From 74506934356dcb10b1704e3e66d4648e99ba6308 Mon Sep 17 00:00:00 2001 From: Erik Johnston Date: Mon, 27 Mar 2017 15:40:37 +0100 Subject: [PATCH] Initial TCP protocol implementation This defines the low level TCP replication protocol --- docs/tcp_replication.rst | 174 ++++++++ synapse/replication/tcp/__init__.py | 32 ++ synapse/replication/tcp/commands.py | 341 ++++++++++++++++ synapse/replication/tcp/protocol.py | 601 ++++++++++++++++++++++++++++ 4 files changed, 1148 insertions(+) create mode 100644 docs/tcp_replication.rst create mode 100644 synapse/replication/tcp/commands.py create mode 100644 synapse/replication/tcp/protocol.py diff --git a/docs/tcp_replication.rst b/docs/tcp_replication.rst new file mode 100644 index 0000000000..946add2849 --- /dev/null +++ b/docs/tcp_replication.rst @@ -0,0 +1,174 @@ +TCP Replication +=============== + +This describes the TCP replication protocol that replaces the HTTP protocol. + +Motivation +---------- + +The HTTP API used long poll from the workers to the master, this has the problem +of causing a lot of duplicate work on the server. This TCP protocol aims to +solve. + +Overview +-------- + +The protocol is based on fire and forget, line based commands. An example flow +would be (where '>' indicates master->worker and '<' worker->master flows):: + + > SERVER example.com + < REPLICATE events 53 + > RDATA events 54 ["$foo1:bar.com", ...] + > RDATA events 55 ["$foo4:bar.com", ...] + +The example shows the server accepting a new connection and sending its identity +with the ``SERVER`` command, followed by the client asking to subscribe to the +``events`` stream from the token ``53``. The server then periodically sends ``RDATA`` +commands which have the format ``RDATA ```, where the +format of ```` is defined by the individual streams. + +Error reporting happens by either the client or server sending an `ERROR` +command, and usually the connection will be closed. + + +Since the protocol is a simple line based, its possible to manually connect to +the server using a tool like netcat. A few things should be noted when manually +using the protocol: + * When subscribing to a stream using ``REPLICATE``, the special token ``NOW`` can + be used to get all future updates. The special stream name ``ALL`` can be used + with ``NOW`` to subscribe to all available streams. + * The federation stream is only available if federation sending has been + disabled on the main process. + * The server will only time connections out that have sent a ``PING`` command. + If a ping is sent then the connection will be closed if no further commands + are receieved within 15s. Both the client and server protocol implementations + will send an initial PING on connection and ensure at least one command every + 5s is sent (not necessarily ``PING``). + * ``RDATA`` commands *usually* include a numeric token, however if the stream + has multiple rows to replicate per token the server will send multiple + ``RDATA`` commands, with all but the last having a token of ``batch``. See + the documentation on ``commands.RdataCommand`` for further details. + + +Architecture +------------ + +The basic structure of the protocol is line based, where the initial word of +each line specifies the command. The rest of the line is parsed based on the +command. For example, the `RDATA` command is defined as:: + + RDATA + +(Note that `` may contains spaces, but cannot contain newlines.) + +Blank lines are ignored. + + +Keep alives +~~~~~~~~~~~ + +Both sides are expected to send at least one command every 5s or so, and +should send a ``PING`` command if necessary. If either side do not receive a +command within e.g. 15s then the connection should be closed. + +Because the server may be connected to manually using e.g. netcat, the timeouts +aren't enabled until an initial ``PING`` command is seen. Both the client and +server implementations below send a ``PING`` command immediately on connection to +ensure the timeouts are enabled. + +This ensures that both sides can quickly realize if the tcp connection has gone +and handle the