650 lines
26 KiB
Python
650 lines
26 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright 2014-2016 OpenMarket Ltd
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# Copyright 2018-2019 New Vector Ltd
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# Copyright 2019 The Matrix.org Foundation C.I.C.
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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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import logging
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from collections import deque, namedtuple
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from six import iteritems
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from six.moves import range
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from prometheus_client import Counter, Histogram
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from twisted.internet import defer
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from synapse.api.constants import EventTypes
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from synapse.logging.context import PreserveLoggingContext, make_deferred_yieldable
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from synapse.metrics.background_process_metrics import run_as_background_process
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from synapse.state import StateResolutionStore
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from synapse.storage.data_stores import DataStores
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from synapse.util.async_helpers import ObservableDeferred
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from synapse.util.metrics import Measure
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logger = logging.getLogger(__name__)
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# The number of times we are recalculating the current state
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state_delta_counter = Counter("synapse_storage_events_state_delta", "")
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# The number of times we are recalculating state when there is only a
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# single forward extremity
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state_delta_single_event_counter = Counter(
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"synapse_storage_events_state_delta_single_event", ""
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)
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# The number of times we are reculating state when we could have resonably
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# calculated the delta when we calculated the state for an event we were
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# persisting.
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state_delta_reuse_delta_counter = Counter(
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"synapse_storage_events_state_delta_reuse_delta", ""
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)
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# The number of forward extremities for each new event.
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forward_extremities_counter = Histogram(
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"synapse_storage_events_forward_extremities_persisted",
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"Number of forward extremities for each new event",
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buckets=(1, 2, 3, 5, 7, 10, 15, 20, 50, 100, 200, 500, "+Inf"),
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)
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# The number of stale forward extremities for each new event. Stale extremities
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# are those that were in the previous set of extremities as well as the new.
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stale_forward_extremities_counter = Histogram(
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"synapse_storage_events_stale_forward_extremities_persisted",
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"Number of unchanged forward extremities for each new event",
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buckets=(0, 1, 2, 3, 5, 7, 10, 15, 20, 50, 100, 200, 500, "+Inf"),
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)
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class _EventPeristenceQueue(object):
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"""Queues up events so that they can be persisted in bulk with only one
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concurrent transaction per room.
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"""
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_EventPersistQueueItem = namedtuple(
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"_EventPersistQueueItem", ("events_and_contexts", "backfilled", "deferred")
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)
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def __init__(self):
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self._event_persist_queues = {}
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self._currently_persisting_rooms = set()
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def add_to_queue(self, room_id, events_and_contexts, backfilled):
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"""Add events to the queue, with the given persist_event options.
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NB: due to the normal usage pattern of this method, it does *not*
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follow the synapse logcontext rules, and leaves the logcontext in
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place whether or not the returned deferred is ready.
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Args:
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room_id (str):
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events_and_contexts (list[(EventBase, EventContext)]):
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backfilled (bool):
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Returns:
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defer.Deferred: a deferred which will resolve once the events are
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persisted. Runs its callbacks *without* a logcontext.
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"""
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queue = self._event_persist_queues.setdefault(room_id, deque())
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if queue:
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# if the last item in the queue has the same `backfilled` setting,
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# we can just add these new events to that item.
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end_item = queue[-1]
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if end_item.backfilled == backfilled:
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end_item.events_and_contexts.extend(events_and_contexts)
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return end_item.deferred.observe()
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deferred = ObservableDeferred(defer.Deferred(), consumeErrors=True)
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queue.append(
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self._EventPersistQueueItem(
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events_and_contexts=events_and_contexts,
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backfilled=backfilled,
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deferred=deferred,
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)
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)
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return deferred.observe()
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def handle_queue(self, room_id, per_item_callback):
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"""Attempts to handle the queue for a room if not already being handled.
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The given callback will be invoked with for each item in the queue,
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of type _EventPersistQueueItem. The per_item_callback will continuously
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be called with new items, unless the queue becomnes empty. The return
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value of the function will be given to the deferreds waiting on the item,
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exceptions will be passed to the deferreds as well.
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This function should therefore be called whenever anything is added
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to the queue.
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If another callback is currently handling the queue then it will not be
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invoked.
