CasperSecurity
# -*- test-case-name: twisted.internet.test.test_pollingfile -*-
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
"""
Implements a simple polling interface for file descriptors that don't work with
select() - this is pretty much only useful on Windows.
"""
from zope.interface import implementer
from twisted.internet.interfaces import IConsumer, IPushProducer
MIN_TIMEOUT = 0.000000001
MAX_TIMEOUT = 0.1
class _PollableResource:
active = True
def activate(self):
self.active = True
def deactivate(self):
self.active = False
class _PollingTimer:
# Everything is private here because it is really an implementation detail.
def __init__(self, reactor):
self.reactor = reactor
self._resources = []
self._pollTimer = None
self._currentTimeout = MAX_TIMEOUT
self._paused = False
def _addPollableResource(self, res):
self._resources.append(res)
self._checkPollingState()
def _checkPollingState(self):
for resource in self._resources:
if resource.active:
self._startPolling()
break
else:
self._stopPolling()
def _startPolling(self):
if self._pollTimer is None:
self._pollTimer = self._reschedule()
def _stopPolling(self):
if self._pollTimer is not None:
self._pollTimer.cancel()
self._pollTimer = None
def _pause(self):
self._paused = True
def _unpause(self):
self._paused = False
self._checkPollingState()
def _reschedule(self):
if not self._paused:
return self.reactor.callLater(self._currentTimeout, self._pollEvent)
def _pollEvent(self):
workUnits = 0.0
anyActive = []
for resource in self._resources:
if resource.active:
workUnits += resource.checkWork()
# Check AFTER work has been done
if resource.active:
anyActive.append(resource)
newTimeout = self._currentTimeout
if workUnits:
newTimeout = self._currentTimeout / (workUnits + 1.0)
if newTimeout < MIN_TIMEOUT:
newTimeout = MIN_TIMEOUT
else:
newTimeout = self._currentTimeout * 2.0
if newTimeout > MAX_TIMEOUT:
newTimeout = MAX_TIMEOUT
self._currentTimeout = newTimeout
if anyActive:
self._pollTimer = self._reschedule()
# If we ever (let's hope not) need the above functionality on UNIX, this could
# be factored into a different module.
import pywintypes # type: ignore[import]
import win32api # type: ignore[import]
import win32file # type: ignore[import]
import win32pipe # type: ignore[import]
@implementer(IPushProducer)
class _PollableReadPipe(_PollableResource):
def __init__(self, pipe, receivedCallback, lostCallback):
# security attributes for pipes
self.pipe = pipe
self.receivedCallback = receivedCallback
self.lostCallback = lostCallback
def checkWork(self):
finished = 0
fullDataRead = []
while 1:
try:
buffer, bytesToRead, result = win32pipe.PeekNamedPipe(self.pipe, 1)
# finished = (result == -1)
if not bytesToRead:
break
hr, data = win32file.ReadFile(self.pipe, bytesToRead, None)
fullDataRead.append(data)
except win32api.error:
finished = 1
break
dataBuf = b"".join(fullDataRead)
if dataBuf:
self.receivedCallback(dataBuf)
if finished:
self.cleanup()
return len(dataBuf)
def cleanup(self):
self.deactivate()
self.lostCallback()
def close(self):
try:
win32api.CloseHandle(self.pipe)
except pywintypes.error:
# You can't close std handles...?
pass
def stopProducing(self):
self.close()
def pauseProducing(self):
self.deactivate()
def resumeProducing(self):
self.activate()
FULL_BUFFER_SIZE = 64 * 1024
@implementer(IConsumer)
class _PollableWritePipe(_PollableResource):
def __init__(self, writePipe, lostCallback):
self.disconnecting = False
self.producer = None
self.producerPaused = False
self.streamingProducer = 0
self.outQueue = []
self.writePipe = writePipe
self.lostCallback = lostCallback
try:
win32pipe.SetNamedPipeHandleState(
writePipe, win32pipe.PIPE_NOWAIT, None, None
)
except pywintypes.error:
# Maybe it's an invalid handle. Who knows.
pass
def close(self):
self.disconnecting = True
def bufferFull(self):
if self.producer is not None:
self.producerPaused = True
self.producer.pauseProducing()
def bufferEmpty(self):
if self.producer is not None and (
(not self.streamingProducer) or self.producerPaused
):
self.producer.producerPaused = False
self.producer.resumeProducing()
return True
return False
# almost-but-not-quite-exact copy-paste from abstract.FileDescriptor... ugh
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 not self.active:
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 writeConnectionLost(self):
self.deactivate()
try:
win32api.CloseHandle(self.writePipe)
except pywintypes.error:
# OMG what
pass
self.lostCallback()
def writeSequence(self, seq):
"""
Append a C{list} or C{tuple} of bytes to the output buffer.
@param seq: C{list} or C{tuple} of C{str} instances to be appended to
the output buffer.
@raise TypeError: If C{seq} contains C{unicode}.
"""
if str in map(type, seq):
raise TypeError("Unicode not allowed in output buffer.")
self.outQueue.extend(seq)
def write(self, data):
"""
Append some bytes to the output buffer.
@param data: C{str} to be appended to the output buffer.
@type data: C{str}.
@raise TypeError: If C{data} is C{unicode} instead of C{str}.
"""
if isinstance(data, str):
raise TypeError("Unicode not allowed in output buffer.")
if self.disconnecting:
return
self.outQueue.append(data)
if sum(map(len, self.outQueue)) > FULL_BUFFER_SIZE:
self.bufferFull()
def checkWork(self):
numBytesWritten = 0
if not self.outQueue:
if self.disconnecting:
self.writeConnectionLost()
return 0
try:
win32file.WriteFile(self.writePipe, b"", None)
except pywintypes.error:
self.writeConnectionLost()
return numBytesWritten
while self.outQueue:
data = self.outQueue.pop(0)
errCode = 0
try:
errCode, nBytesWritten = win32file.WriteFile(self.writePipe, data, None)
except win32api.error:
self.writeConnectionLost()
break
else:
# assert not errCode, "wtf an error code???"
numBytesWritten += nBytesWritten
if len(data) > nBytesWritten:
self.outQueue.insert(0, data[nBytesWritten:])
break
else:
resumed = self.bufferEmpty()
if not resumed and self.disconnecting:
self.writeConnectionLost()
return numBytesWritten