Source code for gevent.greenlet

# Copyright (c) 2009-2012 Denis Bilenko. See LICENSE for details.
# cython: auto_pickle=False,embedsignature=True,always_allow_keywords=False
# pylint:disable=too-many-lines
from __future__ import absolute_import, print_function, division

from sys import _getframe as sys_getframe
from sys import exc_info as sys_exc_info
from weakref import ref as wref

# XXX: How to get cython to let us rename this as RawGreenlet
# like we prefer?
from greenlet import greenlet
from greenlet import GreenletExit

from gevent._compat import reraise
from gevent._compat import PYPY as _PYPY
from gevent._tblib import dump_traceback
from gevent._tblib import load_traceback

from gevent.exceptions import InvalidSwitchError

from gevent._hub_primitives import iwait_on_objects as iwait
from gevent._hub_primitives import wait_on_objects as wait

from gevent.timeout import Timeout

from gevent._config import config as GEVENT_CONFIG
from gevent._util import readproperty
from gevent._hub_local import get_hub_noargs as get_hub
from gevent import _waiter


__all__ = [
    'Greenlet',
    'joinall',
    'killall',
]


# In Cython, we define these as 'cdef inline' functions. The
# compilation unit cannot have a direct assignment to them (import
# is assignment) without generating a 'lvalue is not valid target'
# error.
locals()['getcurrent'] = __import__('greenlet').getcurrent
locals()['greenlet_init'] = lambda: None
locals()['Waiter'] = _waiter.Waiter
# With Cython, this raises a TypeError if the parent is *not*
# the hub (SwitchOutGreenletWithLoop); in pure-Python, we will
# very likely get an AttributeError immediately after when we access `loop`;
# The TypeError message is more informative on Python 2.
# This must ONLY be called when we know that `s` is not None and is in fact a greenlet
# object (e.g., when called on `self`)
locals()['get_my_hub'] = lambda s: s.parent
# This must also ONLY be called when we know that S is not None and is in fact a greenlet
# object (including the result of getcurrent())
locals()['get_generic_parent'] = lambda s: s.parent

# Frame access
locals()['get_f_back'] = lambda frame: frame.f_back
locals()['get_f_lineno'] = lambda frame: frame.f_lineno

if _PYPY:
    import _continuation # pylint:disable=import-error
    _continulet = _continuation.continulet


class SpawnedLink(object):
    """
    A wrapper around link that calls it in another greenlet.

    Can be called only from main loop.
    """
    __slots__ = ['callback']

    def __init__(self, callback):
        if not callable(callback):
            raise TypeError("Expected callable: %r" % (callback, ))
        self.callback = callback

    def __call__(self, source):
        g = greenlet(self.callback, get_hub())
        g.switch(source)

    def __hash__(self):
        return hash(self.callback)

    def __eq__(self, other):
        return self.callback == getattr(other, 'callback', other)

    def __str__(self):
        return str(self.callback)

    def __repr__(self):
        return repr(self.callback)

    def __getattr__(self, item):
        assert item != 'callback'
        return getattr(self.callback, item)


class SuccessSpawnedLink(SpawnedLink):
    """A wrapper around link that calls it in another greenlet only if source succeed.

    Can be called only from main loop.
    """
    __slots__ = []

    def __call__(self, source):
        if source.successful():
            return SpawnedLink.__call__(self, source)


class FailureSpawnedLink(SpawnedLink):
    """A wrapper around link that calls it in another greenlet only if source failed.

    Can be called only from main loop.
    """
    __slots__ = []

    def __call__(self, source):
        if not source.successful():
            return SpawnedLink.__call__(self, source)

class _Frame(object):

    __slots__ = ('f_code', 'f_lineno', 'f_back')

    def __init__(self):
        self.f_code = None
        self.f_back = None
        self.f_lineno = 0