situation appropriately. + + +Start up +~~~~~~~~ + +When a new connection is made, the server: + * Sends a ``SERVER`` command, which includes the identity of the server, allowing + the client to detect if its connected to the expected server + * Sends a ``PING`` command as above, to enable the client to time out connections + promptly. + +The client: + * Sends a ``NAME`` command, allowing the server to associate a human friendly + name with the connection. This is optional. + * Sends a ``PING`` as above + * For each stream the client wishes to subscribe to it sends a ``REPLICATE`` + with the stream_name and token it wants to subscribe from. + * On receipt of a ``SERVER`` command, checks that the server name matches the + expected server name. + + +Error handling +~~~~~~~~~~~~~~ + +If either side detects an error it can send an ``ERROR`` command and close the +connection. + +If the client side loses the connection to the server it should reconnect, +following the steps above. + + +Congestion +~~~~~~~~~~ + +If the server sends messages faster than the client can consume them the server +will first buffer a (fairly large) number of commands and then disconnect the +client. This ensures that we don't queue up an unbounded number of commands in +memory and gives us a potential oppurtunity to squawk loudly. When/if the client +recovers it can reconnect to the server and ask for missed messages. + + +Reliability +~~~~~~~~~~~ + +In general the replication stream should be consisdered an unreliable transport +since e.g. commands are not resent if the connection disappears. + +The exception to that are the replication streams, i.e. RDATA commands, since +these include tokens which can be used to restart the stream on connection +errors. + +The client should keep track of the token in the last RDATA command received +for each stream so that on reconneciton it can start streaming from the correct +place. Note: not all RDATA have valid tokens due to batching. See +``RdataCommand`` for more details. + + +Example +~~~~~~~ + +An example iteraction is shown below. Each line is prefixed with '>' or '<' to +indicate which side is sending, these are *not* included on the wire:: + + * connection established * + > SERVER localhost:8823 + > PING 1490197665618 + < NAME synapse.app.appservice + < PING 1490197665618 + < REPLICATE events 1 + < REPLICATE backfill 1 + < REPLICATE caches 1 + > POSITION events 1 + > POSITION backfill 1 + > POSITION caches 1 + > RDATA caches 2 ["get_user_by_id",["@01register-user:localhost:8823"],1490197670513] + > RDATA events 14 ["$149019767112vOHxz:localhost:8823", + "!AFDCvgApUmpdfVjIXm:localhost:8823","m.room.guest_access","",null] + < PING 1490197675618 + > ERROR server stopping + * connection closed by server * + +The ``POSITION`` command sent by the server is used to set the clients position +without needing to send data with the ``RDATA`` command. + + +An example of a batched set of ``RDATA`` is:: + + > RDATA caches batch ["get_user_by_id",["@test:localhost:8823"],1490197670513] + > RDATA caches batch ["get_user_by_id",["@test2:localhost:8823"],1490197670513] + > RDATA caches batch ["get_user_by_id",["@test3:localhost:8823"],1490197670513] + > RDATA caches 54 ["get_user_by_id",["@test4:localhost:8823"],1490197670513] + +In this case the client shouldn't advance their caches token until it sees the +the last ``RDATA``. diff --git a/synapse/replication/tcp/__init__.py b/synapse/replication/tcp/__init__.py index 451dae3b6c..8b4e886d4e 100644 --- a/synapse/replication/tcp/__init__.py +++ b/synapse/replication/tcp/__init__.py @@ -12,3 +12,35 @@ # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. + +"""This module implements the TCP replication protocol used by synapse to +communicate between the master process and its workers (when they're enabled). + +The protocol is based on fire and forget, line based commands. An example flow +would be (where '>' indicates master->worker and '<' worker->master flows):: + + > SERVER example.com + < REPLICATE events 53 + > RDATA events 54 ["$foo1:bar.com", ...] + > RDATA