# -*- coding: utf-8 -*- # Copyright 2018 New Vector 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. import itertools import logging from collections import namedtuple from canonicaljson import json from twisted.internet import defer from synapse.api.constants import EventFormatVersions, EventTypes from synapse.api.errors import NotFoundError from synapse.events import FrozenEvent, event_type_from_format_version # noqa: F401 # these are only included to make the type annotations work from synapse.events.snapshot import EventContext # noqa: F401 from synapse.events.utils import prune_event from synapse.metrics.background_process_metrics import run_as_background_process from synapse.types import get_domain_from_id from synapse.util.logcontext import ( LoggingContext, PreserveLoggingContext, make_deferred_yieldable, run_in_background, ) from synapse.util.metrics import Measure from ._base import SQLBaseStore logger = logging.getLogger(__name__) # These values are used in the `enqueus_event` and `_do_fetch` methods to # control how we batch/bulk fetch events from the database. # The values are plucked out of thing air to make initial sync run faster # on jki.re # TODO: Make these configurable. EVENT_QUEUE_THREADS = 3 # Max number of threads that will fetch events EVENT_QUEUE_ITERATIONS = 3 # No. times we block waiting for requests for events EVENT_QUEUE_TIMEOUT_S = 0.1 # Timeout when waiting for requests for events _EventCacheEntry = namedtuple("_EventCacheEntry", ("event", "redacted_event")) class EventsWorkerStore(SQLBaseStore): def get_received_ts(self, event_id): """Get received_ts (when it was persisted) for the event. Raises an exception for unknown events. Args: event_id (str) Returns: Deferred[int|None]: Timestamp in milliseconds, or None for events that were persisted before received_ts was implemented. """ return self._simple_select_one_onecol( table="events", keyvalues={ "event_id": event_id, }, retcol="received_ts", desc="get_received_ts", ) @defer.inlineCallbacks def get_event(self, event_id, check_redacted=True, get_prev_content=False, allow_rejected=False, allow_none=False, check_room_id=None): """Get an event from the database by event_id. Args: event_id (str): The event_id of the event to fetch check_redacted (bool): If True, check if event has been redacted and redact it. get_prev_content (bool): If True and event is a state event, include the previous states content in the unsigned field. allow_rejected (bool): If True return rejected events. allow_none (bool): If True, return None if no event found, if False throw a NotFoundError check_room_id (str|None): if not None, check the room of the found event. If there is a mismatch, behave as per allow_none. Returns: Deferred : A FrozenEvent. """ events = yield self._get_events( [event_id], check_redacted=check_redacted, get_prev_content=get_prev_content, allow_rejected=allow_rejected, ) event = events[0] if events else None if event is not None and check_room_id is not None: if event.room_id != check_room_id: event = None if event is None and not allow_none: raise NotFoundError("Could not find event %s" % (event_id,)) defer.returnValue(event) @defer.inlineCallbacks def get_events(self, event_ids, check_redacted=True, get_prev_content=False, allow_rejected=False): """Get events from the database Args: event_ids (list): The event_ids of the events to fetch check_redacted (bool): If True, check if event has been redacted and redact it. get_prev_content (bool): If True and event is a state event, include the previous states content in the unsigned field. allow_rejected (bool): If True return rejected events. Returns: Deferred : Dict from event_id to event. """ events = yield self._get_events( event_ids, check_redacted=check_redacted, get_prev_content=get_prev_content, allow_rejected=allow_rejected, ) defer.returnValue({e.event_id: e for e in events}) @defer.inlineCallbacks def _get_events(self, event_ids, check_redacted=True, get_prev_content=False, allow_rejected=False): if not event_ids: defer.returnValue([]) event_id_list = event_ids event_ids = set(event_ids) event_entry_map = self._get_events_from_cache( event_ids, allow_rejected=allow_rejected, ) missing_events_ids = [e for e in event_ids if e not in event_entry_map] if missing_events_ids: log_ctx = LoggingContext.current_context() log_ctx.record_event_fetch(len(missing_events_ids)) # Note that _enqueue_events is also responsible for turning db rows # into FrozenEvents (via _get_event_from_row), which involves seeing if # the events have been redacted, and if so pulling the redaction event out # of the database to check it. # # _enqueue_events is a bit of a rubbish name but naming is hard. missing_events = yield self._enqueue_events( missing_events_ids, allow_rejected=allow_rejected, ) event_entry_map.update(missing_events) events = [] for event_id in event_id_list: entry = event_entry_map.get(event_id, None) if not entry: continue # Starting in room version v3, some redactions need to be rechecked if we # didn't have the redacted event at the time, so we recheck on read # instead. if not allow_rejected and entry.event.type == EventTypes.Redaction: if entry.event.internal_metadata.need_to_check_redaction(): # XXX: