417 lines
		
	
	
		
			14 KiB
		
	
	
	
		
			Python
		
	
	
			
		
		
	
	
			417 lines
		
	
	
		
			14 KiB
		
	
	
	
		
			Python
		
	
	
# -*- coding: utf-8 -*-
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# Copyright 2018 New Vector 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 ._base import SQLBaseStore
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from twisted.internet import defer, reactor
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from synapse.events import FrozenEvent
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from synapse.events.utils import prune_event
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from synapse.util.logcontext import (
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    PreserveLoggingContext, make_deferred_yieldable, run_in_background,
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)
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from synapse.util.metrics import Measure
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from synapse.api.errors import SynapseError
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from collections import namedtuple
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import logging
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import simplejson as json
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# these are only included to make the type annotations work
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from synapse.events import EventBase    # noqa: F401
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from synapse.events.snapshot import EventContext   # noqa: F401
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logger = logging.getLogger(__name__)
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# These values are used in the `enqueus_event` and `_do_fetch` methods to
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# control how we batch/bulk fetch events from the database.
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# The values are plucked out of thing air to make initial sync run faster
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# on jki.re
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# TODO: Make these configurable.
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EVENT_QUEUE_THREADS = 3  # Max number of threads that will fetch events
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EVENT_QUEUE_ITERATIONS = 3  # No. times we block waiting for requests for events
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EVENT_QUEUE_TIMEOUT_S = 0.1  # Timeout when waiting for requests for events
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_EventCacheEntry = namedtuple("_EventCacheEntry", ("event", "redacted_event"))
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class EventsWorkerStore(SQLBaseStore):
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    def get_received_ts(self, event_id):
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        """Get received_ts (when it was persisted) for the event.
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        Raises an exception for unknown events.
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        Args:
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            event_id (str)
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        Returns:
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            Deferred[int|None]: Timestamp in milliseconds, or None for events
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            that were persisted before received_ts was implemented.
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        """
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        return self._simple_select_one_onecol(
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            table="events",
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            keyvalues={
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                "event_id": event_id,
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            },
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            retcol="received_ts",
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            desc="get_received_ts",
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        )
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    @defer.inlineCallbacks
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    def get_event(self, event_id, check_redacted=True,
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                  get_prev_content=False, allow_rejected=False,
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                  allow_none=False):
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        """Get an event from the database by event_id.
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        Args:
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            event_id (str): The event_id of the event to fetch
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            check_redacted (bool): If True, check if event has been redacted
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                and redact it.
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            get_prev_content (bool): If True and event is a state event,
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                include the previous states content in the unsigned field.
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            allow_rejected (bool): If True return rejected events.
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            allow_none (bool): If True, return None if no event found, if
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                False throw an exception.
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        Returns:
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            Deferred : A FrozenEvent.
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        """
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        events = yield self._get_events(
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            [event_id],
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            check_redacted=check_redacted,
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            get_prev_content=get_prev_content,
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            allow_rejected=allow_rejected,
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        )
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        if not events and not allow_none:
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            raise SynapseError(404, "Could not find event %s" % (event_id,))
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        defer.returnValue(events[0] if events else None)
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    @defer.inlineCallbacks
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    def get_events(self, event_ids, check_redacted=True,
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                   get_prev_content=False, allow_rejected=False):
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        """Get events from the database
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        Args:
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            event_ids (list): The event_ids of the events to fetch
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            check_redacted (bool): If True, check if event has been redacted
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                and redact it.
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            get_prev_content (bool): If True and event is a state event,
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                include the previous states content in the unsigned field.
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            allow_rejected (bool): If True return rejected events.
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        Returns:
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            Deferred : Dict from event_id to event.
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        """
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        events = yield self._get_events(
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            event_ids,
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            check_redacted=check_redacted,
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            get_prev_content=get_prev_content,
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            allow_rejected=allow_rejected,
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        )
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        defer.returnValue({e.event_id: e for e in events})
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    @defer.inlineCallbacks
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    def _get_events(self, event_ids, check_redacted=True,
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                    get_prev_content=False, allow_rejected=False):
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        if not event_ids:
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            defer.returnValue([])
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        event_id_list = event_ids
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        event_ids = set(event_ids)
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        event_entry_map = self._get_events_from_cache(
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            event_ids,
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            allow_rejected=allow_rejected,
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        )
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        missing_events_ids = [e for e in event_ids if e not in event_entry_map]
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        if missing_events_ids:
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            missing_events = yield self._enqueue_events(
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                missing_events_ids,
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                check_redacted=check_redacted,
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                allow_rejected=allow_rejected,
