Current File : //lib/python3/dist-packages/twisted/internet/_threadedselect.py
# -*- test-case-name: twisted.test.test_internet -*-
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
"""
Threaded select reactor
The threadedselectreactor is a specialized reactor for integrating with
arbitrary foreign event loop, such as those you find in GUI toolkits.
There are three things you'll need to do to use this reactor.
Install the reactor at the beginning of your program, before importing
the rest of Twisted::
| from twisted.internet import _threadedselect
| _threadedselect.install()
Interleave this reactor with your foreign event loop, at some point after
your event loop is initialized::
| from twisted.internet import reactor
| reactor.interleave(foreignEventLoopWakerFunction)
| self.addSystemEventTrigger('after', 'shutdown', foreignEventLoopStop)
Instead of shutting down the foreign event loop directly, shut down the
reactor::
| from twisted.internet import reactor
| reactor.stop()
In order for Twisted to do its work in the main thread (the thread that
interleave is called from), a waker function is necessary. The waker function
will be called from a "background" thread with one argument: func.
The waker function's purpose is to call func() from the main thread.
Many GUI toolkits ship with appropriate waker functions.
Some examples of this are wxPython's wx.callAfter (may be wxCallAfter in
older versions of wxPython) or PyObjC's PyObjCTools.AppHelper.callAfter.
These would be used in place of "foreignEventLoopWakerFunction" in the above
example.
The other integration point at which the foreign event loop and this reactor
must integrate is shutdown. In order to ensure clean shutdown of Twisted,
you must allow for Twisted to come to a complete stop before quitting the
application. Typically, you will do this by setting up an after shutdown
trigger to stop your foreign event loop, and call reactor.stop() where you
would normally have initiated the shutdown procedure for the foreign event
loop. Shutdown functions that could be used in place of
"foreignEventloopStop" would be the ExitMainLoop method of the wxApp instance
with wxPython, or the PyObjCTools.AppHelper.stopEventLoop function.
"""
import select
import sys
from errno import EBADF, EINTR
from functools import partial
from queue import Empty, Queue
from threading import Thread
from zope.interface import implementer
from twisted.internet import posixbase
from twisted.internet.interfaces import IReactorFDSet
from twisted.internet.posixbase import _NO_FILEDESC, _NO_FILENO
from twisted.internet.selectreactor import _select
from twisted.python import failure, log, threadable
def dictRemove(dct, value):
try:
del dct[value]
except KeyError:
pass
def raiseException(e):
raise e
@implementer(IReactorFDSet)
class ThreadedSelectReactor(posixbase.PosixReactorBase):
"""A threaded select() based reactor - runs on all POSIX platforms and on
Win32.
"""
def __init__(self):
threadable.init(1)
self.reads = {}
self.writes = {}
self.toThreadQueue = Queue()
self.toMainThread = Queue()
self.workerThread = None
self.mainWaker = None
posixbase.PosixReactorBase.__init__(self)
self.addSystemEventTrigger("after", "shutdown", self._mainLoopShutdown)
def wakeUp(self):
# we want to wake up from any thread
self.waker.wakeUp()
def callLater(self, *args, **kw):
tple = posixbase.PosixReactorBase.callLater(self, *args, **kw)
self.wakeUp()
return tple
def _sendToMain(self, msg, *args):
self.toMainThread.put((msg, args))
if self.mainWaker is not None:
self.mainWaker()
def _sendToThread(self, fn, *args):
self.toThreadQueue.put((fn, args))
def _preenDescriptorsInThread(self):
log.msg("Malformed file descriptor found. Preening lists.")
readers = self.reads.keys()
writers = self.writes.keys()
self.reads.clear()
self.writes.clear()
for selDict, selList in ((self.reads, readers), (self.writes, writers)):
for selectable in selList:
try:
select.select([selectable], [selectable], [selectable], 0)
except BaseException:
log.msg("bad descriptor %s" % selectable)
else:
selDict[selectable] = 1
def _workerInThread(self):
try:
while 1:
fn, args = self.toThreadQueue.get()
fn(*args)
except SystemExit:
pass # Exception indicates this thread should exit
except BaseException:
f = failure.Failure()
self._sendToMain("Failure", f)
def _doSelectInThread(self, timeout):
"""Run one iteration of the I/O monitor loop.
This will run all selectables who had input or output readiness
waiting for them.
