Current File : //usr/lib/python3/dist-packages/twisted/internet/kqreactor.py
# -*- test-case-name: twisted.test.test_kqueuereactor -*-
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
"""
A kqueue()/kevent() based implementation of the Twisted main loop.
To use this reactor, start your application specifying the kqueue reactor::
twistd --reactor kqueue ...
To install the event loop from code (and you should do this before any
connections, listeners or connectors are added)::
from twisted.internet import kqreactor
kqreactor.install()
"""
import errno
import select
from zope.interface import Attribute, Interface, declarations, implementer
from twisted.internet import main, posixbase
from twisted.internet.interfaces import IReactorDaemonize, IReactorFDSet
from twisted.python import failure, log
try:
# This is to keep mypy from complaining
# We don't use type: ignore[attr-defined] on import, because mypy only complains
# on on some platforms, and then the unused ignore is an issue if the undefined
# attribute isn't.
KQ_EV_ADD = getattr(select, "KQ_EV_ADD")
KQ_EV_DELETE = getattr(select, "KQ_EV_DELETE")
KQ_EV_EOF = getattr(select, "KQ_EV_EOF")
KQ_FILTER_READ = getattr(select, "KQ_FILTER_READ")
KQ_FILTER_WRITE = getattr(select, "KQ_FILTER_WRITE")
except AttributeError as e:
raise ImportError(e)
class _IKQueue(Interface):
"""
An interface for KQueue implementations.
"""
kqueue = Attribute("An implementation of kqueue(2).")
kevent = Attribute("An implementation of kevent(2).")
declarations.directlyProvides(select, _IKQueue)
@implementer(IReactorFDSet, IReactorDaemonize)
class KQueueReactor(posixbase.PosixReactorBase):
"""
A reactor that uses kqueue(2)/kevent(2) and relies on Python 2.6 or higher
which has built in support for kqueue in the select module.
@ivar _kq: A C{kqueue} which will be used to check for I/O readiness.
@ivar _impl: The implementation of L{_IKQueue} to use.
@ivar _selectables: A dictionary mapping integer file descriptors to
instances of L{FileDescriptor} which have been registered with the
reactor. All L{FileDescriptor}s which are currently receiving read or
write readiness notifications will be present as values in this
dictionary.
@ivar _reads: A set containing integer file descriptors. Values in this
set will be registered with C{_kq} for read readiness notifications
which will be dispatched to the corresponding L{FileDescriptor}
instances in C{_selectables}.
@ivar _writes: A set containing integer file descriptors. Values in this
set will be registered with C{_kq} for write readiness notifications
which will be dispatched to the corresponding L{FileDescriptor}
instances in C{_selectables}.
"""
def __init__(self, _kqueueImpl=select):
"""
Initialize kqueue object, file descriptor tracking dictionaries, and
the base class.
See:
- http://docs.python.org/library/select.html
- www.freebsd.org/cgi/man.cgi?query=kqueue
- people.freebsd.org/~jlemon/papers/kqueue.pdf
@param _kqueueImpl: The implementation of L{_IKQueue} to use. A
hook for testing.
"""
self._impl = _kqueueImpl
self._kq = self._impl.kqueue()
self._reads = set()
self._writes = set()
self._selectables = {}
posixbase.PosixReactorBase.__init__(self)
def _updateRegistration(self, fd, filter, op):
"""
Private method for changing kqueue registration on a given FD
filtering for events given filter/op. This will never block and
returns nothing.
"""
self._kq.control([self._impl.kevent(fd, filter, op)], 0, 0)
def beforeDaemonize(self):
"""
Implement L{IReactorDaemonize.beforeDaemonize}.
"""
# Twisted-internal method called during daemonization (when application
# is started via twistd). This is called right before the magic double
# forking done for daemonization. We cleanly close the kqueue() and later
# recreate it. This is needed since a) kqueue() are not inherited across
# forks and b) twistd will create the reactor already before daemonization
# (and will also add at least 1 reader to the reactor, an instance of
# twisted.internet.posixbase._UnixWaker).
#
# See: twisted.scripts._twistd_unix.daemonize()
self._kq.close()
self._kq = None
def afterDaemonize(self):
"""
Implement L{IReactorDaemonize.afterDaemonize}.
