Add server side resource for tcp replication
This commit is contained in:
Erik Johnston
parent
7450693435
commit
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# -*- coding: utf-8 -*-
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# Copyright 2017 Vector Creations Ltd
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""The server side of the replication stream.
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"""
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from twisted.internet import defer, reactor
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from twisted.internet.protocol import Factory
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from streams import STREAMS_MAP, FederationStream
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from protocol import ServerReplicationStreamProtocol
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from synapse.util.logcontext import preserve_fn
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from synapse.util.metrics import Measure, measure_func
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import logging
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import synapse.metrics
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metrics = synapse.metrics.get_metrics_for(__name__)
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stream_updates_counter = metrics.register_counter(
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"stream_updates", labels=["stream_name"]
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)
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user_sync_counter = metrics.register_counter("user_sync")
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federation_ack_counter = metrics.register_counter("federation_ack")
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remove_pusher_counter = metrics.register_counter("remove_pusher")
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invalidate_cache_counter = metrics.register_counter("invalidate_cache")
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logger = logging.getLogger(__name__)
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class ReplicationStreamProtocolFactory(Factory):
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"""Factory for new replication connections.
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"""
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def __init__(self, hs):
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self.streamer = ReplicationStreamer(hs)
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self.clock = hs.get_clock()
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self.server_name = hs.config.server_name
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def buildProtocol(self, addr):
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return ServerReplicationStreamProtocol(
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self.server_name,
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self.clock,
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self.streamer,
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addr
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)
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class ReplicationStreamer(object):
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"""Handles replication connections.
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This needs to be poked when new replication data may be available. When new
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data is available it will propagate to all connected clients.
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"""
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def __init__(self, hs):
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self.store = hs.get_datastore()
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self.notifier = hs.get_notifier()
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self.presence_handler = hs.get_presence_handler()
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self.clock = hs.get_clock()
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# Current connections.
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self.connections = []
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metrics.register_callback("total_connections", lambda: len(self.connections))
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# List of streams that clients can subscribe to.
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# We only support federation stream if federation sending hase been
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# disabled on the master.
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self.streams = [
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stream(hs) for stream in STREAMS_MAP.itervalues()
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if stream != FederationStream or not hs.config.send_federation
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]
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self.streams_by_name = {stream.NAME: stream for stream in self.streams}
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metrics.register_callback(
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"connections_per_stream",
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lambda: {
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(stream_name,): len([
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conn for conn in self.connections
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if stream_name in conn.replication_streams
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])
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for stream_name in self.streams_by_name
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},
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labels=["stream_name"],
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)
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self.federation_sender = None
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if not hs.config.send_federation:
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self.federation_sender = hs.get_federation_sender()
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# Start listening for updates from the notifier
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preserve_fn(self.notifier_listener)()
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# Keeps track of whether we are currently checking for updates
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self.is_looping = False
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self.pending_updates = False
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reactor.addSystemEventTrigger("before", "shutdown", self.on_shutdown)
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def on_shutdown(self):
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# close all connections on shutdown
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for conn in self.connections:
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conn.send_error("server shutting down")
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@defer.inlineCallbacks
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def notifier_listener(self):
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"""Sits forever looping on the notifier waiting for new data.
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"""
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while True:
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yield self.notifier.wait_once_for_replication()
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logger.debug("Woken up by notifier")
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# We need to call this each time we get woken up, as per docstring
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preserve_fn(self.on_notifier_poke)()
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@defer.inlineCallbacks
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def on_notifier_poke(self):
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"""Checks if there is actually any new data and sends it to the
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connections if there are.
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This should get called each time new data is available, even if it
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is currently being executed, so that nothing gets missed
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"""
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if not self.connections:
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# Don't bother if nothing is listening
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return
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# If we're in the process of checking for new updates, mark that fact
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# and return
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if self.is_looping:
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logger.debug("Noitifier poke loop already running")
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self.pending_updates = True
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return
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self.pending_updates = True
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self.is_looping = True
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try:
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# Keep looping while there have been pokes about potential updates.
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# This protects against the race where a stream we already checked
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# gets an update while we're handling other streams.