    @property
    def f_globals(self):
        return None


def _extract_stack(limit):
    try:
        frame = sys_getframe()
    except ValueError:
        # In certain embedded cases that directly use the Python C api
        # to call Greenlet.spawn (e.g., uwsgi) this can raise
        # `ValueError: call stack is not deep enough`. This is because
        # the Cython stack frames for Greenlet.spawn ->
        # Greenlet.__init__ -> _extract_stack are all on the C level,
        # not the Python level.
        # See https://github.com/gevent/gevent/issues/1212
        frame = None

    newest_Frame = None
    newer_Frame = None

    while limit and frame is not None:
        limit -= 1
        older_Frame = _Frame()
        # Arguments are always passed to the constructor as Python objects,
        # meaning we wind up boxing the f_lineno just to unbox it if we pass it.
        # It's faster to simply assign once the object is created.
        older_Frame.f_code = frame.f_code
        older_Frame.f_lineno = get_f_lineno(frame) # pylint:disable=undefined-variable
        if newer_Frame is not None:
            newer_Frame.f_back = older_Frame
        newer_Frame = older_Frame
        if newest_Frame is None:
            newest_Frame = newer_Frame

        frame = get_f_back(frame) # pylint:disable=undefined-variable

    return newest_Frame


_greenlet__init__ = greenlet.__init__

[docs]class Greenlet(greenlet): """ A light-weight cooperatively-scheduled execution unit. """ # pylint:disable=too-many-public-methods,too-many-instance-attributes spawning_stack_limit = 10 # pylint:disable=keyword-arg-before-vararg,super-init-not-called
[docs] def __init__(self, run=None, *args, **kwargs): """ :param args: The arguments passed to the ``run`` function. :param kwargs: The keyword arguments passed to the ``run`` function. :keyword callable run: The callable object to run. If not given, this object's `_run` method will be invoked (typically defined by subclasses). .. versionchanged:: 1.1b1 The ``run`` argument to the constructor is now verified to be a callable object. Previously, passing a non-callable object would fail after the greenlet was spawned. .. versionchanged:: 1.3b1 The ``GEVENT_TRACK_GREENLET_TREE`` configuration value may be set to a false value to disable ``spawn_tree_locals``, ``spawning_greenlet``, and ``spawning_stack``. The first two will be None in that case, and the latter will be empty. .. versionchanged:: 1.5 Greenlet objects are now more careful to verify that their ``parent`` is really a gevent hub, raising a ``TypeError`` earlier instead of an ``AttributeError`` later. .. versionchanged:: 20.12.1 Greenlet objects now function as context managers. Exiting the ``with`` suite ensures that the greenlet has completed by :meth:`joining <join>` the greenlet (blocking, with no timeout). If the body of the suite raises an exception, the greenlet is :meth:`killed <kill>` with the default arguments and not joined in that case. """ # The attributes are documented in the .rst file # greenlet.greenlet(run=None, parent=None) # Calling it with both positional arguments instead of a keyword # argument (parent=get_hub()) speeds up creation of this object ~30%: # python -m timeit -s 'import gevent' 'gevent.Greenlet()' # Python 3.5: 2.70usec with keywords vs 1.94usec with positional # Python 3.4: 2.32usec with keywords vs 1.74usec with positional # Python 3.3: 2.55usec with keywords vs 1.92usec with positional # Python 2.7: 1.73usec with keywords vs 1.40usec with positional # Timings taken Feb 21 2018 prior to integration of #755 # python -m perf timeit -s 'import gevent' 'gevent.Greenlet()' # 3.6.4 : Mean +- std dev: 1.08 us +- 0.05 us # 2.7.14 : Mean +- std dev: 1.44 us +- 0.06 us # PyPy2 5.10.0: Mean +- std dev: 2.14 ns +- 0.08 ns # After the integration of spawning_stack, spawning_greenlet, # and spawn_tree_locals on that same date: # 3.6.4 : Mean +- std dev: 8.92 us +- 0.36 us -> 8.2x # 2.7.14 : Mean +- std dev: 14.8 us +- 0.5 us -> 10.2x # PyPy2 5.10.0: Mean +- std dev: 3.24 us +- 0.17 us -> 1.5x # Compiling with Cython gets us to these numbers: # 3.6.4 : Mean +- std dev: 3.63 us +- 0.14 us # 2.7.14 : Mean +- std dev: 3.37 us +- 0.20 us # PyPy2 5.10.0 : Mean +- std dev: 4.44 us +- 0.28 us # Switching to reified frames and some more tuning gets us here: # 3.7.2 : Mean +- std dev: 2.53 us +- 0.15 us # 2.7.16 : Mean +- std dev: 2.35 us +- 0.12 us # PyPy2 7.1 : Mean +- std dev: 11.6 us +- 0.4 us # Compared to the released 1.4 (tested at the same time): # 