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# -*- test-case-name: twisted.test.test_internet -*-
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
"""
Select reactor
Maintainer: Itamar Shtull-Trauring
"""
from time import sleep
import sys
import select
from errno import EINTR, EBADF
from zope.interface import implements
from twisted.internet.interfaces import IReactorFDSet
from twisted.internet import error
from twisted.internet import posixbase
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
# Exceptions that doSelect might return frequently
_NO_FILENO = error.ConnectionFdescWentAway('Handler has no fileno method')
_NO_FILEDESC = error.ConnectionFdescWentAway('Filedescriptor went away')
class SelectReactor(posixbase.PosixReactorBase):
"""
A select() based reactor - runs on all POSIX platforms and on Win32.
@ivar _reads: A dictionary mapping L{FileDescriptor} instances to arbitrary
values (this is essentially a set). Keys in this dictionary will be
checked for read events.
@ivar _writes: A dictionary mapping L{FileDescriptor} instances to
arbitrary values (this is essentially a set). Keys in this dictionary
will be checked for writability.
"""
implements(IReactorFDSet)
def __init__(self):
"""
Initialize file descriptor tracking dictionaries and the base class.
"""
self._reads = {}
self._writes = {}
posixbase.PosixReactorBase.__init__(self)
def _preenDescriptors(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 Exception, e:
log.msg("bad descriptor %s" % selectable)
self._disconnectSelectable(selectable, e, False)
else:
selDict[selectable] = 1
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.
"""
while 1:
try:
r, w, ignored = _select(self._reads.keys(),
self._writes.keys(),
[], timeout)
break
except ValueError, ve:
# Possibly a file descriptor has gone negative?
log.err()
self._preenDescriptors()
except TypeError, te:
# Something *totally* invalid (object w/o fileno, non-integral
# result) was passed
log.err()
self._preenDescriptors()
except (select.error, IOError), se:
# select(2) encountered an error
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()
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, dict)
doIteration = doSelect
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:
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[reader] = 1
def addWriter(self, writer):
"""
Add a FileDescriptor for notification of data available to write.
"""
self._writes[writer] = 1
def removeReader(self, reader):
"""
Remove a Selectable for notification of data available to read.
"""
if reader in self._reads:
del self._reads[reader]
def removeWriter(self, writer):
"""
Remove a Selectable for notification of data available to write.
"""
if writer in self._writes:
del self._writes[writer]
def removeAll(self):
return self._removeAll(self._reads, self._writes)
def getReaders(self):
return self._reads.keys()
def getWriters(self):
return self._writes.keys()
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']
