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Add helper base class for generating new replication endpoints #3632

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merged 9 commits into from
Aug 9, 2018
Empty file added changelog.d/3632.misc
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11 changes: 4 additions & 7 deletions synapse/handlers/message.py
Original file line number Diff line number Diff line change
Expand Up @@ -30,7 +30,7 @@
from synapse.crypto.event_signing import add_hashes_and_signatures
from synapse.events.utils import serialize_event
from synapse.events.validator import EventValidator
from synapse.replication.http.send_event import send_event_to_master
from synapse.replication.http.send_event import ReplicationSendEventRestServlet
from synapse.types import RoomAlias, UserID
from synapse.util.async import Linearizer
from synapse.util.frozenutils import frozendict_json_encoder
Expand Down Expand Up @@ -171,7 +171,7 @@ def __init__(self, hs):
self.notifier = hs.get_notifier()
self.config = hs.config

self.http_client = hs.get_simple_http_client()
self.send_event_to_master = ReplicationSendEventRestServlet.make_client(hs)

# This is only used to get at ratelimit function, and maybe_kick_guest_users
self.base_handler = BaseHandler(hs)
Expand Down Expand Up @@ -559,12 +559,9 @@ def handle_new_client_event(
try:
# If we're a worker we need to hit out to the master.
if self.config.worker_app:
yield send_event_to_master(
clock=self.hs.get_clock(),
yield self.send_event_to_master(
event_id=event.event_id,
store=self.store,
client=self.http_client,
host=self.config.worker_replication_host,
port=self.config.worker_replication_http_port,
requester=requester,
event=event,
context=context,
Expand Down
41 changes: 17 additions & 24 deletions synapse/handlers/room_member_worker.py
Original file line number Diff line number Diff line change
Expand Up @@ -20,27 +20,32 @@
from synapse.api.errors import SynapseError
from synapse.handlers.room_member import RoomMemberHandler
from synapse.replication.http.membership import (
get_or_register_3pid_guest,
notify_user_membership_change,
remote_join,
remote_reject_invite,
ReplicationRegister3PIDGuestRestServlet as Repl3PID,
ReplicationRemoteJoinRestServlet as ReplRemoteJoin,
ReplicationRemoteRejectInviteRestServlet as ReplRejectInvite,
ReplicationUserJoinedLeftRoomRestServlet as ReplJoinedLeft,
)

logger = logging.getLogger(__name__)


class RoomMemberWorkerHandler(RoomMemberHandler):
def __init__(self, hs):
super(RoomMemberWorkerHandler, self).__init__(hs)

self._get_register_3pid_client = Repl3PID.make_client(hs)
self._remote_join_client = ReplRemoteJoin.make_client(hs)
self._remote_reject_client = ReplRejectInvite.make_client(hs)
self._notify_change_client = ReplJoinedLeft.make_client(hs)

@defer.inlineCallbacks
def _remote_join(self, requester, remote_room_hosts, room_id, user, content):
"""Implements RoomMemberHandler._remote_join
"""
if len(remote_room_hosts) == 0:
raise SynapseError(404, "No known servers")

ret = yield remote_join(
self.simple_http_client,
host=self.config.worker_replication_host,
port=self.config.worker_replication_http_port,
ret = yield self._remote_join_client(
requester=requester,
remote_room_hosts=remote_room_hosts,
room_id=room_id,
Expand All @@ -55,10 +60,7 @@ def _remote_join(self, requester, remote_room_hosts, room_id, user, content):
def _remote_reject_invite(self, requester, remote_room_hosts, room_id, target):
"""Implements RoomMemberHandler._remote_reject_invite
"""
return remote_reject_invite(
self.simple_http_client,
host=self.config.worker_replication_host,
port=self.config.worker_replication_http_port,
return self._remote_reject_client(
requester=requester,
remote_room_hosts=remote_room_hosts,
room_id=room_id,
Expand All @@ -68,10 +70,7 @@ def _remote_reject_invite(self, requester, remote_room_hosts, room_id, target):
def _user_joined_room(self, target, room_id):
"""Implements RoomMemberHandler._user_joined_room
"""
return notify_user_membership_change(
self.simple_http_client,
host=self.config.worker_replication_host,
port=self.config.worker_replication_http_port,
return self._notify_change_client(
user_id=target.to_string(),
room_id=room_id,
change="joined",
Expand All @@ -80,10 +79,7 @@ def _user_joined_room(self, target, room_id):
def _user_left_room(self, target, room_id):
"""Implements RoomMemberHandler._user_left_room
"""
return notify_user_membership_change(
self.simple_http_client,
host=self.config.worker_replication_host,
port=self.config.worker_replication_http_port,
return self._notify_change_client(
user_id=target.to_string(),
room_id=room_id,
change="left",
Expand All @@ -92,10 +88,7 @@ def _user_left_room(self, target, room_id):
def get_or_register_3pid_guest(self, requester, medium, address, inviter_user_id):
"""Implements RoomMemberHandler.get_or_register_3pid_guest
"""
return get_or_register_3pid_guest(
self.simple_http_client,
host=self.config.worker_replication_host,
port=self.config.worker_replication_http_port,
return self._get_register_3pid_client(
requester=requester,
medium=medium,
address=address,
Expand Down
216 changes: 216 additions & 0 deletions synapse/replication/http/_base.py
Original file line number Diff line number Diff line change
@@ -0,0 +1,216 @@
# -*- coding: utf-8 -*-
# Copyright 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 abc
import logging
import re

from six.moves import urllib

from twisted.internet import defer

from synapse.api.errors import CodeMessageException, HttpResponseException
from synapse.util.caches.response_cache import ResponseCache
from synapse.util.stringutils import random_string

logger = logging.getLogger(__name__)


class ReplicationEndpoint(object):
"""Helper base class for defining new replication HTTP endpoints.

