lib/python2.7/multiprocessing/synchronize.py - platform/prebuilts/python/darwin-x86/2.7.5 - Git at Google

 #
 # Module implementing synchronization primitives
 #
 # multiprocessing/synchronize.py
 #
 # Copyright (c) 2006-2008, R Oudkerk
 # All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions
 # are met:
 #
 # 1. Redistributions of source code must retain the above copyright
 #    notice, this list of conditions and the following disclaimer.
 # 2. Redistributions in binary form must reproduce the above copyright
 #    notice, this list of conditions and the following disclaimer in the
 #    documentation and/or other materials provided with the distribution.
 # 3. Neither the name of author nor the names of any contributors may be
 #    used to endorse or promote products derived from this software
 #    without specific prior written permission.
 #
 # THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS "AS IS" AND
 # ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 # IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 # ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 # FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 # DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 # OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 # HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 # LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 # OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 # SUCH DAMAGE.
 #

 __all__ = [
     'Lock', 'RLock', 'Semaphore', 'BoundedSemaphore', 'Condition', 'Event'
     ]

 import threading
 import os
 import sys

 from time import time as _time, sleep as _sleep

 import _multiprocessing
 from multiprocessing.process import current_process
 from multiprocessing.util import Finalize, register_after_fork, debug
 from multiprocessing.forking import assert_spawning, Popen

 # Try to import the mp.synchronize module cleanly, if it fails
 # raise ImportError for platforms lacking a working sem_open implementation.
 # See issue 3770
 try:
     from _multiprocessing import SemLock
 except (ImportError):
     raise ImportError("This platform lacks a functioning sem_open" +
                       " implementation, therefore, the required" +
                       " synchronization primitives needed will not" +
                       " function, see issue 3770.")

 #
 # Constants
 #

 RECURSIVE_MUTEX, SEMAPHORE = range(2)
 SEM_VALUE_MAX = _multiprocessing.SemLock.SEM_VALUE_MAX

 #
 # Base class for semaphores and mutexes; wraps `_multiprocessing.SemLock`
 #

 class SemLock(object):

     def __init__(self, kind, value, maxvalue):
         sl = self._semlock = _multiprocessing.SemLock(kind, value, maxvalue)
         debug('created semlock with handle %s' % sl.handle)
         self._make_methods()

         if sys.platform != 'win32':
             def _after_fork(obj):
                 obj._semlock._after_fork()
             register_after_fork(self, _after_fork)

     def _make_methods(self):
         self.acquire = self._semlock.acquire
         self.release = self._semlock.release

     def __enter__(self):
         return self._semlock.__enter__()

     def __exit__(self, *args):
         return self._semlock.__exit__(*args)

     def __getstate__(self):
         assert_spawning(self)
         sl = self._semlock
         return (Popen.duplicate_for_child(sl.handle), sl.kind, sl.maxvalue)

     def __setstate__(self, state):
         self._semlock = _multiprocessing.SemLock._rebuild(*state)
         debug('recreated blocker with handle %r' % state[0])
         self._make_methods()

 #
 # Semaphore
 #

 class Semaphore(SemLock):

     def __init__(self, value=1):
         SemLock.__init__(self, SEMAPHORE, value, SEM_VALUE_MAX)

     def get_value(self):
         return self._semlock._get_value()

     def __repr__(self):
         try:
             value = self._semlock._get_value()
         except Exception:
             value = 'unknown'
         return '<Semaphore(value=%s)>' % value

 #
 # Bounded semaphore
 #

 class BoundedSemaphore(Semaphore):

     def __init__(self, value=1):
         SemLock.__init__(self, SEMAPHORE, value, value)

     def __repr__(self):
         try:
             value = self._semlock._get_value()
         except Exception:
             value = 'unknown'
         return '<BoundedSemaphore(value=%s, maxvalue=%s)>' % \
                (value, self._semlock.maxvalue)

 #
 # Non-recursive lock
 #

 class Lock(SemLock):

     def __init__(self):
         SemLock.__init__(self, SEMAPHORE, 1, 1)

     def __repr__(self):
         try:
             if self._semlock._is_mine():
                 name = current_process().name
                 if threading.current_thread().name != 'MainThread':
                     name += '|' + threading.current_thread().name
             elif self._semlock._get_value() == 1:
                 name = 'None'
             elif self._semlock._count() > 0:
                 name = 'SomeOtherThread'
             else:
                 name = 'SomeOtherProcess'
         except Exception:
             name = 'unknown'
         return '<Lock(owner=%s)>' % name

