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Python

# -*- coding: utf-8 -*-
# copyright (c) 2018 gevent. See LICENSE.
# cython: auto_pickle=False,embedsignature=True,always_allow_keywords=False,binding=True
"""
A collection of primitives used by the hub, and suitable for
compilation with Cython because of their frequency of use.
"""
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
import traceback
from gevent.exceptions import InvalidSwitchError
from gevent.exceptions import ConcurrentObjectUseError
from gevent import _greenlet_primitives
from gevent import _waiter
from gevent._util import _NONE
from gevent._hub_local import get_hub_noargs as get_hub
from gevent.timeout import Timeout
# 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
locals()['MultipleWaiter'] = _waiter.MultipleWaiter
locals()['SwitchOutGreenletWithLoop'] = _greenlet_primitives.SwitchOutGreenletWithLoop
__all__ = [
'WaitOperationsGreenlet',
'iwait_on_objects',
'wait_on_objects',
'wait_read',
'wait_write',
'wait_readwrite',
]
class WaitOperationsGreenlet(SwitchOutGreenletWithLoop): # pylint:disable=undefined-variable
def wait(self, watcher):
"""
Wait until the *watcher* (which must not be started) is ready.
The current greenlet will be unscheduled during this time.
"""
waiter = Waiter(self) # pylint:disable=undefined-variable
watcher.start(waiter.switch, waiter)
try:
result = waiter.get()
if result is not waiter:
raise InvalidSwitchError(
'Invalid switch into %s: got %r (expected %r; waiting on %r with %r)' % (
getcurrent(), # pylint:disable=undefined-variable
result,
waiter,
self,
watcher
)
)
finally:
watcher.stop()
def cancel_waits_close_and_then(self, watchers, exc_kind, then, *then_args):
deferred = []
for watcher in watchers:
if watcher is None:
continue
if watcher.callback is None:
watcher.close()
else:
deferred.append(watcher)
if deferred:
self.loop.run_callback(self._cancel_waits_then, deferred, exc_kind, then, then_args)
else:
then(*then_args)
def _cancel_waits_then(self, watchers, exc_kind, then, then_args):
for watcher in watchers:
self._cancel_wait(watcher, exc_kind, True)
then(*then_args)
def cancel_wait(self, watcher, error, close_watcher=False):
"""
Cancel an in-progress call to :meth:`wait` by throwing the given *error*
in the waiting greenlet.
.. versionchanged:: 1.3a1
Added the *close_watcher* parameter. If true, the watcher
will be closed after the exception is thrown. The watcher should then
be discarded. Closing the watcher is important to release native resources.
.. versionchanged:: 1.3a2
Allow the *watcher* to be ``None``. No action is taken in that case.
"""
if watcher is None:
# Presumably already closed.
# See https://github.com/gevent/gevent/issues/1089
return
if watcher.callback is not None:
self.loop.run_callback(self._cancel_wait, watcher, error, close_watcher)
return
if close_watcher:
watcher.close()
def _cancel_wait(self, watcher, error, close_watcher):
# Running in the hub. Switches to the waiting greenlet to raise
# the error; assuming the waiting greenlet dies, switches back
# to this (because the waiting greenlet's parent is the hub.)
# We have to check again to see if it was still active by the time
# our callback actually runs.
active = watcher.active
cb = watcher.callback
if close_watcher:
watcher.close()
if active:
# The callback should be greenlet.switch(). It may or may not be None.
glet = getattr(cb, '__self__', None)
if glet is not None:
glet.throw(error)
class _WaitIterator(object):
def __init__(self, objects, hub, timeout, count):