3.7.2 : Mean +- std dev: 3.21 us +- 0.32 us # 2.7.16 : Mean +- std dev: 3.11 us +- 0.19 us # PyPy2 7.1 : Mean +- std dev: 12.3 us +- 0.8 us _greenlet__init__(self, None, get_hub()) if run is not None: self._run = run # If they didn't pass a callable at all, then they must # already have one. Note that subclassing to override the run() method # itself has never been documented or supported. if not callable(self._run): raise TypeError("The run argument or self._run must be callable") self.args = args self.kwargs = kwargs self.value = None #: An event, such as a timer or a callback that fires. It is established in #: start() and start_later() as those two objects, respectively. #: Once this becomes non-None, the Greenlet cannot be started again. Conversely, #: kill() and throw() check for non-None to determine if this object has ever been #: scheduled for starting. A placeholder _cancelled_start_event is assigned by them to prevent #: the greenlet from being started in the future, if necessary. #: In the usual case, this transitions as follows: None -> event -> _start_completed_event. #: A value of None means we've never been started. self._start_event = None self._notifier = None self._formatted_info = None self._links = [] self._ident = None # Initial state: None. # Completed successfully: (None, None, None) # Failed with exception: (t, v, dump_traceback(tb))) self._exc_info = None if GEVENT_CONFIG.track_greenlet_tree: spawner = getcurrent() # pylint:disable=undefined-variable self.spawning_greenlet = wref(spawner) try: self.spawn_tree_locals = spawner.spawn_tree_locals except AttributeError: self.spawn_tree_locals = {} if get_generic_parent(spawner) is not None: # pylint:disable=undefined-variable # The main greenlet has no parent. # Its children get separate locals. spawner.spawn_tree_locals = self.spawn_tree_locals self.spawning_stack = _extract_stack(self.spawning_stack_limit) # Don't copy the spawning greenlet's # '_spawning_stack_frames' into ours. That's somewhat # confusing, and, if we're not careful, a deep spawn tree # can lead to excessive memory usage (an infinite spawning # tree could lead to unbounded memory usage without care # --- see https://github.com/gevent/gevent/issues/1371) # The _spawning_stack_frames may be cleared out later if we access spawning_stack else: # None is the default for all of these in Cython, but we # need to declare them for pure-Python mode. self.spawning_greenlet = None self.spawn_tree_locals = None self.spawning_stack = None
def _get_minimal_ident(self): # Helper function for cython, to allow typing `reg` and making a # C call to get_ident. # If we're being accessed from a hub different than the one running # us, aka get_hub() is not self.parent, then calling hub.ident_registry.get_ident() # may be quietly broken: it's not thread safe. # If our parent is no longer the hub for whatever reason, this will raise a # AttributeError or TypeError. hub = get_my_hub(self) # pylint:disable=undefined-variable reg = hub.ident_registry return reg.get_ident(self) @property def minimal_ident(self): """ A small, unique non-negative integer that identifies this object. This is similar to :attr:`threading.Thread.ident` (and `id`) in that as long as this object is alive, no other greenlet *in this hub* will have the same id, but it makes a stronger guarantee that the assigned values will be small and sequential. Sometime after this object has died, the value will be available for reuse. To get ids that are unique across all hubs, combine this with the hub's (``self.parent``) ``minimal_ident``. Accessing this property from threads other than the thread running this greenlet is not defined. .. versionadded:: 1.3a2 """ # Not @Lazy, implemented manually because _ident is in the structure # of the greenlet for fast access if self._ident is None: self._ident = self._get_minimal_ident() return self._ident
[docs] @readproperty def name(self): """ The greenlet name. By default, a unique name is constructed using the :attr:`minimal_ident`. You can assign a string to this value to change it. It is shown in the `repr` of this object if it has been assigned to or if the `minimal_ident` has already been generated. .. versionadded:: 1.3a2 .. versionchanged:: 1.4 Stop showing generated names in the `repr` when the ``minimal_ident`` hasn't been requested. This reduces overhead and may be less confusing, since ``minimal_ident`` can get reused. """ return 'Greenlet-%d' % (self.minimal_ident,)
