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