MatrixSynapse/synapse/storage/data_stores/main/event_federation.py

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# -*- coding: utf-8 -*-
# Copyright 2014-2016 OpenMarket Ltd
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import itertools
import logging
from queue import Empty, PriorityQueue
from typing import Dict, List, Optional, Set, Tuple
from twisted.internet import defer
from synapse.api.errors import StoreError
from synapse.metrics.background_process_metrics import run_as_background_process
from synapse.storage._base import SQLBaseStore, make_in_list_sql_clause
from synapse.storage.data_stores.main.events_worker import EventsWorkerStore
from synapse.storage.data_stores.main.signatures import SignatureWorkerStore
from synapse.storage.database import Database
from synapse.util.caches.descriptors import cached
from synapse.util.iterutils import batch_iter
logger = logging.getLogger(__name__)
class EventFederationWorkerStore(EventsWorkerStore, SignatureWorkerStore, SQLBaseStore):
def get_auth_chain(self, event_ids, include_given=False):
"""Get auth events for given event_ids. The events *must* be state events.
Args:
event_ids (list): state events
include_given (bool): include the given events in result
Returns:
list of events
"""
return self.get_auth_chain_ids(
event_ids, include_given=include_given
).addCallback(self.get_events_as_list)
def get_auth_chain_ids(
self,
event_ids: List[str],
include_given: bool = False,
ignore_events: Optional[Set[str]] = None,
):
"""Get auth events for given event_ids. The events *must* be state events.
Args:
event_ids: state events
include_given: include the given events in result
ignore_events: Set of events to exclude from the returned auth
chain. This is useful if the caller will just discard the
given events anyway, and saves us from figuring out their auth
chains if not required.
Returns:
list of event_ids
"""
return self.db.runInteraction(
"get_auth_chain_ids",
self._get_auth_chain_ids_txn,
event_ids,
include_given,
ignore_events,
)
def _get_auth_chain_ids_txn(self, txn, event_ids, include_given, ignore_events):
if ignore_events is None:
ignore_events = set()
if include_given:
results = set(event_ids)
else:
results = set()
base_sql = "SELECT auth_id FROM event_auth WHERE "
front = set(event_ids)
while front:
new_front = set()
for chunk in batch_iter(front, 100):
clause, args = make_in_list_sql_clause(
txn.database_engine, "event_id", chunk
)
txn.execute(base_sql + clause, args)
new_front.update(r[0] for r in txn)
new_front -= ignore_events
new_front -= results
front = new_front
results.update(front)
return list(results)
def get_auth_chain_difference(self, state_sets: List[Set[str]]):
"""Given sets of state events figure out the auth chain difference (as
per state res v2 algorithm).
This equivalent to fetching the full auth chain for each set of state
and returning the events that don't appear in each and every auth
chain.
Returns:
Deferred[Set[str]]
"""
return self.db.runInteraction(
"get_auth_chain_difference",
self._get_auth_chain_difference_txn,
state_sets,
)
def _get_auth_chain_difference_txn(
self, txn, state_sets: List[Set[str]]
) -> Set[str]:
