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ByronByron
committed
Provide handle with a snapshot of the store's state (#266)
1 parent d5565da commit 6e0cd6d

13 files changed

Lines changed: 123 additions & 81 deletions

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‎experiments/odb-redesign/src/lib.rs‎

Lines changed: 26 additions & 14 deletions
Original file line numberDiff line numberDiff line change
@@ -1,33 +1,41 @@
11
#![allow(dead_code, unused_variables, unreachable_code)]
22

33
mod odb {
4-
use arc_swap::ArcSwap;
5-
use std::path::PathBuf;
6-
use std::sync::atomic::{AtomicUsize, Ordering};
7-
use std::sync::Arc;
4+
use std::{
5+
path::PathBuf,
6+
sync::{
7+
atomic::{AtomicUsize, Ordering},
8+
Arc,
9+
},
10+
};
811

12+
use arc_swap::ArcSwap;
913
use git_hash::oid;
1014
use git_odb::pack::{data::entry::Location, find::Entry};
1115

1216
use crate::odb::store::{load_indices, SlotIndexMarker, SlotMapIndex};
1317

1418
pub mod store {
15-
use arc_swap::ArcSwap;
16-
use std::ops::Deref;
17-
use std::sync::atomic::{AtomicUsize, Ordering};
18-
use std::sync::Arc;
1919
use std::{
2020
io,
21+
ops::Deref,
2122
path::{Path, PathBuf},
23+
sync::{
24+
atomic::{AtomicUsize, Ordering},
25+
Arc,
26+
},
2227
};
2328

24-
use crate::odb::Store;
29+
use arc_swap::ArcSwap;
2530
use git_hash::oid;
2631

32+
use crate::odb::Store;
33+
2734
mod index_file {
28-
use crate::odb::store;
2935
use std::sync::Arc;
3036

37+
use crate::odb::store;
38+
3139
pub enum SingleOrMulti {
3240
Single {
3341
index: Arc<git_pack::index::File>,
@@ -342,9 +350,10 @@ mod odb {
342350
}
343351

344352
pub mod load_indices {
345-
use crate::odb::{store, store::SlotIndexMarker};
346353
use std::sync::Arc;
347354

355+
use crate::odb::{store, store::SlotIndexMarker};
356+
348357
pub(crate) enum Outcome {
349358
/// Drop all data and fully replace it with `indices`.
350359
/// This happens if we have witnessed a generational change invalidating all of our ids and causing currently loaded
@@ -603,8 +612,10 @@ mod odb {
603612
}
604613

605614
mod refs {
606-
use std::path::{Path, PathBuf};
607-
use std::sync::Arc;
615+
use std::{
616+
path::{Path, PathBuf},
617+
sync::Arc,
618+
};
608619

609620
pub struct LooseStore {
610621
path: PathBuf,
@@ -669,9 +680,10 @@ mod refs {
669680
}
670681

671682
mod repository {
672-
use crate::{odb, refs};
673683
use std::sync::Arc;
674684

685+
use crate::{odb, refs};
686+
675687
mod raw {
676688
use git_pack::Find;
677689

‎git-odb/src/lib.rs‎

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -15,9 +15,10 @@
1515
//! * This is the database closely resembling the object database in a git repository, and probably what most people would want to use.
1616
//! * [`linked::Store`]
1717
//! * A database containing various [`compound::Stores`][compound::Store] as gathered from `alternates` files.
18+
use std::path::PathBuf;
19+
1820
use git_features::threading::OwnShared;
1921
pub use git_pack as pack;
20-
use std::path::PathBuf;
2122

2223
mod store;
2324
pub use store::{compound, general, handle, linked, loose, sink, Cache, RefreshMode, Sink};

‎git-odb/src/store/general/find.rs‎

Lines changed: 3 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -1,9 +1,8 @@
1+
use std::ops::Deref;
2+
13
use git_hash::oid;
24
use git_object::Data;
3-
use git_pack::cache::DecodeEntry;
4-
use git_pack::data::entry::Location;
5-
use git_pack::index::Entry;
6-
use std::ops::Deref;
5+
use git_pack::{cache::DecodeEntry, data::entry::Location, index::Entry};
76

87
impl<S> crate::pack::Find for super::Handle<S>
98
where

‎git-odb/src/store/general/handle.rs‎

Lines changed: 13 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -1,8 +1,11 @@
1-
use crate::general::store;
1+
use std::{
2+
ops::Deref,
3+
sync::{atomic::Ordering, Arc},
4+
};
5+
26
use git_features::threading::OwnShared;
3-
use std::ops::Deref;
4-
use std::sync::atomic::Ordering;
5-
use std::sync::Arc;
7+
8+
use crate::general::store;
69

710
pub(crate) mod multi_index {
811
// TODO: replace this one with an actual implementation of a multi-pack index.
@@ -33,10 +36,12 @@ pub struct IndexForObjectInPack {
3336
}
3437

3538
pub(crate) mod index_lookup {
36-
use crate::general::{handle, store};
37-
use git_hash::oid;
3839
use std::sync::Arc;
3940

