/usr/lib/python2.7/dist-packages/twext/internet/sendfdport.py is in calendarserver 5.2+dfsg-1.
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##
# Copyright (c) 2010-2014 Apple Inc. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
##
"""
Implementation of a TCP/SSL port that uses sendmsg/recvmsg as implemented by
L{twext.python.sendfd}.
"""
from os import close
from errno import EAGAIN, ENOBUFS
from socket import (socketpair, fromfd, error as SocketError, AF_UNIX,
SOCK_STREAM, SOCK_DGRAM)
from zope.interface import Interface
from twisted.internet.abstract import FileDescriptor
from twisted.internet.protocol import Protocol, Factory
from twext.python.log import Logger
from twext.python.sendmsg import sendmsg, recvmsg
from twext.python.sendfd import sendfd, recvfd
from twext.python.sendmsg import getsockfam
log = Logger()
class InheritingProtocol(Protocol, object):
"""
When a connection comes in on this protocol, stop reading and writing, and
dispatch the socket to another process via its factory.
"""
def connectionMade(self):
"""
A connection was received; transmit the file descriptor to another
process via L{InheritingProtocolFactory} and remove my transport from
the reactor.
"""
self.transport.stopReading()
self.transport.stopWriting()
skt = self.transport.getHandle()
self.factory.sendSocket(skt)
class InheritingProtocolFactory(Factory, object):
"""
An L{InheritingProtocolFactory} is a protocol factory which listens for
incoming connections in a I{master process}, then sends those connections
off to be inherited by a I{worker process} via an
L{InheritedSocketDispatcher}.
L{InheritingProtocolFactory} is instantiated in the master process.
@ivar dispatcher: an L{InheritedSocketDispatcher} to use to dispatch
incoming connections to an appropriate subprocess.
@ivar description: the string to send along with connections received on
this factory.
"""
protocol = InheritingProtocol
def __init__(self, dispatcher, description):
self.dispatcher = dispatcher
self.description = description
def sendSocket(self, socketObject):
"""
Send the given socket object on to my dispatcher.
"""
self.dispatcher.sendFileDescriptor(socketObject, self.description)
class _SubprocessSocket(FileDescriptor, object):
"""
A socket in the master process pointing at a file descriptor that can be
used to transmit sockets to a subprocess.
@ivar outSocket: the UNIX socket used as the sendmsg() transport.
@type outSocket: L{socket.socket}
@ivar outgoingSocketQueue: an outgoing queue of sockets to send to the
subprocess, along with their descriptions (strings describing their
protocol so that the subprocess knows how to handle them; as of this
writing, either C{"TCP"} or C{"SSL"})
@ivar outgoingSocketQueue: a C{list} of 2-tuples of C{(socket-object,
bytes)}
@ivar status: a record of the last status message received (via recvmsg)
from the subprocess: this is an application-specific indication of how
ready this subprocess is to receive more connections. A typical usage
would be to count the open connections: this is what is passed to
@type status: See L{IStatusWatcher} for an explanation of which methods
determine this type.
@ivar dispatcher: The socket dispatcher that owns this L{_SubprocessSocket}
@type dispatcher: L{InheritedSocketDispatcher}
"""
def __init__(self, dispatcher, inSocket, outSocket, status, slavenum):
FileDescriptor.__init__(self, dispatcher.reactor)
self.status = status
self.slavenum = slavenum
self.dispatcher = dispatcher
self.inSocket = inSocket
self.outSocket = outSocket # XXX needs to be set non-blocking by somebody
self.fileno = outSocket.fileno
self.outgoingSocketQueue = []
self.pendingCloseSocketQueue = []
def childSocket(self):
"""
Return the socket that the child process will use to communicate with the master.
"""
return self.inSocket
def start(self):
"""
The master process monitor is about to start the child process associated with this socket.
Update status to ensure dispatcher know what is going on.
"""
self.status.start()
self.dispatcher.statusChanged()
def restarted(self):
"""
The child process associated with this socket has signaled it is ready.
Update status to ensure dispatcher know what is going on.
"""
self.status.restarted()
self.dispatcher.statusChanged()
def stop(self):
"""
The master process monitor has determined the child process associated with this socket
has died. Update status to ensure dispatcher know what is going on.
"""
self.status.stop()
self.dispatcher.statusChanged()
def remove(self):
"""
Remove this socket.
"""
self.status.stop()
self.dispatcher.statusChanged()
self.dispatcher.removeSocket()
def sendSocketToPeer(self, skt, description):
"""
Enqueue a socket to send to the subprocess.
"""
self.outgoingSocketQueue.append((skt, description))
self.startWriting()
def doRead(self, recvmsg=recvmsg):
"""
Receive a status / health message and record it.