 #
 # Recursive lock
 #

 class RLock(SemLock):

     def __init__(self):
         SemLock.__init__(self, RECURSIVE_MUTEX, 1, 1)

     def __repr__(self):
         try:
             if self._semlock._is_mine():
                 name = current_process().name
                 if threading.current_thread().name != 'MainThread':
                     name += '|' + threading.current_thread().name
                 count = self._semlock._count()
             elif self._semlock._get_value() == 1:
                 name, count = 'None', 0
             elif self._semlock._count() > 0:
                 name, count = 'SomeOtherThread', 'nonzero'
             else:
                 name, count = 'SomeOtherProcess', 'nonzero'
         except Exception:
             name, count = 'unknown', 'unknown'
         return '<RLock(%s, %s)>' % (name, count)

 #
 # Condition variable
 #

 class Condition(object):

     def __init__(self, lock=None):
         self._lock = lock or RLock()
         self._sleeping_count = Semaphore(0)
         self._woken_count = Semaphore(0)
         self._wait_semaphore = Semaphore(0)
         self._make_methods()

     def __getstate__(self):
         assert_spawning(self)
         return (self._lock, self._sleeping_count,
                 self._woken_count, self._wait_semaphore)

     def __setstate__(self, state):
         (self._lock, self._sleeping_count,
          self._woken_count, self._wait_semaphore) = state
         self._make_methods()

     def __enter__(self):
         return self._lock.__enter__()

     def __exit__(self, *args):
         return self._lock.__exit__(*args)

     def _make_methods(self):
         self.acquire = self._lock.acquire
         self.release = self._lock.release

     def __repr__(self):
         try:
             num_waiters = (self._sleeping_count._semlock._get_value() -
                            self._woken_count._semlock._get_value())
         except Exception:
             num_waiters = 'unkown'
         return '<Condition(%s, %s)>' % (self._lock, num_waiters)

     def wait(self, timeout=None):
         assert self._lock._semlock._is_mine(), \
                'must acquire() condition before using wait()'

         # indicate that this thread is going to sleep
         self._sleeping_count.release()

         # release lock
         count = self._lock._semlock._count()
         for i in xrange(count):
             self._lock.release()

         try:
             # wait for notification or timeout
             self._wait_semaphore.acquire(True, timeout)
         finally:
             # indicate that this thread has woken
             self._woken_count.release()

             # reacquire lock
             for i in xrange(count):
                 self._lock.acquire()

     def notify(self):
         assert self._lock._semlock._is_mine(), 'lock is not owned'
         assert not self._wait_semaphore.acquire(False)

         # to take account of timeouts since last notify() we subtract
         # woken_count from sleeping_count and rezero woken_count
         while self._woken_count.acquire(False):
             res = self._sleeping_count.acquire(False)
             assert res

         if self._sleeping_count.acquire(False): # try grabbing a sleeper
             self._wait_semaphore.release()      # wake up one sleeper
             self._woken_count.acquire()         # wait for the sleeper to wake

             # rezero _wait_semaphore in case a timeout just happened
             self._wait_semaphore.acquire(False)

     def notify_all(self):
         assert self._lock._semlock._is_mine(), 'lock is not owned'
         assert not self._wait_semaphore.acquire(False)

         # to take account of timeouts since last notify*() we subtract
         # woken_count from sleeping_count and rezero woken_count
         while self._woken_count.acquire(False):
             res = self._sleeping_count.acquire(False)
             assert res

         sleepers = 0
         while self._sleeping_count.acquire(False):
             self._wait_semaphore.release()        # wake up one sleeper
             sleepers += 1

         if sleepers:
             for i in xrange(sleepers):
                 self._woken_count.acquire()       # wait for a sleeper to wake

             # rezero wait_semaphore in case some timeouts just happened
             while self._wait_semaphore.acquire(False):
                 pass

 #
 # Event
 #

 class Event(object):

     def __init__(self):
         self._cond = Condition(Lock())
         self._flag = Semaphore(0)

     def is_set(self):
         self._cond.acquire()
         try:
             if self._flag.acquire(False):
                 self._flag.release()
                 return True
             return False
         finally:
             self._cond.release()

     def set(self):
         self._cond.acquire()
         try:
             self._flag.acquire(False)
             self._flag.release()
             self._cond.notify_all()
         finally:
             self._cond.release()

     def clear(self):
         self._cond.acquire()
         try:
             self._flag.acquire(False)
         finally:
             self._cond.release()

     def wait(self, timeout=None):
         self._cond.acquire()
         try:
             if self._flag.acquire(False):
                 self._flag.release()
             else:
                 self._cond.wait(timeout)