"""
reads = self.reads
writes = self.writes
while 1:
try:
r, w, ignored = _select(reads.keys(), writes.keys(), [], timeout)
break
except ValueError:
# Possibly a file descriptor has gone negative?
log.err()
self._preenDescriptorsInThread()
except TypeError:
# Something *totally* invalid (object w/o fileno, non-integral
# result) was passed
log.err()
self._preenDescriptorsInThread()
except OSError as se:
# select(2) encountered an error
if se.args[0] in (0, 2):
# windows does this if it got an empty list
if (not reads) and (not writes):
return
else:
raise
elif se.args[0] == EINTR:
return
elif se.args[0] == EBADF:
self._preenDescriptorsInThread()
else:
# OK, I really don't know what's going on. Blow up.
raise
self._sendToMain("Notify", r, w)
def _process_Notify(self, r, w):
reads = self.reads
writes = self.writes
_drdw = self._doReadOrWrite
_logrun = log.callWithLogger
for selectables, method, dct in ((r, "doRead", reads), (w, "doWrite", writes)):
for selectable in selectables:
# if this was disconnected in another thread, kill it.
if selectable not in dct:
continue
# This for pausing input when we're not ready for more.
_logrun(selectable, _drdw, selectable, method, dct)
def _process_Failure(self, f):
f.raiseException()
_doIterationInThread = _doSelectInThread
def ensureWorkerThread(self):
if self.workerThread is None or not self.workerThread.isAlive():
self.workerThread = Thread(target=self._workerInThread)
self.workerThread.start()
def doThreadIteration(self, timeout):
self._sendToThread(self._doIterationInThread, timeout)
self.ensureWorkerThread()
msg, args = self.toMainThread.get()
getattr(self, "_process_" + msg)(*args)
doIteration = doThreadIteration
def _interleave(self):
while self.running:
self.runUntilCurrent()
t2 = self.timeout()
t = self.running and t2
self._sendToThread(self._doIterationInThread, t)
yield None
msg, args = self.toMainThread.get_nowait()
getattr(self, "_process_" + msg)(*args)
def interleave(self, waker, *args, **kw):
"""
interleave(waker) interleaves this reactor with the
current application by moving the blocking parts of
the reactor (select() in this case) to a separate
thread. This is typically useful for integration with
GUI applications which have their own event loop
already running.
See the module docstring for more information.
"""
self.startRunning(*args, **kw)
loop = self._interleave()
def mainWaker(waker=waker, loop=loop):
waker(partial(next, loop))
self.mainWaker = mainWaker
next(loop)
self.ensureWorkerThread()
def _mainLoopShutdown(self):
self.mainWaker = None
if self.workerThread is not None:
self._sendToThread(raiseException, SystemExit)
self.wakeUp()
try:
while 1:
msg, args = self.toMainThread.get_nowait()
except Empty:
pass
self.workerThread.join()
self.workerThread = None
try:
while 1:
fn, args = self.toThreadQueue.get_nowait()
if fn is self._doIterationInThread:
log.msg("Iteration is still in the thread queue!")
elif fn is raiseException and args[0] is SystemExit:
pass
else:
fn(*args)
except Empty:
pass
def _doReadOrWrite(self, selectable, method, dict):
try:
why = getattr(selectable, method)()
handfn = getattr(selectable, "fileno", None)
if not handfn:
why = _NO_FILENO
elif handfn() == -1:
why = _NO_FILEDESC
except BaseException:
why = sys.exc_info()[1]
log.err()
if why:
self._disconnectSelectable(selectable, why, method == "doRead")
def addReader(self, reader):
"""Add a FileDescriptor for notification of data available to read."""
self._sendToThread(self.reads.__setitem__, reader, 1)
self.wakeUp()
def addWriter(self, writer):
"""Add a FileDescriptor for notification of data available to write."""
self._sendToThread(self.writes.__setitem__, writer, 1)
self.wakeUp()
def removeReader(self, reader):
"""Remove a Selectable for notification of data available to read."""
self._sendToThread(dictRemove, self.reads, reader)
def removeWriter(self, writer):
"""Remove a Selectable for notification of data available to write."""
self._sendToThread(dictRemove, self.writes, writer)
def removeAll(self):
return self._removeAll(self.reads, self.writes)
def getReaders(self):
return list(self.reads.keys())
def getWriters(self):
return list(self.writes.keys())
def stop(self):
"""
Extend the base stop implementation to also wake up the select thread so
that C{runUntilCurrent} notices the reactor should stop.
"""
posixbase.PosixReactorBase.stop(self)
self.wakeUp()
def run(self, installSignalHandlers=True):
self.startRunning(installSignalHandlers=installSignalHandlers)
self.mainLoop()
def mainLoop(self):
q = Queue()
self.interleave(q.put)
while self.running:
try:
q.get()()
except StopIteration:
break
def install():
"""Configure the twisted mainloop to be run using the select() reactor."""
reactor = ThreadedSelectReactor()
from twisted.internet.main import installReactor
installReactor(reactor)
return reactor
__all__ = ["install"]
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