events 55 ["$foo4:bar.com", ...] + +The example shows the server accepting a new connection and sending its identity +with the `SERVER` command, followed by the client asking to subscribe to the +`events` stream from the token `53`. The server then periodically sends `RDATA` +commands which have the format `RDATA `, where the +format of `` is defined by the individual streams. + +Error reporting happens by either the client or server sending an `ERROR` +command, and usually the connection will be closed. + + +Structure of the module: + * client.py - the client classes used for workers to connect to master + * command.py - the definitions of all the valid commands + * protocol.py - contains bot the client and server protocol implementations, + these should not be used directly + * resource.py - the server classes that accepts and handle client connections + * streams.py - the definitons of all the valid streams + +Further details can be found in docs/tcp_replication.rst +""" diff --git a/synapse/replication/tcp/commands.py b/synapse/replication/tcp/commands.py new file mode 100644 index 0000000000..68165cf2dc --- /dev/null +++ b/synapse/replication/tcp/commands.py @@ -0,0 +1,341 @@ +# -*- 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. +"""Defines the various valid commands + +The VALID_SERVER_COMMANDS and VALID_CLIENT_COMMANDS define which commands are +allowed to be sent by which side. +""" + +import logging +import ujson as json + + +logger = logging.getLogger(__name__) + + +class Command(object): + """The base command class. + + All subclasses must set the NAME variable which equates to the name of the + command on the wire. + + A full command line on the wire is constructed from `NAME + " " + to_line()` + + The default implementation creates a command of form ` ` + """ + NAME = None + + def __init__(self, data): + self.data = data + + @classmethod + def from_line(cls, line): + """Deserialises a line from the wire into this command. `line` does not + include the command. + """ + return cls(line) + + def to_line(self): + """Serialises the comamnd for the wire. Does not include the command + prefix. + """ + return self.data + + +class ServerCommand(Command): + """Sent by the server on new connection and includes the server_name. + + Format:: + + SERVER + """ + NAME = "SERVER" + + +class RdataCommand(Command): + """Sent by server when a subscribed stream has an update. + + Format:: + + RDATA + + The `` may either be a numeric stream id OR "batch". The latter case + is used to support sending multiple updates with the same stream ID. This + is done by sending an RDATA for each row, with all but the last RDATA having + a token of "batch" and the last having the final stream ID. + + The client should batch all incoming RDATA with a token of "batch" (per + stream_name) until it sees an RDATA with a numeric stream ID. + + `` of "batch" maps to the instance variable `token` being None. + + An example of a batched series of RDATA:: + + RDATA presence batch ["@foo:example.com", "online", ...] + RDATA presence batch ["@bar:example.com", "online", ...] + RDATA presence 59 ["@baz:example.com", "online", ...] + """ + NAME = "RDATA" + + def __init__(self, stream_name, token, row): + self.stream_name = stream_name + self.token = token + self.row = row + + @classmethod + def from_line(cls, line): + stream_name, token, row_json = line.split(" ", 2) + return cls( + stream_name, + None if token == "batch" else int(token), + json.loads(row_json) + ) + + def to_line(self): + return " ".join(( + self.stream_name, + str(self.token) if self.token is not None else "batch", + json.dumps(self.row), + )) + + +class PositionCommand(Command): + """Sent by the client to tell the client the stream postition without + needing to send an RDATA. + """ + NAME = "POSITION" + + def __init__(self, stream_name, token): + self.stream_name = stream_name + self.token = token + + @classmethod + def from_line(cls, line): + stream_name, token = line.split(" ", 1) + return cls(stream_name, int(token)) + + def to_line(self): + return " ".join((self.stream_name, str(self.token),)) + + +class ErrorCommand(Command): + """Sent by either side if there was an ERROR. The data is a string describing + the error. + """ + NAME = "ERROR" + + +class PingCommand(Command): + """Sent by either side as a keep alive. The data is arbitary (often timestamp) + """ + NAME = "PING" + + +class NameCommand(Command): + """Sent by client to inform the server of the client's identity. The data + is the name + """ + NAME = "NAME" + + +class ReplicateCommand(Command): + """Sent by the client to subscribe to the stream. + + Format:: + + REPLICATE + + Where may be either: + * a numeric stream_id to stream updates from + * "NOW" to stream all subsequent updates. + + The can be "ALL" to subscribe to all known streams, in which + case the must be set to "NOW", i.e.:: + + REPLICATE ALL NOW + """ + NAME = "REPLICATE" + + def __init__(self, stream_name, token): + self.stream_name = stream_name + self.token = token + + @classmethod + def from_line(cls, line): + stream_name, token = line.split(" ", 1) + if token in ("NOW", "now"): + token = "NOW" + else: + token = int(token) + return cls(stream_name, token) + + def to_line(self): + return " ".join((self.stream_name, str(self.token),)) + + +class UserSyncCommand(Command): + """Sent by the client to inform the server that a user has started or + stopped syncing. Used to calculate presence on the master. + + Format:: + + USER_SYNC + + Where is either "start" or "stop" + """ + NAME = "USER_SYNC" + + def __init__(self, user_id, is_syncing): + self.user_id = user_id + self.is_syncing = is_syncing + + @classmethod + def from_line(cls, line): + user_id, state = line.split(" ", 1) + + if state not in ("start", "end"): + raise Exception("Invalid USER_SYNC state %r" % (state,)) + + return cls(user_id, state == "start") + + def to_line(self): + return " ".join((self.user_id, "start" if self.is_syncing else "end")) + + +class FederationAckCommand(Command): + """Sent by the client when it has processed up to a given point in the + federation stream. This allows the master to drop in-memory caches of the + federation stream. + + This must only be sent from one worker (i.e. the one sending federation) + + Format:: + + FEDERATION_ACK + """ + NAME = "FEDERATION_ACK" + + def __init__(self, token): + self.token = token + + @classmethod + def from_line(cls, line): + return cls(int(line)) + + def to_line(self): + return str(self.token) + + +class SyncCommand(Command): + """Used for testing. The client protocol implementation allows waiting + on a SYNC command with a specified data. + """ + NAME = "SYNC" + + +class RemovePusherCommand(Command): + """Sent by the client to request the master remove the given pusher. + + Format:: + + REMOVE_PUSHER + """ + NAME = "REMOVE_PUSHER" + + def __init__(self, app_id, push_key, user_id): + self.user_id = user_id + self.app_id = app_id + self.push_key = push_key + + @classmethod + def from_line(cls, line): + app_id, push_key, user_id = line.split(" ", 2) + + return cls(app_id, push_key, user_id) + + def to_line(self): + return " ".join((self.app_id, self.push_key, self.user_id)) + + +class InvalidateCacheCommand(Command): + """Sent by the client to invalidate an upstream cache. + + THIS IS NOT RELIABLE, AND SHOULD *NOT* BE USED ACCEPT FOR THINGS THAT ARE + NOT DISASTROUS IF WE DROP ON THE FLOOR. + + Mainly used to invalidate destination retry timing caches. + + Format:: + + INVALIDATE_CACHE + + Where is a json list. + """ + NAME = "INVALIDATE_CACHE" + + def __init__(self, cache_func, keys): + self.cache_func = cache_func + self.keys = keys + + @classmethod + def from_line(cls, line): + cache_func, keys_json = line.split(" ", 1) + + return cls(cache_func, json.loads(keys_json)) + + def to_line(self): + return " ".join((self.cache_func, json.dumps(self.keys))) + + +# Map of command name to command type. +COMMAND_MAP = { + cmd.NAME: cmd + for cmd in ( + ServerCommand, + RdataCommand, + PositionCommand, + ErrorCommand, + PingCommand, + NameCommand, + ReplicateCommand, + UserSyncCommand, + FederationAckCommand, + SyncCommand, + RemovePusherCommand, + InvalidateCacheCommand, + ) +} + +# The