1 # Copyright (c) 2010 Google Inc. All rights reserved. 2 # 3 # Redistribution and use in source and binary forms, with or without 4 # modification, are permitted provided that the following conditions are 5 # met: 6 # 7 # * Redistributions of source code must retain the above copyright 8 # notice, this list of conditions and the following disclaimer. 9 # * Redistributions in binary form must reproduce the above 10 # copyright notice, this list of conditions and the following disclaimer 11 # in the documentation and/or other materials provided with the 12 # distribution. 13 # * Neither the name of Google Inc. nor the names of its 14 # contributors may be used to endorse or promote products derived from 15 # this software without specific prior written permission. 16 # 17 # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 18 # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 19 # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 20 # A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 21 # OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 22 # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 23 # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 24 # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 25 # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 26 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 27 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28 29 30 class MessagePumpDelegate(object): 31 def schedule(self, interval, callback): 32 raise NotImplementedError, "subclasses must implement" 33 34 def message_available(self, message): 35 raise NotImplementedError, "subclasses must implement" 36 37 def final_message_delivered(self): 38 raise NotImplementedError, "subclasses must implement" 39 40 41 class MessagePump(object): 42 interval = 10 # seconds 43 44 def __init__(self, delegate, message_queue): 45 self._delegate = delegate 46 self._message_queue = message_queue 47 self._schedule() 48 49 def _schedule(self): 50 self._delegate.schedule(self.interval, self._callback) 51 52 def _callback(self): 53 (messages, is_running) = self._message_queue.take_all() 54 for message in messages: 55 self._delegate.message_available(message) 56 if not is_running: 57 self._delegate.final_message_delivered() 58 return 59 self._schedule() 60
