mit neuen venv und exe-Files

venv3_12/Lib/site-packages/gevent/threading.py

@@ -0,0 +1,421 @@
+"""
+Implementation of the standard :mod:`threading` using greenlets.
+
+.. note::
+
+    This module is a helper for :mod:`gevent.monkey` and is not
+    intended to be used directly. For spawning greenlets in your
+    applications, prefer higher level constructs like
+    :class:`gevent.Greenlet` class or :func:`gevent.spawn`. Attributes
+    in this module like ``__threading__`` are implementation artifacts subject
+    to change at any time.
+
+.. versionchanged:: 1.2.3
+
+   Defer adjusting the stdlib's list of active threads until we are
+   monkey patched. Previously this was done at import time. We are
+   documented to only be used as a helper for monkey patching, so this should
+   functionally be the same, but some applications ignore the documentation and
+   directly import this module anyway.
+
+   A positive consequence is that ``import gevent.threading,
+   threading; threading.current_thread()`` will no longer return a DummyThread
+   before monkey-patching.
+"""
+
+
+import os
+import sys
+
+__implements__ = [
+    'local',
+    '_allocate_lock',
+    'Lock',
+    '_get_ident',
+    '_sleep',
+    '_DummyThread',
+    # RLock cannot go here, even though we need to import it.
+    # If it goes here, it replaces the RLock from the native
+    # threading module, but we really just need it here when some
+    # things import this module.
+    #'RLock',
+] + ([
+    '_start_new_thread',
+] if sys.version_info[:2] < (3, 13) else [
+    '_start_joinable_thread',
+    '_ThreadHandle',
+    '_make_thread_handle',
+])
+
+
+__extensions__ = [
+]
+
+
+import threading as __threading__ # imports os, sys, _thread, functools, time, itertools
+_DummyThread_ = __threading__._DummyThread
+_MainThread_ = __threading__._MainThread
+
+
+from gevent.local import local
+from gevent.thread import start_new_thread as _start_new_thread
+from gevent.thread import start_joinable_thread
+from gevent.thread import _ThreadHandle
+from gevent.thread import _make_thread_handle
+from gevent.thread import allocate_lock as _allocate_lock
+from gevent.thread import get_ident as _get_ident
+from gevent.hub import sleep as _sleep, getcurrent
+from gevent.lock import RLock
+
+
+from gevent._util import LazyOnClass
+
+# Exports, prevent unused import warnings.
+# XXX: Why don't we use __all__?
+local = local
+start_new_thread = _start_new_thread
+_start_joinable_thread = start_joinable_thread
+_make_thread_handle = _make_thread_handle
+_ThreadHandle = _ThreadHandle
+allocate_lock = _allocate_lock
+_get_ident = _get_ident
+_sleep = _sleep
+getcurrent = getcurrent
+
+Lock = _allocate_lock
+RLock = RLock
+
+
+def _cleanup(g):
+    __threading__._active.pop(_get_ident(g), None)
+
+def _make_cleanup_id(gid):
+    def _(_r):
+        __threading__._active.pop(gid, None)
+    return _
+
+_weakref = None
+
+
+class _DummyThread(_DummyThread_):
+    # We avoid calling the superclass constructor. This makes us about
+    # twice as fast:
+    #
+    # - 1.16 vs 0.68usec on PyPy (unknown version, older Intel mac)
+    # - 29.3 vs 17.7usec on CPython 2.7 (older intel Mac)
+    # - 0.98 vs 2.95usec on CPython 3.12.2 (newer M2 mac)
+    #
+    # It als has the important effect of avoiding allocation and then
+    # immediate deletion of _Thread__block, a lock. This is especially
+    # important on PyPy where locks go through the cpyext API and
+    # Cython, which is known to be slow and potentially buggy (e.g.,
+    # https://bitbucket.org/pypy/pypy/issues/2149/memory-leak-for-python-subclass-of-cpyext#comment-22347393)
+
+    # These objects are constructed quite frequently in some cases, so
+    # the optimization matters: for example, in gunicorn, which uses
+    # pywsgi.WSGIServer, most every request is handled in a new greenlet,
+    # and every request uses a logging.Logger to write the access log,
+    # and every call to a log method captures the current thread (by
+    # default).