41+
use git_hash::oid;
42+
43+
use crate::general::{handle, store};
44+
4045
impl handle::IndexLookup {
4146
/// See if the oid is contained in this index, and return its full id for lookup possibly alongside its data file if already
4247
/// loaded.
@@ -111,6 +116,7 @@ impl super::Store {
111116
store: self.clone(),
112117
refresh_mode,
113118
token: Some(token),
119+
snapshot: self.collect_snapshot(),
114120
}
115121
}
116122
}
@@ -151,6 +157,7 @@ where
151157
store: self.store.clone(),
152158
refresh_mode: self.refresh_mode,
153159
token: self.store.register_handle().into(),
160+
snapshot: self.store.collect_snapshot(),
154161
}
155162
}
156163
}

‎git-odb/src/store/general/init.rs‎

Lines changed: 12 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -1,12 +1,17 @@
1-
use crate::general::store;
2-
use crate::general::store::{MutableIndexAndPack, SlotMapIndex};
1+
use std::{
2+
iter::FromIterator,
3+
ops::Deref,
4+
path::PathBuf,
5+
sync::{atomic::AtomicUsize, Arc},
6+
};
7+
38
use arc_swap::ArcSwap;
49
use git_features::threading::OwnShared;
5-
use std::iter::FromIterator;
6-
use std::ops::Deref;
7-
use std::path::PathBuf;
8-
use std::sync::atomic::AtomicUsize;
9-
use std::sync::Arc;
10+
11+
use crate::general::{
12+
store,
13+
store::{MutableIndexAndPack, SlotMapIndex},
14+
};
1015

1116
impl super::Store {
1217
pub fn at(objects_dir: impl Into<PathBuf>) -> std::io::Result<Self> {

‎git-odb/src/store/general/load_indices.rs‎

Lines changed: 36 additions & 35 deletions
Original file line numberDiff line numberDiff line change
@@ -1,48 +1,48 @@
1-
use crate::general::{handle, store};
2-
use std::path::PathBuf;
1+
use std::{
2+
path::PathBuf,
3+
sync::{atomic::Ordering, Arc},
4+
};
35

4-
use crate::general::store::StateId;
5-
use crate::RefreshMode;
6-
use std::sync::atomic::Ordering;
7-
use std::sync::Arc;
6+
use crate::{
7+
general::{handle, store, store::StateId},
8+
RefreshMode,
9+
};
810

911
pub(crate) enum Outcome {
1012
/// Drop all data and fully replace it with `indices`.
1113
/// This happens if we have witnessed a generational change invalidating all of our ids and causing currently loaded
1214
/// indices and maps to be dropped.
13-
Replace {
14-
indices: Vec<handle::IndexLookup>, // should probably be SmallVec to get around most allocations
15-
loose_dbs: Arc<Vec<crate::loose::Store>>,
16-
marker: store::SlotIndexMarker, // use to show where the caller left off last time
17-
},
15+
Replace(Snapshot),
1816
/// Despite all values being full copies, indices are still compatible to what was before. This also means
1917
/// the caller can continue searching the added indices and loose-dbs.
2018
/// Or in other words, new indices were only added to the known list, and what was seen before is known not to have changed.
2119
/// Besides that, the full internal state can be replaced as with `Replace`.
22-
ReplaceStable {
23-
indices: Vec<handle::IndexLookup>, // should probably be SmallVec to get around most allocations
24-
loose_dbs: Arc<Vec<crate::loose::Store>>,
25-
marker: store::SlotIndexMarker, // use to show where the caller left off last time
26-
},
27-
/// No new indices to look at, caller should give up
28-
NoMoreIndices,
20+
ReplaceStable(Snapshot),
21+
}
22+
23+
pub(crate) struct Snapshot {
24+
indices: Vec<handle::IndexLookup>, // should probably be SmallVec to get around most allocations
25+
loose_dbs: Arc<Vec<crate::loose::Store>>,
26+
marker: store::SlotIndexMarker, // use to show where the caller left off last time
2927
}
3028

3129
impl super::Store {
30+
/// If `None` is returned, there is new indices and the caller should give up. This is a possibility even if it's allowed to refresh
31+
/// as here might be no change to pick up.
3232
pub(crate) fn load_next_indices(
3333
&self,
3434
refresh_mode: RefreshMode,
3535
marker: Option<store::SlotIndexMarker>,
36-
) -> std::io::Result<Outcome> {
36+
) -> std::io::Result<Option<Outcome>> {
3737
let index = self.index.load();
3838
let state_id = index.state_id();
39-
if index.loose_dbs.is_empty() {
39+
if !index.is_initialized() {
4040
// TODO: figure out what kind of refreshes we need. This one loads in the initial slot map, but I think this cost is paid
4141
// in full during instantiation.
4242
return self.consolidate_with_disk_state(state_id);
4343
}
4444

45-
Ok(match marker {
45+
Ok(Some(match marker {
4646
Some(marker) => {
4747
if marker.generation != index.generation {
4848
self.collect_replace_outcome(false /*stable*/)
@@ -51,19 +51,19 @@ impl super::Store {
5151

