# Twisted, the Framework of Your Internet
# Copyright (C) 2001 Matthew W. Lefkowitz
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of version 2.1 of the GNU Lesser General Public
# License as published by the Free Software Foundation.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
"""Support for generic select()able objects.
API Stability: stable
Maintainer: U{Itamar Shtull-Trauring<mailto:twisted@itamarst.org>}
"""
# System Imports
import types, string
# Twisted Imports
from twisted.python import log, reflect
from twisted.persisted import styles
# Sibling Imports
import interfaces
class _BufferBufferMixin:
dataBuffer = ""
offset = 0
def init(self):
pass
def writeSomeData(self, data):
"""Write as much as possible of the given data, immediately.
This is called to invoke the lower-level writing functionality, such as
a socket's send() method, or a file's write(); this method returns an
integer. If positive, it is the number of bytes written; if negative,
it indicates the connection was lost.
"""
raise NotImplementedError("%s does not implement writeSomeData" %
reflect.qual(self.__class__))
def doWrite(self):
"""Called when data is available for writing.
A result that is true (which will be a negative number) implies the
connection was lost. A false result implies the connection is still
there; a result of 0 implies no write was done, and a result of None
indicates that a write was done.
"""
# Send as much data as you can.
if self.offset:
l = self.writeSomeData(buffer(self.dataBuffer, self.offset))
else:
l = self.writeSomeData(self.dataBuffer)
if l < 0 or isinstance(l, Exception):
return l
if l == 0 and self.dataBuffer:
result = 0
else:
result = None
self.offset += l
# If there is nothing left to send,
if self.offset == len(self.dataBuffer):
self.dataBuffer = ""
self.offset = 0
# stop writing.
self.stopWriting()
# If I've got a producer who is supposed to supply me with data,
if self.producer is not None and ((not self.streamingProducer)
or self.producerPaused):
# tell them to supply some more.
self.producer.resumeProducing()
self.producerPaused = 0
elif self.disconnecting:
# But if I was previously asked to let the connection die, do
# so.
return self._postLoseConnection()
return result
def write(self, data):
"""Reliably write some data.
If there is no buffered data this tries to write this data immediately,
otherwise this adds data to be written the next time this file descriptor is
ready for writing.
"""
assert isinstance(data, str), "Data must be a string."
if not self.connected or not data:
return
if (not self.dataBuffer) and (self.producer is None):
l = self.writeSomeData(data)
if l == len(data):
# all data was sent, our work here is done
return
elif not isinstance(l, Exception) and l > 0:
# some data was sent
self.dataBuffer = data
self.offset = l
else:
# either no data was sent, or we were disconnected.
# if we were disconnected we still continue, so that
# the event loop can figure it out later on.
self.dataBuffer = data
else:
self.dataBuffer = self.dataBuffer + data
if self.producer is not None:
if len(self.dataBuffer) > self.bufferSize:
self.producerPaused = 1
self.producer.pauseProducing()
self.startWriting()
def writeSequence(self, iovec):
self.write("".join(iovec))
class _IOVecBufferMixin:
vector = None
def init(self):
self.bytes = 0
self.vector = []
def checkProducer(self):
if self.bytes > self.bufferSize and self.producer is not None:
self.producerPaused = True
self.producer.pauseProducing()
def writeVector(self, data):
raise NotImplementedError("%s does not implement writeVector()" % (self.__class__.__name__,))
def doWrite(self):
result = None
if self.vector:
l = self.writeVector(self.vector)
if l < 0 or isinstance(l, Exception):
return l
if l == 0 and self.vector:
result = 0
if not self.vector:
self.stopWriting()
if self.producer is not None and ((not self.streamingProducer)
or self.producerPaused):
self.producer.resumeProducing()
self.producerPaused = False
elif self.disconnecting:
return self._postLoseConnection()
return result
def write(self, data):
assert isinstance(data, str), "Data must be a string."
if not self.connected or not data:
return
self.vector.append(data)
self.checkProducer()
self.startWriting()
def writeSequence(self, iovec):
if not self.connected or not iovec:
return
self.vector.extend(iovec)
self.checkProducer()
self.startWriting()
try:
from twisted.python import iovec
except ImportError:
_BufferMixin = _BufferBufferMixin
else:
_BufferMixin = _IOVecBufferMixin
class FileDescriptor(log.Logger, styles.Ephemeral, _BufferMixin):
"""An object which can be operated on by select().
