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# -*- coding: utf-8 -*-
# Copyright 2020 The Matrix.org Foundation C.I.C.
#
# 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
import txredisapi
from synapse.logging.context import PreserveLoggingContext
from synapse.metrics.background_process_metrics import run_as_background_process
from synapse.replication.tcp.commands import (
COMMAND_MAP,
Command,
RdataCommand,
ReplicateCommand,
)
from synapse.util.stringutils import random_string
logger = logging.getLogger(__name__)
class RedisSubscriber(txredisapi.SubscriberProtocol):
"""Connection to redis subscribed to replication stream.
"""
def connectionMade(self):
logger.info("Connected to redis instance")
self.subscribe(self.stream_name)
self.send_command(ReplicateCommand())
self.handler.new_connection(self)
def messageReceived(self, pattern: str, channel: str, message: str):
"""Received a message from redis.
"""
if message.strip() == "":
# Ignore blank lines
return
line = message
cmd_name, rest_of_line = line.split(" ", 1)
cmd_cls = COMMAND_MAP[cmd_name]
try:
cmd = cmd_cls.from_line(rest_of_line)
except Exception as e:
logger.exception(
"[%s] failed to parse line %r: %r", self.id(), cmd_name, rest_of_line
)
self.send_error(
"failed to parse line for %r: %r (%r):" % (cmd_name, e, rest_of_line)
)
return
# Now lets try and call on_<CMD_NAME> function
run_as_background_process(
"replication-" + cmd.get_logcontext_id(), self.handle_command, cmd
)
async def handle_command(self, cmd: Command):
"""Handle a command we have received over the replication stream.
By default delegates to on_<COMMAND>, which should return an awaitable.
Args:
cmd: received command
"""
handled = False
# First call any command handlers on this instance. These are for redis
# specific handling.
cmd_func = getattr(self, "on_%s" % (cmd.NAME,), None)
if cmd_func:
await cmd_func(cmd)
handled = True
# Then call out to the handler.
cmd_func = getattr(self.handler, "on_%s" % (cmd.NAME,), None)
if cmd_func:
await cmd_func(cmd)
handled = True
if not handled:
logger.warning("Unhandled command: %r", cmd)
def connectionLost(self, reason):
logger.info("Lost connection to redis instance")
self.handler.lost_connection(self)
def send_command(self, cmd):
"""Send a command if connection has been established.
Args:
cmd (Command)
"""
string = "%s %s" % (cmd.NAME, cmd.to_line())
if "\n" in string:
raise Exception("Unexpected newline in command: %r", string)
encoded_string = string.encode("utf-8")
async def _send():
with PreserveLoggingContext():
await self.redis_connection.publish(self.stream_name, encoded_string)
run_as_background_process("send-cmd", _send)
def stream_update(self, stream_name, token, data):
"""Called when a new update is available to stream to clients.
We need to check if the client is interested in the stream or not
"""
self.send_command(RdataCommand(stream_name, token, data))
class RedisFactory(txredisapi.SubscriberFactory):
maxDelay = 5
continueTrying = True
protocol = RedisSubscriber
def __init__(self, hs):
super(RedisFactory, self).__init__()
self.password = hs.config.redis.redis_password
self.handler = hs.get_tcp_replication()
self.stream_name = hs.hostname
self.redis_connection = txredisapi.lazyConnection(
host=hs.config.redis_host,
port=hs.config.redis_port,
dbid=hs.config.redis_dbid,
password=hs.config.redis.redis_password,
reconnect=True,
)
self.conn_id = random_string(5)
def buildProtocol(self, addr):
p = super(RedisFactory, self).buildProtocol(addr)
p.handler = self.handler
p.redis_connection = self.redis_connection
p.conn_id = self.conn_id
p.stream_name = self.stream_name
return p
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