"""
# Twisted-internal method called during daemonization. This is called right
# after daemonization and recreates the kqueue() and any readers/writers
# that were added before. Note that you MUST NOT call any reactor methods
# in between beforeDaemonize() and afterDaemonize()!
self._kq = self._impl.kqueue()
for fd in self._reads:
self._updateRegistration(fd, KQ_FILTER_READ, KQ_EV_ADD)
for fd in self._writes:
self._updateRegistration(fd, KQ_FILTER_WRITE, KQ_EV_ADD)
def addReader(self, reader):
"""
Implement L{IReactorFDSet.addReader}.
"""
fd = reader.fileno()
if fd not in self._reads:
try:
self._updateRegistration(fd, KQ_FILTER_READ, KQ_EV_ADD)
except OSError:
pass
finally:
self._selectables[fd] = reader
self._reads.add(fd)
def addWriter(self, writer):
"""
Implement L{IReactorFDSet.addWriter}.
"""
fd = writer.fileno()
if fd not in self._writes:
try:
self._updateRegistration(fd, KQ_FILTER_WRITE, KQ_EV_ADD)
except OSError:
pass
finally:
self._selectables[fd] = writer
self._writes.add(fd)
def removeReader(self, reader):
"""
Implement L{IReactorFDSet.removeReader}.
"""
wasLost = False
try:
fd = reader.fileno()
except BaseException:
fd = -1
if fd == -1:
for fd, fdes in self._selectables.items():
if reader is fdes:
wasLost = True
break
else:
return
if fd in self._reads:
self._reads.remove(fd)
if fd not in self._writes:
del self._selectables[fd]
if not wasLost:
try:
self._updateRegistration(fd, KQ_FILTER_READ, KQ_EV_DELETE)
except OSError:
pass
def removeWriter(self, writer):
"""
Implement L{IReactorFDSet.removeWriter}.
"""
wasLost = False
try:
fd = writer.fileno()
except BaseException:
fd = -1
if fd == -1:
for fd, fdes in self._selectables.items():
if writer is fdes:
wasLost = True
break
else:
return
if fd in self._writes:
self._writes.remove(fd)
if fd not in self._reads:
del self._selectables[fd]
if not wasLost:
try:
self._updateRegistration(fd, KQ_FILTER_WRITE, KQ_EV_DELETE)
except OSError:
pass
def removeAll(self):
"""
Implement L{IReactorFDSet.removeAll}.
"""
return self._removeAll(
[self._selectables[fd] for fd in self._reads],
[self._selectables[fd] for fd in self._writes],
)
def getReaders(self):
"""
Implement L{IReactorFDSet.getReaders}.
"""
return [self._selectables[fd] for fd in self._reads]
def getWriters(self):
"""
Implement L{IReactorFDSet.getWriters}.
"""
return [self._selectables[fd] for fd in self._writes]
def doKEvent(self, timeout):
"""
Poll the kqueue for new events.
"""
if timeout is None:
timeout = 1
try:
events = self._kq.control([], len(self._selectables), timeout)
except OSError as e:
# Since this command blocks for potentially a while, it's possible
# EINTR can be raised for various reasons (for example, if the user
# hits ^C).
if e.errno == errno.EINTR:
return
else:
raise
_drdw = self._doWriteOrRead
for event in events:
fd = event.ident
try:
selectable = self._selectables[fd]
except KeyError:
# Handles the infrequent case where one selectable's
# handler disconnects another.
continue
else:
log.callWithLogger(selectable, _drdw, selectable, fd, event)
def _doWriteOrRead(self, selectable, fd, event):
"""
Private method called when a FD is ready for reading, writing or was
lost. Do the work and raise errors where necessary.
"""
why = None
inRead = False
(filter, flags, data, fflags) = (
event.filter,
event.flags,
event.data,
event.fflags,
)
if flags & KQ_EV_EOF and data and fflags:
why = main.CONNECTION_LOST
else:
try:
if selectable.fileno() == -1:
inRead = False
why = posixbase._NO_FILEDESC
else:
if filter == KQ_FILTER_READ:
inRead = True
why = selectable.doRead()
if filter == KQ_FILTER_WRITE:
inRead = False
why = selectable.doWrite()
except BaseException:
# Any exception from application code gets logged and will
# cause us to disconnect the selectable.
why = failure.Failure()
log.err(
why,
"An exception was raised from application code"
" while processing a reactor selectable",
)
if why:
self._disconnectSelectable(selectable, why, inRead)
doIteration = doKEvent
def install():
"""
Install the kqueue() reactor.
"""
p = KQueueReactor()
from twisted.internet.main import installReactor
installReactor(p)
__all__ = ["KQueueReactor", "install"]
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