def _raise_exception(self): reraise(*self.exc_info) @property def loop(self): # needed by killall hub = get_my_hub(self) # type:SwitchOutGreenletWithLoop pylint:disable=undefined-variable return hub.loop def __nonzero__(self): return self._start_event is not None and self._exc_info is None try: __bool__ = __nonzero__ # Python 3 except NameError: # pragma: no cover # When we're compiled with Cython, the __nonzero__ function # goes directly into the slot and can't be accessed by name. pass ### Lifecycle if _PYPY: # oops - pypy's .dead relies on __nonzero__ which we overriden above @property def dead(self): "Boolean indicating that the greenlet is dead and will not run again." # pylint:disable=no-member if self._greenlet__main: return False if self.__start_cancelled_by_kill() or self.__started_but_aborted(): return True return self._greenlet__started and not _continulet.is_pending(self) else: @property def dead(self): """ Boolean indicating that the greenlet is dead and will not run again. This is true if: 1. We were never started, but were :meth:`killed <kill>` immediately after creation (not possible with :meth:`spawn`); OR 2. We were started, but were killed before running; OR 3. We have run and terminated (by raising an exception out of the started function or by reaching the end of the started function). """ return ( self.__start_cancelled_by_kill() or self.__started_but_aborted() or greenlet.dead.__get__(self) ) def __never_started_or_killed(self): return self._start_event is None def __start_pending(self): return ( self._start_event is not None and (self._start_event.pending or getattr(self._start_event, 'active', False)) ) def __start_cancelled_by_kill(self): return self._start_event is _cancelled_start_event def __start_completed(self): return self._start_event is _start_completed_event def __started_but_aborted(self): return ( not self.__never_started_or_killed() # we have been started or killed and not self.__start_cancelled_by_kill() # we weren't killed, so we must have been started and not self.__start_completed() # the start never completed and not self.__start_pending() # and we're not pending, so we must have been aborted ) def __cancel_start(self): if self._start_event is None: # prevent self from ever being started in the future self._start_event = _cancelled_start_event # cancel any pending start event # NOTE: If this was a real pending start event, this will leave a # "dangling" callback/timer object in the hub.loop.callbacks list; # depending on where we are in the event loop, it may even be in a local # variable copy of that list (in _run_callbacks). This isn't a problem, # except for the leak-tests. self._start_event.stop() self._start_event.close() def __handle_death_before_start(self, args): # args is (t, v, tb) or simply t or v. # The last two cases are transformed into (t, v, None); # if the single argument is an exception type, a new instance # is created; if the single argument is not an exception type and also # not an exception, it is wrapped in a BaseException (this is not # documented, but should result in better behaviour in the event of a # user error---instead of silently printing something to stderr, we still # kill the greenlet). if self._exc_info is None and self.dead: # the greenlet was never switched to before and it will # never be; _report_error was not called, the result was # not set, and the links weren't notified. Let's do it # here. # # checking that self.dead is true is essential, because # throw() does not necessarily kill the greenlet (if the # exception raised by throw() is caught somewhere inside # the greenlet). if len(args) == 1: arg = args[0] if isinstance(arg, type) and issubclass(arg, BaseException): args = (arg, arg(), None) else: args = (type(arg), arg, None) elif not args: args = (GreenletExit, GreenletExit(), None) if not issubclass(args[0], BaseException): # Random non-type, non-exception arguments. print("RANDOM CRAP", args) import traceback; traceback.print_stack() args = (BaseException, BaseException(args), None) assert issubclass(args[0], BaseException) self.__report_error(args) @property def started(self): # DEPRECATED return bool(self)
[docs] def ready(self): """ Return a true value if and only if the greenlet has finished execution. .. versionchanged:: 1.1 This function is only guaranteed to return true or false *values*, not necessarily the literal constants ``True`` or ``False``. """ return self.dead or self._exc_info is not None