commands the server is allowed to send +VALID_SERVER_COMMANDS = ( + ServerCommand.NAME, + RdataCommand.NAME, + PositionCommand.NAME, + ErrorCommand.NAME, + PingCommand.NAME, + SyncCommand.NAME, +) + +# The commands the client is allowed to send +VALID_CLIENT_COMMANDS = ( + NameCommand.NAME, + ReplicateCommand.NAME, + PingCommand.NAME, + UserSyncCommand.NAME, + FederationAckCommand.NAME, + RemovePusherCommand.NAME, + InvalidateCacheCommand.NAME, + ErrorCommand.NAME, +) diff --git a/synapse/replication/tcp/protocol.py b/synapse/replication/tcp/protocol.py new file mode 100644 index 0000000000..c1dc91bdb7 --- /dev/null +++ b/synapse/replication/tcp/protocol.py @@ -0,0 +1,601 @@ +# -*- 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. +"""This module contains the implementation of both the client and server +protocols. + +The basic structure of the protocol is line based, where the initial word of +each line specifies the command. The rest of the line is parsed based on the +command. For example, the `RDATA` command is defined as:: + + RDATA + +(Note that `` may contains spaces, but cannot contain newlines.) + +Blank lines are ignored. + +# Example + +An example iteraction is shown below. Each line is prefixed with '>' or '<' to +indicate which side is sending, these are *not* included on the wire:: + + * connection established * + > SERVER localhost:8823 + > PING 1490197665618 + < NAME synapse.app.appservice + < PING 1490197665618 + < REPLICATE events 1 + < REPLICATE backfill 1 + < REPLICATE caches 1 + > POSITION events 1 + > POSITION backfill 1 + > POSITION caches 1 + > RDATA caches 2 ["get_user_by_id",["@01register-user:localhost:8823"],1490197670513] + > RDATA events 14 ["$149019767112vOHxz:localhost:8823", + "!AFDCvgApUmpdfVjIXm:localhost:8823","m.room.guest_access","",null] + < PING 1490197675618 + > ERROR server stopping + * connection closed by server * +""" + +from twisted.internet import defer +from twisted.protocols.basic import LineOnlyReceiver + +from commands import ( + COMMAND_MAP, VALID_CLIENT_COMMANDS, VALID_SERVER_COMMANDS, + ErrorCommand, ServerCommand, RdataCommand, PositionCommand, PingCommand, + NameCommand, ReplicateCommand, UserSyncCommand, SyncCommand, +) +from streams import STREAMS_MAP + +from synapse.util.stringutils import random_string + +import logging +import synapse.metrics +import struct +import fcntl + + +metrics = synapse.metrics.get_metrics_for(__name__) + +inbound_commands_counter = metrics.register_counter( + "inbound_commands", labels=["command", "name", "conn_id"], +) +outbound_commands_counter = metrics.register_counter( + "outbound_commands", labels=["command", "name", "conn_id"], +) + + +# A list of all connected protocols. This allows us to send metrics about the +# connections. +connected_connections = [] + + +logger = logging.getLogger(__name__) + + +PING_TIME = 5000 + + +class ConnectionStates(object): + CONNECTING = "connecting" + ESTABLISHED = "established" + PAUSED = "paused" + CLOSED = "closed" + + +class BaseReplicationStreamProtocol(LineOnlyReceiver): + """Base replication protocol shared between client and server. + + Reads lines (ignoring blank ones) and parses them into command classes, + asserting that they are valid for the given direction, i.e. server commands + are only sent by the server. + + On receiving a new command it calls `on_` with the parsed + command. + + It also sends `PING` periodically, and correctly times out remote connections + (if they send a `PING` command) + """ + delimiter = b'\n' + + VALID_INBOUND_COMMANDS = [] # Valid commands we expect to receive + VALID_OUTBOUND_COMMANDS = [] # Valid commans we can send + + max_line_buffer = 10000 + + def __init__(self, clock): + self.clock = clock + + self.last_received_command = self.clock.time_msec() + self.last_sent_command = 0 + self.time_we_closed = None # When we requested the connection be closed + + self.received_ping = False # Have we reecived a ping from the other side + + self.state = ConnectionStates.CONNECTING + + self.name = "anon" # The name sent by a client. + self.conn_id = random_string(5) # To dedupe in case of name clashes. + + # List of pending commands to send once we've established the connection + self.pending_commands = [] + + # The LoopingCall for sending pings. + self._send_ping_loop = None + + def connectionMade(self): + logger.info("[%s] Connection established", self.id()) + + self.state = ConnectionStates.ESTABLISHED + + connected_connections.append(self) # Register connection for metrics + + self.transport.registerProducer(self, True) # For the *Producing callbacks + + self._send_pending_commands() + + # Starts sending pings + self._send_ping_loop = self.clock.looping_call(self.send_ping, 5000) + + # Always send the initial PING so that the other side knows that they + # can time us out. + self.send_command(PingCommand(self.clock.time_msec())) + + def send_ping(self): + """Periodically sends a ping and checks if we should close the connection + due to the other side timing out. + """ + now = self.clock.time_msec() + + if self.time_we_closed: + if now - self.time_we_closed > PING_TIME * 3: + logger.info( + "[%s] Failed to close connection gracefully, aborting", self.id() + ) + self.transport.abortConnection() + else: + if now - self.last_sent_command >= PING_TIME: + self.send_command(PingCommand(now)) + + if self.received_ping and now - self.last_received_command > PING_TIME * 3: + logger.info( + "[%s] Connection hasn't received command in %r ms. Closing.", + self.id(), now - self.last_received_command + ) + self.send_error("ping timeout") + + def lineReceived(self, line): + """Called when we've received a line + """ + if line.strip() == "": + # Ignore blank lines + return + + line = line.decode("utf-8") + cmd_name, rest_of_line = line.split(" ", 1) + + if cmd_name not in self.VALID_INBOUND_COMMANDS: + logger.error("[%s] invalid command %s", self.id(), cmd_name) + self.send_error("invalid command: %s", cmd_name) + return + + self.last_received_command = self.clock.time_msec() + + inbound_commands_counter.inc(cmd_name, self.name, self.conn_id) + + 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_ function + try: + getattr(self, "on_%s" % (cmd_name,))(cmd) + except Exception: + logger.exception("[%s] Failed to handle line: %r", self.id(), line) + + def close(self): + self.time_we_closed = self.clock.time_msec() + self.transport.loseConnection() + self.on_connection_closed() + + def send_error(self, error_string, *args): + """Send an error to remote and close the connection. + """ + self.send_command(ErrorCommand(error_string % args)) + self.close() + + def send_command(self, cmd, do_buffer=True): + """Send a command if connection has been established. + + Args: + cmd (Command) + do_buffer (bool): Whether to buffer the message or always attempt + to send the command. This is mostly used to send an error + message if we're about to close the connection due our buffers + becoming full. + """ + if self.state == ConnectionStates.CLOSED: + logger.info("[%s] Not sending, connection closed", self.id()) + return + + if do_buffer and self.state != ConnectionStates.ESTABLISHED: + self._queue_command(cmd) + return + + outbound_commands_counter.inc(cmd.NAME, self.name, self.conn_id) + + string = "%s %s" % (cmd.NAME, cmd.to_line(),) + if "\n" in string: + raise Exception("Unexpected newline in command: %r", string) + + self.sendLine(string.encode("utf-8")) + + self.last_sent_command = self.clock.time_msec() + + def _queue_command(self, cmd): + """Queue the command until the connection is ready to write to again. + """ + logger.info("[%s] Queing as conn %r, cmd: %r", self.id(), self.state, cmd) + self.pending_commands.append(cmd) + + if len(self.pending_commands) > self.max_line_buffer: + # The other side is failing to keep up and out buffers are becoming + # full, so lets close the connection. + # XXX: should we squawk more loudly? + logger.error("[%s] Remote failed to keep up", self.id()) + self.send_command(ErrorCommand("Failed to keep up"), do_buffer=False) + self.close() + + def _send_pending_commands(self): + """Send