+    #
+    # (Obviously we have to duplicate the effects of the constructor,
+    # at least for external state purposes, which is potentially
+    # slightly fragile.)
+
+    # For the same reason, instances of this class will cleanup their own entry
+    # in ``threading._active``
+
+    # This class also solves a problem forking process with subprocess: after forking,
+    # Thread.__stop is called, which throws an exception when __block doesn't
+    # exist.
+
+    # Capture the static things as class vars to save on memory/
+    # construction time.
+    # In Py2, they're all private; in Py3, they become protected
+    _Thread__stopped = _is_stopped = _stopped = False
+    _Thread__initialized = _initialized = True
+    _Thread__daemonic = _daemonic = True
+    _Thread__args = _args = ()
+    _Thread__kwargs = _kwargs = None
+    _Thread__target = _target = None
+    _Thread_ident = _ident = None
+    _Thread__started = _started = __threading__.Event()
+    _Thread__started.set()
+    _tstate_lock = None
+    _handle = None # 3.13
+
+    def __init__(self): # pylint:disable=super-init-not-called
+        #_DummyThread_.__init__(self)
+
+        # It'd be nice to use a pattern like "greenlet-%d", but there are definitely
+        # third-party libraries checking thread names to detect DummyThread objects.
+        self._name = self._Thread__name = __threading__._newname("Dummy-%d")
+        # All dummy threads in the same native thread share the same ident
+        # (that of the native thread), unless we're monkey-patched.
+        self._set_ident()
+        # _handle is only needed for 3.13; keeps a weak reference
+        # to the greenlet.
+        self._handle = _make_thread_handle(self._ident)
+        # ``_native_id`` backs the ``native_id`` property.
+        self._native_id = __threading__.get_native_id()
+
+        g = getcurrent()
+        gid = _get_ident(g)
+        __threading__._active[gid] = self
+        rawlink = getattr(g, 'rawlink', None)
+        if rawlink is not None:
+            # raw greenlet.greenlet greenlets don't
+            # have rawlink...
+            rawlink(_cleanup)
+        else:
+            # ... so for them we use weakrefs.
+            # See https://github.com/gevent/gevent/issues/918
+            ref = self.__weakref_ref
+            ref = ref(g, _make_cleanup_id(gid)) # pylint:disable=too-many-function-args
+            self.__raw_ref = ref
+            assert self.__raw_ref is ref # prevent pylint thinking its unused
+
+    def _Thread__stop(self):
+        pass
+
+    _stop = _Thread__stop # py3
+
+    def _wait_for_tstate_lock(self, *args, **kwargs): # pylint:disable=signature-differs
+        pass
+
+    @LazyOnClass
+    def __weakref_ref(self):
+        return __import__('weakref').ref
+
+    # In Python 3.11.8+ and 3.12.2+ (yes, minor patch releases),
+    # CPython's ``threading._after_fork`` hook began swizzling the
+    # type of the _DummyThread into _MainThread if such a dummy thread
+    # was the current thread when ``os.fork()`` gets called.
+    # From CPython's perspective, that's a more-or-less fine thing to do.
+    # While _DummyThread isn't a subclass of _MainThread, they are both
+    # subclasses of Thread, and _MainThread doesn't add any new instance
+    # variables.
+    #
+    # From gevent's perspective, that's NOT good. Our _DummyThread
+    # doesn't have all the instance variables that Thread does, and so
+    # attempting to do anything with this now-fake _MainThread doesn't work.
+    # You in fact immediately get assertion errors from inside ``_after_fork``.
+    # Now, these are basically harmless ---  they're printed, and they prevent the cleanup
+    # of some globals in _threading, but that probably doesn't matter --- but
+    # people complained, and it could break some test scenarios (due to unexpected
+    # output on stderr, for example)
+    #
+    # We thought of a few options to patch around this:
+    #
+    # - Live with the performance penalty. Newer CPythons are making it
+    #   harder and harder to perform well, so if we can possibly avoid
+    #   adding our own performance regressions, that would be good.
+    #
+    # - ``after_fork`` uses ``isinstance(current, _DummyThread)``
+    #   before swizzling, so we could use a metaclass to make that
+    #   check return false. That's a fairly large compatibility risk,
+    #   both because of the use of a metaclass (what if some other
+    #   subclass of _DummyTHread is using an incompatible metaclass?)