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"""
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if room_id in self._currently_persisting_rooms:
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return
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self._currently_persisting_rooms.add(room_id)
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@defer.inlineCallbacks
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def handle_queue_loop():
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try:
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queue = self._get_drainining_queue(room_id)
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for item in queue:
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try:
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ret = yield per_item_callback(item)
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except Exception:
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with PreserveLoggingContext():
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item.deferred.errback()
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else:
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with PreserveLoggingContext():
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item.deferred.callback(ret)
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finally:
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queue = self._event_persist_queues.pop(room_id, None)
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if queue:
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self._event_persist_queues[room_id] = queue
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self._currently_persisting_rooms.discard(room_id)
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# set handle_queue_loop off in the background
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run_as_background_process("persist_events", handle_queue_loop)
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def _get_drainining_queue(self, room_id):
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queue = self._event_persist_queues.setdefault(room_id, deque())
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try:
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while True:
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yield queue.popleft()
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except IndexError:
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# Queue has been drained.
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pass
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class EventsPersistenceStorage(object):
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"""High level interface for handling persisting newly received events.
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Takes care of batching up events by room, and calculating the necessary
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current state and forward extremity changes.
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"""
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def __init__(self, hs, stores: DataStores):
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# We ultimately want to split out the state store from the main store,
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# so we use separate variables here even though they point to the same
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# store for now.
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self.main_store = stores.main
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self.state_store = stores.main
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self._clock = hs.get_clock()
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self.is_mine_id = hs.is_mine_id
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self._event_persist_queue = _EventPeristenceQueue()
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self._state_resolution_handler = hs.get_state_resolution_handler()
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@defer.inlineCallbacks
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def persist_events(self, events_and_contexts, backfilled=False):
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"""
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Write events to the database
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Args:
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events_and_contexts: list of tuples of (event, context)
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backfilled (bool): Whether the results are retrieved from federation
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via backfill or not. Used to determine if they're "new" events
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which might update the current state etc.
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Returns:
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Deferred[int]: the stream ordering of the latest persisted event
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"""
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partitioned = {}
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for event, ctx in events_and_contexts:
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partitioned.setdefault(event.room_id, []).append((event, ctx))
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deferreds = []
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for room_id, evs_ctxs in iteritems(partitioned):
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d = self._event_persist_queue.add_to_queue(
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room_id, evs_ctxs, backfilled=backfilled
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)
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deferreds.append(d)
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for room_id in partitioned:
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self._maybe_start_persisting(room_id)
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yield make_deferred_yieldable(
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defer.gatherResults(deferreds, consumeErrors=True)
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)
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max_persisted_id = yield self.main_store.get_current_events_token()
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return max_persisted_id
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@defer.inlineCallbacks
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def persist_event(self, event, context, backfilled=False):
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"""
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Args:
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event (EventBase):
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context (EventContext):
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backfilled (bool):
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Returns:
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Deferred: resolves to (int, int): the stream ordering of ``event``,
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and the stream ordering of the latest persisted event
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"""
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deferred = self._event_persist_queue.add_to_queue(
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event.room_id, [(event, context)], backfilled=backfilled
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)
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self._maybe_start_persisting(event.room_id)
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yield make_deferred_yieldable(deferred)
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max_persisted_id = yield self.main_store.get_current_events_token()
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return (event.internal_metadata.stream_ordering, max_persisted_id)
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def _maybe_start_persisting(self, room_id):
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@defer.inlineCallbacks
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def persisting_queue(item):
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with Measure(self._clock, "persist_events"):
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yield self._persist_events(
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item.events_and_contexts, backfilled=item.backfilled
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)
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self._event_persist_queue.handle_queue(room_id, persisting_queue)
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@defer.inlineCallbacks
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def _persist_events(self, events_and_contexts, backfilled=False):
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"""Calculates the change to current state and forward extremities, and
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persists the given events and with those updates.
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Args:
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events_and_contexts (list[(EventBase, EventContext)]):
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backfilled (bool):
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delete_existing (bool):
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Returns:
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Deferred: resolves when the events have been persisted
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"""
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if not events_and_contexts:
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return
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chunks = [
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events_and_contexts[x : x + 100]
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for x in range(0, len(events_and_contexts), 100)
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]
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for chunk in chunks:
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# We can't easily parallelize these since different chunks
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# might contain the same event. :(
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# NB: Assumes that we are only persisting events for one room
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# at a time.
