Index: third_party/cherrypy/_cpthreadinglocal.py |
=================================================================== |
--- third_party/cherrypy/_cpthreadinglocal.py (revision 0) |
+++ third_party/cherrypy/_cpthreadinglocal.py (revision 0) |
@@ -0,0 +1,239 @@ |
+# This is a backport of Python-2.4's threading.local() implementation |
+ |
+"""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 = '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__() |
+ |
+from threading import currentThread, enumerate, RLock |
Property changes on: third_party/cherrypy/_cpthreadinglocal.py |
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Added: svn:eol-style |
+ LF |