self._hub = hub
self._waiter = MultipleWaiter(hub) # pylint:disable=undefined-variable
self._switch = self._waiter.switch
self._timeout = timeout
self._objects = objects
self._timer = None
self._begun = False
# Even if we're only going to return 1 object,
# we must still rawlink() *all* of them, so that no
# matter which one finishes first we find it.
self._count = len(objects) if count is None else min(count, len(objects))
def _begin(self):
if self._begun:
return
self._begun = True
# XXX: If iteration doesn't actually happen, we
# could leave these links around!
for obj in self._objects:
obj.rawlink(self._switch)
if self._timeout is not None:
self._timer = self._hub.loop.timer(self._timeout, priority=-1)
self._timer.start(self._switch, self)
def __iter__(self):
return self
def __next__(self):
self._begin()
if self._count == 0:
# Exhausted
self._cleanup()
raise StopIteration()
self._count -= 1
try:
item = self._waiter.get()
self._waiter.clear()
if item is self:
# Timer expired, no more
self._cleanup()
raise StopIteration()
return item
except:
self._cleanup()
raise
next = __next__
def _cleanup(self):
if self._timer is not None:
self._timer.close()
self._timer = None
objs = self._objects
self._objects = ()
for aobj in objs:
unlink = getattr(aobj, 'unlink', None)
if unlink is not None:
try:
unlink(self._switch)
except: # pylint:disable=bare-except
traceback.print_exc()
def __enter__(self):
return self
def __exit__(self, typ, value, tb):
self._cleanup()
def iwait_on_objects(objects, timeout=None, count=None):
"""
Iteratively yield *objects* as they are ready, until all (or *count*) are ready
or *timeout* expired.
If you will only be consuming a portion of the *objects*, you should
do so inside a ``with`` block on this object to avoid leaking resources::
with gevent.iwait((a, b, c)) as it:
for i in it:
if i is a:
break
:param objects: A sequence (supporting :func:`len`) containing objects
implementing the wait protocol (rawlink() and unlink()).
:keyword int count: If not `None`, then a number specifying the maximum number
of objects to wait for. If ``None`` (the default), all objects
are waited for.
:keyword float timeout: If given, specifies a maximum number of seconds
to wait. If the timeout expires before the desired waited-for objects
are available, then this method returns immediately.
.. seealso:: :func:`wait`
.. versionchanged:: 1.1a1
Add the *count* parameter.
.. versionchanged:: 1.1a2
No longer raise :exc:`LoopExit` if our caller switches greenlets
in between items yielded by this function.
.. versionchanged:: 1.4
Add support to use the returned object as a context manager.
"""
# QQQ would be nice to support iterable here that can be generated slowly (why?)
hub = get_hub()
if objects is None:
return [hub.join(timeout=timeout)]
return _WaitIterator(objects, hub, timeout, count)
def wait_on_objects(objects=None, timeout=None, count=None):
"""
Wait for ``objects`` to become ready or for event loop to finish.
If ``objects`` is provided, it must be a list containing objects
implementing the wait protocol (rawlink() and unlink() methods):
- :class:`gevent.Greenlet` instance
- :class:`gevent.event.Event` instance
- :class:`gevent.lock.Semaphore` instance
- :class:`gevent.subprocess.Popen` instance
If ``objects`` is ``None`` (the default), ``wait()`` blocks until
the current event loop has nothing to do (or until ``timeout`` passes):
- all greenlets have finished
- all servers were stopped
- all event loop watchers were stopped.
If ``count`` is ``None`` (the default), wait for all ``objects``
to become ready.
If ``count`` is a number, wait for (up to) ``count`` objects to become
ready. (For example, if count is ``1`` then the function exits
when any object in the list is ready).
If ``timeout`` is provided, it specifies the maximum number of
seconds ``wait()`` will block.
Returns the list of ready objects, in the order in which they were
ready.