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# map room_id->list[event_ids] giving the new forward
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# extremities in each room
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new_forward_extremeties = {}
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# map room_id->(type,state_key)->event_id tracking the full
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# state in each room after adding these events.
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# This is simply used to prefill the get_current_state_ids
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# cache
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current_state_for_room = {}
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# map room_id->(to_delete, to_insert) where to_delete is a list
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# of type/state keys to remove from current state, and to_insert
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# is a map (type,key)->event_id giving the state delta in each
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# room
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state_delta_for_room = {}
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if not backfilled:
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with Measure(self._clock, "_calculate_state_and_extrem"):
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# Work out the new "current state" for each room.
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# We do this by working out what the new extremities are and then
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# calculating the state from that.
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events_by_room = {}
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for event, context in chunk:
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events_by_room.setdefault(event.room_id, []).append(
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(event, context)
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)
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for room_id, ev_ctx_rm in iteritems(events_by_room):
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latest_event_ids = yield self.main_store.get_latest_event_ids_in_room(
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room_id
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)
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new_latest_event_ids = yield self._calculate_new_extremities(
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room_id, ev_ctx_rm, latest_event_ids
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)
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latest_event_ids = set(latest_event_ids)
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if new_latest_event_ids == latest_event_ids:
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# No change in extremities, so no change in state
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continue
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# there should always be at least one forward extremity.
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# (except during the initial persistence of the send_join
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# results, in which case there will be no existing
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# extremities, so we'll `continue` above and skip this bit.)
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assert new_latest_event_ids, "No forward extremities left!"
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new_forward_extremeties[room_id] = new_latest_event_ids
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len_1 = (
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len(latest_event_ids) == 1
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and len(new_latest_event_ids) == 1
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)
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if len_1:
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all_single_prev_not_state = all(
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len(event.prev_event_ids()) == 1
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and not event.is_state()
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for event, ctx in ev_ctx_rm
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)
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# Don't bother calculating state if they're just
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# a long chain of single ancestor non-state events.
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if all_single_prev_not_state:
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continue
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state_delta_counter.inc()
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if len(new_latest_event_ids) == 1:
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state_delta_single_event_counter.inc()
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# This is a fairly handwavey check to see if we could
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# have guessed what the delta would have been when
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# processing one of these events.
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# What we're interested in is if the latest extremities
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# were the same when we created the event as they are
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# now. When this server creates a new event (as opposed
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# to receiving it over federation) it will use the
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# forward extremities as the prev_events, so we can
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# guess this by looking at the prev_events and checking
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# if they match the current forward extremities.
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for ev, _ in ev_ctx_rm:
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prev_event_ids = set(ev.prev_event_ids())
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if latest_event_ids == prev_event_ids:
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state_delta_reuse_delta_counter.inc()
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break
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logger.info("Calculating state delta for room %s", room_id)
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with Measure(
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self._clock, "persist_events.get_new_state_after_events"
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):
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res = yield self._get_new_state_after_events(
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room_id,
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ev_ctx_rm,
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latest_event_ids,
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new_latest_event_ids,
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)
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current_state, delta_ids = res
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# If either are not None then there has been a change,
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# and we need to work out the delta (or use that
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# given)
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if delta_ids is not None:
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# If there is a delta we know that we've
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# only added or replaced state, never
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# removed keys entirely.
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state_delta_for_room[room_id] = ([], delta_ids)
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elif current_state is not None:
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with Measure(
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self._clock, "persist_events.calculate_state_delta"
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):
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delta = yield self._calculate_state_delta(
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room_id, current_state
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)
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state_delta_for_room[room_id] = delta
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# If we have the current_state then lets prefill
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# the cache with it.
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if current_state is not None:
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current_state_for_room[room_id] = current_state
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yield self.main_store._persist_events_and_state_updates(
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chunk,
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current_state_for_room=current_state_for_room,
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state_delta_for_room=state_delta_for_room,
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new_forward_extremeties=new_forward_extremeties,
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backfilled=backfilled,
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)
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@defer.inlineCallbacks
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def _calculate_new_extremities(self, room_id, event_contexts, latest_event_ids):
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"""Calculates the new forward extremities for a room given events to
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persist.
