1019 lines
36 KiB
Python
1019 lines
36 KiB
Python
"""\
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@file coros.py
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@author Donovan Preston
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Copyright (c) 2007, Linden Research, Inc.
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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THE SOFTWARE.
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"""
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import collections
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import sys
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import time
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import traceback
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from eventlet import api
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from eventlet import channel
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from eventlet import pools
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from eventlet import greenlib
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try:
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set
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except NameError: # python 2.3 compatibility
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from sets import Set as set
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class Cancelled(RuntimeError):
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pass
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class ExceptionWrapper(object):
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def __init__(self, e):
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self.e = e
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NOT_USED = object()
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class event(object):
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"""An abstraction where an arbitrary number of coroutines
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can wait for one event from another.
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Events differ from channels in two ways:
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1) calling send() does not unschedule the current coroutine
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2) send() can only be called once; use reset() to prepare the event for
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another send()
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They are ideal for communicating return values between coroutines.
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>>> from eventlet import coros, api
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>>> evt = coros.event()
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>>> def baz(b):
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... evt.send(b + 1)
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...
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>>> _ = api.spawn(baz, 3)
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>>> evt.wait()
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4
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"""
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_result = None
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def __init__(self):
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self.reset()
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def reset(self):
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""" Reset this event so it can be used to send again.
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Can only be called after send has been called.
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>>> from eventlet import coros
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>>> evt = coros.event()
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>>> evt.send(1)
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>>> evt.reset()
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>>> evt.send(2)
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>>> evt.wait()
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2
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Calling reset multiple times in a row is an error.
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>>> evt.reset()
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>>> evt.reset()
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Traceback (most recent call last):
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...
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AssertionError: Trying to re-reset() a fresh event.
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"""
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assert self._result is not NOT_USED, 'Trying to re-reset() a fresh event.'
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self.epoch = time.time()
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self._result = NOT_USED
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self._waiters = {}
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def ready(self):
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""" Return true if the wait() call will return immediately.
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Used to avoid waiting for things that might take a while to time out.
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For example, you can put a bunch of events into a list, and then visit
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them all repeatedly, calling ready() until one returns True, and then
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you can wait() on that one."""
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return self._result is not NOT_USED
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def wait(self):
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"""Wait until another coroutine calls send.
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Returns the value the other coroutine passed to
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send.
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>>> from eventlet import coros, api
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>>> evt = coros.event()
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>>> def wait_on():
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... retval = evt.wait()
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... print "waited for", retval
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>>> _ = api.spawn(wait_on)
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>>> evt.send('result')
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>>> api.sleep(0)
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waited for result
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Returns immediately if the event has already
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occured.
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>>> evt.wait()
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'result'
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"""
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if self._result is NOT_USED:
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self._waiters[api.getcurrent()] = True
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return api.get_hub().switch()
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if self._exc is not None:
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raise self._exc
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return self._result
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def cancel(self, waiter):
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"""Raise an exception into a coroutine which called
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wait() an this event instead of returning a value
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from wait. Sends the eventlet.coros.Cancelled
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exception
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waiter: The greenlet (greenlet.getcurrent()) of the
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coroutine to cancel
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>>> from eventlet import coros, api
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>>> evt = coros.event()
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>>> def wait_on():
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... try:
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... print "received " + evt.wait()
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... except coros.Cancelled, c:
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... print "Cancelled"
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...
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>>> waiter = api.spawn(wait_on)
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The cancel call works on coroutines that are in the wait() call.
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>>> api.sleep(0) # enter the wait()
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>>> evt.cancel(waiter)
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>>> api.sleep(0) # receive the exception
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Cancelled
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The cancel is invisible to coroutines that call wait() after cancel()
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is called. This is different from send()'s behavior, where the result
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is passed to any waiter regardless of the ordering of the calls.
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>>> waiter = api.spawn(wait_on)
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>>> api.sleep(0)
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Cancels have no effect on the ability to send() to the event.
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>>> evt.send('stuff')
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>>> api.sleep(0)
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received stuff
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"""
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if waiter in self._waiters:
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del self._waiters[waiter]
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api.get_hub().schedule_call(
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0, greenlib.switch, waiter, None, Cancelled())
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def send(self, result=None, exc=None):
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"""Makes arrangements for the waiters to be woken with the
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result and then returns immediately to the parent.