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            )
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            event_entry_map.update(missing_events)
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        events = []
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        for event_id in event_id_list:
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            entry = event_entry_map.get(event_id, None)
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            if not entry:
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                continue
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            if allow_rejected or not entry.event.rejected_reason:
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                if check_redacted and entry.redacted_event:
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                    event = entry.redacted_event
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                else:
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                    event = entry.event
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                events.append(event)
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                if get_prev_content:
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                    if "replaces_state" in event.unsigned:
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                        prev = yield self.get_event(
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                            event.unsigned["replaces_state"],
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                            get_prev_content=False,
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                            allow_none=True,
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                        )
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                        if prev:
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                            event.unsigned = dict(event.unsigned)
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                            event.unsigned["prev_content"] = prev.content
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                            event.unsigned["prev_sender"] = prev.sender
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        defer.returnValue(events)
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    def _invalidate_get_event_cache(self, event_id):
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            self._get_event_cache.invalidate((event_id,))
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    def _get_events_from_cache(self, events, allow_rejected, update_metrics=True):
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        """Fetch events from the caches
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        Args:
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            events (list(str)): list of event_ids to fetch
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            allow_rejected (bool): Whether to teturn events that were rejected
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            update_metrics (bool): Whether to update the cache hit ratio metrics
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        Returns:
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            dict of event_id -> _EventCacheEntry for each event_id in cache. If
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            allow_rejected is `False` then there will still be an entry but it
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            will be `None`
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        """
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        event_map = {}
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        for event_id in events:
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            ret = self._get_event_cache.get(
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                (event_id,), None,
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                update_metrics=update_metrics,
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            )
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            if not ret:
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                continue
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            if allow_rejected or not ret.event.rejected_reason:
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                event_map[event_id] = ret
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            else:
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                event_map[event_id] = None
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        return event_map
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    def _do_fetch(self, conn):
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        """Takes a database connection and waits for requests for events from
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        the _event_fetch_list queue.
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        """
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        event_list = []
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        i = 0
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        while True:
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            try:
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                with self._event_fetch_lock:
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                    event_list = self._event_fetch_list
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                    self._event_fetch_list = []
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                    if not event_list:
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                        single_threaded = self.database_engine.single_threaded
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                        if single_threaded or i > EVENT_QUEUE_ITERATIONS:
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                            self._event_fetch_ongoing -= 1
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                            return
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                        else:
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                            self._event_fetch_lock.wait(EVENT_QUEUE_TIMEOUT_S)
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                            i += 1
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                            continue
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                    i = 0
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                event_id_lists = zip(*event_list)[0]
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                event_ids = [
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                    item for sublist in event_id_lists for item in sublist
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                ]
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                rows = self._new_transaction(
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                    conn, "do_fetch", [], [], None, self._fetch_event_rows, event_ids
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                )
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                row_dict = {
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                    r["event_id"]: r
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                    for r in rows
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                }
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                # We only want to resolve deferreds from the main thread
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                def fire(lst, res):
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                    for ids, d in lst:
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                        if not d.called:
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                            try:
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                                with PreserveLoggingContext():
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                                    d.callback([
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                                        res[i]
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                                        for i in ids
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                                        if i in res
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                                    ])
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                            except Exception:
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                                logger.exception("Failed to callback")
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                with PreserveLoggingContext():
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                    reactor.callFromThread(fire, event_list, row_dict)
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            except Exception as e:
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                logger.exception("do_fetch")
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                # We only want to resolve deferreds from the main thread
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                def fire(evs):
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                    for _, d in evs:
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                        if not d.called:
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                            with PreserveLoggingContext():
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                                d.errback(e)
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                if event_list:
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                    with PreserveLoggingContext():
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                        reactor.callFromThread(fire, event_list)
