497 lines
18 KiB
Python
497 lines
18 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright 2014 - 2016 OpenMarket Ltd
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from twisted.internet import defer
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from synapse.api.constants import EventTypes, Membership
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from synapse.api.errors import AuthError
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from synapse.util.logutils import log_function
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from synapse.util.async import ObservableDeferred
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from synapse.util.logcontext import PreserveLoggingContext
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from synapse.types import StreamToken
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from synapse.visibility import filter_events_for_client
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import synapse.metrics
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from collections import namedtuple
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import logging
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logger = logging.getLogger(__name__)
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metrics = synapse.metrics.get_metrics_for(__name__)
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notified_events_counter = metrics.register_counter("notified_events")
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# TODO(paul): Should be shared somewhere
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def count(func, l):
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"""Return the number of items in l for which func returns true."""
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n = 0
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for x in l:
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if func(x):
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n += 1
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return n
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class _NotificationListener(object):
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""" This represents a single client connection to the events stream.
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The events stream handler will have yielded to the deferred, so to
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notify the handler it is sufficient to resolve the deferred.
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"""
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__slots__ = ["deferred"]
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def __init__(self, deferred):
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self.deferred = deferred
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class _NotifierUserStream(object):
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"""This represents a user connected to the event stream.
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It tracks the most recent stream token for that user.
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At a given point a user may have a number of streams listening for
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events.
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This listener will also keep track of which rooms it is listening in
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so that it can remove itself from the indexes in the Notifier class.
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"""
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def __init__(self, user_id, rooms, current_token, time_now_ms):
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self.user_id = user_id
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self.rooms = set(rooms)
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self.current_token = current_token
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self.last_notified_ms = time_now_ms
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with PreserveLoggingContext():
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self.notify_deferred = ObservableDeferred(defer.Deferred())
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def notify(self, stream_key, stream_id, time_now_ms):
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"""Notify any listeners for this user of a new event from an
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event source.
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Args:
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stream_key(str): The stream the event came from.
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stream_id(str): The new id for the stream the event came from.
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time_now_ms(int): The current time in milliseconds.
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"""
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self.current_token = self.current_token.copy_and_advance(
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stream_key, stream_id
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)
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self.last_notified_ms = time_now_ms
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noify_deferred = self.notify_deferred
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with PreserveLoggingContext():
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self.notify_deferred = ObservableDeferred(defer.Deferred())
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noify_deferred.callback(self.current_token)
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def remove(self, notifier):
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""" Remove this listener from all the indexes in the Notifier
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it knows about.
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"""
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for room in self.rooms:
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lst = notifier.room_to_user_streams.get(room, set())
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lst.discard(self)
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notifier.user_to_user_stream.pop(self.user_id)
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def count_listeners(self):
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return len(self.notify_deferred.observers())
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def new_listener(self, token):
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"""Returns a deferred that is resolved when there is a new token
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greater than the given token.
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"""
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if self.current_token.is_after(token):
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return _NotificationListener(defer.succeed(self.current_token))
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else:
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return _NotificationListener(self.notify_deferred.observe())
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class EventStreamResult(namedtuple("EventStreamResult", ("events", "tokens"))):
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def __nonzero__(self):
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return bool(self.events)
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class Notifier(object):
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""" This class is responsible for notifying any listeners when there are
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new events available for it.
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Primarily used from the /events stream.
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"""
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UNUSED_STREAM_EXPIRY_MS = 10 * 60 * 1000
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def __init__(self, hs):
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self.user_to_user_stream = {}
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self.room_to_user_streams = {}
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self.event_sources = hs.get_event_sources()
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self.store = hs.get_datastore()
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self.pending_new_room_events = []
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self.clock = hs.get_clock()
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self.appservice_handler = hs.get_application_service_handler()
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self.state_handler = hs.get_state_handler()
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self.clock.looping_call(
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self.remove_expired_streams, self.UNUSED_STREAM_EXPIRY_MS
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)
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self.replication_deferred = ObservableDeferred(defer.Deferred())
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# This is not a very cheap test to perform, but it's only executed
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# when rendering the metrics page, which is likely once per minute at
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# most when scraping it.
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def count_listeners():
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all_user_streams = set()
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for x in self.room_to_user_streams.values():
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all_user_streams |= x
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for x in self.user_to_user_stream.values():
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all_user_streams.add(x)
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return sum(stream.count_listeners() for stream in all_user_streams)
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metrics.register_callback("listeners", count_listeners)
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metrics.register_callback(
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"rooms",
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lambda: count(bool, self.room_to_user_streams.values()),
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)
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metrics.register_callback(
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"users",
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lambda: len(self.user_to_user_stream),
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)
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def on_new_room_event(self, event, room_stream_id, max_room_stream_id,
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extra_users=[]):
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""" Used by handlers to inform the notifier something has happened
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in the room, room event wise.
