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# -*- coding: utf-8 -*-
# Copyright 2017 Vector Creations 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.
"""A replication client for use by synapse workers.
"""
import logging
from typing import TYPE_CHECKING, Dict, List, Tuple
from twisted.internet.defer import Deferred
from twisted.internet.protocol import ReconnectingClientFactory
from synapse.api.constants import EventTypes
from synapse.logging.context import PreserveLoggingContext, make_deferred_yieldable
from synapse.replication.tcp.protocol import ClientReplicationStreamProtocol
from synapse.replication.tcp.streams import TypingStream
from synapse.replication.tcp.streams.events import (
EventsStream,
EventsStreamEventRow,
EventsStreamRow,
)
from synapse.types import PersistedEventPosition, UserID
from synapse.util.async_helpers import timeout_deferred
from synapse.util.metrics import Measure
if TYPE_CHECKING:
from synapse.replication.tcp.handler import ReplicationCommandHandler
from synapse.server import HomeServer
logger = logging.getLogger(__name__)
# How long we allow callers to wait for replication updates before timing out.
_WAIT_FOR_REPLICATION_TIMEOUT_SECONDS = 30
class DirectTcpReplicationClientFactory(ReconnectingClientFactory):
"""Factory for building connections to the master. Will reconnect if the
connection is lost.
Accepts a handler that is passed to `ClientReplicationStreamProtocol`.
"""
initialDelay = 0.1
maxDelay = 1 # Try at least once every N seconds
def __init__(
self,
hs: "HomeServer",
client_name: str,
command_handler: "ReplicationCommandHandler",
):
self.client_name = client_name
self.command_handler = command_handler
self.server_name = hs.config.server_name
self.hs = hs
self._clock = hs.get_clock() # As self.clock is defined in super class
hs.get_reactor().addSystemEventTrigger("before", "shutdown", self.stopTrying)
def startedConnecting(self, connector):
logger.info("Connecting to replication: %r", connector.getDestination())
def buildProtocol(self, addr):
logger.info("Connected to replication: %r", addr)
return ClientReplicationStreamProtocol(
self.hs,
self.client_name,
self.server_name,
self._clock,
self.command_handler,
)
def clientConnectionLost(self, connector, reason):
logger.error("Lost replication conn: %r", reason)
ReconnectingClientFactory.clientConnectionLost(self, connector, reason)
def clientConnectionFailed(self, connector, reason):
logger.error("Failed to connect to replication: %r", reason)
ReconnectingClientFactory.clientConnectionFailed(self, connector, reason)
class ReplicationDataHandler:
"""Handles incoming stream updates from replication.
This instance notifies the slave data store about updates. Can be subclassed
to handle updates in additional ways.
"""
def __init__(self, hs: "HomeServer"):
self.store = hs.get_datastore()
self.notifier = hs.get_notifier()
self._reactor = hs.get_reactor()
self._clock = hs.get_clock()
self._streams = hs.get_replication_streams()
self._instance_name = hs.get_instance_name()
self._typing_handler = hs.get_typing_handler()
# Map from stream to list of deferreds waiting for the stream to
# arrive at a particular position. The lists are sorted by stream position.
self._streams_to_waiters = (
{}
) # type: Dict[str, List[Tuple[int, Deferred[None]]]]
async def on_rdata(
self, stream_name: str, instance_name: str, token: int, rows: list
):
"""Called to handle a batch of replication data with a given stream token.
By default this just pokes the slave store. Can be overridden in subclasses to
handle more.
Args:
stream_name: name of the replication stream for this batch of rows
instance_name: the instance that wrote the rows.
token: stream token for this batch of rows
rows: a list of Stream.ROW_TYPE objects as returned by Stream.parse_row.
"""
self.store.process_replication_rows(stream_name, instance_name, token, rows)
if stream_name == TypingStream.NAME:
self._typing_handler.process_replication_rows(token, rows)
self.notifier.on_new_event(
"typing_key", token, rooms=[row.room_id for row in rows]
)
if stream_name == EventsStream.NAME:
# We shouldn't get multiple rows per token for events stream, so
# we don't need to optimise this for multiple rows.
for row in rows:
if row.type != EventsStreamEventRow.TypeId:
continue
assert isinstance(row, EventsStreamRow)
event = await self.store.get_event(
row.data.event_id, allow_rejected=True
)
if event.rejected_reason:
continue
extra_users = () # type: Tuple[UserID, ...]
if event.type == EventTypes.Member:
extra_users = (UserID.from_string(event.state_key),)
max_token = self.store.get_room_max_token()
event_pos = PersistedEventPosition(instance_name, token)
self.notifier.on_new_room_event(
event, event_pos, max_token, extra_users
)
# Notify any waiting deferreds. The list is ordered by position so we
# just iterate through the list until we reach a position that is
# greater than the received row position.
waiting_list = self._streams_to_waiters.get(stream_name, [])
# Index of first item with a position after the current token, i.e we
# have called all deferreds before this index. If not overwritten by
# loop below means either a) no items in list so no-op or b) all items
# in list were called and so the list should be cleared. Setting it to
# `len(list)` works for both cases.
index_of_first_deferred_not_called = len(waiting_list)
for idx, (position, deferred) in enumerate(waiting_list):
if position <= token:
try:
with PreserveLoggingContext():
deferred.callback(None)
except Exception:
# The deferred has been cancelled or timed out.
pass
else:
# The list is sorted by position so we don't need to continue
# checking any further entries in the list.
index_of_first_deferred_not_called = idx
break
# Drop all entries in the waiting list that were called in the above
# loop. (This maintains the order so no need to resort)
waiting_list[:] = waiting_list[index_of_first_deferred_not_called:]
async def on_position(self, stream_name: str, instance_name: str, token: int):
self.store.process_replication_rows(stream_name, instance_name, token, [])
def on_remote_server_up(self, server: str):
"""Called when get a new REMOTE_SERVER_UP command."""
async def wait_for_stream_position(
self, instance_name: str, stream_name: str, position: int
):
"""Wait until this instance has received updates up to and including
the given stream position.
"""
if instance_name == self._instance_name:
# We don't get told about updates written by this process, and
# anyway in that case we don't need to wait.
return
current_position = self._streams[stream_name].current_token(self._instance_name)
if position <= current_position:
# We're already past the position
return
# Create a new deferred that times out after N seconds, as we don't want
# to wedge here forever.
deferred = Deferred()
deferred = timeout_deferred(
deferred, _WAIT_FOR_REPLICATION_TIMEOUT_SECONDS, self._reactor
)
waiting_list = self._streams_to_waiters.setdefault(stream_name, [])
waiting_list.append((position, deferred))
waiting_list.sort(key=lambda t: t[0])
# We measure here to get in flight counts and average waiting time.
with Measure(self._clock, "repl.wait_for_stream_position"):
logger.info("Waiting for repl stream %r to reach %s", stream_name, position)
await make_deferred_yieldable(deferred)
logger.info(
"Finished waiting for repl stream %r to reach %s", stream_name, position
)
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