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>>> from eventlet import coros, api
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>>> evt = coros.event()
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>>> def waiter():
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... print 'about to wait'
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... result = evt.wait()
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... print 'waited for', result
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>>> _ = api.spawn(waiter)
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>>> api.sleep(0)
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about to wait
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>>> evt.send('a')
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>>> api.sleep(0)
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waited for a
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It is an error to call send() multiple times on the same event.
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>>> evt.send('whoops')
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Traceback (most recent call last):
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...
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AssertionError: Trying to re-send() an already-triggered event.
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Use reset() between send()s to reuse an event object.
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"""
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assert self._result is NOT_USED, 'Trying to re-send() an already-triggered event.'
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self._result = result
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self._exc = exc
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hub = api.get_hub()
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for waiter in self._waiters:
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hub.schedule_call(0, greenlib.switch, waiter, self._result)
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class semaphore(object):
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"""Classic semaphore implemented with a counter and an event.
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Optionally initialize with a resource count, then acquire() and release()
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resources as needed. Attempting to acquire() when count is zero suspends
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the calling coroutine until count becomes nonzero again.
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>>> from eventlet import coros, api
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>>> sem = coros.semaphore(2, limit=3)
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>>> sem.acquire()
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>>> sem.acquire()
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>>> def releaser(sem):
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... print "releasing one"
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... sem.release()
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...
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>>> _ = api.spawn(releaser, sem)
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>>> sem.acquire()
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releasing one
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>>> sem.counter
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0
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>>> for x in xrange(3):
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... sem.release()
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...
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>>> def acquirer(sem):
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... print "acquiring one"
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... sem.acquire()
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...
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>>> _ = api.spawn(acquirer, sem)
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>>> sem.release()
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acquiring one
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>>> sem.counter
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3
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"""
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def __init__(self, count=0, limit=None):
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if limit is not None and count > limit:
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# Prevent initializing with inconsistent values
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count = limit
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self.counter = count
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self.limit = limit
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self.acqevent = event()
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self.relevent = event()
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if self.counter > 0:
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# If we initially have items, then don't block acquire()s.
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self.acqevent.send()
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if self.limit is None or self.counter < self.limit:
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# If either there's no limit or we're below it, don't block on
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# release()s.
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self.relevent.send()
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def locked(self):
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return self.counter <= 0
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def acquire(self, blocking=1):
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if blocking==0 and self.locked():
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return False
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# This logic handles the self.limit is None case because None != any integer.
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while self.counter == 0:
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# Loop until there are resources to acquire. We loop because we
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# could be one of several coroutines waiting for a single item. If
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# we all get notified, only one is going to claim it, and the rest
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# of us must continue waiting.
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self.acqevent.wait()
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# claim the resource
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self.counter -= 1
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if self.counter == 0:
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# If we just transitioned from having a resource to having none,
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# make anyone else's wait() actually wait.
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self.acqevent.reset()
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if self.counter + 1 == self.limit:
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# If we just transitioned from being full to having room for one
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# more resource, notify whoever was waiting to release one.
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self.relevent.send()
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return True
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__enter__ = acquire
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def release(self):
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# This logic handles the self.limit is None case because None != any integer.
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while self.counter == self.limit:
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self.relevent.wait()
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self.counter += 1
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if self.counter == self.limit:
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self.relevent.reset()
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if self.counter == 1:
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# If self.counter was 0 before we incremented it, then wake up
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# anybody who was waiting
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self.acqevent.send()
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def __exit__(self, typ, val, tb):
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self.release()
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class metaphore(object):
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"""This is sort of an inverse semaphore: a counter that starts at 0 and
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waits only if nonzero. It's used to implement a "wait for all" scenario.
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>>> from eventlet import api, coros
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>>> count = coros.metaphore()
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>>> count.wait()
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>>> def decrementer(count, id):
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... print "%s decrementing" % id
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... count.dec()
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...