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Assumes that we are only persisting events for one room at a time.
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"""
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# we're only interested in new events which aren't outliers and which aren't
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# being rejected.
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new_events = [
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event
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for event, ctx in event_contexts
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if not event.internal_metadata.is_outlier()
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and not ctx.rejected
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and not event.internal_metadata.is_soft_failed()
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]
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latest_event_ids = set(latest_event_ids)
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# start with the existing forward extremities
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result = set(latest_event_ids)
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# add all the new events to the list
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result.update(event.event_id for event in new_events)
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# Now remove all events which are prev_events of any of the new events
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result.difference_update(
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e_id for event in new_events for e_id in event.prev_event_ids()
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)
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# Remove any events which are prev_events of any existing events.
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existing_prevs = yield self.main_store._get_events_which_are_prevs(result)
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result.difference_update(existing_prevs)
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# Finally handle the case where the new events have soft-failed prev
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# events. If they do we need to remove them and their prev events,
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# otherwise we end up with dangling extremities.
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existing_prevs = yield self.main_store._get_prevs_before_rejected(
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e_id for event in new_events for e_id in event.prev_event_ids()
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)
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result.difference_update(existing_prevs)
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# We only update metrics for events that change forward extremities
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# (e.g. we ignore backfill/outliers/etc)
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if result != latest_event_ids:
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forward_extremities_counter.observe(len(result))
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stale = latest_event_ids & result
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stale_forward_extremities_counter.observe(len(stale))
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return result
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@defer.inlineCallbacks
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def _get_new_state_after_events(
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self, room_id, events_context, old_latest_event_ids, new_latest_event_ids
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):
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"""Calculate the current state dict after adding some new events to
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a room
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Args:
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room_id (str):
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room to which the events are being added. Used for logging etc
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events_context (list[(EventBase, EventContext)]):
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events and contexts which are being added to the room
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old_latest_event_ids (iterable[str]):
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the old forward extremities for the room.
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new_latest_event_ids (iterable[str]):
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the new forward extremities for the room.
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Returns:
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Deferred[tuple[dict[(str,str), str]|None, dict[(str,str), str]|None]]:
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Returns a tuple of two state maps, the first being the full new current
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state and the second being the delta to the existing current state.
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If both are None then there has been no change.
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If there has been a change then we only return the delta if its
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already been calculated. Conversely if we do know the delta then
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the new current state is only returned if we've already calculated
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it.
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"""
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# map from state_group to ((type, key) -> event_id) state map
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state_groups_map = {}
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# Map from (prev state group, new state group) -> delta state dict
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state_group_deltas = {}
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for ev, ctx in events_context:
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if ctx.state_group is None:
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# This should only happen for outlier events.
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if not ev.internal_metadata.is_outlier():
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raise Exception(
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"Context for new event %s has no state "
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|
"group" % (ev.event_id,)
|
|
)
|
|
continue
|
|
|
|
if ctx.state_group in state_groups_map:
|
|
continue
|
|
|
|
# We're only interested in pulling out state that has already
|
|
# been cached in the context. We'll pull stuff out of the DB later
|
|
# if necessary.
|
|
current_state_ids = ctx.get_cached_current_state_ids()
|
|
if current_state_ids is not None:
|
|
state_groups_map[ctx.state_group] = current_state_ids
|
|
|
|
if ctx.prev_group:
|
|
state_group_deltas[(ctx.prev_group, ctx.state_group)] = ctx.delta_ids
|
|
|
|
# We need to map the event_ids to their state groups. First, let's
|
|
# check if the event is one we're persisting, in which case we can
|
|
# pull the state group from its context.
|
|
# Otherwise we need to pull the state group from the database.
|
|
|
|
# Set of events we need to fetch groups for. (We know none of the old
|
|
# extremities are going to be in events_context).
|
|
missing_event_ids = set(old_latest_event_ids)
|
|
|
|
event_id_to_state_group = {}
|
|
for event_id in new_latest_event_ids:
