXactLockTableCleanup().

log_lock_failures

bool log_lock_failures = false

Definition at line 54 of file lock.c.

Referenced by heap_acquire_tuplock(), heap_lock_tuple(), and heapam_tuple_lock().

max_locks_per_xact

int max_locks_per_xact

Definition at line 53 of file lock.c.

Referenced by CheckRequiredParameterValues(), InitControlFile(), InitializeFastPathLocks(), and XLogReportParameters().

PG_USED_FOR_ASSERTS_ONLY

bool IsRelationExtensionLockHeld PG_USED_FOR_ASSERTS_ONLY = false

static

Definition at line 191 of file lock.c.

StrongLockInProgress

LOCALLOCK* StrongLockInProgress

static

Definition at line 327 of file lock.c.

Referenced by AbortStrongLockAcquire(), BeginStrongLockAcquire(), and FinishStrongLockAcquire().

user_lockmethod

const LockMethodData user_lockmethod

static

Initial value:

= {
    MaxLockMode,
    LockConflicts,
    lock_mode_names,
 
 
 
    &Dummy_trace
 
}

Definition at line 136 of file lock.c.