* simplify lock acquiration for received messages, review code
* try to fix seldomly occuring race condition with setcallback/receive and closing of channel --HG-- branch : trunk
This commit is contained in:
holger krekel
parent
f636ed8ced
commit
5d2504df0a
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@ -223,7 +223,7 @@ def _setupmessages():
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class CHANNEL_LAST_MESSAGE(Message):
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def received(self, gateway):
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gateway._channelfactory._local_last_message(self.channelid)
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gateway._channelfactory._local_close(self.channelid, sendonly=True)
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classes = [CHANNEL_OPEN, CHANNEL_NEW, CHANNEL_DATA,
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CHANNEL_CLOSE, CHANNEL_CLOSE_ERROR, CHANNEL_LAST_MESSAGE]
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@ -269,31 +269,36 @@ class Channel(object):
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self._remoteerrors = []
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def setcallback(self, callback, endmarker=NO_ENDMARKER_WANTED):
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items = self._items
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lock = self.gateway._channelfactory._receivelock
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lock.acquire()
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# we first execute the callback on all already received
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# items. We need to hold the receivelock to prevent
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# race conditions with newly arriving items.
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# after having cleared the queue we register
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# the callback only if the channel is not closed already.
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_callbacks = self.gateway._channelfactory._callbacks
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_receivelock = self.gateway._channelfactory._receivelock
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_receivelock.acquire()
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try:
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_callbacks = self.gateway._channelfactory._callbacks
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dictvalue = (callback, endmarker)
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if _callbacks.setdefault(self.id, dictvalue) != dictvalue:
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if self._items is None:
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raise IOError("%r has callback already registered" %(self,))
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items = self._items
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self._items = None
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while 1:
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try:
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olditem = items.get(block=False)
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except queue.Empty:
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if not (self._closed or self._receiveclosed.isSet()):
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_callbacks[self.id] = (callback, endmarker)
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break
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else:
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if olditem is ENDMARKER:
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items.put(olditem)
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items.put(olditem) # for other receivers
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if endmarker is not NO_ENDMARKER_WANTED:
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callback(endmarker)
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break
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else:
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callback(olditem)
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if self._closed or self._receiveclosed.isSet():
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# no need to keep a callback
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self.gateway._channelfactory._close_callback(self.id)
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finally:
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lock.release()
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_receivelock.release()
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def __repr__(self):
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flag = self.isclosed() and "closed" or "open"
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@ -462,9 +467,6 @@ class ChannelFactory(object):
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del self._channels[id]
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except KeyError:
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pass
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self._close_callback(id)
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def _close_callback(self, id):
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try:
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callback, endmarker = self._callbacks.pop(id)
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except KeyError:
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@ -473,7 +475,7 @@ class ChannelFactory(object):
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if endmarker is not NO_ENDMARKER_WANTED:
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callback(endmarker)
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def _local_close(self, id, remoteerror=None):
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def _local_close(self, id, remoteerror=None, sendonly=False):
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channel = self._channels.get(id)
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if channel is None:
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# channel already in "deleted" state
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@ -483,20 +485,8 @@ class ChannelFactory(object):
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# state transition to "closed" state
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if remoteerror:
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channel._remoteerrors.append(remoteerror)
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channel._closed = True # --> "closed"
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channel._receiveclosed.set()
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queue = channel._items
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if queue is not None:
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queue.put(ENDMARKER)
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self._no_longer_opened(id)
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def _local_last_message(self, id):
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channel = self._channels.get(id)
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if channel is None:
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# channel already in "deleted" state
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pass
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else:
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# state transition: if "opened", change to "sendonly"
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if not sendonly: # otherwise #--> "sendonly"
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channel._closed = True # --> "closed"
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channel._receiveclosed.set()
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queue = channel._items
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if queue is not None:
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@ -505,21 +495,17 @@ class ChannelFactory(object):
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def _local_receive(self, id, data):
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# executes in receiver thread
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self._receivelock.acquire()
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try:
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try:
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callback, endmarker = self._callbacks[id]
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except KeyError:
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channel = self._channels.get(id)
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queue = channel and channel._items
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if queue is None:
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pass # drop data
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else:
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queue.put(data)
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callback, endmarker = self._callbacks[id]
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except KeyError:
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channel = self._channels.get(id)
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queue = channel and channel._items
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if queue is None:
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pass # drop data
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else:
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callback(data) # even if channel may be already closed
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finally:
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self._receivelock.release()
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queue.put(data)
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else:
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callback(data) # even if channel may be already closed
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def _finished_receiving(self):
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self._writelock.acquire()
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@ -528,9 +514,9 @@ class ChannelFactory(object):
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finally:
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self._writelock.release()
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for id in list(self._channels):
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self._local_last_message(id)
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self._local_close(id, sendonly=True)
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for id in list(self._callbacks):
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self._close_callback(id)
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self._no_longer_opened(id)
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class ChannelFile(object):
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def __init__(self, channel, proxyclose=True):
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@ -648,7 +634,12 @@ class BaseGateway(object):
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try:
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msg = Message.readfrom(self._io)
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self._trace("received <- %r" % msg)
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msg.received(self)
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_receivelock = self._channelfactory._receivelock
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_receivelock.acquire()
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try:
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msg.received(self)
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finally:
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_receivelock.release()
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except sysex:
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break
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except EOFError:
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@ -736,7 +727,7 @@ class BaseGateway(object):
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finally:
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close()
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self._trace("execution finished:", repr(source)[:50])
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except (KeyboardInterrupt, SystemExit):
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except sysex:
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pass
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except self._StopExecLoop:
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channel.close()
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