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author | Ori Bernstein <ori@eigenstate.org> | 2021-06-14 00:00:37 +0000 |
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committer | Ori Bernstein <ori@eigenstate.org> | 2021-06-14 00:00:37 +0000 |
commit | a73a964e51247ed169d322c725a3a18859f109a3 (patch) | |
tree | 3f752d117274d444bda44e85609aeac1acf313f3 /sys/lib/python/_threading_local.py | |
parent | e64efe273fcb921a61bf27d33b230c4e64fcd425 (diff) |
python, hg: tow outside the environment.
they've served us well, and can ride off into the sunset.
Diffstat (limited to 'sys/lib/python/_threading_local.py')
-rw-r--r-- | sys/lib/python/_threading_local.py | 241 |
1 files changed, 0 insertions, 241 deletions
diff --git a/sys/lib/python/_threading_local.py b/sys/lib/python/_threading_local.py deleted file mode 100644 index f0ce85716..000000000 --- a/sys/lib/python/_threading_local.py +++ /dev/null @@ -1,241 +0,0 @@ -"""Thread-local objects. - -(Note that this module provides a Python version of the 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 -""" - -__all__ = ["local"] - -# We need to use objects from the threading module, but the threading -# module may also want to use our `local` class, if support for locals -# isn't compiled in to the `thread` module. This creates potential problems -# with circular imports. For that reason, we don't import `threading` -# until the bottom of this file (a hack sufficient to worm around the -# potential problems). Note that almost all platforms do have support for -# locals in the `thread` module, and there is no circular import problem -# then, so problems introduced by fiddling the order of imports here won't -# manifest on most boxes. - -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__(self): - import threading - - key = object.__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 - -from threading import currentThread, RLock |