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while self.pending_updates:
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self.pending_updates = False
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with Measure(self.clock, "repl.stream.get_updates"):
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# First we tell the streams that they should update their
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# current tokens.
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for stream in self.streams:
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stream.advance_current_token()
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for stream in self.streams:
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if stream.last_token == stream.upto_token:
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continue
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logger.debug(
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"Getting stream: %s: %s -> %s",
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stream.NAME, stream.last_token, stream.upto_token
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)
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updates, current_token = yield stream.get_updates()
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logger.debug(
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"Sending %d updates to %d connections",
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len(updates), len(self.connections),
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)
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if updates:
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logger.info(
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"Streaming: %s -> %s", stream.NAME, updates[-1][0]
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)
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stream_updates_counter.inc_by(len(updates), stream.NAME)
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# Some streams return multiple rows with the same stream IDs,
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# we need to make sure they get sent out in batches. We do
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# this by setting the current token to all but the last of
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# a series of updates with the same token to have a None
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# token. See RdataCommand for more details.
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batched_updates = _batch_updates(updates)
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for conn in self.connections:
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for token, row in batched_updates:
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try:
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conn.stream_update(stream.NAME, token, row)
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except Exception:
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logger.exception("Failed to replicate")
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logger.debug("No more pending updates, breaking poke loop")
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finally:
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self.pending_updates = False
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self.is_looping = False
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@measure_func("repl.get_stream_updates")
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def get_stream_updates(self, stream_name, token):
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"""For a given stream get all updates since token. This is called when
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a client first subscribes to a stream.
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"""
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stream = self.streams_by_name.get(stream_name, None)
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if not stream:
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raise Exception("unknown stream %s", stream_name)
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return stream.get_updates_since(token)
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@measure_func("repl.federation_ack")
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def federation_ack(self, token):
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"""We've received an ack for federation stream from a client.
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"""
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federation_ack_counter.inc()
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if self.federation_sender:
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self.federation_sender.federation_ack(token)
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@measure_func("repl.on_user_sync")
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def on_user_sync(self, conn_id, user_id, is_syncing):
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"""A client has started/stopped syncing on a worker.
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"""
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user_sync_counter.inc()
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self.presence_handler.update_external_syncs_row(
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conn_id, user_id, is_syncing
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)
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@measure_func("repl.on_remove_pusher")
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@defer.inlineCallbacks
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def on_remove_pusher(self, app_id, push_key, user_id):
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"""A client has asked us to remove a pusher
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"""
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remove_pusher_counter.inc()
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yield self.store.delete_pusher_by_app_id_pushkey_user_id(
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app_id=app_id, pushkey=push_key, user_id=user_id
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)
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self.notifier.on_new_replication_data()
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@measure_func("repl.on_invalidate_cache")
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def on_invalidate_cache(self, cache_func, keys):
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"""The client has asked us to invalidate a cache
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"""
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invalidate_cache_counter.inc()
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getattr(self.store, cache_func).invalidate(tuple(keys))
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def send_sync_to_all_connections(self, data):
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"""Sends a SYNC command to all clients.
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Used in tests.
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"""
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for conn in self.connections:
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conn.send_sync(data)
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def new_connection(self, connection):
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"""A new client connection has been established
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"""
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self.connections.append(connection)
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def lost_connection(self, connection):
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"""A client connection has been lost
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"""
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try:
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self.connections.remove(connection)
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except ValueError:
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pass
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# We need to tell the presence handler that the connection has been
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# lost so that it can handle any ongoing syncs on that connection.
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self.presence_handler.update_external_syncs_clear(connection.conn_id)
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def _batch_updates(updates):
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"""Takes a list of updates of form [(token, row)] and sets the token to
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None for all rows where the next row has the same token. This is used to
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implement batching.
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For example:
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[(1, _), (1, _), (2, _), (3, _), (3, _)]
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becomes:
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[(None, _), (1, _), (2, _), (None, _), (3, _)]
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"""
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if not updates:
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return []
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new_updates = []
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for i, update in enumerate(updates[:-1]):
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if update[0] == updates[i + 1][0]:
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new_updates.append((None, update[1]))
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else:
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new_updates.append(update)
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new_updates.append(updates[-1])
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return new_updates
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