[docs] def successful(self): """ Return a true value if and only if the greenlet has finished execution successfully, that is, without raising an error. .. tip:: A greenlet that has been killed with the default :class:`GreenletExit` exception is considered successful. That is, ``GreenletExit`` is not considered an error. .. note:: This function is only guaranteed to return true or false *values*, not necessarily the literal constants ``True`` or ``False``. """ return self._exc_info is not None and self._exc_info[1] is None
def __repr__(self): classname = self.__class__.__name__ # If no name has been assigned, don't generate one, including a minimal_ident, # if not necessary. This reduces the use of weak references and associated # overhead. if 'name' not in self.__dict__ and self._ident is None: name = ' ' else: name = ' "%s" ' % (self.name,) result = '<%s%sat %s' % (classname, name, hex(id(self))) formatted = self._formatinfo() if formatted: result += ': ' + formatted return result + '>' def _formatinfo(self): info = self._formatted_info if info is not None: return info # Are we running an arbitrary function provided to the constructor, # or did a subclass override _run? func = self._run im_self = getattr(func, '__self__', None) if im_self is self: funcname = '_run' elif im_self is not None: funcname = repr(func) else: funcname = getattr(func, '__name__', '') or repr(func) result = funcname args = [] if self.args: args = [repr(x)[:50] for x in self.args] if self.kwargs: args.extend(['%s=%s' % (key, repr(value)[:50]) for (key, value) in self.kwargs.items()]) if args: result += '(' + ', '.join(args) + ')' # it is important to save the result here, because once the greenlet exits '_run' attribute will be removed self._formatted_info = result return result @property def exception(self): """ Holds the exception instance raised by the function if the greenlet has finished with an error. Otherwise ``None``. """ return self._exc_info[1] if self._exc_info is not None else None @property def exc_info(self): """ Holds the exc_info three-tuple raised by the function if the greenlet finished with an error. Otherwise a false value. .. note:: This is a provisional API and may change. .. versionadded:: 1.1 """ ei = self._exc_info if ei is not None and ei[0] is not None: return ( ei[0], ei[1], # The pickled traceback may be None if we couldn't pickle it. load_traceback(ei[2]) if ei[2] else None ) def throw(self, *args): """Immediately switch into the greenlet and raise an exception in it. Should only be called from the HUB, otherwise the current greenlet is left unscheduled forever. To raise an exception in a safe manner from any greenlet, use :meth:`kill`. If a greenlet was started but never switched to yet, then also a) cancel the event that will start it b) fire the notifications as if an exception was raised in a greenlet """ self.__cancel_start() try: if not self.dead: # Prevent switching into a greenlet *at all* if we had never # started it. Usually this is the same thing that happens by throwing, # but if this is done from the hub with nothing else running, prevents a # LoopExit. greenlet.throw(self, *args) finally: self.__handle_death_before_start(args)
[docs] def start(self): """Schedule the greenlet to run in this loop iteration""" if self._start_event is None: _call_spawn_callbacks(self) hub = get_my_hub(self) # type:SwitchOutGreenletWithLoop pylint:disable=undefined-variable self._start_event = hub.loop.run_callback(self.switch)
[docs] def start_later(self, seconds): """ start_later(seconds) -> None Schedule the greenlet to run in the future loop iteration *seconds* later """ if self._start_event is None: _call_spawn_callbacks(self) hub = get_my_hub(self) # pylint:disable=undefined-variable self._start_event = hub.loop.timer(seconds) self._start_event.start(self.switch)
[docs] @staticmethod def add_spawn_callback(callback): """ add_spawn_callback(callback) -> None Set up a *callback* to be invoked when :class:`Greenlet` objects are started. The invocation order of spawn callbacks is unspecified. Adding the same callback more than one time will not cause it to be called more than once. .. versionadded:: 1.4.0 """ global _spawn_callbacks if _spawn_callbacks is None: # pylint:disable=used-before-assignment _spawn_callbacks = set() _spawn_callbacks.add(callback)
[docs] @staticmethod def remove_spawn_callback(callback): """ remove_spawn_callback(callback) -> None Remove *callback* function added with :meth:`Greenlet.add_spawn_callback`. This function will not fail if *callback* has been already removed or if *callback* was never added. .. versionadded:: 1.4.0 """ global _spawn_callbacks if _spawn_callbacks is not None: _spawn_callbacks.discard(callback) if not _spawn_callbacks: _spawn_callbacks = None
