[Python-checkins] cpython: asyncio: Change bounded semaphore into a subclass, like
guido.van.rossum
python-checkins at python.org
Sun Nov 24 00:09:25 CET 2013
http://hg.python.org/cpython/rev/6bee0fdcba39
changeset: 87468:6bee0fdcba39
user: Guido van Rossum <guido at python.org>
date: Sat Nov 23 15:09:16 2013 -0800
summary:
asyncio: Change bounded semaphore into a subclass, like threading.[Bounded]Semaphore.
files:
Lib/asyncio/locks.py | 36 ++++++++--------
Lib/test/test_asyncio/test_locks.py | 2 +-
2 files changed, 20 insertions(+), 18 deletions(-)
diff --git a/Lib/asyncio/locks.py b/Lib/asyncio/locks.py
--- a/Lib/asyncio/locks.py
+++ b/Lib/asyncio/locks.py
@@ -336,22 +336,15 @@
Semaphores also support the context manager protocol.
- The first optional argument gives the initial value for the internal
+ The optional argument gives the initial value for the internal
counter; it defaults to 1. If the value given is less than 0,
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):
+ def __init__(self, value=1, *, loop=None):
if value < 0:
raise ValueError("Semaphore initial value must be >= 0")
self._value = value
- self._bound = bound
- self._bound_value = value
self._waiters = collections.deque()
self._locked = (value == 0)
if loop is not None:
@@ -402,17 +395,9 @@
"""Release a semaphore, incrementing the internal counter by one.
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 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.
"""
- if self._bound and self._value >= self._bound_value:
- raise ValueError('Semaphore released too many times')
-
self._value += 1
self._locked = False
-
for waiter in self._waiters:
if not waiter.done():
waiter.set_result(True)
@@ -429,3 +414,20 @@
def __iter__(self):
yield from self.acquire()
return self
+
+
+class BoundedSemaphore(Semaphore):
+ """A bounded semaphore implementation.
+
+ This raises ValueError in release() if it would increase the value
+ above the initial value.
+ """
+
+ def __init__(self, value=1, *, loop=None):
+ self._bound_value = value
+ super().__init__(value, loop=loop)
+
+ def release(self):
+ if self._value >= self._bound_value:
+ raise ValueError('BoundedSemaphore released too many times')
+ super().release()
diff --git a/Lib/test/test_asyncio/test_locks.py b/Lib/test/test_asyncio/test_locks.py
--- a/Lib/test/test_asyncio/test_locks.py
+++ b/Lib/test/test_asyncio/test_locks.py
@@ -805,7 +805,7 @@
self.assertFalse(sem._waiters)
def test_release_not_acquired(self):
- sem = locks.Semaphore(bound=True, loop=self.loop)
+ sem = locks.BoundedSemaphore(loop=self.loop)
self.assertRaises(ValueError, sem.release)
--
Repository URL: http://hg.python.org/cpython
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