# Algorithm Description
# ~~~~~~~~~~~~~~~~~~~~~
#
# The idea here is to basically walk the auth graph of each state set in
# tandem, keeping track of which auth events are reachable by each state
# set. If we reach an auth event we've already visited (via a different
# state set) then we mark that auth event and all ancestors as reachable
# by the state set. This requires that we keep track of the auth chains
# in memory.
#
# Doing it in a such a way means that we can stop early if all auth
# events we're currently walking are reachable by all state sets.
#
# *Note*: We can't stop walking an event's auth chain if it is reachable
# by all state sets. This is because other auth chains we're walking
# might be reachable only via the original auth chain. For example,
# given the following auth chain:
#
# A -> C -> D -> E
# / /
# B -´---------´
#
# and state sets {A} and {B} then walking the auth chains of A and B
# would immediately show that C is reachable by both. However, if we
# stopped at C then we'd only reach E via the auth chain of B and so E
# would errornously get included in the returned difference.
#
# The other thing that we do is limit the number of auth chains we walk
# at once, due to practical limits (i.e. we can only query the database
# with a limited set of parameters). We pick the auth chains we walk
# each iteration based on their depth, in the hope that events with a
# lower depth are likely reachable by those with higher depths.
#
# We could use any ordering that we believe would give a rough
# topological ordering, e.g. origin server timestamp. If the ordering
# chosen is not topological then the algorithm still produces the right
# result, but perhaps a bit more inefficiently. This is why it is safe
# to use "depth" here.
initial_events = set(state_sets[0]).union(*state_sets[1:])
# Dict from events in auth chains to which sets *cannot* reach them.
# I.e. if the set is empty then all sets can reach the event.
event_to_missing_sets = {
event_id: {i for i, a in enumerate(state_sets) if event_id not in a}
for event_id in initial_events
}
# The sorted list of events whose auth chains we should walk.
search = [] # type: List[Tuple[int, str]]
# We need to get the depth of the initial events for sorting purposes.
sql = """
SELECT depth, event_id FROM events
WHERE %s
"""
# the list can be huge, so let's avoid looking them all up in one massive
# query.
for batch in batch_iter(initial_events, 1000):
clause, args = make_in_list_sql_clause(
txn.database_engine, "event_id", batch
)
txn.execute(sql % (clause,), args)
# I think building a temporary list with fetchall is more efficient than
# just `search.extend(txn)`, but this is unconfirmed
search.extend(txn.fetchall())
# sort by depth
search.sort()
# Map from event to its auth events
event_to_auth_events = {} # type: Dict[str, Set[str]]
base_sql = """
SELECT a.event_id, auth_id, depth
FROM event_auth AS a
INNER JOIN events AS e ON (e.event_id = a.auth_id)
WHERE
"""
while search:
# Check whether all our current walks are reachable by all state
# sets. If so we can bail.
if all(not event_to_missing_sets[eid] for _, eid in search):
break
# Fetch the auth events and their depths of the N last events we're
# currently walking
search, chunk = search[:-100], search[-100:]
clause, args = make_in_list_sql_clause(
txn.database_engine, "a.event_id", [e_id for _, e_id in chunk]
)
txn.execute(base_sql + clause, args)
for event_id, auth_event_id, auth_event_depth in txn:
event_to_auth_events.setdefault(event_id, set()).add(auth_event_id)
sets = event_to_missing_sets.get(auth_event_id)
if sets is None:
# First time we're seeing this event, so we add it to the
# queue of things to fetch.
search.append((auth_event_depth, auth_event_id))
# Assume that this event is unreachable from any of the
# state sets until proven otherwise
sets = event_to_missing_sets[auth_event_id] = set(
range(len(state_sets))
)
else:
# We've previously seen this event, so look up its auth
# events and recursively mark all ancestors as reachable
# by the current event's state set.
a_ids = event_to_auth_events.get(auth_event_id)
while a_ids:
new_aids = set()
for a_id in a_ids:
event_to_missing_sets[a_id].intersection_update(
event_to_missing_sets[event_id]
)
b = event_to_auth_events.get(a_id)
if b:
new_aids.update(b)
a_ids = new_aids
# Mark that the auth event is reachable by the approriate sets.
sets.intersection_update(event_to_missing_sets[event_id])
search.sort()
# Return all events where not all sets can reach them.
return {eid for eid, n in event_to_missing_sets.items() if n}
def get_oldest_events_in_room(self, room_id):
return self.db.runInteraction(
"get_oldest_events_in_room", self._get_oldest_events_in_room_txn, room_id
)
def get_oldest_events_with_depth_in_room(self, room_id):
return self.db.runInteraction(
"get_oldest_events_with_depth_in_room",
self.get_oldest_events_with_depth_in_room_txn,
room_id,
)
def get_oldest_events_with_depth_in_room_txn(self, txn, room_id):
sql = (
"SELECT b.event_id, MAX(e.depth) FROM events as e"
" INNER JOIN event_edges as g"
" ON g.event_id = e.event_id"
" INNER JOIN event_backward_extremities as b"
" ON g.prev_event_id = b.event_id"
" WHERE b.room_id = ? AND g.is_state is ?"