[docs] @classmethod def spawn(cls, *args, **kwargs): """ spawn(function, *args, **kwargs) -> Greenlet Create a new :class:`Greenlet` object and schedule it to run ``function(*args, **kwargs)``. This can be used as ``gevent.spawn`` or ``Greenlet.spawn``. The arguments are passed to :meth:`Greenlet.__init__`. .. versionchanged:: 1.1b1 If a *function* is given that is not callable, immediately raise a :exc:`TypeError` instead of spawning a greenlet that will raise an uncaught TypeError. """ g = cls(*args, **kwargs) g.start() return g
@classmethod def spawn_later(cls, seconds, *args, **kwargs): """ spawn_later(seconds, function, *args, **kwargs) -> Greenlet Create and return a new `Greenlet` object scheduled to run ``function(*args, **kwargs)`` in a future loop iteration *seconds* later. This can be used as ``Greenlet.spawn_later`` or ``gevent.spawn_later``. The arguments are passed to :meth:`Greenlet.__init__`. .. versionchanged:: 1.1b1 If an argument that's meant to be a function (the first argument in *args*, or the ``run`` keyword ) is given to this classmethod (and not a classmethod of a subclass), it is verified to be callable. Previously, the spawned greenlet would have failed when it started running. """ if cls is Greenlet and not args and 'run' not in kwargs: raise TypeError("") g = cls(*args, **kwargs) g.start_later(seconds) return g def _maybe_kill_before_start(self, exception): # Helper for Greenlet.kill(), and also for killall() self.__cancel_start() self.__free() dead = self.dead if dead: if isinstance(exception, tuple) and len(exception) == 3: args = exception else: args = (exception,) self.__handle_death_before_start(args) return dead
[docs] def kill(self, exception=GreenletExit, block=True, timeout=None): """ Raise the ``exception`` in the greenlet. If ``block`` is ``True`` (the default), wait until the greenlet dies or the optional timeout expires; this may require switching greenlets. If block is ``False``, the current greenlet is not unscheduled. This function always returns ``None`` and never raises an error. It may be called multpile times on the same greenlet object, and may be called on an unstarted or dead greenlet. .. note:: Depending on what this greenlet is executing and the state of the event loop, the exception may or may not be raised immediately when this greenlet resumes execution. It may be raised on a subsequent green call, or, if this greenlet exits before making such a call, it may not be raised at all. As of 1.1, an example where the exception is raised later is if this greenlet had called :func:`sleep(0) <gevent.sleep>`; an example where the exception is raised immediately is if this greenlet had called :func:`sleep(0.1) <gevent.sleep>`. .. caution:: Use care when killing greenlets. If the code executing is not exception safe (e.g., makes proper use of ``finally``) then an unexpected exception could result in corrupted state. Using a :meth:`link` or :meth:`rawlink` (cheaper) may be a safer way to clean up resources. See also :func:`gevent.kill` and :func:`gevent.killall`. :keyword type exception: The type of exception to raise in the greenlet. The default is :class:`GreenletExit`, which indicates a :meth:`successful` completion of the greenlet. .. versionchanged:: 0.13.0 *block* is now ``True`` by default. .. versionchanged:: 1.1a2 If this greenlet had never been switched to, killing it will prevent it from *ever* being switched to. Links (:meth:`rawlink`) will still be executed, though. .. versionchanged:: 20.12.1 If this greenlet is :meth:`ready`, immediately return instead of requiring a trip around the event loop. """ if not self._maybe_kill_before_start(exception): if self.ready(): return waiter = Waiter() if block else None # pylint:disable=undefined-variable hub = get_my_hub(self) # pylint:disable=undefined-variable hub.loop.run_callback(_kill, self, exception, waiter) if waiter is not None: waiter.get() self.join(timeout)