             if self._flag.acquire(False):
                 self._flag.release()
                 return True
             return False
         finally:
             self._cond.release()
	#
	# Module implementing synchronization primitives
	#
	# multiprocessing/synchronize.py
	#
	# Copyright (c) 2006-2008, R Oudkerk
	# All rights reserved.
	#
	# Redistribution and use in source and binary forms, with or without
	# modification, are permitted provided that the following conditions
	# are met:
	#
	# 1. Redistributions of source code must retain the above copyright
	# notice, this list of conditions and the following disclaimer.
	# 2. Redistributions in binary form must reproduce the above copyright
	# notice, this list of conditions and the following disclaimer in the
	# documentation and/or other materials provided with the distribution.
	# 3. Neither the name of author nor the names of any contributors may be
	# used to endorse or promote products derived from this software
	# without specific prior written permission.
	#
	# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS "AS IS" AND
	# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	# ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
	# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	# SUCH DAMAGE.
	#

	__all__ = [
	'Lock', 'RLock', 'Semaphore', 'BoundedSemaphore', 'Condition', 'Event'
	]

	import threading
	import os
	import sys

	from time import time as _time, sleep as _sleep

	import _multiprocessing
	from multiprocessing.process import current_process
	from multiprocessing.util import Finalize, register_after_fork, debug
	from multiprocessing.forking import assert_spawning, Popen

	# Try to import the mp.synchronize module cleanly, if it fails
	# raise ImportError for platforms lacking a working sem_open implementation.
	# See issue 3770
	try:
	from _multiprocessing import SemLock
	except (ImportError):
	raise ImportError("This platform lacks a functioning sem_open" +
	" implementation, therefore, the required" +
	" synchronization primitives needed will not" +
	" function, see issue 3770.")

	#
	# Constants
	#

	RECURSIVE_MUTEX, SEMAPHORE = range(2)
	SEM_VALUE_MAX = _multiprocessing.SemLock.SEM_VALUE_MAX

	#
	# Base class for semaphores and mutexes; wraps `_multiprocessing.SemLock`
	#

	class SemLock(object):

	def __init__(self, kind, value, maxvalue):
	sl = self._semlock = _multiprocessing.SemLock(kind, value, maxvalue)
	debug('created semlock with handle %s' % sl.handle)
	self._make_methods()

	if sys.platform != 'win32':
	def _after_fork(obj):
	obj._semlock._after_fork()
	register_after_fork(self, _after_fork)

	def _make_methods(self):
	self.acquire = self._semlock.acquire
	self.release = self._semlock.release

	def __enter__(self):
	return self._semlock.__enter__()

	def __exit__(self, *args):
	return self._semlock.__exit__(*args)

	def __getstate__(self):
	assert_spawning(self)
	sl = self._semlock
	return (Popen.duplicate_for_child(sl.handle), sl.kind, sl.maxvalue)

	def __setstate__(self, state):
	self._semlock = _multiprocessing.SemLock._rebuild(*state)
	debug('recreated blocker with handle %r' % state[0])
	self._make_methods()

	#
	# Semaphore
	#

	class Semaphore(SemLock):

	def __init__(self, value=1):
	SemLock.__init__(self, SEMAPHORE, value, SEM_VALUE_MAX)

	def get_value(self):
	return self._semlock._get_value()

	def __repr__(self):
	try:
	value = self._semlock._get_value()
	except Exception:
	value = 'unknown'
	return '<Semaphore(value=%s)>' % value

	#
	# Bounded semaphore
	#

	class BoundedSemaphore(Semaphore):

	def __init__(self, value=1):
	SemLock.__init__(self, SEMAPHORE, value, value)

	def __repr__(self):
	try:
	value = self._semlock._get_value()
	except Exception:
	value = 'unknown'
	return '<BoundedSemaphore(value=%s, maxvalue=%s)>' % \
	(value, self._semlock.maxvalue)

	#
	# Non-recursive lock
	#

	class Lock(SemLock):

	def __init__(self):
	SemLock.__init__(self, SEMAPHORE, 1, 1)

	def __repr__(self):
	try:
	if self._semlock._is_mine():
	name = current_process().name
	if threading.current_thread().name != 'MainThread':
	name += '\|' + threading.current_thread().name
	elif self._semlock._get_value() == 1:
	name = 'None'
	elif self._semlock._count() > 0:
	name = 'SomeOtherThread'
	else:
	name = 'SomeOtherProcess'
	except Exception:
	name = 'unknown'
	return '<Lock(owner=%s)>' % name