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This triggers the notifier to wake up any listeners that are
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listening to the room, and any listeners for the users in the
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`extra_users` param.
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The events can be peristed out of order. The notifier will wait
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until all previous events have been persisted before notifying
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the client streams.
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"""
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with PreserveLoggingContext():
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self.pending_new_room_events.append((
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room_stream_id, event, extra_users
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))
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self._notify_pending_new_room_events(max_room_stream_id)
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self.notify_replication()
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def _notify_pending_new_room_events(self, max_room_stream_id):
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"""Notify for the room events that were queued waiting for a previous
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event to be persisted.
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Args:
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max_room_stream_id(int): The highest stream_id below which all
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events have been persisted.
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"""
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pending = self.pending_new_room_events
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self.pending_new_room_events = []
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for room_stream_id, event, extra_users in pending:
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if room_stream_id > max_room_stream_id:
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self.pending_new_room_events.append((
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room_stream_id, event, extra_users
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))
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else:
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self._on_new_room_event(event, room_stream_id, extra_users)
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def _on_new_room_event(self, event, room_stream_id, extra_users=[]):
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"""Notify any user streams that are interested in this room event"""
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# poke any interested application service.
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self.appservice_handler.notify_interested_services(event)
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if event.type == EventTypes.Member and event.membership == Membership.JOIN:
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self._user_joined_room(event.state_key, event.room_id)
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self.on_new_event(
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"room_key", room_stream_id,
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users=extra_users,
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rooms=[event.room_id],
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)
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def on_new_event(self, stream_key, new_token, users=[], rooms=[]):
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""" Used to inform listeners that something has happend event wise.
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Will wake up all listeners for the given users and rooms.
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"""
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with PreserveLoggingContext():
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user_streams = set()
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for user in users:
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user_stream = self.user_to_user_stream.get(str(user))
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if user_stream is not None:
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user_streams.add(user_stream)
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for room in rooms:
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user_streams |= self.room_to_user_streams.get(room, set())
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time_now_ms = self.clock.time_msec()
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for user_stream in user_streams:
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try:
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user_stream.notify(stream_key, new_token, time_now_ms)
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except:
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logger.exception("Failed to notify listener")
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self.notify_replication()
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def on_new_replication_data(self):
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"""Used to inform replication listeners that something has happend
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without waking up any of the normal user event streams"""
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with PreserveLoggingContext():
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self.notify_replication()
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@defer.inlineCallbacks
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def wait_for_events(self, user_id, timeout, callback, room_ids=None,
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from_token=StreamToken.START):
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"""Wait until the callback returns a non empty response or the
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timeout fires.
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"""
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user_stream = self.user_to_user_stream.get(user_id)
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if user_stream is None:
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current_token = yield self.event_sources.get_current_token()
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if room_ids is None:
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rooms = yield self.store.get_rooms_for_user(user_id)
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room_ids = [room.room_id for room in rooms]
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user_stream = _NotifierUserStream(
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user_id=user_id,
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rooms=room_ids,
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current_token=current_token,
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time_now_ms=self.clock.time_msec(),
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)
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self._register_with_keys(user_stream)
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result = None
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if timeout:
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# Will be set to a _NotificationListener that we'll be waiting on.
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# Allows us to cancel it.
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listener = None
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def timed_out():
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if listener:
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listener.deferred.cancel()
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timer = self.clock.call_later(timeout / 1000., timed_out)
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prev_token = from_token
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while not result:
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try:
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current_token = user_stream.current_token
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result = yield callback(prev_token, current_token)
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if result:
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break
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# Now we wait for the _NotifierUserStream to be told there
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# is a new token.
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# We need to supply the token we supplied to callback so
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# that we don't miss any current_token updates.
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prev_token = current_token
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listener = user_stream.new_listener(prev_token)
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with PreserveLoggingContext():
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yield listener.deferred
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except defer.CancelledError:
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break
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self.clock.cancel_call_later(timer, ignore_errs=True)
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else:
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current_token = user_stream.current_token
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result = yield callback(from_token, current_token)
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defer.returnValue(result)
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@defer.inlineCallbacks
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def get_events_for(self, user, pagination_config, timeout,
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only_keys=None,
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is_guest=False, explicit_room_id=None):
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""" For the given user and rooms, return any new events for them. If
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there are no new events wait for up to `timeout` milliseconds for any
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new events to happen before returning.
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If `only_keys` is not None, events from keys will be sent down.
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If explicit_room_id is not set, the user's joined rooms will be polled
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for events.
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If explicit_room_id is set, that room will be polled for events only if
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it is world readable or the user has joined the room.