" GROUP BY b.event_id"
)
txn.execute(sql, (room_id, False))
return dict(txn)
@defer.inlineCallbacks
def get_max_depth_of(self, event_ids):
"""Returns the max depth of a set of event IDs
Args:
event_ids (list[str])
Returns
Deferred[int]
"""
rows = yield self.db.simple_select_many_batch(
table="events",
column="event_id",
iterable=event_ids,
retcols=("depth",),
desc="get_max_depth_of",
)
if not rows:
return 0
else:
return max(row["depth"] for row in rows)
def _get_oldest_events_in_room_txn(self, txn, room_id):
return self.db.simple_select_onecol_txn(
txn,
table="event_backward_extremities",
keyvalues={"room_id": room_id},
retcol="event_id",
)
def get_prev_events_for_room(self, room_id: str):
"""
Gets a subset of the current forward extremities in the given room.
Limits the result to 10 extremities, so that we can avoid creating
events which refer to hundreds of prev_events.
Args:
room_id (str): room_id
Returns:
Deferred[List[str]]: the event ids of the forward extremites
"""
return self.db.runInteraction(
"get_prev_events_for_room", self._get_prev_events_for_room_txn, room_id
)
def _get_prev_events_for_room_txn(self, txn, room_id: str):
# we just use the 10 newest events. Older events will become
# prev_events of future events.
sql = """
SELECT e.event_id FROM event_forward_extremities AS f
INNER JOIN events AS e USING (event_id)
WHERE f.room_id = ?
ORDER BY e.depth DESC
LIMIT 10
"""
txn.execute(sql, (room_id,))
return [row[0] for row in txn]
def get_rooms_with_many_extremities(self, min_count, limit, room_id_filter):
"""Get the top rooms with at least N extremities.
Args:
min_count (int): The minimum number of extremities
limit (int): The maximum number of rooms to return.
room_id_filter (iterable[str]): room_ids to exclude from the results
Returns:
Deferred[list]: At most `limit` room IDs that have at least
`min_count` extremities, sorted by extremity count.
"""
def _get_rooms_with_many_extremities_txn(txn):
where_clause = "1=1"
if room_id_filter:
where_clause = "room_id NOT IN (%s)" % (
",".join("?" for _ in room_id_filter),
)
sql = """
SELECT room_id FROM event_forward_extremities
WHERE %s
GROUP BY room_id
HAVING count(*) > ?
ORDER BY count(*) DESC
LIMIT ?
""" % (
where_clause,
)
query_args = list(itertools.chain(room_id_filter, [min_count, limit]))
txn.execute(sql, query_args)
return [room_id for room_id, in txn]
return self.db.runInteraction(
"get_rooms_with_many_extremities", _get_rooms_with_many_extremities_txn
)
@cached(max_entries=5000, iterable=True)
def get_latest_event_ids_in_room(self, room_id):
return self.db.simple_select_onecol(
table="event_forward_extremities",
keyvalues={"room_id": room_id},
retcol="event_id",
desc="get_latest_event_ids_in_room",
)
def get_min_depth(self, room_id):
""" For hte given room, get the minimum depth we have seen for it.
"""
return self.db.runInteraction(
"get_min_depth", self._get_min_depth_interaction, room_id
)
def _get_min_depth_interaction(self, txn, room_id):
min_depth = self.db.simple_select_one_onecol_txn(
txn,
table="room_depth",
keyvalues={"room_id": room_id},
retcol="min_depth",
allow_none=True,
)
return int(min_depth) if min_depth is not None else None
def get_forward_extremeties_for_room(self, room_id, stream_ordering):
"""For a given room_id and stream_ordering, return the forward
extremeties of the room at that point in "time".
Throws a StoreError if we have since purged the index for
stream_orderings from that point.