+    #   and the change in ``isinstance`` behaviour. We could limit the latter
+    #   to a window around the fork, using ``os.register_at_fork(before, after_in_parent=)``,
+    #   but that's a lot of moving pieces requiring the use of a global or class
+    #   variable to track state.
+    #
+    # - We could copy the ivars of the current main thread into the
+    #   _DummyThread in ``register_at_fork(before=)``. That appears to
+    #   work, but also requires the use of
+    #   ``register_at_fork(after_in_parent=)`` to reverse it.
+    #
+    # - We could simply prevent swizzling the class in the first
+    #   place. In combination with
+    #   ``register_at_fork(after_in_child=)`` to establish a *real*
+    #   new _MainThread, that's a clean solution. Establishing a real
+    #   new _MainThread is something that CPython itself is prepared
+    #   to do if it can't figure out what the current thread is. The
+    #   compatibility risk of this is relatively low: swizzling
+    #   classes is frowned upon and uncommon, and we can limit it to
+    #   just preventing this specific case. And if somebody was
+    #   attempting this already with some other thread subclass, it
+    #   would (probably?) have the exact same issues, so we can be pretty
+    #   sure nobody is doing that.
+    #
+    # We're initially going with the last fix; the __class__ part is here,
+    # the ``after_in_child`` fixup we only apply if we're monkey-patching.
+    #
+    # Now, all of this is moot in 3.13, which takes a very different
+    # approach to handling this, and also changes some names. See
+    # https://github.com/python/cpython/commit/0e9c364f4ac18a2237bdbac702b96bcf8ef9cb09
+
+    # Tests pass just fine in 3.8 (and presumably 3.9 and 3.10) with these fixes
+    # applied, but just in case, we only do it where we know it's necessary.
+    _NEEDS_CLASS_FORK_FIXUP = (
+        (sys.version_info[:2] == (3, 11) and sys.version_info[:3] >= (3, 11, 8))
+        or sys.version_info[:3] >= (3, 12, 2)
+    )
+
+    if _NEEDS_CLASS_FORK_FIXUP:
+        # Override with a property, as opposed to using __setattr__,
+        # to avoid adding overhead on any other attribute setting.
+        @property
+        def __class__(self):
+            return type(self)
+
+        @__class__.setter
+        def __class__(self, new_class):
+            # Even if we wanted to allow setting this, I'm not sure
+            # exactly how to do so when we have a property object handling it.
+            # Getting the descriptor from ``object.__dict__['__class__']``
+            # and using its ``__set__`` method raises a TypeError (as does
+            # the simpler ``super().__class__``).
+            #
+            # Better allow the TypeError for now as opposed to silently ignoring
+            # the assignment.
+            if new_class is not _MainThread_:
+                object.__dict__['__class__'].__set__(self, new_class)
+
+
+
+
+
+
+def main_native_thread():
+    return __threading__.main_thread() # pylint:disable=no-member
+
+
+# XXX: Issue 18808 breaks us on Python 3.4+.
+# Thread objects now expect a callback from the interpreter itself
+# (threadmodule.c:release_sentinel) when the C-level PyThreadState
+# object is being deallocated. Because this never happens
+# when a greenlet exits, join() and friends will block forever.
+# Fortunately this is easy to fix: just ensure that the allocation of the
+# lock, _set_sentinel, creates a *gevent* lock, and release it when
+# we're done. The main _shutdown code is in Python and deals with
+# this gracefully.
