CasperSecurity
# -*- test-case-name: twisted.python.test_threadable -*-
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
"""
A module to provide some very basic threading primitives, such as
synchronization.
"""
from functools import wraps
class DummyLock:
"""
Hack to allow locks to be unpickled on an unthreaded system.
"""
def __reduce__(self):
return (unpickle_lock, ())
def unpickle_lock():
if threadingmodule is not None:
return XLock()
else:
return DummyLock()
unpickle_lock.__safe_for_unpickling__ = True # type: ignore[attr-defined]
def _synchPre(self):
if "_threadable_lock" not in self.__dict__:
_synchLockCreator.acquire()
if "_threadable_lock" not in self.__dict__:
self.__dict__["_threadable_lock"] = XLock()
_synchLockCreator.release()
self._threadable_lock.acquire()
def _synchPost(self):
self._threadable_lock.release()
def _sync(klass, function):
@wraps(function)
def sync(self, *args, **kwargs):
_synchPre(self)
try:
return function(self, *args, **kwargs)
finally:
_synchPost(self)
return sync
def synchronize(*klasses):
"""
Make all methods listed in each class' synchronized attribute synchronized.
The synchronized attribute should be a list of strings, consisting of the
names of methods that must be synchronized. If we are running in threaded
mode these methods will be wrapped with a lock.
"""
if threadingmodule is not None:
for klass in klasses:
for methodName in klass.synchronized:
sync = _sync(klass, klass.__dict__[methodName])
setattr(klass, methodName, sync)
def init(with_threads=1):
"""Initialize threading.
Don't bother calling this. If it needs to happen, it will happen.
"""
global threaded, _synchLockCreator, XLock
if with_threads:
if not threaded:
if threadingmodule is not None:
threaded = True
class XLock(threadingmodule._RLock):
def __reduce__(self):
return (unpickle_lock, ())
_synchLockCreator = XLock()
else:
raise RuntimeError(
"Cannot initialize threading, platform lacks thread support"
)
else:
if threaded:
raise RuntimeError("Cannot uninitialize threads")
else:
pass
_dummyID = object()
def getThreadID():
if threadingmodule is None:
return _dummyID
return threadingmodule.current_thread().ident
def isInIOThread():
"""Are we in the thread responsible for I/O requests (the event loop)?"""
return ioThread == getThreadID()
def registerAsIOThread():
"""Mark the current thread as responsible for I/O requests."""
global ioThread
ioThread = getThreadID()
ioThread = None
threaded = False
# Define these globals which might be overwritten in init().
_synchLockCreator = None
XLock = None
try:
import threading as _threadingmodule
except ImportError:
threadingmodule = None
else:
threadingmodule = _threadingmodule
init(True)
__all__ = ["isInIOThread", "registerAsIOThread", "getThreadID", "XLock"]