--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/app/django/utils/_threading_local.py Fri Jul 18 18:22:23 2008 +0000
@@ -0,0 +1,240 @@
+"""Thread-local objects
+
+(Note that this module provides a Python version of thread
+ threading.local class. Depending on the version of Python you're
+ using, there may be a faster one available. You should always import
+ the local class from threading.)
+
+Thread-local objects support the management of thread-local data.
+If you have data that you want to be local to a thread, simply create
+a thread-local object and use its attributes:
+
+ >>> mydata = local()
+ >>> mydata.number = 42
+ >>> mydata.number
+ 42
+
+You can also access the local-object's dictionary:
+
+ >>> mydata.__dict__
+ {'number': 42}
+ >>> mydata.__dict__.setdefault('widgets', [])
+ []
+ >>> mydata.widgets
+ []
+
+What's important about thread-local objects is that their data are
+local to a thread. If we access the data in a different thread:
+
+ >>> log = []
+ >>> def f():
+ ... items = mydata.__dict__.items()
+ ... items.sort()
+ ... log.append(items)
+ ... mydata.number = 11
+ ... log.append(mydata.number)
+
+ >>> import threading
+ >>> thread = threading.Thread(target=f)
+ >>> thread.start()
+ >>> thread.join()
+ >>> log
+ [[], 11]
+
+we get different data. Furthermore, changes made in the other thread
+don't affect data seen in this thread:
+
+ >>> mydata.number
+ 42
+
+Of course, values you get from a local object, including a __dict__
+attribute, are for whatever thread was current at the time the
+attribute was read. For that reason, you generally don't want to save
+these values across threads, as they apply only to the thread they
+came from.
+
+You can create custom local objects by subclassing the local class:
+
+ >>> class MyLocal(local):
+ ... number = 2
+ ... initialized = False
+ ... def __init__(self, **kw):
+ ... if self.initialized:
+ ... raise SystemError('__init__ called too many times')
+ ... self.initialized = True
+ ... self.__dict__.update(kw)
+ ... def squared(self):
+ ... return self.number ** 2
+
+This can be useful to support default values, methods and
+initialization. Note that if you define an __init__ method, it will be
+called each time the local object is used in a separate thread. This
+is necessary to initialize each thread's dictionary.
+
+Now if we create a local object:
+
+ >>> mydata = MyLocal(color='red')
+
+Now we have a default number:
+
+ >>> mydata.number
+ 2
+
+an initial color:
+
+ >>> mydata.color
+ 'red'
+ >>> del mydata.color
+
+And a method that operates on the data:
+
+ >>> mydata.squared()
+ 4
+
+As before, we can access the data in a separate thread:
+
+ >>> log = []
+ >>> thread = threading.Thread(target=f)
+ >>> thread.start()
+ >>> thread.join()
+ >>> log
+ [[('color', 'red'), ('initialized', True)], 11]
+
+without affecting this thread's data:
+
+ >>> mydata.number
+ 2
+ >>> mydata.color
+ Traceback (most recent call last):
+ ...
+ AttributeError: 'MyLocal' object has no attribute 'color'
+
+Note that subclasses can define slots, but they are not thread
+local. They are shared across threads:
+
+ >>> class MyLocal(local):
+ ... __slots__ = 'number'
+
+ >>> mydata = MyLocal()
+ >>> mydata.number = 42
+ >>> mydata.color = 'red'
+
+So, the separate thread:
+
+ >>> thread = threading.Thread(target=f)
+ >>> thread.start()
+ >>> thread.join()
+
+affects what we see:
+
+ >>> mydata.number
+ 11
+
+>>> del mydata
+"""
+
+# Threading import is at end
+
+class _localbase(object):
+ __slots__ = '_local__key', '_local__args', '_local__lock'
+
+ def __new__(cls, *args, **kw):
+ self = object.__new__(cls)
+ key = '_local__key', 'thread.local.' + str(id(self))
+ object.__setattr__(self, '_local__key', key)
+ object.__setattr__(self, '_local__args', (args, kw))
+ object.__setattr__(self, '_local__lock', RLock())
+
+ if args or kw and (cls.__init__ is object.__init__):
+ raise TypeError("Initialization arguments are not supported")
+
+ # We need to create the thread dict in anticipation of
+ # __init__ being called, to make sure we don't call it
+ # again ourselves.
+ dict = object.__getattribute__(self, '__dict__')
+ currentThread().__dict__[key] = dict
+
+ return self
+
+def _patch(self):
+ key = object.__getattribute__(self, '_local__key')
+ d = currentThread().__dict__.get(key)
+ if d is None:
+ d = {}
+ currentThread().__dict__[key] = d
+ object.__setattr__(self, '__dict__', d)
+
+ # we have a new instance dict, so call out __init__ if we have
+ # one
+ cls = type(self)
+ if cls.__init__ is not object.__init__:
+ args, kw = object.__getattribute__(self, '_local__args')
+ cls.__init__(self, *args, **kw)
+ else:
+ object.__setattr__(self, '__dict__', d)
+
+class local(_localbase):
+
+ def __getattribute__(self, name):
+ lock = object.__getattribute__(self, '_local__lock')
+ lock.acquire()
+ try:
+ _patch(self)
+ return object.__getattribute__(self, name)
+ finally:
+ lock.release()
+
+ def __setattr__(self, name, value):
+ lock = object.__getattribute__(self, '_local__lock')
+ lock.acquire()
+ try:
+ _patch(self)
+ return object.__setattr__(self, name, value)
+ finally:
+ lock.release()
+
+ def __delattr__(self, name):
+ lock = object.__getattribute__(self, '_local__lock')
+ lock.acquire()
+ try:
+ _patch(self)
+ return object.__delattr__(self, name)
+ finally:
+ lock.release()
+
+
+ def __del__():
+ threading_enumerate = enumerate
+ __getattribute__ = object.__getattribute__
+
+ def __del__(self):
+ key = __getattribute__(self, '_local__key')
+
+ try:
+ threads = list(threading_enumerate())
+ except:
+ # if enumerate fails, as it seems to do during
+ # shutdown, we'll skip cleanup under the assumption
+ # that there is nothing to clean up
+ return
+
+ for thread in threads:
+ try:
+ __dict__ = thread.__dict__
+ except AttributeError:
+ # Thread is dying, rest in peace
+ continue
+
+ if key in __dict__:
+ try:
+ del __dict__[key]
+ except KeyError:
+ pass # didn't have anything in this thread
+
+ return __del__
+ __del__ = __del__()
+
+try:
+ from threading import currentThread, enumerate, RLock
+except ImportError:
+ from dummy_threading import currentThread, enumerate, RLock