|
|
# First search in the list of new events we're adding.
|
|
for ev, ctx in events_context:
|
|
if event_id == ev.event_id and ctx.state_group is not None:
|
|
event_id_to_state_group[event_id] = ctx.state_group
|
|
break
|
|
else:
|
|
# If we couldn't find it, then we'll need to pull
|
|
# the state from the database
|
|
missing_event_ids.add(event_id)
|
|
|
|
if missing_event_ids:
|
|
# Now pull out the state groups for any missing events from DB
|
|
event_to_groups = yield self.main_store._get_state_group_for_events(
|
|
missing_event_ids
|
|
)
|
|
event_id_to_state_group.update(event_to_groups)
|
|
|
|
# State groups of old_latest_event_ids
|
|
old_state_groups = set(
|
|
event_id_to_state_group[evid] for evid in old_latest_event_ids
|
|
)
|
|
|
|
# State groups of new_latest_event_ids
|
|
new_state_groups = set(
|
|
event_id_to_state_group[evid] for evid in new_latest_event_ids
|
|
)
|
|
|
|
# If they old and new groups are the same then we don't need to do
|
|
# anything.
|
|
if old_state_groups == new_state_groups:
|
|
return None, None
|
|
|
|
if len(new_state_groups) == 1 and len(old_state_groups) == 1:
|
|
# If we're going from one state group to another, lets check if
|
|
# we have a delta for that transition. If we do then we can just
|
|
# return that.
|
|
|
|
new_state_group = next(iter(new_state_groups))
|
|
old_state_group = next(iter(old_state_groups))
|
|
|
|
delta_ids = state_group_deltas.get((old_state_group, new_state_group), None)
|
|
if delta_ids is not None:
|
|
# We have a delta from the existing to new current state,
|
|
# so lets just return that. If we happen to already have
|
|
# the current state in memory then lets also return that,
|
|
# but it doesn't matter if we don't.
|
|
new_state = state_groups_map.get(new_state_group)
|
|
return new_state, delta_ids
|
|
|
|
# Now that we have calculated new_state_groups we need to get
|
|
# their state IDs so we can resolve to a single state set.
|
|
missing_state = new_state_groups - set(state_groups_map)
|
|
if missing_state:
|
|
group_to_state = yield self.state_store._get_state_for_groups(missing_state)
|
|
state_groups_map.update(group_to_state)
|
|
|
|
if len(new_state_groups) == 1:
|
|
# If there is only one state group, then we know what the current
|
|
# state is.
|
|
return state_groups_map[new_state_groups.pop()], None
|
|
|
|
# Ok, we need to defer to the state handler to resolve our state sets.
|
|
|
|
state_groups = {sg: state_groups_map[sg] for sg in new_state_groups}
|
|
|
|
events_map = {ev.event_id: ev for ev, _ in events_context}
|
|
|
|
# We need to get the room version, which is in the create event.
|
|
# Normally that'd be in the database, but its also possible that we're
|
|
# currently trying to persist it.
|
|
room_version = None
|
|
for ev, _ in events_context:
|
|
if ev.type == EventTypes.Create and ev.state_key == "":
|
|
room_version = ev.content.get("room_version", "1")
|
|
break
|
|
|
|
if not room_version:
|
|
room_version = yield self.main_store.get_room_version(room_id)
|
|
|
|
logger.debug("calling resolve_state_groups from preserve_events")
|
|
res = yield self._state_resolution_handler.resolve_state_groups(
|
|
room_id,
|
|
room_version,
|
|
state_groups,
|
|
events_map,
|
|
state_res_store=StateResolutionStore(self.main_store),
|
|
)
|
|
|
|
return res.state, None
|
|
|
|
@defer.inlineCallbacks
|
|
def _calculate_state_delta(self, room_id, current_state):
|
|
"""Calculate the new state deltas for a room.
|
|
|
|
Assumes that we are only persisting events for one room at a time.
|
|
|
|
Returns:
|
|
tuple[list, dict] (to_delete, to_insert): where to_delete are the
|
|
type/state_keys to remove from current_state_events and `to_insert`
|
|
are the updates to current_state_events.
|
|
"""
|
|
existing_state = yield self.main_store.get_current_state_ids(room_id)
|
|
|
|
to_delete = [key for key in existing_state if key not in current_state]
|
|
|
|
to_insert = {
|
|
key: ev_id
|
|
for key, ev_id in iteritems(current_state)
|
|
if ev_id != existing_state.get(key)
|
|
}
|
|
|
|
return to_delete, to_insert
|