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Diffstat (limited to 'src/leap/mail/messageflow.py')
| -rw-r--r-- | src/leap/mail/messageflow.py | 200 |
1 files changed, 0 insertions, 200 deletions
diff --git a/src/leap/mail/messageflow.py b/src/leap/mail/messageflow.py deleted file mode 100644 index c8f224c..0000000 --- a/src/leap/mail/messageflow.py +++ /dev/null @@ -1,200 +0,0 @@ -# -*- coding: utf-8 -*- -# messageflow.py -# Copyright (C) 2013 LEAP -# -# This program is free software: you can redistribute it and/or modify -# it under the terms of the GNU General Public License as published by -# the Free Software Foundation, either version 3 of the License, or -# (at your option) any later version. -# -# This program 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 General Public License for more details. -# -# You should have received a copy of the GNU General Public License -# along with this program. If not, see <http://www.gnu.org/licenses/>. -""" -Message Producers and Consumers for flow control. -""" -import Queue - -from twisted.internet.task import LoopingCall - -from zope.interface import Interface, implements - - -class IMessageConsumer(Interface): - """ - I consume messages from a queue. - """ - - def consume(self, queue): - """ - Consumes the passed item. - - :param item: a queue where we put the object to be consumed. - :type item: object - """ - # TODO we could add an optional type to be passed - # for doing type check. - - # TODO in case of errors, we could return the object to - # the queue, maybe wrapped in an object with a retries attribute. - - -class IMessageProducer(Interface): - """ - I produce messages and put them in a store to be consumed by other - entities. - """ - - def push(self, item, state=None): - """ - Push a new item in the queue. - """ - - def start(self): - """ - Start producing items. - """ - - def stop(self): - """ - Stop producing items. - """ - - def flush(self): - """ - Flush queued messages to consumer. - """ - - -class DummyMsgConsumer(object): - - implements(IMessageConsumer) - - def consume(self, queue): - """ - Just prints the passed item. - """ - if not queue.empty(): - print "got item %s" % queue.get() - - -class MessageProducer(object): - """ - A Producer class that we can use to temporarily buffer the production - of messages so that different objects can consume them. - - This is useful for serializing the consumption of the messages stream - in the case of an slow resource (db), or for returning early from a - deferred chain and leave further processing detached from the calling loop, - as in the case of smtp. - """ - implements(IMessageProducer) - - # TODO this can be seen as a first step towards properly implementing - # components that implement IPushProducer / IConsumer interfaces. - # However, I need to think more about how to pause the streaming. - # In any case, the differential rate between message production - # and consumption is not likely (?) to consume huge amounts of memory in - # our current settings, so the need to pause the stream is not urgent now. - - # TODO use enum - STATE_NEW = 1 - STATE_DIRTY = 2 - - def __init__(self, consumer, queue=Queue.Queue, period=1): - """ - Initializes the MessageProducer - - :param consumer: an instance of a IMessageConsumer that will consume - the new messages. - :param queue: any queue implementation to be used as the temporary - buffer for new items. Default is a FIFO Queue. - :param period: the period to check for new items, in seconds. - """ - # XXX should assert it implements IConsumer / IMailConsumer - # it should implement a `consume` method - self._consumer = consumer - - self._queue_new = queue() - self._queue_dirty = queue() - self._period = period - - self._loop = LoopingCall(self._check_for_new) - - # private methods - - def _check_for_new(self): - """ - Check for new items in the internal queue, and calls the consume - method in the consumer. - - If the queue is found empty, the loop is stopped. It will be started - again after the addition of new items. - """ - self._consumer.consume((self._queue_new, self._queue_dirty)) - if self.is_queue_empty(): - self.stop() - - def is_queue_empty(self): - """ - Return True if queue is empty, False otherwise. - """ - new = self._queue_new - dirty = self._queue_dirty - return new.empty() and dirty.empty() - - # public methods: IMessageProducer - - def push(self, item, state=None): - """ - Push a new item in the queue. - - If the queue was empty, we will start the loop again. - """ - # XXX this might raise if the queue does not accept any new - # items. what to do then? - queue = self._queue_new - - if state == self.STATE_NEW: - queue = self._queue_new - if state == self.STATE_DIRTY: - queue = self._queue_dirty - - queue.put(item) - self.start() - - def start(self): - """ - Start polling for new items. - """ - if not self._loop.running: - self._loop.start(self._period, now=True) - - def stop(self): - """ - Stop polling for new items. - """ - if self._loop.running: - self._loop.stop() - - def flush(self): - """ - Flush queued messages to consumer. - """ - self._check_for_new() - - -if __name__ == "__main__": - from twisted.internet import reactor - producer = MessageProducer(DummyMsgConsumer()) - producer.start() - - for delay, item in ((2, 1), (3, 2), (4, 3), - (6, 4), (7, 5), (8, 6), (8.2, 7), - (15, 'a'), (16, 'b'), (17, 'c')): - reactor.callLater(delay, producer.put, item) - reactor.run() |