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Diffstat (limited to 'synapse/storage/events_worker.py')
| -rw-r--r-- | synapse/storage/events_worker.py | 436 |
1 files changed, 436 insertions, 0 deletions
diff --git a/synapse/storage/events_worker.py b/synapse/storage/events_worker.py new file mode 100644 index 0000000000..f28239a808 --- /dev/null +++ b/synapse/storage/events_worker.py @@ -0,0 +1,436 @@ +# -*- 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 logging +from collections import namedtuple + +from canonicaljson import json + +from twisted.internet import defer + +from synapse.api.errors import SynapseError +# these are only included to make the type annotations work +from synapse.events import EventBase # noqa: F401 +from synapse.events import FrozenEvent +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.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): + """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 an exception. + + 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, + ) + + if not events and not allow_none: + raise SynapseError(404, "Could not find event %s" % (event_id,)) + + defer.returnValue(events[0] if events else None) + + @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)) + + missing_events = yield self._enqueue_events( + missing_events_ids, + check_redacted=check_redacted, + 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 + + 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 = 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): + for _, d in evs: + if not d.called: + with PreserveLoggingContext(): + d.errback(e) + + with PreserveLoggingContext(): + self.hs.get_reactor().callFromThread(fire, event_list) + + @defer.inlineCallbacks + def _enqueue_events(self, events, check_redacted=True, 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"], + ) + 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," + " 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, + 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", + ) + + original_ev = FrozenEvent( + 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 + + 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) |