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>>> _ = api.spawn(decrementer, count, 'A')
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>>> _ = api.spawn(decrementer, count, 'B')
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>>> count.inc(2)
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>>> count.wait()
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A decrementing
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B decrementing
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"""
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def __init__(self):
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self.counter = 0
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self.event = event()
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# send() right away, else we'd wait on the default 0 count!
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self.event.send()
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def inc(self, by=1):
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"""Increment our counter. If this transitions the counter from zero to
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nonzero, make any subsequent wait() call wait.
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"""
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assert by > 0
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self.counter += by
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if self.counter == by:
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# If we just incremented self.counter by 'by', and the new count
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# equals 'by', then the old value of self.counter was 0.
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# Transitioning from 0 to a nonzero value means wait() must
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# actually wait.
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self.event.reset()
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def dec(self, by=1):
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"""Decrement our counter. If this transitions the counter from nonzero
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to zero, a current or subsequent wait() call need no longer wait.
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"""
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assert by > 0
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self.counter -= by
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if self.counter <= 0:
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# Don't leave self.counter < 0, that will screw things up in
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# future calls.
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self.counter = 0
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# Transitioning from nonzero to 0 means wait() need no longer wait.
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self.event.send()
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def wait(self):
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"""Suspend the caller only if our count is nonzero. In that case,
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resume the caller once the count decrements to zero again.
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"""
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self.event.wait()
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def execute(func, *args, **kw):
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""" Executes an operation asynchronously in a new coroutine, returning
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an event to retrieve the return value.
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This has the same api as the CoroutinePool.execute method; the only
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difference is that this one creates a new coroutine instead of drawing
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from a pool.
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>>> from eventlet import coros
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>>> evt = coros.execute(lambda a: ('foo', a), 1)
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>>> evt.wait()
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('foo', 1)
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"""
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evt = event()
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def _really_execute():
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evt.send(func(*args, **kw))
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api.spawn(_really_execute)
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return evt
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class CoroutinePool(pools.Pool):
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""" Like a thread pool, but with coroutines.
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Coroutine pools are useful for splitting up tasks or globally controlling
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concurrency. You don't retrieve the coroutines directly with get() --
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instead use the execute() and execute_async() methods to run code.
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>>> from eventlet import coros, api
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>>> p = coros.CoroutinePool(max_size=2)
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>>> def foo(a):
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... print "foo", a
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...
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>>> evt = p.execute(foo, 1)
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>>> evt.wait()
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foo 1
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Once the pool is exhausted, calling an execute forces a yield.
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>>> p.execute_async(foo, 2)
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>>> p.execute_async(foo, 3)
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>>> p.free()
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0
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>>> p.execute_async(foo, 4)
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foo 2
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foo 3
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>>> api.sleep(0)
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foo 4
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"""
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def __init__(self, min_size=0, max_size=4, track_events=False):
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self._greenlets = set()
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if track_events:
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self._tracked_events = []
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self._next_event = None
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else:
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self._tracked_events = None
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self.requested = metaphore()
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super(CoroutinePool, self).__init__(min_size, max_size)
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## This doesn't yet pass its own doctest -- but I'm not even sure it's a
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## wonderful idea.
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## def __del__(self):
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## """Experimental: try to prevent the calling script from exiting until
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## all coroutines in this pool have run to completion.
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## >>> from eventlet import coros
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## >>> pool = coros.CoroutinePool()
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## >>> def saw(x): print "I saw %s!"
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## ...
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## >>> pool.launch_all(saw, "GHI")
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## >>> del pool
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## I saw G!
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## I saw H!
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## I saw I!
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## """
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## self.wait_all()
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def _main_loop(self, sender):
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""" Private, infinite loop run by a pooled coroutine. """
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try:
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while True:
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recvd = sender.wait()
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# Delete the sender's result here because the very
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# first event through the loop is referenced by
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# spawn_startup, and therefore is not itself deleted.
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# This means that we have to free up its argument
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# because otherwise said argument persists in memory
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# forever. This is generally only a problem in unit
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# tests.
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sender._result = NOT_USED
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sender = event()
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(evt, func, args, kw) = recvd
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self._safe_apply(evt, func, args, kw)
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api.get_hub().cancel_timers(api.getcurrent())
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# Likewise, delete these variables or else they will
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# be referenced by this frame until replaced by the
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# next recvd, which may or may not be a long time from
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# now.