This creates an endpoint under `/_synapse/replication/:NAME/:PATH_ARGS..`
(with an `/:txn_id` prefix for cached requests.), where NAME is a name,
PATH_ARGS are a tuple of parameters to be encoded in the URL.

For example, if `NAME` is "send_event" and `PATH_ARGS` is `("event_id",)`,
with `CACHE` set to true then this generates an endpoint:

/_synapse/replication/send_event/:event_id/:txn_id

For POST/PUT requests the payload is serialized to json and sent as the
body, while for GET requests the payload is added as query parameters. See
`_serialize_payload` for details.

Incoming requests are handled by overriding `_handle_request`. Servers
must call `register` to register the path with the HTTP server.

Requests can be sent by calling the client returned by `make_client`.

Attributes:
NAME (str): A name for the endpoint, added to the path as well as used
in logging and metrics.
PATH_ARGS (tuple[str]): A list of parameters to be added to the path.
Adding parameters to the path (rather than payload) can make it
easier to follow along in the log files.
METHOD (str): The method of the HTTP request, defaults to POST. Can be
one of POST, PUT or GET. If GET then the payload is sent as query
parameters rather than a JSON body.
CACHE (bool): Whether server should cache the result of the request/
If true then transparently adds a txn_id to all requests, and
`_handle_request` must return a Deferred.
RETRY_ON_TIMEOUT(bool): Whether or not to retry the request when a 504
is received.
"""

__metaclass__ = abc.ABCMeta

NAME = abc.abstractproperty()
PATH_ARGS = abc.abstractproperty()

METHOD = "POST"
CACHE = True
RETRY_ON_TIMEOUT = True

def __init__(self, hs):
if self.CACHE:
self.response_cache = ResponseCache(
hs, "repl." + self.NAME,
timeout_ms=30 * 60 * 1000,
)

assert self.METHOD in ("PUT", "POST", "GET")

@abc.abstractmethod
def _serialize_payload(**kwargs):
"""Static method that is called when creating a request.

Concrete implementations should have explicit parameters (rather than
kwargs) so that an appropriate exception is raised if the client is
called with unexpected parameters. All PATH_ARGS must appear in
argument list.

Returns:
Deferred[dict]|dict: If POST/PUT request then dictionary must be
JSON serialisable, otherwise must be appropriate for adding as
query args.
"""
return {}

@abc.abstractmethod
def _handle_request(self, request, **kwargs):
"""Handle incoming request.

This is called with the request object and PATH_ARGS.

Returns:
Deferred[dict]: A JSON serialisable dict to be used as response
body of request.
"""
pass

@classmethod
def make_client(cls, hs):
"""Create a client that makes requests.

Returns a callable that accepts the same parameters as `_serialize_payload`.
"""
clock = hs.get_clock()
host = hs.config.worker_replication_host
port = hs.config.worker_replication_http_port

client = hs.get_simple_http_client()

@defer.inlineCallbacks
def send_request(**kwargs):
data = yield cls._serialize_payload(**kwargs)

url_args = [urllib.parse.quote(kwargs[name]) for name in cls.PATH_ARGS]

if cls.CACHE:
txn_id = random_string(10)
url_args.append(txn_id)

if cls.METHOD == "POST":
request_func = client.post_json_get_json
elif cls.METHOD == "PUT":
request_func = client.put_json
elif cls.METHOD == "GET":
request_func = client.get_json
else:
# We have already asserted in the constructor that a
# compatible was picked, but lets be paranoid.
raise Exception(
"Unknown METHOD on %s replication endpoint" % (cls.NAME,)
)

uri = "http://%s:%s/_synapse/replication/%s/%s" % (
host, port, cls.NAME, "/".join(url_args)
)

try:
# We keep retrying the same request for timeouts. This is so that we
# have a good idea that the request has either succeeded or failed on
# the master, and so whether we should clean up or not.
while True:
try:
result = yield request_func(uri, data)
break
except CodeMessageException as e:
if e.code != 504 or not cls.RETRY_ON_TIMEOUT:
raise

logger.warn("%s request timed out", cls.NAME)

# If we timed out we probably don't need to worry about backing
# off too much, but lets just wait a little anyway.
yield clock.sleep(1)
except HttpResponseException as e:
# We convert to SynapseError as we know that it was a SynapseError
# on the master process that we should send to the client. (And
# importantly, not stack traces everywhere)
raise e.to_synapse_error()

defer.returnValue(result)

return send_request

def register(self, http_server):
"""Called by the server to register this as a handler to the
appropriate path.
"""

url_args = list(self.PATH_ARGS)
method = "GET"
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this is dead

handler = self._handle_request
method = self.METHOD

if self.CACHE:
handler = self._cached_handler
url_args.append("txn_id")

args = "/".join("(?P<%s>[^/]+)" % (arg,) for arg in url_args)
pattern = re.compile("^/_synapse/replication/%s/%s$" % (
self.NAME,
args
))

http_server.register_paths(method, [pattern], handler)

def _cached_handler(self, request, txn_id, **kwargs):
"""Called on new incoming requests when caching is enabled. Checks
if their is a cached response for the request and returns that,
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there

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their

otherwise calls `_handle_request` and caches its response.
"""
# We just use the txn_id here, but we probably also want to use the
# other PATH_ARGS as well.

assert self.CACHE

return self.response_cache.wrap(
txn_id,
self._handle_request,
request, **kwargs
)
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