+
+class Thread(__threading__.Thread):
+
+    # Only happens in < 3.13
+    def _set_tstate_lock(self):
+        super(Thread, self)._set_tstate_lock()
+        greenlet = getcurrent()
+        greenlet.rawlink(self.__greenlet_finished)
+
+    def __greenlet_finished(self, _):
+        if self._tstate_lock:
+            self._tstate_lock.release()
+            self._stop()
+
+__implements__.append('Thread')
+
+class Timer(Thread, __threading__.Timer): # pylint:disable=abstract-method,inherit-non-class
+    pass
+
+__implements__.append('Timer')
+
+_set_sentinel = allocate_lock
+if sys.version_info[:2] < (3, 13):
+    __implements__.append('_set_sentinel')
+else:
+    __extensions__.append('_set_sentinel')
+# The main thread is patched up with more care
+# in _gevent_will_monkey_patch
+
+__implements__.remove('_get_ident')
+__implements__.append('get_ident')
+get_ident = _get_ident
+__implements__.remove('_sleep')
+
+if hasattr(__threading__, '_CRLock'):
+    # Python 3 changed the implementation of threading.RLock
+    # Previously it was a factory function around threading._RLock
+    # which in turn used _allocate_lock. Now, it wants to use
+    # threading._CRLock, which is imported from _thread.RLock and as such
+    # is implemented in C. So it bypasses our _allocate_lock function.
+    # Fortunately they left the Python fallback in place and use it
+    # if the imported _CRLock is None; this arranges for that to be the case.
+
+    # This was also backported to PyPy 2.7-7.0
+    _CRLock = None
+    __implements__.append('_CRLock')
+
+
+class _ForkHooks:
+
+    _before_fork_current_thread = None
+    _before_fork_active = None
+
+
+    def before_fork_in_parent(self):
+        self._before_fork_active = dict(__threading__._active)
+        self._before_fork_current_thread = __threading__.current_thread()
+
+    def after_fork_in_child(self):
+        # We've already imported threading, which installed its "after" hook,
+        # so we're going to be called after that hook.
+        # Note that this is only installed when monkey-patching.
+        # TODO: Is there any point to checking to see if the current thread is
+        # our dummy thread before doing this?
+        active = __threading__._active
+        assert len(active) == 1
+
+        # We cannot actually kill the greenlets via throw():
+        # - If it was the main greenlet, the process will exit
+        # - In any case, that would unwind the stack and execute
+        #   code that, before 2024-10-03, would never have executed.
+        #
+        # But we can take them out of the map and make them appear
+        # stopped; if they truly are no longer referenced, GC will
+        # kick in a nd delete the greenlet. If gevent is still waiting
+        # to switch to them, that will still happen...
+        #
+        # This happens automatically on <= 3.12 which hardcodes the call to
+        # ``Thread._stop``; for 3.13, we need to go through the handle.
+        current_ident = get_ident()
+        for green_ident, thread in self._before_fork_active.items():
+            if green_ident != current_ident:
+                try:
+                    handle = thread._handle
+                except AttributeError:
+                    assert sys.version_info[:2] < (3, 13)
+                    assert not thread.is_alive()
+                else:
+                    # We DO NOT want to bounce to the hub. We're running
+                    # at a very sensitive time and it's best to keep tight control
+                    # over what gets to run.
+                    handle._set_done(enter_hub=False)
+
+
+        main = __threading__._MainThread()
+        main._ident = get_ident() # 3.13: reset to the greenlet version.
+        __threading__._active[__threading__.get_ident()] = main
+        __threading__._main_thread = main
+
+        main = __threading__.main_thread()
+        # XXX: Not the case. Maybe don't save main.
+        assert main.ident == __threading__.get_ident()
+
+
+_fork_hooks = _ForkHooks()
+
+def _gevent_will_monkey_patch(native_module, items, warn): # pylint:disable=unused-argument
+    # Make sure the MainThread can be found by our current greenlet ID,
+    # otherwise we get a new DummyThread, which cannot be joined.
+    # Fixes tests in test_threading_2 under PyPy.
+    main_thread = main_native_thread()
+    if __threading__.current_thread() != main_thread:
+        warn("Monkey-patching outside the main native thread. Some APIs "
+             "will not be available. Expect a KeyError to be printed at shutdown.")
+        return
+
+    if _get_ident() not in __threading__._active:
+        main_id = main_thread.ident
+        del __threading__._active[main_id]
+        main_thread._ident = main_thread._Thread__ident = _get_ident()
+        __threading__._active[_get_ident()] = main_thread
+
+    register_at_fork = getattr(os, 'register_at_fork', None)
+    if register_at_fork:
+        #if _DummyThread._NEEDS_CLASS_FORK_FIXUP:
+        register_at_fork(
+            before=_fork_hooks.before_fork_in_parent,
+            after_in_child=_fork_hooks.after_fork_in_child)