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# -*- test-case-name: twisted.test.test_internet -*-
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
"""
Select reactor
"""
import select
import sys
from errno import EBADF, EINTR
from time import sleep
from typing import Type
from zope.interface import implementer
from twisted.internet import posixbase
from twisted.internet.interfaces import IReactorFDSet
from twisted.python import log
from twisted.python.runtime import platformType
def win32select(r, w, e, timeout=None):
"""Win32 select wrapper."""
if not (r or w):
# windows select() exits immediately when no sockets
if timeout is None:
timeout = 0.01
else:
timeout = min(timeout, 0.001)
sleep(timeout)
return [], [], []
# windows doesn't process 'signals' inside select(), so we set a max
# time or ctrl-c will never be recognized
if timeout is None or timeout > 0.5:
timeout = 0.5
r, w, e = select.select(r, w, w, timeout)
return r, w + e, []
if platformType == "win32":
_select = win32select
else:
_select = select.select
try:
from twisted.internet.win32eventreactor import _ThreadedWin32EventsMixin
except ImportError:
_extraBase: Type[object] = object
else:
_extraBase = _ThreadedWin32EventsMixin
@implementer(IReactorFDSet)
class SelectReactor(posixbase.PosixReactorBase, _extraBase): # type: ignore[misc,valid-type]
"""
A select() based reactor - runs on all POSIX platforms and on Win32.
@ivar _reads: A set containing L{FileDescriptor} instances which will be
checked for read events.
@ivar _writes: A set containing L{FileDescriptor} instances which will be
checked for writability.
"""
def __init__(self):
"""
Initialize file descriptor tracking dictionaries and the base class.
"""
self._reads = set()
self._writes = set()
posixbase.PosixReactorBase.__init__(self)
def _preenDescriptors(self):
log.msg("Malformed file descriptor found. Preening lists.")
readers = list(self._reads)
writers = list(self._writes)
self._reads.clear()
self._writes.clear()
for selSet, selList in ((self._reads, readers), (self._writes, writers)):
for selectable in selList:
try:
select.select([selectable], [selectable], [selectable], 0)
except Exception as e:
log.msg("bad descriptor %s" % selectable)
self._disconnectSelectable(selectable, e, False)
else:
selSet.add(selectable)
def doSelect(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.
"""
try:
r, w, ignored = _select(self._reads, self._writes, [], timeout)
except ValueError:
# Possibly a file descriptor has gone negative?
self._preenDescriptors()
return
except TypeError:
# Something *totally* invalid (object w/o fileno, non-integral
# result) was passed
log.err()
self._preenDescriptors()
return
except OSError as se:
# select(2) encountered an error, perhaps while calling the fileno()
# method of a socket. (Python 2.6 socket.error is an IOError
# subclass, but on Python 2.5 and earlier it is not.)
if se.args[0] in (0, 2):
# windows does this if it got an empty list
if (not self._reads) and (not self._writes):
return
else:
raise
elif se.args[0] == EINTR:
return
elif se.args[0] == EBADF:
self._preenDescriptors()
return
else:
# OK, I really don't know what's going on. Blow up.
raise
_drdw = self._doReadOrWrite
_logrun = log.callWithLogger
for selectables, method, fdset in (
(r, "doRead", self._reads),
(w, "doWrite", self._writes),
):
for selectable in selectables:
# if this was disconnected in another thread, kill it.
# ^^^^ --- what the !@#*? serious! -exarkun
if selectable not in fdset:
continue
# This for pausing input when we're not ready for more.
_logrun(selectable, _drdw, selectable, method)
doIteration = doSelect
def _doReadOrWrite(self, selectable, method):
try:
why = getattr(selectable, method)()
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._reads.add(reader)
def addWriter(self, writer):
"""
Add a FileDescriptor for notification of data available to write.
"""
self._writes.add(writer)
def removeReader(self, reader):
"""
Remove a Selectable for notification of data available to read.
"""
self._reads.discard(reader)
def removeWriter(self, writer):
"""
Remove a Selectable for notification of data available to write.
"""
self._writes.discard(writer)
def removeAll(self):
return self._removeAll(self._reads, self._writes)
def getReaders(self):
return list(self._reads)
def getWriters(self):
return list(self._writes)
def install():
"""Configure the twisted mainloop to be run using the select() reactor."""
reactor = SelectReactor()
from twisted.internet.main import installReactor
installReactor(reactor)
__all__ = ["install"]