	#
	# Recursive lock
	#

	class RLock(SemLock):

	def __init__(self):
	SemLock.__init__(self, RECURSIVE_MUTEX, 1, 1)

	def __repr__(self):
	try:
	if self._semlock._is_mine():
	name = current_process().name
	if threading.current_thread().name != 'MainThread':
	name += '\|' + threading.current_thread().name
	count = self._semlock._count()
	elif self._semlock._get_value() == 1:
	name, count = 'None', 0
	elif self._semlock._count() > 0:
	name, count = 'SomeOtherThread', 'nonzero'
	else:
	name, count = 'SomeOtherProcess', 'nonzero'
	except Exception:
	name, count = 'unknown', 'unknown'
	return '<RLock(%s, %s)>' % (name, count)

	#
	# Condition variable
	#

	class Condition(object):

	def __init__(self, lock=None):
	self._lock = lock or RLock()
	self._sleeping_count = Semaphore(0)
	self._woken_count = Semaphore(0)
	self._wait_semaphore = Semaphore(0)
	self._make_methods()

	def __getstate__(self):
	assert_spawning(self)
	return (self._lock, self._sleeping_count,
	self._woken_count, self._wait_semaphore)

	def __setstate__(self, state):
	(self._lock, self._sleeping_count,
	self._woken_count, self._wait_semaphore) = state
	self._make_methods()

	def __enter__(self):
	return self._lock.__enter__()

	def __exit__(self, *args):
	return self._lock.__exit__(*args)

	def _make_methods(self):
	self.acquire = self._lock.acquire
	self.release = self._lock.release

	def __repr__(self):
	try:
	num_waiters = (self._sleeping_count._semlock._get_value() -
	self._woken_count._semlock._get_value())
	except Exception:
	num_waiters = 'unkown'
	return '<Condition(%s, %s)>' % (self._lock, num_waiters)

	def wait(self, timeout=None):
	assert self._lock._semlock._is_mine(), \
	'must acquire() condition before using wait()'

	# indicate that this thread is going to sleep
	self._sleeping_count.release()

	# release lock
	count = self._lock._semlock._count()
	for i in xrange(count):
	self._lock.release()

	try:
	# wait for notification or timeout
	self._wait_semaphore.acquire(True, timeout)
	finally:
	# indicate that this thread has woken
	self._woken_count.release()

	# reacquire lock
	for i in xrange(count):
	self._lock.acquire()

	def notify(self):
	assert self._lock._semlock._is_mine(), 'lock is not owned'
	assert not self._wait_semaphore.acquire(False)

	# to take account of timeouts since last notify() we subtract
	# woken_count from sleeping_count and rezero woken_count
	while self._woken_count.acquire(False):
	res = self._sleeping_count.acquire(False)
	assert res

	if self._sleeping_count.acquire(False): # try grabbing a sleeper
	self._wait_semaphore.release() # wake up one sleeper
	self._woken_count.acquire() # wait for the sleeper to wake

	# rezero _wait_semaphore in case a timeout just happened
	self._wait_semaphore.acquire(False)

	def notify_all(self):
	assert self._lock._semlock._is_mine(), 'lock is not owned'
	assert not self._wait_semaphore.acquire(False)

	# to take account of timeouts since last notify*() we subtract
	# woken_count from sleeping_count and rezero woken_count
	while self._woken_count.acquire(False):
	res = self._sleeping_count.acquire(False)
	assert res

	sleepers = 0
	while self._sleeping_count.acquire(False):
	self._wait_semaphore.release() # wake up one sleeper
	sleepers += 1

	if sleepers:
	for i in xrange(sleepers):
	self._woken_count.acquire() # wait for a sleeper to wake

	# rezero wait_semaphore in case some timeouts just happened
	while self._wait_semaphore.acquire(False):
	pass

	#
	# Event
	#

	class Event(object):

	def __init__(self):
	self._cond = Condition(Lock())
	self._flag = Semaphore(0)

	def is_set(self):
	self._cond.acquire()
	try:
	if self._flag.acquire(False):
	self._flag.release()
	return True
	return False
	finally:
	self._cond.release()

	def set(self):
	self._cond.acquire()
	try:
	self._flag.acquire(False)
	self._flag.release()
	self._cond.notify_all()
	finally:
	self._cond.release()

	def clear(self):
	self._cond.acquire()
	try:
	self._flag.acquire(False)
	finally:
	self._cond.release()

	def wait(self, timeout=None):
	self._cond.acquire()
	try:
	if self._flag.acquire(False):
	self._flag.release()
	else:
	self._cond.wait(timeout)

	if self._flag.acquire(False):
	self._flag.release()
	return True
	return False
	finally:
	self._cond.release()