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del evt, func, args, kw, recvd
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self.put(sender)
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finally:
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# if we get here, something broke badly, and all we can really
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# do is try to keep the pool from leaking items.
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# Shouldn't even try to print the exception.
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self.put(self.create())
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def _safe_apply(self, evt, func, args, kw):
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""" Private method that runs the function, catches exceptions, and
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passes back the return value in the event."""
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try:
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result = func(*args, **kw)
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if evt is not None:
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evt.send(result)
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if self._tracked_events is not None:
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if self._next_event is None:
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self._tracked_events.append(result)
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else:
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ne = self._next_event
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self._next_event = None
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ne.send(result)
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except api.GreenletExit, e:
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# we're printing this out to see if it ever happens
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# in practice
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print "GreenletExit raised in coroutine pool", e
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if evt is not None:
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evt.send(e) # sent as a return value, not an exception
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except KeyboardInterrupt:
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raise # allow program to exit
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except Exception, e:
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traceback.print_exc()
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if evt is not None:
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evt.send(exc=e)
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if self._tracked_events is not None:
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if self._next_event is None:
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self._tracked_events.append(ExceptionWrapper(e))
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else:
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ne = self._next_event
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self._next_event = None
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ne.send(exc=e)
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def _execute(self, evt, func, args, kw):
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""" Private implementation of the execute methods.
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"""
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# if reentering an empty pool, don't try to wait on a coroutine freeing
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# itself -- instead, just execute in the current coroutine
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if self.free() == 0 and api.getcurrent() in self._greenlets:
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self._safe_apply(evt, func, args, kw)
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else:
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sender = self.get()
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sender.send((evt, func, args, kw))
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def create(self):
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"""Private implementation of eventlet.pools.Pool
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interface. Creates an event and spawns the
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_main_loop coroutine, passing the event.
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The event is used to send a callable into the
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new coroutine, to be executed.
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"""
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sender = event()
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self._greenlets.add(api.spawn(self._main_loop, sender))
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return sender
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def get(self):
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"""Override of eventlet.pools.Pool interface"""
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# Track the number of requested CoroutinePool coroutines
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self.requested.inc()
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# forward call to base class
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return super(CoroutinePool, self).get()
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|
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def put(self, item):
|
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"""Override of eventlet.pools.Pool interface"""
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|
# forward call to base class
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super(CoroutinePool, self).put(item)
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# Track the number of outstanding CoroutinePool coroutines
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self.requested.dec()
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|
|
def execute(self, func, *args, **kw):
|
|
"""Execute func in one of the coroutines maintained
|
|
by the pool, when one is free.
|
|
|
|
Immediately returns an eventlet.coros.event object which
|
|
func's result will be sent to when it is available.
|
|
|
|
>>> from eventlet import coros
|
|
>>> p = coros.CoroutinePool()
|
|
>>> evt = p.execute(lambda a: ('foo', a), 1)
|
|
>>> evt.wait()
|
|
('foo', 1)
|
|
"""
|
|
receiver = event()
|
|
self._execute(receiver, func, args, kw)
|
|
return receiver
|
|
|
|
def execute_async(self, func, *args, **kw):
|
|
"""Execute func in one of the coroutines maintained
|
|
by the pool, when one is free.
|
|
|
|
No return value is provided.
|
|
>>> from eventlet import coros, api
|
|
>>> p = coros.CoroutinePool()
|
|
>>> def foo(a):
|
|
... print "foo", a
|
|
...
|
|
>>> p.execute_async(foo, 1)
|
|
>>> api.sleep(0)
|
|
foo 1
|
|
"""
|
|
self._execute(None, func, args, kw)
|
|
|
|
def wait(self):
|
|
"""Wait for the next execute in the pool to complete,
|
|
and return the result.
|
|
|
|
You must pass track_events=True to the CoroutinePool constructor
|
|
in order to use this method.