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"""
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from_token = pagination_config.from_token
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if not from_token:
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from_token = yield self.event_sources.get_current_token()
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limit = pagination_config.limit
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room_ids, is_joined = yield self._get_room_ids(user, explicit_room_id)
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is_peeking = not is_joined
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@defer.inlineCallbacks
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def check_for_updates(before_token, after_token):
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if not after_token.is_after(before_token):
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defer.returnValue(EventStreamResult([], (from_token, from_token)))
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events = []
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end_token = from_token
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for name, source in self.event_sources.sources.items():
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keyname = "%s_key" % name
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before_id = getattr(before_token, keyname)
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after_id = getattr(after_token, keyname)
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if before_id == after_id:
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continue
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if only_keys and name not in only_keys:
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continue
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new_events, new_key = yield source.get_new_events(
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user=user,
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from_key=getattr(from_token, keyname),
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limit=limit,
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is_guest=is_peeking,
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room_ids=room_ids,
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)
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if name == "room":
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new_events = yield filter_events_for_client(
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self.store,
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user.to_string(),
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new_events,
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is_peeking=is_peeking,
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)
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events.extend(new_events)
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end_token = end_token.copy_and_replace(keyname, new_key)
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defer.returnValue(EventStreamResult(events, (from_token, end_token)))
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user_id_for_stream = user.to_string()
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if is_peeking:
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# Internally, the notifier keeps an event stream per user_id.
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# This is used by both /sync and /events.
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# We want /events to be used for peeking independently of /sync,
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# without polluting its contents. So we invent an illegal user ID
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# (which thus cannot clash with any real users) for keying peeking
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# over /events.
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#
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# I am sorry for what I have done.
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user_id_for_stream = "_PEEKING_%s_%s" % (
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explicit_room_id, user_id_for_stream
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)
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result = yield self.wait_for_events(
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user_id_for_stream,
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timeout,
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check_for_updates,
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room_ids=room_ids,
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from_token=from_token,
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)
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defer.returnValue(result)
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@defer.inlineCallbacks
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def _get_room_ids(self, user, explicit_room_id):
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joined_rooms = yield self.store.get_rooms_for_user(user.to_string())
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joined_room_ids = map(lambda r: r.room_id, joined_rooms)
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if explicit_room_id:
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if explicit_room_id in joined_room_ids:
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defer.returnValue(([explicit_room_id], True))
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if (yield self._is_world_readable(explicit_room_id)):
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defer.returnValue(([explicit_room_id], False))
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raise AuthError(403, "Non-joined access not allowed")
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defer.returnValue((joined_room_ids, True))
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@defer.inlineCallbacks
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def _is_world_readable(self, room_id):
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state = yield self.state_handler.get_current_state(
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room_id,
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EventTypes.RoomHistoryVisibility
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)
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if state and "history_visibility" in state.content:
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defer.returnValue(state.content["history_visibility"] == "world_readable")
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else:
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defer.returnValue(False)
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@log_function
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def remove_expired_streams(self):
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time_now_ms = self.clock.time_msec()
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expired_streams = []
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expire_before_ts = time_now_ms - self.UNUSED_STREAM_EXPIRY_MS
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for stream in self.user_to_user_stream.values():
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if stream.count_listeners():
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continue
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if stream.last_notified_ms < expire_before_ts:
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expired_streams.append(stream)
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for expired_stream in expired_streams:
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expired_stream.remove(self)
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@log_function
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def _register_with_keys(self, user_stream):
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self.user_to_user_stream[user_stream.user_id] = user_stream
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for room in user_stream.rooms:
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s = self.room_to_user_streams.setdefault(room, set())
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s.add(user_stream)
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def _user_joined_room(self, user_id, room_id):
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new_user_stream = self.user_to_user_stream.get(user_id)
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if new_user_stream is not None:
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room_streams = self.room_to_user_streams.setdefault(room_id, set())
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room_streams.add(new_user_stream)
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new_user_stream.rooms.add(room_id)
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def notify_replication(self):
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"""Notify the any replication listeners that there's a new event"""
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with PreserveLoggingContext():
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deferred = self.replication_deferred
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self.replication_deferred = ObservableDeferred(defer.Deferred())
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deferred.callback(None)
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@defer.inlineCallbacks
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def wait_for_replication(self, callback, timeout):
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"""Wait for an event to happen.
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Args:
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callback: Gets called whenever an event happens. If this returns a
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truthy value then ``wait_for_replication`` returns, otherwise
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it waits for another event.
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timeout: How many milliseconds to wait for callback return a truthy
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value.
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Returns:
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A deferred that resolves with the value returned by the callback.
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"""
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listener = _NotificationListener(None)
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def timed_out():
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listener.deferred.cancel()
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timer = self.clock.call_later(timeout / 1000., timed_out)
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while True:
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listener.deferred = self.replication_deferred.observe()
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result = yield callback()
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if result:
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break
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try:
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with PreserveLoggingContext():
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yield listener.deferred
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except defer.CancelledError:
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break
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self.clock.cancel_call_later(timer, ignore_errs=True)
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defer.returnValue(result)
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