asyncio: Locks improvements by Arnaud Faure: better repr(), change Conditio\

Guido van Rossum · Guido van Rossum · commit ccea08462b75 · 2013-11-04T13:18:19.000-08:00
n structure.
diff --git a/Lib/asyncio/locks.py b/Lib/asyncio/locks.py
@@ -155,9 +155,11 @@ def __init__(self, *, loop=None):
             self._loop = events.get_event_loop()
 
     def __repr__(self):
-        # TODO: add waiters:N if > 0.
         res = super().__repr__()
-        return '<{} [{}]>'.format(res[1:-1], 'set' if self._value else 'unset')
+        extra = 'set' if self._value else 'unset'
+        if self._waiters:
+            extra = '{},waiters:{}'.format(extra, len(self._waiters))
+        return '<{} [{}]>'.format(res[1:-1], extra)
 
     def is_set(self):
         """Return true if and only if the internal flag is true."""
@@ -201,20 +203,38 @@ def wait(self):
             self._waiters.remove(fut)
 
 
-# TODO: Why is this a Lock subclass?  threading.Condition *has* a lock.
-class Condition(Lock):
-    """A Condition implementation.
+class Condition:
+    """A Condition implementation, our equivalent to threading.Condition.
 
     This class implements condition variable objects. A condition variable
     allows one or more coroutines to wait until they are notified by another
     coroutine.
+
+    A new Lock object is created and used as the underlying lock.
     """
 
     def __init__(self, *, loop=None):
-        super().__init__(loop=loop)
-        self._condition_waiters = collections.deque()
+        if loop is not None:
+            self._loop = loop
+        else:
+            self._loop = events.get_event_loop()
 
-    # TODO: Add __repr__() with len(_condition_waiters).
+        # Lock as an attribute as in threading.Condition.
+        lock = Lock(loop=self._loop)
+        self._lock = lock
+        # Export the lock's locked(), acquire() and release() methods.
+        self.locked = lock.locked
+        self.acquire = lock.acquire
+        self.release = lock.release
+
+        self._waiters = collections.deque()
+
+    def __repr__(self):
+        res = super().__repr__()
+        extra = 'locked' if self.locked() else 'unlocked'
+        if self._waiters:
+            extra = '{},waiters:{}'.format(extra, len(self._waiters))
+        return '<{} [{}]>'.format(res[1:-1], extra)
 
     @tasks.coroutine
     def wait(self):
@@ -228,19 +248,19 @@ def wait(self):
         the same condition variable in another coroutine.  Once
         awakened, it re-acquires the lock and returns True.
         """
-        if not self._locked:
+        if not self.locked():
             raise RuntimeError('cannot wait on un-acquired lock')
 
         keep_lock = True
         self.release()
         try:
             fut = futures.Future(loop=self._loop)
-            self._condition_waiters.append(fut)
+            self._waiters.append(fut)
             try:
                 yield from fut
                 return True
             finally:
-                self._condition_waiters.remove(fut)
+                self._waiters.remove(fut)
 
         except GeneratorExit:
             keep_lock = False  # Prevent yield in finally clause.
@@ -275,11 +295,11 @@ def notify(self, n=1):
         wait() call until it can reacquire the lock. Since notify() does
         not release the lock, its caller should.
         """
-        if not self._locked:
+        if not self.locked():
             raise RuntimeError('cannot notify on un-acquired lock')
 
         idx = 0
-        for fut in self._condition_waiters:
+        for fut in self._waiters:
             if idx >= n:
                 break
 
@@ -293,7 +313,17 @@ def notify_all(self):
         calling thread has not acquired the lock when this method is called,
         a RuntimeError is raised.
         """
-        self.notify(len(self._condition_waiters))
+        self.notify(len(self._waiters))
+
+    def __enter__(self):
+        return self._lock.__enter__()
+
+    def __exit__(self, *args):
+        return self._lock.__exit__(*args)
+
+    def __iter__(self):
+        yield from self.acquire()
+        return self
 
 
 class Semaphore:
@@ -310,10 +340,10 @@ class Semaphore:
     counter; it defaults to 1. If the value given is less than 0,
     ValueError is raised.
 
-    The second optional argument determins can semophore be released more than
-    initial internal counter value; it defaults to False. If the value given
-    is True and number of release() is more than number of successfull
-    acquire() calls ValueError is raised.
+    The second optional argument determines if the semaphore can be released
+    more than initial internal counter value; it defaults to False. If the
+    value given is True and number of release() is more than number of
+    successful acquire() calls ValueError is raised.
     """
 
     def __init__(self, value=1, bound=False, *, loop=None):
@@ -330,12 +360,12 @@ def __init__(self, value=1, bound=False, *, loop=None):
             self._loop = events.get_event_loop()
 
     def __repr__(self):
-        # TODO: add waiters:N if > 0.
         res = super().__repr__()
-        return '<{} [{}]>'.format(
-            res[1:-1],
-            'locked' if self._locked else 'unlocked,value:{}'.format(
-                self._value))
+        extra = 'locked' if self._locked else 'unlocked,value:{}'.format(
+            self._value)
+        if self._waiters:
+            extra = '{},waiters:{}'.format(extra, len(self._waiters))
+        return '<{} [{}]>'.format(res[1:-1], extra)
 
     def locked(self):
         """Returns True if semaphore can not be acquired immediately."""
@@ -373,7 +403,7 @@ def release(self):
         When it was zero on entry and another coroutine is waiting for it to
         become larger than zero again, wake up that coroutine.
 