|
|
"""
|
|
assert self._tracked_events is not None, (
|
|
"Must pass track_events=True to the constructor to use CoroutinePool.wait()")
|
|
if self._next_event is not None:
|
|
return self._next_event.wait()
|
|
|
|
if not self._tracked_events:
|
|
self._next_event = event()
|
|
return self._next_event.wait()
|
|
|
|
result = self._tracked_events.pop(0)
|
|
if isinstance(result, ExceptionWrapper):
|
|
raise result.e
|
|
|
|
if not self._tracked_events:
|
|
self._next_event = event()
|
|
return result
|
|
|
|
def killall(self):
|
|
for g in self._greenlets:
|
|
api.kill(g)
|
|
|
|
def wait_all(self):
|
|
"""Wait until all coroutines started either by execute() or
|
|
execute_async() have completed. If you kept the event objects returned
|
|
by execute(), you can then call their individual wait() methods to
|
|
retrieve results with no further actual waiting.
|
|
|
|
>>> from eventlet import coros
|
|
>>> pool = coros.CoroutinePool()
|
|
>>> pool.wait_all()
|
|
>>> def hi(name):
|
|
... print "Hello, %s!" % name
|
|
... return name
|
|
...
|
|
>>> evt = pool.execute(hi, "world")
|
|
>>> pool.execute_async(hi, "darkness, my old friend")
|
|
>>> pool.wait_all()
|
|
Hello, world!
|
|
Hello, darkness, my old friend!
|
|
>>> evt.wait()
|
|
'world'
|
|
>>> pool.wait_all()
|
|
"""
|
|
self.requested.wait()
|
|
|
|
def launch_all(self, function, iterable):
|
|
"""For each tuple (sequence) in iterable, launch function(*tuple) in
|
|
its own coroutine -- like itertools.starmap(), but in parallel.
|
|
Discard values returned by function(). You should call wait_all() to
|
|
wait for all coroutines, newly-launched plus any previously-submitted
|
|
execute() or execute_async() calls, to complete.
|
|
|
|
>>> from eventlet import coros
|
|
>>> pool = coros.CoroutinePool()
|
|
>>> def saw(x):
|
|
... print "I saw %s!" % x
|
|
...
|
|
>>> pool.launch_all(saw, "ABC")
|
|
>>> pool.wait_all()
|
|
I saw A!
|
|
I saw B!
|
|
I saw C!
|
|
"""
|
|
for tup in iterable:
|
|
self.execute_async(function, *tup)
|
|
|
|
def process_all(self, function, iterable):
|
|
"""For each tuple (sequence) in iterable, launch function(*tuple) in
|
|
its own coroutine -- like itertools.starmap(), but in parallel.
|
|
Discard values returned by function(). Don't return until all
|
|
coroutines, newly-launched plus any previously-submitted execute() or
|
|
execute_async() calls, have completed.
|
|
|
|
>>> from eventlet import coros
|
|
>>> pool = coros.CoroutinePool()
|
|
>>> def saw(x): print "I saw %s!" % x
|
|
...
|
|
>>> pool.process_all(saw, "DEF")
|
|
I saw D!
|
|
I saw E!
|
|
I saw F!
|
|
"""
|
|
self.launch_all(function, iterable)
|
|
self.wait_all()
|
|
|
|
def generate_results(self, function, iterable, qsize=None):
|
|
"""For each tuple (sequence) in iterable, launch function(*tuple) in
|
|
its own coroutine -- like itertools.starmap(), but in parallel.
|
|
Yield each of the values returned by function(), in the order they're
|
|
completed rather than the order the coroutines were launched.
|
|
|
|
Iteration stops when we've yielded results for each arguments tuple in
|
|
iterable. Unlike wait_all() and process_all(), this function does not
|
|
wait for any previously-submitted execute() or execute_async() calls.
|
|
|
|
Results are temporarily buffered in a queue. If you pass qsize=, this
|
|
value is used to limit the max size of the queue: an attempt to buffer
|
|
too many results will suspend the completed CoroutinePool coroutine
|
|
until the requesting coroutine (the caller of generate_results()) has
|
|
retrieved one or more results by calling this generator-iterator's
|
|
next().
|
|
|
|
If any coroutine raises an uncaught exception, that exception will
|
|
propagate to the requesting coroutine via the corresponding next() call.