5252
// …and if that didn't yield anything new consider refreshing our disk state.
5353
match refresh_mode {
54-
RefreshMode::Never => Outcome::NoMoreIndices,
54+
RefreshMode::Never => return Ok(None),
5555
RefreshMode::AfterAllIndicesLoaded => return self.consolidate_with_disk_state(state_id),
5656
}
5757
} else {
5858
self.collect_replace_outcome(true /*stable*/)
5959
}
6060
}
6161
None => self.collect_replace_outcome(false /*stable*/),
62-
})
62+
}))
6363
}
6464

6565
/// refresh and possibly clear out our existing data structures, causing all pack ids to be invalidated.
66-
fn consolidate_with_disk_state(&self, seen: StateId) -> std::io::Result<Outcome> {
66+
fn consolidate_with_disk_state(&self, seen: StateId) -> std::io::Result<Option<Outcome>> {
6767
let objects_directory = self.path.lock();
6868
if seen != self.index.load().state_id() {
6969
todo!("return …")
@@ -85,7 +85,7 @@ impl super::Store {
8585
self.num_handles_stable.load(Ordering::SeqCst) == 0
8686
}
8787

88-
fn collect_replace_outcome(&self, is_stable: bool) -> Outcome {
88+
pub(crate) fn collect_snapshot(&self) -> Snapshot {
8989
let index = self.index.load();
9090
let indices = index
9191
.slot_indices
@@ -106,18 +106,19 @@ impl super::Store {
106106
})
107107
.collect();
108108

109+
Snapshot {
110+
indices,
111+
loose_dbs: Arc::clone(&index.loose_dbs),
112+
marker: index.marker(),
113+
}
114+
}
115+
116+
fn collect_replace_outcome(&self, is_stable: bool) -> Outcome {
117+
let snapshot = self.collect_snapshot();
109118
if is_stable {
110-
Outcome::ReplaceStable {
111-
indices,
112-
loose_dbs: Arc::clone(&index.loose_dbs),
113-
marker: index.marker(),
114-
}
119+
Outcome::ReplaceStable(snapshot)
115120
} else {
116-
Outcome::Replace {
117-
indices,
118-
loose_dbs: Arc::clone(&index.loose_dbs),
119-
marker: index.marker(),
120-
}
121+
Outcome::Replace(snapshot)
121122
}
122123
}
123124
}

‎git-odb/src/store/general/metrics.rs‎

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1,7 +1,7 @@
1-
use crate::general::store;
2-
use crate::general::store::IndexAndPacks;
31
use std::sync::atomic::Ordering;
42

3+
use crate::general::{store, store::IndexAndPacks};
4+
55
impl super::Store {
66
pub fn metrics(&self) -> store::Metrics {
77
let mut open_packs = 0;

‎git-odb/src/store/general/mod.rs‎

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -1,9 +1,8 @@
11
#![allow(missing_docs, unused, dead_code)]
22

3+
use std::{ops::Deref, path::PathBuf, sync::atomic::AtomicUsize};
4+
35
use arc_swap::ArcSwap;
4-
use std::ops::Deref;
5-
use std::path::PathBuf;
6-
use std::sync::atomic::AtomicUsize;
76

87
/// This effectively acts like a handle but exists to be usable from the actual `crate::Handle` implementation which adds caches on top.
98
/// Each store is quickly cloned and contains thread-local state for shared packs.
@@ -15,6 +14,7 @@ where
1514
pub refresh_mode: crate::RefreshMode,
1615

1716
pub(crate) token: Option<handle::Mode>,
17+
snapshot: load_indices::Snapshot,
1818
}
1919

2020
pub struct Store {

‎git-odb/src/store/general/store.rs‎

Lines changed: 14 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -1,9 +1,14 @@
1+
use std::{
2+
ops::BitXor,
3+
path::{Path, PathBuf},
4+
sync::{
5+
atomic::{AtomicUsize, Ordering},
6+
Arc,
7+
},
8+
};
9+
110
use arc_swap::ArcSwap;
211
use git_features::hash;
3-
use std::ops::BitXor;
4-
use std::path::{Path, PathBuf};
5-
use std::sync::atomic::{AtomicUsize, Ordering};
6-
use std::sync::Arc;
712

813
/// An id to refer to an index file or a multipack index file
914
pub type IndexId = usize;
@@ -68,6 +73,11 @@ impl SlotMapIndex {
6873
state_id: self.state_id(),
6974
}
7075
}
76+
77+
/// Returns true if we already know at least one loose object db, a sign of being initialized
78+
pub(crate) fn is_initialized(&self) -> bool {
79+
!self.loose_dbs.is_empty()
80+
}
7181
}
7282

7383
#[derive(Clone)]

‎git-traverse/tests/commit/mod.rs‎

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1,9 +1,10 @@
11
mod ancestor {
2-
use crate::hex_to_id;
32
use git_hash::{oid, ObjectId};
43
use git_odb::{linked::Store, pack::FindExt};
54
use git_traverse::commit;
65

6+
use crate::hex_to_id;
7+
78
struct TraversalAssertion<'a> {
89
init_script: &'a str,
910
tips: &'a [&'a str],

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