Args:
room_id (str):
stream_ordering (int):
Returns:
deferred, which resolves to a list of event_ids
"""
# We want to make the cache more effective, so we clamp to the last
# change before the given ordering.
last_change = self._events_stream_cache.get_max_pos_of_last_change(room_id)
# We don't always have a full stream_to_exterm_id table, e.g. after
# the upgrade that introduced it, so we make sure we never ask for a
# stream_ordering from before a restart
last_change = max(self._stream_order_on_start, last_change)
# provided the last_change is recent enough, we now clamp the requested
# stream_ordering to it.
if last_change > self.stream_ordering_month_ago:
stream_ordering = min(last_change, stream_ordering)
return self._get_forward_extremeties_for_room(room_id, stream_ordering)
@cached(max_entries=5000, num_args=2)
def _get_forward_extremeties_for_room(self, room_id, stream_ordering):
"""For a given room_id and stream_ordering, return the forward
extremeties of the room at that point in "time".
Throws a StoreError if we have since purged the index for
stream_orderings from that point.
"""
if stream_ordering <= self.stream_ordering_month_ago:
raise StoreError(400, "stream_ordering too old")
sql = """
SELECT event_id FROM stream_ordering_to_exterm
INNER JOIN (
SELECT room_id, MAX(stream_ordering) AS stream_ordering
FROM stream_ordering_to_exterm
WHERE stream_ordering <= ? GROUP BY room_id
) AS rms USING (room_id, stream_ordering)
WHERE room_id = ?
"""
def get_forward_extremeties_for_room_txn(txn):
txn.execute(sql, (stream_ordering, room_id))
return [event_id for event_id, in txn]
return self.db.runInteraction(
"get_forward_extremeties_for_room", get_forward_extremeties_for_room_txn
)
def get_backfill_events(self, room_id, event_list, limit):
"""Get a list of Events for a given topic that occurred before (and
including) the events in event_list. Return a list of max size `limit`
Args:
txn
room_id (str)
event_list (list)
limit (int)
"""
return (
self.db.runInteraction(
"get_backfill_events",
self._get_backfill_events,
room_id,
event_list,
limit,
)
.addCallback(self.get_events_as_list)
.addCallback(lambda l: sorted(l, key=lambda e: -e.depth))
)
def _get_backfill_events(self, txn, room_id, event_list, limit):
logger.debug("_get_backfill_events: %s, %r, %s", room_id, event_list, limit)
event_results = set()
# We want to make sure that we do a breadth-first, "depth" ordered
# search.
query = (
"SELECT depth, prev_event_id FROM event_edges"
" INNER JOIN events"
" ON prev_event_id = events.event_id"
" WHERE event_edges.event_id = ?"
" AND event_edges.is_state = ?"
" LIMIT ?"
)
queue = PriorityQueue()
for event_id in event_list:
depth = self.db.simple_select_one_onecol_txn(
txn,
table="events",
keyvalues={"event_id": event_id, "room_id": room_id},
retcol="depth",
allow_none=True,
)
if depth:
queue.put((-depth, event_id))
while not queue.empty() and len(event_results) < limit:
try:
_, event_id = queue.get_nowait()
except Empty:
break
if event_id in event_results:
continue
event_results.add(event_id)
txn.execute(query, (event_id, False, limit - len(event_results)))
for row in txn:
if row[1] not in event_results:
queue.put((-row[0], row[1]))
return event_results
@defer.inlineCallbacks
def get_missing_events(self, room_id, earliest_events, latest_events, limit):
ids = yield self.db.runInteraction(
"get_missing_events",
self._get_missing_events,
room_id,
earliest_events,
latest_events,
limit,
)
events = yield self.get_events_as_list(ids)
return events
def _get_missing_events(self, txn, room_id, earliest_events, latest_events, limit):
seen_events = set(earliest_events)
front = set(latest_events) - seen_events
event_results = []
query = (
"SELECT prev_event_id FROM event_edges "
"WHERE room_id = ? AND event_id = ? AND is_state = ? "
"LIMIT ?"