"""
try:
data, _ignore_flags, _ignore_ancillary = recvmsg(self.outSocket.fileno())
except SocketError, se:
if se.errno not in (EAGAIN, ENOBUFS):
raise
else:
closeCount = self.dispatcher.statusMessage(self, data)
for ignored in xrange(closeCount):
self.pendingCloseSocketQueue.pop(0).close()
def doWrite(self, sendfd=sendfd):
"""
Transmit as many queued pending file descriptors as we can.
"""
while self.outgoingSocketQueue:
skt, desc = self.outgoingSocketQueue.pop(0)
try:
sendfd(self.outSocket.fileno(), skt.fileno(), desc)
except SocketError, se:
if se.errno in (EAGAIN, ENOBUFS):
self.outgoingSocketQueue.insert(0, (skt, desc))
return
raise
# Ready to close this socket; wait until it is acknowledged.
self.pendingCloseSocketQueue.append(skt)
if not self.outgoingSocketQueue:
self.stopWriting()
class IStatus(Interface):
"""
Defines the status of a socket. This keeps track of active connections etc.
"""
def effective():
"""
The current effective load.
@return: The current effective load.
@rtype: L{int}
"""
def active():
"""
Whether the socket should be active (able to be dispatched to).
@return: Active state.
@rtype: L{bool}
"""
def start():
"""
Worker process is starting. Mark status accordingly but do not make
it active.
@return: C{self}
"""
def restarted():
"""
Worker process has signaled it is ready so make this active.
@return: C{self}
"""
def stop():
"""
Worker process has stopped so make this inactive.
@return: C{self}
"""
class IStatusWatcher(Interface):
"""
A provider of L{IStatusWatcher} tracks the I{status messages} reported by
the worker processes over their control sockets, and computes internal
I{status values} for those messages. The I{messages} are individual
octets, representing one of three operations. C{0} meaning "a new worker
process has started, with zero connections being processed", C{+} meaning
"I have received and am processing your request; I am confirming that my
requests-being-processed count has gone up by one", and C{-} meaning "I
have completed processing a request, my requests-being-processed count has
gone down by one". The I{status value} tracked by
L{_SubprocessSocket.status} is an integer, indicating the current
requests-being-processed value. (FIXME: the intended design here is
actually just that all I{this} object knows about is that
L{_SubprocessSocket.status} is an orderable value, and that this
C{statusWatcher} will compute appropriate values so the status that I{sorts
the least} is the socket to which new connections should be directed; also,
the format of the status messages is only known / understood by the
C{statusWatcher}, not the L{InheritedSocketDispatcher}. It's hard to
explain it in that manner though.)
@note: the intention of this interface is to eventually provide a broader
notion of what might constitute 'status', so the above explanation just
explains the current implementation, in for expediency's sake, rather
than the somewhat more abstract language that would be accurate.
"""
def initialStatus():
"""
A new socket was created and added to the dispatcher. Compute an
initial value for its status.
@return: the new status.
"""
def newConnectionStatus(previousStatus):
"""
A new connection was sent to a given socket. Compute its status based
on the previous status of that socket.
@param previousStatus: A status value for the socket being sent work,
previously returned by one of the methods on this interface.
@return: the socket's status after incrementing its outstanding work.
"""
def statusFromMessage(previousStatus, message):
"""
A status message was received by a worker. Convert the previous status
value (returned from L{newConnectionStatus}, L{initialStatus}, or
L{statusFromMessage}).
@param previousStatus: A status value for the socket being sent work,
previously returned by one of the methods on this interface.
@return: the socket's status after taking the reported message into
account.
"""
def closeCountFromStatus(previousStatus):
"""
Based on a status previously returned from a method on this
L{IStatusWatcher}, determine how many sockets may be closed.
@return: a 2-tuple of C{number of sockets that may safely be closed},
C{new status}.
@rtype: 2-tuple of (C{int}, C{<opaque>})
"""
class InheritedSocketDispatcher(object):
"""
Used by one or more L{InheritingProtocolFactory}s, this keeps track of a
list of available sockets that connect to I{worker process}es and sends
inbound connections to be inherited over those sockets, by those processes.
L{InheritedSocketDispatcher} is therefore instantiated in the I{master
process}.
@ivar statusWatcher: The object which will handle status messages and
convert them into current statuses, as well as .
@type statusWatcher: L{IStatusWatcher}
"""
def __init__(self, statusWatcher):
"""
Create a socket dispatcher.
"""
self._subprocessSockets = []
self.statusWatcher = statusWatcher
from twisted.internet import reactor
self.reactor = reactor
self._isDispatching = False
@property
def statuses(self):
"""
Yield the current status of all subprocess sockets in the current priority order.
"""
for subsocket in self._subprocessSockets:
yield subsocket.status
@property
def slavestates(self):
"""
Yield the current status of all subprocess sockets, ordered by slave number.
