From 2419060dfa640186dc22cb461a21d0eaf0b32307 Mon Sep 17 00:00:00 2001
From: Guido Trotter <ultrotter@google.com>
Date: Wed, 30 Sep 2009 18:30:07 +0100
Subject: [PATCH] Abstract "base" condition code in a separate class
Each condition has an underlying lock, the acquire and release methods,
and a few helper methods to check that it's called in the proper way.
Abstract them to a separate class so we can have more than one without
duplicating this code.
Signed-off-by: Guido Trotter <ultrotter@google.com>
Reviewed-by: Michael Hanselmann <hansmi@google.com>
---
lib/locking.py | 86 ++++++++++++++++++++++++++++++--------------------
1 file changed, 52 insertions(+), 34 deletions(-)
diff --git a/lib/locking.py b/lib/locking.py
index f7a62d279..1e14f6588 100644
--- a/lib/locking.py
+++ b/lib/locking.py
@@ -103,6 +103,55 @@ class _SingleActionPipeConditionWaiter(object):
remaining_time = start_time + timeout - time.time()
+class _BaseCondition(object):
+ """Base class containing common code for conditions.
+
+ Some of this code is taken from python's threading module.
+
+ """
+ __slots__ = [
+ "_lock",
+ "acquire",
+ "release",
+ ]
+
+ def __init__(self, lock):
+ """Constructor for _BaseCondition.
+
+ @type lock: L{threading.Lock}
+ @param lock: condition base lock
+
+ """
+ object.__init__(self)
+
+ # Recursive locks are not supported
+ assert not hasattr(lock, "_acquire_restore")
+ assert not hasattr(lock, "_release_save")
+
+ self._lock = lock
+
+ # Export the lock's acquire() and release() methods
+ self.acquire = lock.acquire
+ self.release = lock.release
+
+ def _is_owned(self):
+ """Check whether lock is owned by current thread.
+
+ """
+ if self._lock.acquire(0):
+ self._lock.release()
+ return False
+
+ return True
+
+ def _check_owned(self):
+ """Raise an exception if the current thread doesn't own the lock.
+
+ """
+ if not self._is_owned():
+ raise RuntimeError("cannot work with un-aquired lock")
+
+
class _SingleActionPipeCondition(object):
"""Wrapper around a pipe for usage inside conditions.
@@ -223,7 +272,7 @@ class _SingleActionPipeCondition(object):
self._Cleanup()
-class _PipeCondition(object):
+class _PipeCondition(_BaseCondition):
"""Group-only non-polling condition with counters.
This condition class uses pipes and poll, internally, to be able to wait for
@@ -233,12 +282,9 @@ class _PipeCondition(object):
there are any waiting threads.
"""
- __slots__ = [
- "_lock",
+ __slots__ = _BaseCondition.__slots__ + [
"_nwaiters",
"_pipe",
- "acquire",
- "release",
]
_pipe_class = _SingleActionPipeCondition
@@ -247,38 +293,10 @@ class _PipeCondition(object):
"""Initializes this class.
"""
- object.__init__(self)
-
- # Recursive locks are not supported
- assert not hasattr(lock, "_acquire_restore")
- assert not hasattr(lock, "_release_save")
-
- self._lock = lock
-
- # Export the lock's acquire() and release() methods
- self.acquire = lock.acquire
- self.release = lock.release
-
+ _BaseCondition.__init__(self, lock)
self._nwaiters = 0
self._pipe = None
- def _is_owned(self):
- """Check whether lock is owned by current thread.
-
- """
- if self._lock.acquire(0):
- self._lock.release()
- return False
-
- return True
-
- def _check_owned(self):
- """Raise an exception if the current thread doesn't own the lock.
-
- """
- if not self._is_owned():
- raise RuntimeError("cannot work with un-aquired lock")
-
def wait(self, timeout=None):
"""Wait for a notification.
--
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