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    @defer.inlineCallbacks
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    def _enqueue_events(self, events, check_redacted=True, allow_rejected=False):
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        """Fetches events from the database using the _event_fetch_list. This
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        allows batch and bulk fetching of events - it allows us to fetch events
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        without having to create a new transaction for each request for events.
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        """
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        if not events:
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            defer.returnValue({})
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        events_d = defer.Deferred()
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        with self._event_fetch_lock:
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            self._event_fetch_list.append(
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                (events, events_d)
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            )
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            self._event_fetch_lock.notify()
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            if self._event_fetch_ongoing < EVENT_QUEUE_THREADS:
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                self._event_fetch_ongoing += 1
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                should_start = True
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            else:
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                should_start = False
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        if should_start:
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            with PreserveLoggingContext():
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                self.runWithConnection(
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                    self._do_fetch
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                )
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        logger.debug("Loading %d events", len(events))
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        with PreserveLoggingContext():
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            rows = yield events_d
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        logger.debug("Loaded %d events (%d rows)", len(events), len(rows))
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        if not allow_rejected:
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            rows[:] = [r for r in rows if not r["rejects"]]
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        res = yield make_deferred_yieldable(defer.gatherResults(
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            [
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                run_in_background(
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                    self._get_event_from_row,
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                    row["internal_metadata"], row["json"], row["redacts"],
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                    rejected_reason=row["rejects"],
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                )
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                for row in rows
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            ],
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            consumeErrors=True
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        ))
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        defer.returnValue({
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            e.event.event_id: e
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            for e in res if e
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        })
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    def _fetch_event_rows(self, txn, events):
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        rows = []
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        N = 200
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        for i in range(1 + len(events) / N):
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            evs = events[i * N:(i + 1) * N]
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            if not evs:
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                break
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            sql = (
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                "SELECT "
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                " e.event_id as event_id, "
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                " e.internal_metadata,"
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                " e.json,"
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                " r.redacts as redacts,"
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                " rej.event_id as rejects "
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                " FROM event_json as e"
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                " LEFT JOIN rejections as rej USING (event_id)"
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                " LEFT JOIN redactions as r ON e.event_id = r.redacts"
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                " WHERE e.event_id IN (%s)"
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            ) % (",".join(["?"] * len(evs)),)
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            txn.execute(sql, evs)
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            rows.extend(self.cursor_to_dict(txn))
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        return rows
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    @defer.inlineCallbacks
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    def _get_event_from_row(self, internal_metadata, js, redacted,
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                            rejected_reason=None):
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        with Measure(self._clock, "_get_event_from_row"):
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            d = json.loads(js)
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            internal_metadata = json.loads(internal_metadata)
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            if rejected_reason:
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                rejected_reason = yield self._simple_select_one_onecol(
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                    table="rejections",
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                    keyvalues={"event_id": rejected_reason},
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                    retcol="reason",
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                    desc="_get_event_from_row_rejected_reason",
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                )
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            original_ev = FrozenEvent(
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                d,
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                internal_metadata_dict=internal_metadata,
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                rejected_reason=rejected_reason,
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            )
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            redacted_event = None
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            if redacted:
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                redacted_event = prune_event(original_ev)
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                redaction_id = yield self._simple_select_one_onecol(
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                    table="redactions",
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                    keyvalues={"redacts": redacted_event.event_id},
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                    retcol="event_id",
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                    desc="_get_event_from_row_redactions",
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                )
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                redacted_event.unsigned["redacted_by"] = redaction_id
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                # Get the redaction event.
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                because = yield self.get_event(
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                    redaction_id,
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                    check_redacted=False,
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                    allow_none=True,
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                )
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                if because:
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                    # It's fine to do add the event directly, since get_pdu_json
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                    # will serialise this field correctly
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                    redacted_event.unsigned["redacted_because"] = because
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            cache_entry = _EventCacheEntry(
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                event=original_ev,
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                redacted_event=redacted_event,
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            )
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            self._get_event_cache.prefill((original_ev.event_id,), cache_entry)
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        defer.returnValue(cache_entry)
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