"""
for subsocket in sorted(self._subprocessSockets, key=lambda x: x.slavenum):
yield (subsocket.slavenum, subsocket.status,)
def statusChanged(self):
"""
Someone is telling us a child socket status changed.
"""
self.statusWatcher.statusesChanged(self.statuses)
def statusMessage(self, subsocket, message):
"""
The status of a connection has changed; update all registered status
change listeners.
"""
status = self.statusWatcher.statusFromMessage(subsocket.status, message)
closeCount, subsocket.status = self.statusWatcher.closeCountFromStatus(status)
self.statusChanged()
return closeCount
def sendFileDescriptor(self, skt, description):
"""
A connection has been received. Dispatch it to active sockets, sorted by
how much work they have.
@param skt: the I{connection socket} (i.e.: not the listening socket)
@type skt: L{socket.socket}
@param description: some text to identify to the subprocess's
L{InheritedPort} what type of transport to create for this socket.
@type description: C{bytes}
"""
self._subprocessSockets.sort(key=lambda x: x.status.effective())
selectedSocket = filter(lambda x: x.status.active(), self._subprocessSockets)[0]
selectedSocket.sendSocketToPeer(skt, description)
# XXX Maybe want to send along 'description' or 'skt' or some
# properties thereof? -glyph
selectedSocket.status = self.statusWatcher.newConnectionStatus(
selectedSocket.status
)
self.statusChanged()
def startDispatching(self):
"""
Start listening on all subprocess sockets.
"""
self._isDispatching = True
for subSocket in self._subprocessSockets:
subSocket.startReading()
def addSocket(self, slavenum=0, socketpair=lambda: socketpair(AF_UNIX, SOCK_DGRAM)):
"""
Add a C{sendmsg()}-oriented AF_UNIX socket to the pool of sockets being
used for transmitting file descriptors to child processes.
@return: a socket object for the receiving side; pass this object's
C{fileno()} as part of the C{childFDs} argument to
C{spawnProcess()}, then close it.
"""
i, o = socketpair()
i.setblocking(False)
o.setblocking(False)
a = _SubprocessSocket(self, i, o, self.statusWatcher.initialStatus(), slavenum)
self._subprocessSockets.append(a)
if self._isDispatching:
a.startReading()
return a
def removeSocket(self, skt):
"""
Removes a previously added socket from the pool of sockets being used
for transmitting file descriptors to child processes.
"""
self._subprocessSockets.remove(skt)
class InheritedPort(FileDescriptor, object):
"""
An L{InheritedPort} is an L{IReadDescriptor}/L{IWriteDescriptor} created in
the I{worker process} to handle incoming connections dispatched via
C{sendmsg}.
"""
def __init__(self, fd, transportFactory, protocolFactory):
"""
@param fd: the file descriptor representing a UNIX socket connected to
a I{master process}. We will call C{recvmsg} on this socket to
receive file descriptors.
@type fd: C{int}
@param transportFactory: a 4-argument function that takes the socket
object produced from the file descriptor, the peer address of that
socket, the (non-ancillary) data sent along with the incoming file
descriptor, and the protocol built along with it, and returns an
L{ITransport} provider. Note that this should NOT call
C{makeConnection} on the protocol that it produces, as this class
will do that.
@param protocolFactory: an L{IProtocolFactory}
"""
FileDescriptor.__init__(self)
self.fd = fd
self.transportFactory = transportFactory
self.protocolFactory = protocolFactory
self.statusQueue = []
def fileno(self):
"""
Get the FD number for this socket.
"""
return self.fd
def doRead(self):
"""
A message is ready to read. Receive a file descriptor from our parent
process.
"""
try:
fd, description = recvfd(self.fd)
except SocketError, se:
if se.errno != EAGAIN:
raise
else:
try:
skt = fromfd(fd, getsockfam(fd), SOCK_STREAM)
close(fd) # fromfd() calls dup()
try:
peeraddr = skt.getpeername()
except SocketError:
peeraddr = ('0.0.0.0', 0)
protocol = self.protocolFactory.buildProtocol(peeraddr)
transport = self.transportFactory(skt, peeraddr,
description, protocol)
protocol.makeConnection(transport)
except:
log.failure("doRead()")
def doWrite(self):
"""
Write some data.
"""
while self.statusQueue:
msg = self.statusQueue.pop(0)
try:
sendmsg(self.fd, msg, 0)
except SocketError, se:
if se.errno in (EAGAIN, ENOBUFS):
self.statusQueue.insert(0, msg)
return
raise
self.stopWriting()
def reportStatus(self, statusMessage):
"""
Report a status message to the L{_SubprocessSocket} monitoring this
L{InheritedPort}'s health in the master process.
"""
self.statusQueue.append(statusMessage)
self.startWriting()
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