[docs] def get(self, block=True, timeout=None): """ get(block=True, timeout=None) -> object Return the result the greenlet has returned or re-raise the exception it has raised. If block is ``False``, raise :class:`gevent.Timeout` if the greenlet is still alive. If block is ``True``, unschedule the current greenlet until the result is available or the timeout expires. In the latter case, :class:`gevent.Timeout` is raised. """ if self.ready(): if self.successful(): return self.value self._raise_exception() if not block: raise Timeout() switch = getcurrent().switch # pylint:disable=undefined-variable self.rawlink(switch) try: t = Timeout._start_new_or_dummy(timeout) try: result = get_my_hub(self).switch() # pylint:disable=undefined-variable if result is not self: raise InvalidSwitchError('Invalid switch into Greenlet.get(): %r' % (result, )) finally: t.cancel() except: # unlinking in 'except' instead of finally is an optimization: # if switch occurred normally then link was already removed in _notify_links # and there's no need to touch the links set. # Note, however, that if "Invalid switch" assert was removed and invalid switch # did happen, the link would remain, causing another invalid switch later in this greenlet. self.unlink(switch) raise if self.ready(): if self.successful(): return self.value self._raise_exception()
[docs] def join(self, timeout=None): """ join(timeout=None) -> None Wait until the greenlet finishes or *timeout* expires. Return ``None`` regardless. """ if self.ready(): return switch = getcurrent().switch # pylint:disable=undefined-variable self.rawlink(switch) try: t = Timeout._start_new_or_dummy(timeout) try: result = get_my_hub(self).switch() # pylint:disable=undefined-variable if result is not self: raise InvalidSwitchError('Invalid switch into Greenlet.join(): %r' % (result, )) finally: t.cancel() except Timeout as ex: self.unlink(switch) if ex is not t: raise except: self.unlink(switch) raise
def __enter__(self): return self def __exit__(self, t, v, tb): if t is None: try: self.join() finally: self.kill() else: self.kill((t, v, tb)) def __report_result(self, result): self._exc_info = (None, None, None) self.value = result if self._links and not self._notifier: hub = get_my_hub(self) # pylint:disable=undefined-variable self._notifier = hub.loop.run_callback(self._notify_links) def __report_error(self, exc_info): if isinstance(exc_info[1], GreenletExit): self.__report_result(exc_info[1]) return # Depending on the error, we may not be able to pickle it. # In particular, RecursionError can be a problem. try: tb = dump_traceback(exc_info[2]) except: # pylint:disable=bare-except tb = None self._exc_info = exc_info[0], exc_info[1], tb hub = get_my_hub(self) # pylint:disable=undefined-variable if self._links and not self._notifier: self._notifier = hub.loop.run_callback(self._notify_links) try: hub.handle_error(self, *exc_info) finally: del exc_info def run(self): try: self.__cancel_start() self._start_event = _start_completed_event try: result = self._run(*self.args, **self.kwargs) except: # pylint:disable=bare-except self.__report_error(sys_exc_info()) else: self.__report_result(result) finally: self.__free() def __free(self): try: # It seems that Cython 0.29.13 sometimes miscompiles # self.__dict__.pop('_run', None) ? When we moved this out of the # inline finally: block in run(), we started getting strange # exceptions from places that subclassed Greenlet. del self._run except AttributeError: pass self.args = () self.kwargs.clear() def _run(self): """ Subclasses may override this method to take any number of arguments and keyword arguments. .. versionadded:: 1.1a3 Previously, if no callable object was passed to the constructor, the spawned greenlet would later fail with an AttributeError. """ # We usually override this in __init__ # pylint: disable=method-hidden return def has_links(self): return len(self._links) def unlink_all(self): """ Remove all the callbacks. .. versionadded:: 1.3a2 """ del self._links[:] def _notify_links(self): while self._links: # Early links are allowed to remove later links # before we get to them, and they're also allowed to # add new links, so we have to be careful about iterating. # We don't expect this list to be very large, so the time spent # manipulating it should be small. a deque is probably not justified. # Cython has optimizations to transform this into a memmove anyway. link = self._links.pop(0) try: link(self) except: # pylint:disable=bare-except, undefined-variable get_my_hub(self).handle_error((link, self), *sys_exc_info())
class _dummy_event(object): __slots__ = ('pending', 'active') def __init__(self): self.pending = self.active = False def stop(self): pass def start(self, cb): # pylint:disable=unused-argument raise AssertionError("Cannot start the dummy event") def close(self): pass _cancelled_start_event = _dummy_event() _start_completed_event = _dummy_event() # This is *only* called as a callback from the hub via Greenlet.kill(), # and its first argument is the Greenlet. So we can be sure about the types. def _kill(glet, exception, waiter): try: if isinstance(exception, tuple) and len(exception) == 3: glet.throw(*exception) else: glet.throw(exception) except: # pylint:disable=bare-except, undefined-variable # XXX do we need this here? get_my_hub(glet).handle_error(glet, *sys_exc_info()) if waiter is not None: waiter.switch(None)