.. seealso:: :func:`iwait`
"""
if objects is None:
hub = get_hub()
return hub.join(timeout=timeout) # pylint:disable=
return list(iwait_on_objects(objects, timeout, count))
_timeout_error = Exception
def set_default_timeout_error(e):
global _timeout_error
_timeout_error = e
def _primitive_wait(watcher, timeout, timeout_exc, hub):
if watcher.callback is not None:
raise ConcurrentObjectUseError('This socket is already used by another greenlet: %r'
% (watcher.callback, ))
if hub is None:
hub = get_hub()
if timeout is None:
hub.wait(watcher)
return
timeout = Timeout._start_new_or_dummy(
timeout,
(timeout_exc
if timeout_exc is not _NONE or timeout is None
else _timeout_error('timed out')))
with timeout:
hub.wait(watcher)
# Suitable to be bound as an instance method
def wait_on_socket(socket, watcher, timeout_exc=None):
if socket is None or watcher is None:
# test__hub TestCloseSocketWhilePolling, on Python 2; Python 3
# catches the EBADF differently.
raise ConcurrentObjectUseError("The socket has already been closed by another greenlet")
_primitive_wait(watcher, socket.timeout,
timeout_exc if timeout_exc is not None else _NONE,
socket.hub)
def wait_on_watcher(watcher, timeout=None, timeout_exc=_NONE, hub=None):
"""
wait(watcher, timeout=None, [timeout_exc=None]) -> None
Block the current greenlet until *watcher* is ready.
If *timeout* is non-negative, then *timeout_exc* is raised after
*timeout* second has passed.
If :func:`cancel_wait` is called on *io* by another greenlet,
raise an exception in this blocking greenlet
(``socket.error(EBADF, 'File descriptor was closed in another
greenlet')`` by default).
:param io: An event loop watcher, most commonly an IO watcher obtained from
:meth:`gevent.core.loop.io`
:keyword timeout_exc: The exception to raise if the timeout expires.
By default, a :class:`socket.timeout` exception is raised.
If you pass a value for this keyword, it is interpreted as for
:class:`gevent.timeout.Timeout`.
:raises ~gevent.hub.ConcurrentObjectUseError: If the *watcher* is
already started.
"""
_primitive_wait(watcher, timeout, timeout_exc, hub)
def wait_read(fileno, timeout=None, timeout_exc=_NONE):
"""
wait_read(fileno, timeout=None, [timeout_exc=None]) -> None
Block the current greenlet until *fileno* is ready to read.
For the meaning of the other parameters and possible exceptions,
see :func:`wait`.
.. seealso:: :func:`cancel_wait`
"""
hub = get_hub()
io = hub.loop.io(fileno, 1)
try:
return wait_on_watcher(io, timeout, timeout_exc, hub)
finally:
io.close()
def wait_write(fileno, timeout=None, timeout_exc=_NONE, event=_NONE):
"""
wait_write(fileno, timeout=None, [timeout_exc=None]) -> None
Block the current greenlet until *fileno* is ready to write.
For the meaning of the other parameters and possible exceptions,
see :func:`wait`.
.. deprecated:: 1.1
The keyword argument *event* is ignored. Applications should not pass this parameter.
In the future, doing so will become an error.
.. seealso:: :func:`cancel_wait`
"""
# pylint:disable=unused-argument
hub = get_hub()
io = hub.loop.io(fileno, 2)
try:
return wait_on_watcher(io, timeout, timeout_exc, hub)
finally:
io.close()
def wait_readwrite(fileno, timeout=None, timeout_exc=_NONE, event=_NONE):
"""
wait_readwrite(fileno, timeout=None, [timeout_exc=None]) -> None
Block the current greenlet until *fileno* is ready to read or
write.
For the meaning of the other parameters and possible exceptions,
see :func:`wait`.
.. deprecated:: 1.1
The keyword argument *event* is ignored. Applications should not pass this parameter.
In the future, doing so will become an error.
.. seealso:: :func:`cancel_wait`
"""
# pylint:disable=unused-argument
hub = get_hub()
io = hub.loop.io(fileno, 3)
try:
return wait_on_watcher(io, timeout, timeout_exc, hub)
finally:
io.close()
def _init():
greenlet_init() # pylint:disable=undefined-variable
_init()
from gevent._util import import_c_accel
import_c_accel(globals(), 'gevent.__hub_primitives')