we need to avoid calling get_event here. # # The problem is that we end up at this point when an event # which has been redacted is pulled out of the database by # _enqueue_events, because _enqueue_events needs to check the # redaction before it can cache the redacted event. So obviously, # calling get_event to get the redacted event out of the database # gives us an infinite loop. # # For now (quick hack to fix during 0.99 release cycle), we just # go and fetch the relevant row from the db, but it would be nice # to think about how we can cache this rather than hit the db # every time we access a redaction event. # # One thought on how to do this: # 1. split _get_events up so that it is divided into (a) get the # rawish event from the db/cache, (b) do the redaction/rejection # filtering # 2. have _get_event_from_row just call the first half of that orig_sender = yield self._simple_select_one_onecol( table="events", keyvalues={"event_id": entry.event.redacts}, retcol="sender", allow_none=True, ) expected_domain = get_domain_from_id(entry.event.sender) if orig_sender and get_domain_from_id(orig_sender) == expected_domain: # This redaction event is allowed. Mark as not needing a # recheck. entry.event.internal_metadata.recheck_redaction = False else: # We don't have the event that is being redacted, so we # assume that the event isn't authorized for now. (If we # later receive the event, then we will always redact # it anyway, since we have this redaction) continue if allow_rejected or not entry.event.rejected_reason: if check_redacted and entry.redacted_event: event = entry.redacted_event else: event = entry.event events.append(event) if get_prev_content: if "replaces_state" in event.unsigned: prev = yield self.get_event( event.unsigned["replaces_state"], get_prev_content=False, allow_none=True, ) if prev: event.unsigned = dict(event.unsigned) event.unsigned["prev_content"] = prev.content event.unsigned["prev_sender"] = prev.sender defer.returnValue(events) def _invalidate_get_event_cache(self, event_id): self._get_event_cache.invalidate((event_id,)) def _get_events_from_cache(self, events, allow_rejected, update_metrics=True): """Fetch events from the caches Args: events (list(str)): list of event_ids to fetch allow_rejected (bool): Whether to teturn events that were rejected update_metrics (bool): Whether to update the cache hit ratio metrics Returns: dict of event_id -> _EventCacheEntry for each event_id in cache. If allow_rejected is `False` then there will still be an entry but it will be `None` """ event_map = {} for event_id in events: ret = self._get_event_cache.get( (event_id,), None, update_metrics=update_metrics, ) if not ret: continue if allow_rejected or not ret.event.rejected_reason: event_map[event_id] = ret else: event_map[event_id] = None return event_map def _do_fetch(self, conn): """Takes a database connection and waits for requests for events from the _event_fetch_list queue. """ i = 0 while True: with self._event_fetch_lock: event_list = self._event_fetch_list self._event_fetch_list = [] if not event_list: single_threaded = self.database_engine.single_threaded if single_threaded or i > EVENT_QUEUE_ITERATIONS: self._event_fetch_ongoing -= 1 return else: self._event_fetch_lock.wait(EVENT_QUEUE_TIMEOUT_S) i += 1 continue i = 0 self._fetch_event_list(conn, event_list) def _fetch_event_list(self, conn, event_list): """Handle a load of requests from the _event_fetch_list queue Args: conn (twisted.enterprise.adbapi.Connection): database connection event_list (list[Tuple[list[str], Deferred]]): The fetch requests. Each entry consists of a list of event ids to be fetched, and a deferred to be completed once the events have been fetched. """ with Measure(self._clock, "_fetch_event_list"): try: event_id_lists = list(zip(*event_list))[0] event_ids = [ item for sublist in event_id_lists for item in sublist ] rows = self._new_transaction( conn, "do_fetch", [], [], self._fetch_event_rows, event_ids, ) row_dict = { r["event_id"]: r for r in rows } # We only want to resolve deferreds from the main thread def fire(lst, res): for ids, d in lst: if not d.called: try: with PreserveLoggingContext(): d.callback([ res[i] for i in ids if i in res ]) except Exception: logger.exception("Failed to callback") with PreserveLoggingContext(): self.hs.get_reactor().callFromThread(fire, event_list, row_dict) except Exception as e: logger.exception("do_fetch") # We only want to resolve deferreds from the main thread def fire(evs, exc): for _, d in evs: if not d.called: with PreserveLoggingContext(): d.errback(exc) with PreserveLoggingContext(): self.hs.get_reactor().callFromThread(fire, event_list, e) @defer.inlineCallbacks def _enqueue_events(self, events, allow_rejected=False): """Fetches events from the database using the _event_fetch_list. This allows batch and bulk fetching of events - it allows us to fetch events without having to create a new transaction for each request for events. """ if not events: defer.returnValue({}) events_d = defer.Deferred() with self._event_fetch_lock: self._event_fetch_list.append( (events, events_d) ) self._event_fetch_lock.notify() if self._event_fetch_ongoing < EVENT_QUEUE_THREADS: self._event_fetch_ongoing += 1 should_start = True else: should_start = False if should_start: run_as_background_process( "fetch_events", self.runWithConnection, self._do_fetch, ) logger.debug("Loading %d events", len(events)) with PreserveLoggingContext(): rows = yield events_d logger.debug("Loaded %d events (%d rows)", len(events), len(rows)) if not allow_rejected: rows[:] = [r for r in rows if not r["rejects"]] res = yield make_deferred_yieldable(defer.gatherResults( [ run_in_background( self._get_event_from_row, row["internal_metadata"], row["json"], row["redacts"], rejected_reason=row["rejects"], format_version=row["format_version"], ) for row in rows ], consumeErrors=True )) defer.returnValue({ e.event.event_id: e for e in res if e }) def _fetch_event_rows(self, txn, events): rows = [] N = 200 for i in range(1 + len(events) // N): evs = events[i * N:(i + 1) * N] if not evs: break sql = ( "SELECT " " e.event_id as event_id, " " e.internal_metadata," " e.json," " e.format_version, " " r.redacts as redacts," " rej.event_id as rejects " " FROM event_json as e" " LEFT JOIN rejections as rej USING (event_id)" " LEFT JOIN redactions as r ON e.event_id = r.redacts" " WHERE e.event_id IN (%s)" ) % (",".join(["?"] * len(evs)),) txn.execute(sql, evs) rows.extend(self.cursor_to_dict(txn)) return rows @defer.inlineCallbacks def _get_event_from_row(self, internal_metadata, js, redacted, format_version, rejected_reason=None): with Measure(self._clock, "_get_event_from_row"): d = json.loads(js) internal_metadata = json.loads(internal_metadata) if rejected_reason: rejected_reason = yield self._simple_select_one_onecol( table="rejections", keyvalues={"event_id": rejected_reason}, retcol="reason", desc="_get_event_from_row_rejected_reason", ) if format_version is None: # This means that we stored the event before we had the concept # of a event format version, so it must be a V1 event. format_version = EventFormatVersions.V1 original_ev = event_type_from_format_version(format_version)( event_dict=d, internal_metadata_dict=internal_metadata, rejected_reason=rejected_reason, ) redacted_event = None if redacted: redacted_event = prune_event(original_ev) redaction_id = yield self._simple_select_one_onecol( table="redactions", keyvalues={"redacts": redacted_event.event_id}, retcol="event_id", desc="_get_event_from_row_redactions", ) redacted_event.unsigned["redacted_by"] = redaction_id # Get the redaction event. because = yield self.get_event( redaction_id, check_redacted=False, allow_none=True, ) if because: # It's fine to do add the event directly, since get_pdu_json # will serialise this field correctly redacted_event.unsigned["redacted_because"] = because # Starting in room version v3, some redactions need to be # rechecked if we didn't have the redacted event at the # time, so we recheck on read instead. if because.internal_metadata.need_to_check_redaction(): expected_domain = get_domain_from_id(original_ev.sender) if get_domain_from_id(because.sender) == expected_domain: # This redaction event is allowed. Mark as not needing a # recheck. because.internal_metadata.recheck_redaction = False else: # Senders don't match, so the event isn't actually redacted redacted_event = None cache_entry = _EventCacheEntry( event=original_ev, redacted_event=redacted_event, ) self._get_event_cache.prefill((original_ev.event_id,), cache_entry) defer.returnValue(cache_entry) @defer.inlineCallbacks def have_events_in_timeline(self, event_ids): """Given a list of event ids, check if we have already processed and stored them as non outliers. """ rows = yield self._simple_select_many_batch( table="events", retcols=("event_id",), column="event_id", iterable=list(event_ids), keyvalues={"outlier": False}, desc="have_events_in_timeline", ) defer.returnValue(set(r["event_id"] for r in rows)) @defer.inlineCallbacks def have_seen_events(self, event_ids): """Given a list of event ids, check if we have already processed them. Args: event_ids (iterable[str]): Returns: Deferred[set[str]]: The events we have already seen. """ results = set() def have_seen_events_txn(txn, chunk): sql = ( "SELECT event_id FROM events as e WHERE e.event_id IN (%s)" % (",".join("?" * len(chunk)), ) ) txn.execute(sql, chunk) for (event_id, ) in txn: results.add(event_id) # break the input up into chunks of 100 input_iterator = iter(event_ids) for chunk in iter(lambda: list(itertools.islice(input_iterator, 100)), []): yield self.runInteraction( "have_seen_events", have_seen_events_txn, chunk, ) defer.returnValue(results) def get_seen_events_with_rejections(self, event_ids): """Given a list of event ids, check if we rejected them. Args: event_ids (list[str]) Returns: Deferred[dict[str, str|None): Has an entry for each event id we already have seen. Maps to the rejected reason string if we rejected the event, else maps to None. """ if not event_ids: return defer.succeed({}) def f(txn): sql = ( "SELECT e.event_id, reason FROM events as e " "LEFT JOIN rejections as r ON e.event_id = r.event_id " "WHERE e.event_id = ?" ) res = {} for event_id in event_ids: txn.execute(sql, (event_id,)) row = txn.fetchone() if row: _, rejected = row res[event_id] = rejected return res return self.runInteraction("get_rejection_reasons", f)