"""Support for generic select()able objects.
API Stability: stable
Maintainer: U{Itamar Shtull-Trauring<mailto:twisted@itamarst.org>}
"""
import types, string
from twisted.python import log, reflect
from twisted.persisted import styles
import interfaces
class FileDescriptor(log.Logger, styles.Ephemeral):
"""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
dataBuffer = ""
offset = 0
__implements__ = (interfaces.IProducer, interfaces.IReadWriteDescriptor,
interfaces.IConsumer, interfaces.ITransport)
def __init__(self, reactor=None):
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 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.
"""
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 self.offset == len(self.dataBuffer):
self.dataBuffer = ""
self.offset = 0
self.stopWriting()
if self.producer is not None and ((not self.streamingProducer)
or self.producerPaused):
self.producer.resumeProducing()
self.producerPaused = 0
elif self.disconnecting:
return self._postLoseConnection()
return result
def _postLoseConnection(self):
"""Called after a loseConnection(), when all data has been written.
Whatever this returns is then returned by doWrite.
"""
return main.CONNECTION_DONE
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:
return
if data:
if (not self.dataBuffer) and (self.producer is None):
l = self.writeSomeData(data)
if l == len(data):
return
elif not isinstance(l, Exception) and l > 0:
self.dataBuffer = data
self.offset = l
else:
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))
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 = 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))
if self.disconnected:
producer.stopProducing()
else:
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()
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.
"""
return -1
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
import main
__all__ = ["FileDescriptor"]