# 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()

This implementation depends on Python 2.6 or higher which has kqueue support
built in the select module.

Note, that you should use Python 2.6.5 or higher, since previous implementations
of select.kqueue had U{http://bugs.python.org/issue5910} not yet fixed.
"""

import errno

from zope.interface import implements

from select import kqueue, kevent
from select import KQ_FILTER_READ, KQ_FILTER_WRITE
from select import KQ_EV_DELETE, KQ_EV_ADD, KQ_EV_EOF

from twisted.internet.interfaces import IReactorFDSet, IReactorDaemonize

from twisted.python import log, failure
from twisted.internet import main, posixbase


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 L{kqueue} which will be used to check for I/O readiness.

@ivar _selectables: A dictionary mapping integer file descriptors to
instances of L{FileDescriptor} which have been registered with the
reactor. All L{FileDescriptors} 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}.
"""
implements(IReactorFDSet, IReactorDaemonize)


def __init__(self):
"""
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
"""
self._kq = 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([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 = 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:
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:
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:
l = self._kq.control([], len(self._selectables), timeout)
except OSError, e:
if e[0] == errno.EINTR:
return
else:
raise

_drdw = self._doWriteOrRead
for event in l:
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:
# 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"]