add the multiprocessing package to fulfill PEP 371

Lib/multiprocessing/synchronize.py

@@ -0,0 +1,294 @@
+#
+# Module implementing synchronization primitives
+#
+# multiprocessing/synchronize.py
+#
+# Copyright (c) 2006-2008, R Oudkerk --- see COPYING.txt
+#
+
+__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
+
+#
+# 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
+        self.__enter__ = self._semlock.__enter__
+        self.__exit__ = self._semlock.__exit__
+
+    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().get_name()
+                if threading.currentThread().getName() != 'MainThread':
+                    name += '|' + threading.currentThread().getName()
+            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().get_name()
+                if threading.currentThread().getName() != 'MainThread':
+                    name += '|' + threading.currentThread().getName()
+                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 _make_methods(self):
+        self.acquire = self._lock.acquire
+        self.release = self._lock.release
+        self.__enter__ = self._lock.__enter__
+        self.__exit__ = self._lock.__exit__
+
+    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)
+        finally:
+            self._cond.release()