[docs]def joinall(greenlets, timeout=None, raise_error=False, count=None): """ Wait for the ``greenlets`` to finish. :param greenlets: A sequence (supporting :func:`len`) of greenlets to wait for. :keyword float timeout: If given, the maximum number of seconds to wait. :return: A sequence of the greenlets that finished before the timeout (if any) expired. """ if not raise_error: return wait(greenlets, timeout=timeout, count=count) done = [] for obj in iwait(greenlets, timeout=timeout, count=count): if getattr(obj, 'exception', None) is not None: if hasattr(obj, '_raise_exception'): obj._raise_exception() else: raise obj.exception done.append(obj) return done
def _killall3(greenlets, exception, waiter): diehards = [] for g in greenlets: if not g.dead: try: g.throw(exception) except: # pylint:disable=bare-except, undefined-variable get_my_hub(g).handle_error(g, *sys_exc_info()) if not g.dead: diehards.append(g) waiter.switch(diehards) def _killall(greenlets, exception): for g in greenlets: if not g.dead: try: g.throw(exception) except: # pylint:disable=bare-except, undefined-variable get_my_hub(g).handle_error(g, *sys_exc_info()) def _call_spawn_callbacks(gr): if _spawn_callbacks is not None: for cb in _spawn_callbacks: cb(gr) _spawn_callbacks = None
[docs]def killall(greenlets, exception=GreenletExit, block=True, timeout=None): """ Forceably terminate all the *greenlets* by causing them to raise *exception*. .. caution:: Use care when killing greenlets. If they are not prepared for exceptions, this could result in corrupted state. :param greenlets: A **bounded** iterable of the non-None greenlets to terminate. *All* the items in this iterable must be greenlets that belong to the same hub, which should be the hub for this current thread. If this is a generator or iterator that switches greenlets, the results are undefined. :keyword exception: The type of exception to raise in the greenlets. By default this is :class:`GreenletExit`. :keyword bool block: If True (the default) then this function only returns when all the greenlets are dead; the current greenlet is unscheduled during that process. If greenlets ignore the initial exception raised in them, then they will be joined (with :func:`gevent.joinall`) and allowed to die naturally. If False, this function returns immediately and greenlets will raise the exception asynchronously. :keyword float timeout: A time in seconds to wait for greenlets to die. If given, it is only honored when ``block`` is True. :raise Timeout: If blocking and a timeout is given that elapses before all the greenlets are dead. .. versionchanged:: 1.1a2 *greenlets* can be any iterable of greenlets, like an iterator or a set. Previously it had to be a list or tuple. .. versionchanged:: 1.5a3 Any :class:`Greenlet` in the *greenlets* list that hadn't been switched to before calling this method will never be switched to. This makes this function behave like :meth:`Greenlet.kill`. This does not apply to raw greenlets. .. versionchanged:: 1.5a3 Now accepts raw greenlets created by :func:`gevent.spawn_raw`. """ need_killed = [] # type: list for glet in greenlets: # Quick pass through to prevent any greenlet from # actually being switched to if it hasn't already. # (Previously we called ``list(greenlets)`` so we're still # linear.) # # We don't use glet.kill() here because we don't want to schedule # any callbacks in the loop; we're about to handle that more directly. try: cancel = glet._maybe_kill_before_start except AttributeError: need_killed.append(glet) else: if not cancel(exception): need_killed.append(glet) if not need_killed: return loop = glet.loop # pylint:disable=undefined-loop-variable if block: waiter = Waiter() # pylint:disable=undefined-variable loop.run_callback(_killall3, need_killed, exception, waiter) t = Timeout._start_new_or_dummy(timeout) try: alive = waiter.get() if alive: joinall(alive, raise_error=False) finally: t.cancel() else: loop.run_callback(_killall, need_killed, exception)
def _init(): greenlet_init() # pylint:disable=undefined-variable _init() from gevent._util import import_c_accel import_c_accel(globals(), 'gevent._greenlet')