This is an abstract superclass of all objects which may be notified when
they are readable or writable; e.g. they have a file-descriptor that is
valid to be passed to select(2).
"""
connected = 0
producerPaused = 0
streamingProducer = 0
producer = None
disconnected = 0
disconnecting = 0
__implements__ = (interfaces.IProducer, interfaces.IReadWriteDescriptor,
interfaces.IConsumer, interfaces.ITransport)
def __init__(self, reactor=None):
_BufferMixin.init(self)
if not reactor:
from twisted.internet import reactor
self.reactor = reactor
def connectionLost(self, reason):
"""The connection was lost.
This is called when the connection on a selectable object has been
lost. It will be called whether the connection was closed explicitly,
an exception occurred in an event handler, or the other end of the
connection closed it first.
Clean up state here, but make sure to call back up to FileDescriptor.
"""
self.disconnected = 1
self.connected = 0
if self.producer is not None:
self.producer.stopProducing()
self.producer = None
def _postLoseConnection(self):
"""Called after a loseConnection(), when all data has been written.
Whatever this returns is then returned by doWrite.
"""
# default implementation, telling reactor we're finished
return main.CONNECTION_DONE
def loseConnection(self):
"""Close the connection at the next available opportunity.
Call this to cause this FileDescriptor to lose its connection; if this is in
the main loop, it will lose its connection as soon as it's done
flushing its write buffer; otherwise, it will wake up the main thread
and lose the connection immediately.
If you have a producer registered, the connection won't be closed until the
producer is finished. Therefore, make sure you unregister your producer
when it's finished, or the connection will never close.
"""
if self.connected:
self.stopReading()
self.startWriting()
self.disconnecting = 1
def stopReading(self):
"""Stop waiting for read availability.
Call this to remove this selectable from being notified when it is
ready for reading.
"""
self.reactor.removeReader(self)
def stopWriting(self):
"""Stop waiting for write availability.
Call this to remove this selectable from being notified when it is ready
for writing.
"""
self.reactor.removeWriter(self)
def startReading(self):
"""Start waiting for read availability.
"""
self.reactor.addReader(self)
def startWriting(self):
"""Start waiting for write availability.
Call this to have this FileDescriptor be notified whenever it is ready for
writing.
"""
self.reactor.addWriter(self)
# Producer/consumer implementation
# first, the consumer stuff. This requires no additional work, as
# any object you can write to can be a consumer, really.
producer = None
bufferSize = 2**2**2**2
def registerProducer(self, producer, streaming):
"""Register to receive data from a producer.
This sets this selectable to be a consumer for a producer. When this
selectable runs out of data on a write() call, it will ask the producer
to resumeProducing(). A producer should implement the IProducer
interface.
FileDescriptor provides some infrastructure for producer methods.
"""
if self.producer is not None:
raise RuntimeError("Cannot register producer %s, because producer %s was never unregistered." % (producer, self.producer))
self.producer = producer
self.streamingProducer = streaming
if not streaming:
producer.resumeProducing()
def unregisterProducer(self):
"""Stop consuming data from a producer, without disconnecting.
"""
self.producer = None
def stopConsuming(self):
"""Stop consuming data.
This is called when a producer has lost its connection, to tell the
consumer to go lose its connection (and break potential circular
references).
"""
self.unregisterProducer()
self.loseConnection()
# producer interface implementation
def resumeProducing(self):
assert self.connected and not self.disconnecting
self.startReading()
def pauseProducing(self):
self.stopReading()
def stopProducing(self):
self.loseConnection()
def fileno(self):
"""File Descriptor number for select().
This method must be overridden or assigned in subclasses to
indicate a valid file descriptor for the operating system.
"""
raise NotImplementedError(reflect.qual(self.__class__)+' has no fileno method')
def isIPAddress(addr):
parts = string.split(addr, '.')
if len(parts) == 4:
try:
for part in map(int, parts):
if not (0<=part<256):
break
else:
return 1
except ValueError:
pass
return 0
# Sibling Imports
import main
__all__ = ["FileDescriptor"]
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