|
|
|
|
What I particularly want these tests to illustrate is that using this
|
|
generator function:
|
|
|
|
for result in generate_results(function, iterable):
|
|
# ... do something with result ...
|
|
|
|
executes coroutines at least as aggressively as the classic eventlet
|
|
idiom:
|
|
|
|
events = [pool.execute(function, *args) for args in iterable]
|
|
for event in events:
|
|
result = event.wait()
|
|
# ... do something with result ...
|
|
|
|
even without a distinct event object for every arg tuple in iterable,
|
|
and despite the funny flow control from interleaving launches of new
|
|
coroutines with yields of completed coroutines' results.
|
|
|
|
(The use case that makes this function preferable to the classic idiom
|
|
above is when the iterable, which may itself be a generator, produces
|
|
millions of items.)
|
|
|
|
>>> from eventlet import coros
|
|
>>> import string
|
|
>>> pool = coros.CoroutinePool(max_size=5)
|
|
>>> pausers = [coros.event() for x in xrange(2)]
|
|
>>> def longtask(evt, desc):
|
|
... print "%s woke up with %s" % (desc, evt.wait())
|
|
...
|
|
>>> pool.launch_all(longtask, zip(pausers, "AB"))
|
|
>>> def quicktask(desc):
|
|
... print "returning %s" % desc
|
|
... return desc
|
|
...
|
|
|
|
(Instead of using a for loop, step through generate_results()
|
|
items individually to illustrate timing)
|
|
|
|
>>> step = iter(pool.generate_results(quicktask, string.ascii_lowercase))
|
|
>>> print step.next()
|
|
returning a
|
|
returning b
|
|
returning c
|
|
a
|
|
>>> print step.next()
|
|
b
|
|
>>> print step.next()
|
|
c
|
|
>>> print step.next()
|
|
returning d
|
|
returning e
|
|
returning f
|
|
d
|
|
>>> pausers[0].send("A")
|
|
>>> print step.next()
|
|
e
|
|
>>> print step.next()
|
|
f
|
|
>>> print step.next()
|
|
A woke up with A
|
|
returning g
|
|
returning h
|
|
returning i
|
|
g
|
|
>>> print "".join([step.next() for x in xrange(3)])
|
|
returning j
|
|
returning k
|
|
returning l
|
|
returning m
|
|
hij
|
|
>>> pausers[1].send("B")
|
|
>>> print "".join([step.next() for x in xrange(4)])
|
|
B woke up with B
|
|
returning n
|
|
returning o
|
|
returning p
|
|
returning q
|
|
klmn
|
|
"""
|
|
# Get an iterator because of our funny nested loop below. Wrap the
|
|
# iterable in enumerate() so we count items that come through.
|
|
tuples = iter(enumerate(iterable))
|
|
# If the iterable is empty, this whole function is a no-op, and we can
|
|
# save ourselves some grief by just quitting out. In particular, once
|
|
# we enter the outer loop below, we're going to wait on the queue --
|
|
# but if we launched no coroutines with that queue as the destination,
|
|
# we could end up waiting a very long time.
|
|
try:
|
|
index, args = tuples.next()
|
|
except StopIteration:
|
|
return
|
|
# From this point forward, 'args' is the current arguments tuple and
|
|
# 'index+1' counts how many such tuples we've seen.
|
|
# This implementation relies on the fact that _execute() accepts an
|
|
# event-like object, and -- unless it's None -- the completed
|
|
# coroutine calls send(result). We slyly pass a queue rather than an
|
|
# event -- the same queue instance for all coroutines. This is why our
|
|
# queue interface intentionally resembles the event interface.
|
|
q = queue(max_size=qsize)
