diff --git a/synapse/replication/tcp/resource.py b/synapse/replication/tcp/resource.py
new file mode 100644
index 0000000000..d5da0496a8
--- /dev/null
+++ b/synapse/replication/tcp/resource.py
@@ -0,0 +1,300 @@
+# -*- 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.
+"""The server side of the replication stream.
+"""
+
+from twisted.internet import defer, reactor
+from twisted.internet.protocol import Factory
+
+from streams import STREAMS_MAP, FederationStream
+from protocol import ServerReplicationStreamProtocol
+
+from synapse.util.logcontext import preserve_fn
+from synapse.util.metrics import Measure, measure_func
+
+import logging
+import synapse.metrics
+
+
+metrics = synapse.metrics.get_metrics_for(__name__)
+stream_updates_counter = metrics.register_counter(
+ "stream_updates", labels=["stream_name"]
+)
+user_sync_counter = metrics.register_counter("user_sync")
+federation_ack_counter = metrics.register_counter("federation_ack")
+remove_pusher_counter = metrics.register_counter("remove_pusher")
+invalidate_cache_counter = metrics.register_counter("invalidate_cache")
+
+logger = logging.getLogger(__name__)
+
+
+class ReplicationStreamProtocolFactory(Factory):
+ """Factory for new replication connections.
+ """
+ def __init__(self, hs):
+ self.streamer = ReplicationStreamer(hs)
+ self.clock = hs.get_clock()
+ self.server_name = hs.config.server_name
+
+ def buildProtocol(self, addr):
+ return ServerReplicationStreamProtocol(
+ self.server_name,
+ self.clock,
+ self.streamer,
+ addr
+ )
+
+
+class ReplicationStreamer(object):
+ """Handles replication connections.
+
+ This needs to be poked when new replication data may be available. When new
+ data is available it will propagate to all connected clients.
+ """
+
+ def __init__(self, hs):
+ self.store = hs.get_datastore()
+ self.notifier = hs.get_notifier()
+ self.presence_handler = hs.get_presence_handler()
+ self.clock = hs.get_clock()
+
+ # Current connections.
+ self.connections = []
+
+ metrics.register_callback("total_connections", lambda: len(self.connections))
+
+ # List of streams that clients can subscribe to.
+ # We only support federation stream if federation sending hase been
+ # disabled on the master.
+ self.streams = [
+ stream(hs) for stream in STREAMS_MAP.itervalues()
+ if stream != FederationStream or not hs.config.send_federation
+ ]
+
+ self.streams_by_name = {stream.NAME: stream for stream in self.streams}
+
+ metrics.register_callback(
+ "connections_per_stream",
+ lambda: {
+ (stream_name,): len([
+ conn for conn in self.connections
+ if stream_name in conn.replication_streams
+ ])
+ for stream_name in self.streams_by_name
+ },
+ labels=["stream_name"],
+ )
+
+ self.federation_sender = None
+ if not hs.config.send_federation:
+ self.federation_sender = hs.get_federation_sender()
+
+ # Start listening for updates from the notifier
+ preserve_fn(self.notifier_listener)()
+
+ # Keeps track of whether we are currently checking for updates
+ self.is_looping = False
+ self.pending_updates = False
+
+ reactor.addSystemEventTrigger("before", "shutdown", self.on_shutdown)
+
+ def on_shutdown(self):
+ # close all connections on shutdown
+ for conn in self.connections:
+ conn.send_error("server shutting down")
+
+ @defer.inlineCallbacks
+ def notifier_listener(self):
+ """Sits forever looping on the notifier waiting for new data.
+ """
+ while True:
+ yield self.notifier.wait_once_for_replication()
+ logger.debug("Woken up by notifier")
+ # We need to call this each time we get woken up, as per docstring
+ preserve_fn(self.on_notifier_poke)()
+
+ @defer.inlineCallbacks
+ def on_notifier_poke(self):
+ """Checks if there is actually any new data and sends it to the
+ connections if there are.
+
+ This should get called each time new data is available, even if it
+ is currently being executed, so that nothing gets missed
+ """
+ if not self.connections:
+ # Don't bother if nothing is listening
+ return
+
+ # If we're in the process of checking for new updates, mark that fact
+ # and return
+ if self.is_looping:
+ logger.debug("Noitifier poke loop already running")
+ self.pending_updates = True
+ return
+
+ self.pending_updates = True
+ self.is_looping = True
+
+ try:
+ # Keep looping while there have been pokes about potential updates.
+ # This protects against the race where a stream we already checked
+ # gets an update while we're handling other streams.
