3 files changed, 102 insertions, 1 deletions
diff --git a/synapse/replication/http/__init__.py b/synapse/replication/http/__init__.py
index 28dbc6fcba..4613b2538c 100644
--- a/synapse/replication/http/__init__.py
+++ b/synapse/replication/http/__init__.py
@@ -21,6 +21,7 @@ from synapse.replication.http import (
     membership,
     register,
     send_event,
+    streams,
 )
 
 REPLICATION_PREFIX = "/_synapse/replication"
@@ -38,3 +39,4 @@ class ReplicationRestResource(JsonResource):
         login.register_servlets(hs, self)
         register.register_servlets(hs, self)
         devices.register_servlets(hs, self)
+        streams.register_servlets(hs, self)
diff --git a/synapse/replication/http/_base.py b/synapse/replication/http/_base.py
index 1be1ccbdf3..f88c80ae84 100644
--- a/synapse/replication/http/_base.py
+++ b/synapse/replication/http/_base.py
@@ -16,6 +16,7 @@
 import abc
 import logging
 import re
+from inspect import signature
 from typing import Dict, List, Tuple
 
 from six import raise_from
@@ -60,6 +61,8 @@ class ReplicationEndpoint(object):
     must call `register` to register the path with the HTTP server.
 
     Requests can be sent by calling the client returned by `make_client`.
+    Requests are sent to master process by default, but can be sent to other
+    named processes by specifying an `instance_name` keyword argument.
 
     Attributes:
         NAME (str): A name for the endpoint, added to the path as well as used
@@ -91,6 +94,16 @@ class ReplicationEndpoint(object):
                 hs, "repl." + self.NAME, timeout_ms=30 * 60 * 1000
             )
 
+        # We reserve `instance_name` as a parameter to sending requests, so we
+        # assert here that sub classes don't try and use the name.
+        assert (
+            "instance_name" not in self.PATH_ARGS
+        ), "`instance_name` is a reserved paramater name"
+        assert (
+            "instance_name"
+            not in signature(self.__class__._serialize_payload).parameters
+        ), "`instance_name` is a reserved paramater name"
+
         assert self.METHOD in ("PUT", "POST", "GET")
 
     @abc.abstractmethod
@@ -135,7 +148,11 @@ class ReplicationEndpoint(object):
 
         @trace(opname="outgoing_replication_request")
         @defer.inlineCallbacks
-        def send_request(**kwargs):
+        def send_request(instance_name="master", **kwargs):
+            # Currently we only support sending requests to master process.
+            if instance_name != "master":
+                raise Exception("Unknown instance")
+
             data = yield cls._serialize_payload(**kwargs)
 
             url_args = [
diff --git a/synapse/replication/http/streams.py b/synapse/replication/http/streams.py
new file mode 100644
index 0000000000..0459f582bf
--- /dev/null
+++ b/synapse/replication/http/streams.py
@@ -0,0 +1,82 @@
+# -*- 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
+
+from synapse.api.errors import SynapseError
+from synapse.http.servlet import parse_integer
+from synapse.replication.http._base import ReplicationEndpoint
+
+logger = logging.getLogger(__name__)
+
+
+class ReplicationGetStreamUpdates(ReplicationEndpoint):
+    """Fetches stream updates from a server. Used for streams not persisted to
+    the database, e.g. typing notifications.
+
+    The API looks like:
+
+        GET /_synapse/replication/get_repl_stream_updates/<stream name>?from_token=0&to_token=10
+
+        200 OK
+
+        {
+            updates: [ ... ],
+            upto_token: 10,
+            limited: False,
+        }
+
+    If there are more rows than can sensibly be returned in one lump, `limited` will be
+    set to true, and the caller should call again with a new `from_token`.
+
+    """
+
+    NAME = "get_repl_stream_updates"
+    PATH_ARGS = ("stream_name",)
+    METHOD = "GET"
+
+    def __init__(self, hs):
+        super().__init__(hs)
+
+        self._instance_name = hs.get_instance_name()
+
+        # We pull the streams from the replication steamer (if we try and make
+        # them ourselves we end up in an import loop).
+        self.streams = hs.get_replication_streamer().get_streams()
+
+    @staticmethod
+    def _serialize_payload(stream_name, from_token, upto_token):
+        return {"from_token": from_token, "upto_token": upto_token}
+
+    async def _handle_request(self, request, stream_name):
+        stream = self.streams.get(stream_name)
+        if stream is None:
+            raise SynapseError(400, "Unknown stream")
+
+        from_token = parse_integer(request, "from_token", required=True)
+        upto_token = parse_integer(request, "upto_token", required=True)
+
+        updates, upto_token, limited = await stream.get_updates_since(
+            self._instance_name, from_token, upto_token
+        )
+
+        return (
+            200,
+            {"updates": updates, "upto_token": upto_token, "limited": limited},
+        )
+
+
+def register_servlets(hs, http_server):
+    ReplicationGetStreamUpdates(hs).register(http_server)