|
|
# How many results have we yielded so far?
|
|
finished = 0
|
|
# This first loop is only until we've launched all the coroutines. Its
|
|
# complexity is because if iterable contains more args tuples than the
|
|
# size of our pool, attempting to _execute() the (poolsize+1)th
|
|
# coroutine would suspend until something completes and send()s its
|
|
# result to our queue. But to keep down queue overhead and to maximize
|
|
# responsiveness to our caller, we'd rather suspend on reading the
|
|
# queue. So we stuff the pool as full as we can, then wait for
|
|
# something to finish, then stuff more coroutines into the pool.
|
|
try:
|
|
while True:
|
|
# Before each yield, start as many new coroutines as we can fit.
|
|
# (The self.free() test isn't 100% accurate: if we happen to be
|
|
# executing in one of the pool's coroutines, we could _execute()
|
|
# without waiting even if self.free() reports 0. See _execute().)
|
|
# The point is that we don't want to wait in the _execute() call,
|
|
# we want to wait in the q.wait() call.
|
|
# IMPORTANT: at start, and whenever we've caught up with all
|
|
# coroutines we've launched so far, we MUST iterate this inner
|
|
# loop at least once, regardless of self.free() -- otherwise the
|
|
# q.wait() call below will deadlock!
|
|
# Recall that index is the index of the NEXT args tuple that we
|
|
# haven't yet launched. Therefore it counts how many args tuples
|
|
# we've launched so far.
|
|
while self.free() > 0 or finished == index:
|
|
# Just like the implementation of execute_async(), save that
|
|
# we're passing our queue instead of None as the "event" to
|
|
# which to send() the result.
|
|
self._execute(q, function, args, {})
|
|
# We've consumed that args tuple, advance to next.
|
|
index, args = tuples.next()
|
|
# Okay, we've filled up the pool again, yield a result -- which
|
|
# will probably wait for a coroutine to complete. Although we do
|
|
# have q.ready(), so we could iterate without waiting, we avoid
|
|
# that because every yield could involve considerable real time.
|
|
# We don't know how long it takes to return from yield, so every
|
|
# time we do, take the opportunity to stuff more requests into the
|
|
# pool before yielding again.
|
|
yield q.wait()
|
|
# Be sure to count results so we know when to stop!
|
|
finished += 1
|
|
except StopIteration:
|
|
pass
|
|
# Here we've exhausted the input iterable. index+1 is the total number
|
|
# of coroutines we've launched. We probably haven't yielded that many
|
|
# results yet. Wait for the rest of the results, yielding them as they
|
|
# arrive.
|
|
while finished < index + 1:
|
|
yield q.wait()
|
|
finished += 1
|
|
|
|
|
|
class pipe(object):
|
|
""" Implementation of pipe using events. Not tested! Not used, either."""
|
|
def __init__(self):
|
|
self._event = event()
|
|
self._buffer = ''
|
|
|
|
def send(self, txt):
|
|
self._buffer += txt
|
|
evt, self._event = self._event, event()
|
|
evt.send()
|
|
|
|
def recv(self, num=16384):
|
|
if not self._buffer:
|
|
self._event.wait()
|
|
if num >= len(self._buffer):
|
|
buf, self._buffer = self._buffer, ''
|
|
else:
|
|
buf, self._buffer = self._buffer[:num], self._buffer[num:]
|
|
return buf
|
|
|
|
|
|
class queue(object):
|
|
"""Cross-coroutine queue, using semaphore to synchronize.
|
|
The API is like a generalization of event to be able to hold more than one
|
|
item at a time (without reset() or cancel()).
|
|
|
|
>>> from eventlet import coros
|
|
>>> q = coros.queue(max_size=2)
|
|
>>> def putter(q):
|
|
... q.send("first")
|
|
...
|
|
>>> _ = api.spawn(putter, q)
|
|
>>> q.ready()
|
|
False
|
|
>>> q.wait()
|
|
'first'
|
|
>>> q.ready()
|
|
False
|
|
>>> q.send("second")
|
|
>>> q.ready()
|
|
True
|
|
>>> q.send("third")
|
|
>>> def getter(q):
|
|
... print q.wait()
|
|
...
|
|
>>> _ = api.spawn(getter, q)
|
|
>>> q.send("fourth")
|
|
second
|
|
"""
|
|
def __init__(self, max_size=None):
|
|
"""If you omit max_size, the queue will attempt to store an unlimited
|
|
number of items.
|
|
Specifying max_size means that when the queue already contains
|
|
max_size items, an attempt to send() one more item will suspend the
|
|
calling coroutine until someone else retrieves one.
|
|
"""
|
|
self.items = collections.deque()
|
|
self.sem = semaphore(count=0, limit=max_size)
|
|
|
|
def send(self, result=None, exc=None):
|
|
"""If you send(exc=SomeExceptionClass), the corresponding wait() call
|
|
will raise that exception.
