MatrixSynapse/synapse/handlers/pagination.py

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2018-07-20 16:32:23 +02:00
# -*- coding: utf-8 -*-
# Copyright 2014 - 2016 OpenMarket Ltd
# Copyright 2017 - 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 twisted.internet import defer
from twisted.python.failure import Failure
from synapse.api.constants import Membership
from synapse.api.errors import SynapseError
from synapse.events.utils import serialize_event
from synapse.types import RoomStreamToken
from synapse.util.async import ReadWriteLock
from synapse.util.logcontext import run_in_background
from synapse.util.stringutils import random_string
from synapse.visibility import filter_events_for_client
logger = logging.getLogger(__name__)
class PurgeStatus(object):
"""Object tracking the status of a purge request
This class contains information on the progress of a purge request, for
return by get_purge_status.
Attributes:
status (int): Tracks whether this request has completed. One of
STATUS_{ACTIVE,COMPLETE,FAILED}
"""
STATUS_ACTIVE = 0
STATUS_COMPLETE = 1
STATUS_FAILED = 2
STATUS_TEXT = {
STATUS_ACTIVE: "active",
STATUS_COMPLETE: "complete",
STATUS_FAILED: "failed",
}
def __init__(self):
self.status = PurgeStatus.STATUS_ACTIVE
def asdict(self):
return {
"status": PurgeStatus.STATUS_TEXT[self.status]
}
class PaginationHandler(object):
"""Handles pagination and purge history requests.
These are in the same handler due to the fact we need to block clients
paginating during a purge.
"""
def __init__(self, hs):
self.hs = hs
self.auth = hs.get_auth()
self.store = hs.get_datastore()
self.clock = hs.get_clock()
self.pagination_lock = ReadWriteLock()
self._purges_in_progress_by_room = set()
# map from purge id to PurgeStatus
self._purges_by_id = {}
def start_purge_history(self, room_id, token,
delete_local_events=False):
"""Start off a history purge on a room.
Args:
room_id (str): The room to purge from
token (str): topological token to delete events before
delete_local_events (bool): True to delete local events as well as
remote ones
Returns:
str: unique ID for this purge transaction.
"""
if room_id in self._purges_in_progress_by_room:
raise SynapseError(
400,
"History purge already in progress for %s" % (room_id, ),
)
purge_id = random_string(16)
# we log the purge_id here so that it can be tied back to the
# request id in the log lines.
logger.info("[purge] starting purge_id %s", purge_id)
self._purges_by_id[purge_id] = PurgeStatus()
run_in_background(
self._purge_history,
purge_id, room_id, token, delete_local_events,
)
return purge_id
@defer.inlineCallbacks
def _purge_history(self, purge_id, room_id, token,
delete_local_events):
"""Carry out a history purge on a room.
Args:
purge_id (str): The id for this purge
room_id (str): The room to purge from
token (str): topological token to delete events before
delete_local_events (bool): True to delete local events as well as
remote ones
Returns:
Deferred
"""
self._purges_in_progress_by_room.add(room_id)
try:
with (yield self.pagination_lock.write(room_id)):
yield self.store.purge_history(
room_id, token, delete_local_events,
)
logger.info("[purge] complete")
self._purges_by_id[purge_id].status = PurgeStatus.STATUS_COMPLETE
except Exception:
logger.error("[purge] failed: %s", Failure().getTraceback().rstrip())
self._purges_by_id[purge_id].status = PurgeStatus.STATUS_FAILED
finally:
self._purges_in_progress_by_room.discard(room_id)
# remove the purge from the list 24 hours after it completes
def clear_purge():
del self._purges_by_id[purge_id]
self.hs.get_reactor().callLater(24 * 3600, clear_purge)
def get_purge_status(self, purge_id):
"""Get the current status of an active purge
Args:
purge_id (str): purge_id returned by start_purge_history
Returns:
PurgeStatus|None
"""
return self._purges_by_id.get(purge_id)
@defer.inlineCallbacks
def get_messages(self, requester, room_id=None, pagin_config=None,
as_client_event=True, event_filter=None):
"""Get messages in a room.
Args:
requester (Requester): The user requesting messages.
room_id (str): The room they want messages from.
pagin_config (synapse.api.streams.PaginationConfig): The pagination
config rules to apply, if any.
as_client_event (bool): True to get events in client-server format.
event_filter (Filter): Filter to apply to results or None
Returns:
dict: Pagination API results
"""
user_id = requester.user.to_string()
if pagin_config.from_token:
room_token = pagin_config.from_token.room_key
else:
pagin_config.from_token = (
yield self.hs.get_event_sources().get_current_token_for_room(
room_id=room_id
)
)
room_token = pagin_config.from_token.room_key
room_token = RoomStreamToken.parse(room_token)
pagin_config.from_token = pagin_config.from_token.copy_and_replace(
"room_key", str(room_token)
)
source_config = pagin_config.get_source_config("room")
with (yield self.pagination_lock.read(room_id)):
membership, member_event_id = yield self.auth.check_in_room_or_world_readable(
room_id, user_id
)
if source_config.direction == 'b':
# if we're going backwards, we might need to backfill. This
# requires that we have a topo token.
if room_token.topological:
max_topo = room_token.topological
else:
max_topo = yield self.store.get_max_topological_token(
room_id, room_token.stream
)
if membership == Membership.LEAVE:
# If they have left the room then clamp the token to be before
# they left the room, to save the effort of loading from the
# database.
leave_token = yield self.store.get_topological_token_for_event(
member_event_id
)
leave_token = RoomStreamToken.parse(leave_token)
if leave_token.topological < max_topo:
source_config.from_key = str(leave_token)
yield self.hs.get_handlers().federation_handler.maybe_backfill(
room_id, max_topo
)
events, next_key = yield self.store.paginate_room_events(
room_id=room_id,
from_key=source_config.from_key,
to_key=source_config.to_key,
direction=source_config.direction,
limit=source_config.limit,
event_filter=event_filter,
)
next_token = pagin_config.from_token.copy_and_replace(
"room_key", next_key
)
if not events:
defer.returnValue({
"chunk": [],
"start": pagin_config.from_token.to_string(),
"end": next_token.to_string(),
})
if event_filter:
events = event_filter.filter(events)
events = yield filter_events_for_client(
self.store,
user_id,
events,
is_peeking=(member_event_id is None),
)
time_now = self.clock.time_msec()
chunk = {
"chunk": [
serialize_event(e, time_now, as_client_event)
for e in events
],
"start": pagin_config.from_token.to_string(),
"end": next_token.to_string(),
}
defer.returnValue(chunk)