)
while front and len(event_results) < limit:
new_front = set()
for event_id in front:
txn.execute(
query, (room_id, event_id, False, limit - len(event_results))
)
new_results = {t[0] for t in txn} - seen_events
new_front |= new_results
seen_events |= new_results
event_results.extend(new_results)
front = new_front
# we built the list working backwards from latest_events; we now need to
# reverse it so that the events are approximately chronological.
event_results.reverse()
return event_results
@defer.inlineCallbacks
def get_successor_events(self, event_ids):
"""Fetch all events that have the given events as a prev event
Args:
event_ids (iterable[str])
Returns:
Deferred[list[str]]
"""
rows = yield self.db.simple_select_many_batch(
table="event_edges",
column="prev_event_id",
iterable=event_ids,
retcols=("event_id",),
desc="get_successor_events",
)
return [row["event_id"] for row in rows]
class EventFederationStore(EventFederationWorkerStore):
""" Responsible for storing and serving up the various graphs associated
with an event. Including the main event graph and the auth chains for an
event.
Also has methods for getting the front (latest) and back (oldest) edges
of the event graphs. These are used to generate the parents for new events
and backfilling from another server respectively.
"""
EVENT_AUTH_STATE_ONLY = "event_auth_state_only"
def __init__(self, database: Database, db_conn, hs):
super(EventFederationStore, self).__init__(database, db_conn, hs)
self.db.updates.register_background_update_handler(
self.EVENT_AUTH_STATE_ONLY, self._background_delete_non_state_event_auth
)
hs.get_clock().looping_call(
self._delete_old_forward_extrem_cache, 60 * 60 * 1000
)
def _delete_old_forward_extrem_cache(self):
def _delete_old_forward_extrem_cache_txn(txn):
# Delete entries older than a month, while making sure we don't delete
# the only entries for a room.
sql = """
DELETE FROM stream_ordering_to_exterm
WHERE
room_id IN (
SELECT room_id
FROM stream_ordering_to_exterm
WHERE stream_ordering > ?
) AND stream_ordering < ?
"""
txn.execute(
sql, (self.stream_ordering_month_ago, self.stream_ordering_month_ago)
)
return run_as_background_process(
"delete_old_forward_extrem_cache",
self.db.runInteraction,
"_delete_old_forward_extrem_cache",
_delete_old_forward_extrem_cache_txn,
)
def clean_room_for_join(self, room_id):
return self.db.runInteraction(
"clean_room_for_join", self._clean_room_for_join_txn, room_id
)
def _clean_room_for_join_txn(self, txn, room_id):
query = "DELETE FROM event_forward_extremities WHERE room_id = ?"
txn.execute(query, (room_id,))
txn.call_after(self.get_latest_event_ids_in_room.invalidate, (room_id,))
@defer.inlineCallbacks
def _background_delete_non_state_event_auth(self, progress, batch_size):
def delete_event_auth(txn):
target_min_stream_id = progress.get("target_min_stream_id_inclusive")
max_stream_id = progress.get("max_stream_id_exclusive")
if not target_min_stream_id or not max_stream_id:
txn.execute("SELECT COALESCE(MIN(stream_ordering), 0) FROM events")
rows = txn.fetchall()
target_min_stream_id = rows[0][0]
txn.execute("SELECT COALESCE(MAX(stream_ordering), 0) FROM events")
rows = txn.fetchall()
max_stream_id = rows[0][0]
min_stream_id = max_stream_id - batch_size
sql = """
DELETE FROM event_auth
WHERE event_id IN (
SELECT event_id FROM events
LEFT JOIN state_events USING (room_id, event_id)
WHERE ? <= stream_ordering AND stream_ordering < ?
AND state_key IS null
)
"""
txn.execute(sql, (min_stream_id, max_stream_id))
new_progress = {
"target_min_stream_id_inclusive": target_min_stream_id,
"max_stream_id_exclusive": min_stream_id,
}
self.db.updates._background_update_progress_txn(
txn, self.EVENT_AUTH_STATE_ONLY, new_progress
)
return min_stream_id >= target_min_stream_id
result = yield self.db.runInteraction(
self.EVENT_AUTH_STATE_ONLY, delete_event_auth
)
if not result:
yield self.db.updates._end_background_update(self.EVENT_AUTH_STATE_ONLY)
return batch_size