+ while self.pending_updates:
+ self.pending_updates = False
+
+ with Measure(self.clock, "repl.stream.get_updates"):
+ # First we tell the streams that they should update their
+ # current tokens.
+ for stream in self.streams:
+ stream.advance_current_token()
+
+ for stream in self.streams:
+ if stream.last_token == stream.upto_token:
+ continue
+
+ logger.debug(
+ "Getting stream: %s: %s -> %s",
+ stream.NAME, stream.last_token, stream.upto_token
+ )
+ updates, current_token = yield stream.get_updates()
+
+ logger.debug(
+ "Sending %d updates to %d connections",
+ len(updates), len(self.connections),
+ )
+
+ if updates:
+ logger.info(
+ "Streaming: %s -> %s", stream.NAME, updates[-1][0]
+ )
+ stream_updates_counter.inc_by(len(updates), stream.NAME)
+
+ # Some streams return multiple rows with the same stream IDs,
+ # we need to make sure they get sent out in batches. We do
+ # this by setting the current token to all but the last of
+ # a series of updates with the same token to have a None
+ # token. See RdataCommand for more details.
+ batched_updates = _batch_updates(updates)
+
+ for conn in self.connections:
+ for token, row in batched_updates:
+ try:
+ conn.stream_update(stream.NAME, token, row)
+ except Exception:
+ logger.exception("Failed to replicate")
+
+ logger.debug("No more pending updates, breaking poke loop")
+ finally:
+ self.pending_updates = False
+ self.is_looping = False
+
+ @measure_func("repl.get_stream_updates")
+ def get_stream_updates(self, stream_name, token):
+ """For a given stream get all updates since token. This is called when
+ a client first subscribes to a stream.
+ """
+ stream = self.streams_by_name.get(stream_name, None)
+ if not stream:
+ raise Exception("unknown stream %s", stream_name)
+
+ return stream.get_updates_since(token)
+
+ @measure_func("repl.federation_ack")
+ def federation_ack(self, token):
+ """We've received an ack for federation stream from a client.
+ """
+ federation_ack_counter.inc()
+ if self.federation_sender:
+ self.federation_sender.federation_ack(token)
+
+ @measure_func("repl.on_user_sync")
+ def on_user_sync(self, conn_id, user_id, is_syncing):
+ """A client has started/stopped syncing on a worker.
+ """
+ user_sync_counter.inc()
+ self.presence_handler.update_external_syncs_row(
+ conn_id, user_id, is_syncing
+ )
+
+ @measure_func("repl.on_remove_pusher")
+ @defer.inlineCallbacks
+ def on_remove_pusher(self, app_id, push_key, user_id):
+ """A client has asked us to remove a pusher
+ """
+ remove_pusher_counter.inc()
+ yield self.store.delete_pusher_by_app_id_pushkey_user_id(
+ app_id=app_id, pushkey=push_key, user_id=user_id
+ )
+
+ self.notifier.on_new_replication_data()
+
+ @measure_func("repl.on_invalidate_cache")
+ def on_invalidate_cache(self, cache_func, keys):
+ """The client has asked us to invalidate a cache
+ """
+ invalidate_cache_counter.inc()
+ getattr(self.store, cache_func).invalidate(tuple(keys))
+
+ def send_sync_to_all_connections(self, data):
+ """Sends a SYNC command to all clients.
+
+ Used in tests.
+ """
+ for conn in self.connections:
+ conn.send_sync(data)
+
+ def new_connection(self, connection):
+ """A new client connection has been established
+ """
+ self.connections.append(connection)
+
+ def lost_connection(self, connection):
+ """A client connection has been lost
+ """
+ try:
+ self.connections.remove(connection)
+ except ValueError:
+ pass
+
+ # We need to tell the presence handler that the connection has been
+ # lost so that it can handle any ongoing syncs on that connection.
+ self.presence_handler.update_external_syncs_clear(connection.conn_id)
+
+
+def _batch_updates(updates):
+ """Takes a list of updates of form [(token, row)] and sets the token to
+ None for all rows where the next row has the same token. This is used to
+ implement batching.
+
+ For example:
+
+ [(1, _), (1, _), (2, _), (3, _), (3, _)]
+
+ becomes:
+
+ [(None, _), (1, _), (2, _), (None, _), (3, _)]
+ """
+ if not updates:
+ return []
+
+ new_updates = []
+ for i, update in enumerate(updates[:-1]):
+ if update[0] == updates[i + 1][0]:
+ new_updates.append((None, update[1]))
+ else:
+ new_updates.append(update)
+
+ new_updates.append(updates[-1])
+ return new_updates
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