|
|
Otherwise, the corresponding wait() will return result (default None).
|
|
"""
|
|
self.items.append((result, exc))
|
|
self.sem.release()
|
|
|
|
def wait(self):
|
|
"""Wait for an item sent by a send() call, in FIFO order.
|
|
If the corresponding send() specifies exc=SomeExceptionClass, this
|
|
wait() will raise that exception.
|
|
Otherwise, this wait() will return the corresponding send() call's
|
|
result= parameter.
|
|
"""
|
|
self.sem.acquire()
|
|
result, exc = self.items.popleft()
|
|
if exc is not None:
|
|
raise exc
|
|
return result
|
|
|
|
def ready(self):
|
|
# could also base this on self.sem.counter...
|
|
return len(self.items) > 0
|
|
|
|
|
|
class Actor(object):
|
|
""" A free-running coroutine that accepts and processes messages.
|
|
|
|
Kind of the equivalent of an Erlang process, really. It processes
|
|
a queue of messages in the order that they were sent. You must
|
|
subclass this and implement your own version of receive().
|
|
|
|
The actor's reference count will never drop to zero while the
|
|
coroutine exists; if you lose all references to the actor object
|
|
it will never be freed.
|
|
"""
|
|
def __init__(self, concurrency = 1):
|
|
""" Constructs an Actor, kicking off a new coroutine to process the messages.
|
|
|
|
The concurrency argument specifies how many messages the actor will try
|
|
to process concurrently. If it is 1, the actor will process messages
|
|
serially.
|
|
"""
|
|
self._mailbox = collections.deque()
|
|
self._event = event()
|
|
self._killer = api.spawn(self.run_forever)
|
|
self._pool = CoroutinePool(min_size=0, max_size=concurrency)
|
|
|
|
def run_forever(self):
|
|
""" Loops forever, continually checking the mailbox. """
|
|
while True:
|
|
if not self._mailbox:
|
|
self._event.wait()
|
|
self._event = event()
|
|
else:
|
|
# leave the message in the mailbox until after it's
|
|
# been processed so the event doesn't get triggered
|
|
# while in the received method
|
|
self._pool.execute_async(
|
|
self.received, self._mailbox[0])
|
|
self._mailbox.popleft()
|
|
|
|
def cast(self, message):
|
|
""" Send a message to the actor.
|
|
|
|
If the actor is busy, the message will be enqueued for later
|
|
consumption. There is no return value.
|
|
|
|
>>> a = Actor()
|
|
>>> a.received = lambda msg: msg
|
|
>>> a.cast("hello")
|
|
"""
|
|
self._mailbox.append(message)
|
|
# if this is the only message, the coro could be waiting
|
|
if len(self._mailbox) == 1:
|
|
self._event.send()
|
|
|
|
def received(self, message):
|
|
""" Called to process each incoming message.
|
|
|
|
The default implementation just raises an exception, so
|
|
replace it with something useful!
|
|
|
|
>>> class Greeter(Actor):
|
|
... def received(self, (message, evt) ):
|
|
... print "received", message
|
|
... if evt: evt.send()
|
|
...
|
|
>>> a = Greeter()
|
|
|
|
This example uses events to synchronize between the actor and the main
|
|
coroutine in a predictable manner, but this kinda defeats the point of
|
|
the Actor, so don't do it in a real application.
|
|
|
|
>>> evt = event()
|
|
>>> a.cast( ("message 1", evt) )
|
|
>>> evt.wait() # force it to run at this exact moment
|
|
received message 1
|
|
>>> evt.reset()
|
|
>>> a.cast( ("message 2", None) )
|
|
>>> a.cast( ("message 3", evt) )
|
|
>>> evt.wait()
|
|
received message 2
|
|
received message 3
|
|
|
|
>>> api.kill(a._killer) # test cleanup
|
|
"""
|
|
raise NotImplementedError()
|
|
|
|
|
|
def _test():
|
|
print "Running doctests. There will be no further output if they succeed."
|
|
import doctest
|
|
doctest.testmod()
|
|
|
|
if __name__ == "__main__":
|
|
_test()
|