-        If Semaphore is create with "bound" paramter equals true, then
+        If Semaphore is created with "bound" parameter equals true, then
         release() method checks to make sure its current value doesn't exceed
         its initial value. If it does, ValueError is raised.
         """
diff --git a/Lib/test/test_asyncio/test_locks.py b/Lib/test/test_asyncio/test_locks.py
@@ -2,6 +2,7 @@
 
 import unittest
 import unittest.mock
+import re
 
 from asyncio import events
 from asyncio import futures
@@ -10,6 +11,15 @@
 from asyncio import test_utils
 
 
+STR_RGX_REPR = (
+    r'^<(?P<class>.*?) object at (?P<address>.*?)'
+    r'\[(?P<extras>'
+    r'(set|unset|locked|unlocked)(,value:\d)?(,waiters:\d+)?'
+    r')\]>\Z'
+)
+RGX_REPR = re.compile(STR_RGX_REPR)
+
+
 class LockTests(unittest.TestCase):
 
     def setUp(self):
@@ -38,13 +48,15 @@ def test_ctor_noloop(self):
     def test_repr(self):
         lock = locks.Lock(loop=self.loop)
         self.assertTrue(repr(lock).endswith('[unlocked]>'))
+        self.assertTrue(RGX_REPR.match(repr(lock)))
 
         @tasks.coroutine
         def acquire_lock():
             yield from lock
 
         self.loop.run_until_complete(acquire_lock())
         self.assertTrue(repr(lock).endswith('[locked]>'))
+        self.assertTrue(RGX_REPR.match(repr(lock)))
 
     def test_lock(self):
         lock = locks.Lock(loop=self.loop)
@@ -239,9 +251,16 @@ def test_ctor_noloop(self):
     def test_repr(self):
         ev = locks.Event(loop=self.loop)
         self.assertTrue(repr(ev).endswith('[unset]>'))
+        match = RGX_REPR.match(repr(ev))
+        self.assertEqual(match.group('extras'), 'unset')
 
         ev.set()
         self.assertTrue(repr(ev).endswith('[set]>'))
+        self.assertTrue(RGX_REPR.match(repr(ev)))
+
+        ev._waiters.append(unittest.mock.Mock())
+        self.assertTrue('waiters:1' in repr(ev))
+        self.assertTrue(RGX_REPR.match(repr(ev)))
 
     def test_wait(self):
         ev = locks.Event(loop=self.loop)
@@ -440,7 +459,7 @@ def test_wait_cancel(self):
         self.assertRaises(
             futures.CancelledError,
             self.loop.run_until_complete, wait)
-        self.assertFalse(cond._condition_waiters)
+        self.assertFalse(cond._waiters)
         self.assertTrue(cond.locked())
 
     def test_wait_unacquired(self):
@@ -600,6 +619,45 @@ def test_notify_all_unacquired(self):
         cond = locks.Condition(loop=self.loop)
         self.assertRaises(RuntimeError, cond.notify_all)
 
+    def test_repr(self):
+        cond = locks.Condition(loop=self.loop)
+        self.assertTrue('unlocked' in repr(cond))
+        self.assertTrue(RGX_REPR.match(repr(cond)))
+
+        self.loop.run_until_complete(cond.acquire())
+        self.assertTrue('locked' in repr(cond))
+
+        cond._waiters.append(unittest.mock.Mock())
+        self.assertTrue('waiters:1' in repr(cond))
+        self.assertTrue(RGX_REPR.match(repr(cond)))
+
+        cond._waiters.append(unittest.mock.Mock())
+        self.assertTrue('waiters:2' in repr(cond))
+        self.assertTrue(RGX_REPR.match(repr(cond)))
+
+    def test_context_manager(self):
+        cond = locks.Condition(loop=self.loop)
+
+        @tasks.coroutine
+        def acquire_cond():
+            return (yield from cond)
+
+        with self.loop.run_until_complete(acquire_cond()):
+            self.assertTrue(cond.locked())
+
+        self.assertFalse(cond.locked())
+
+    def test_context_manager_no_yield(self):
+        cond = locks.Condition(loop=self.loop)
+
+        try:
+            with cond:
+                self.fail('RuntimeError is not raised in with expression')
+        except RuntimeError as err:
+            self.assertEqual(
+                str(err),
+                '"yield from" should be used as context manager expression')
+
 
 class SemaphoreTests(unittest.TestCase):
 
@@ -629,9 +687,20 @@ def test_ctor_noloop(self):
     def test_repr(self):
         sem = locks.Semaphore(loop=self.loop)
         self.assertTrue(repr(sem).endswith('[unlocked,value:1]>'))
+        self.assertTrue(RGX_REPR.match(repr(sem)))
 
         self.loop.run_until_complete(sem.acquire())
         self.assertTrue(repr(sem).endswith('[locked]>'))
+        self.assertTrue('waiters' not in repr(sem))
+        self.assertTrue(RGX_REPR.match(repr(sem)))
+
+        sem._waiters.append(unittest.mock.Mock())
+        self.assertTrue('waiters:1' in repr(sem))
+        self.assertTrue(RGX_REPR.match(repr(sem)))
+
+        sem._waiters.append(unittest.mock.Mock())
+        self.assertTrue('waiters:2' in repr(sem))
+        self.assertTrue(RGX_REPR.match(repr(sem)))
 
     def test_semaphore(self):
         sem = locks.Semaphore(loop=self.loop)