any queued commandes + """ + pending = self.pending_commands + self.pending_commands = [] + for cmd in pending: + self.send_command(cmd) + + def on_PING(self, line): + self.received_ping = True + + def on_ERROR(self, cmd): + logger.error("[%s] Remote reported error: %r", self.id(), cmd.data) + + def pauseProducing(self): + """This is called when both the kernel send buffer and the twisted + tcp connection send buffers have become full. + + We don't actually have any control over those sizes, so we buffer some + commands ourselves before knifing the connection due to the remote + failing to keep up. + """ + logger.info("[%s] Pause producing", self.id()) + self.state = ConnectionStates.PAUSED + + def resumeProducing(self): + """The remote has caught up after we started buffering! + """ + logger.info("[%s] Resume producing", self.id()) + self.state = ConnectionStates.ESTABLISHED + self._send_pending_commands() + + def stopProducing(self): + """We're never going to send any more data (normally because either + we or the remote has closed the connection) + """ + logger.info("[%s] Stop producing", self.id()) + self.on_connection_closed() + + def connectionLost(self, reason): + logger.info("[%s] Replication connection closed: %r", self.id(), reason) + + try: + # Remove us from list of connections to be monitored + connected_connections.remove(self) + except ValueError: + pass + + # Stop the looping call sending pings. + if self._send_ping_loop and self._send_ping_loop.running: + self._send_ping_loop.stop() + + self.on_connection_closed() + + def on_connection_closed(self): + logger.info("[%s] Connection was closed", self.id()) + + self.state = ConnectionStates.CLOSED + self.pending_commands = [] + + if self.transport: + self.transport.unregisterProducer() + + def __str__(self): + return "ReplicationConnection" % ( + self.name, self.conn_id, self.addr, + ) + + def id(self): + return "%s-%s" % (self.name, self.conn_id) + + +class ServerReplicationStreamProtocol(BaseReplicationStreamProtocol): + VALID_INBOUND_COMMANDS = VALID_CLIENT_COMMANDS + VALID_OUTBOUND_COMMANDS = VALID_SERVER_COMMANDS + + def __init__(self, server_name, clock, streamer, addr): + BaseReplicationStreamProtocol.__init__(self, clock) # Old style class + + self.server_name = server_name + self.streamer = streamer + self.addr = addr + + # The streams the client has subscribed to and is up to date with + self.replication_streams = set() + + # The streams the client is currently subscribing to. + self.connecting_streams = set() + + # Map from stream name to list of updates to send once we've finished + # subscribing the client to the stream. + self.pending_rdata = {} + + def connectionMade(self): + self.send_command(ServerCommand(self.server_name)) + BaseReplicationStreamProtocol.connectionMade(self) + self.streamer.new_connection(self) + + def on_NAME(self, cmd): + self.name = cmd.data + + def on_USER_SYNC(self, cmd): + self.streamer.on_user_sync(self.conn_id, cmd.user_id, cmd.is_syncing) + + def on_REPLICATE(self, cmd): + stream_name = cmd.stream_name + token = cmd.token + + if stream_name == "ALL": + # Subscribe to all streams we're publishing to. + for stream in self.streamer.streams_by_name.iterkeys(): + self.subscribe_to_stream(stream, token) + else: + self.subscribe_to_stream(stream_name, token) + + def on_FEDERATION_ACK(self, cmd): + self.streamer.federation_ack(cmd.token) + + def on_REMOVE_PUSHER(self, cmd): + self.streamer.on_remove_pusher(cmd.app_id, cmd.push_key, cmd.user_id) + + def onINVALIDATE_CACHE(self, cmd): + self.streamer.on_invalidate_cache(cmd.cache_func, cmd.keys) + + @defer.inlineCallbacks + def subscribe_to_stream(self, stream_name, token): + """Subscribe the remote to a streams. + + This invloves checking if they've missed anything and sending those + updates down if they have. During that time new updates for the stream + are queued and sent once we've sent down any missed updates. + """ + self.replication_streams.discard(stream_name) + self.connecting_streams.add(stream_name) + + try: + # Get missing updates + updates, current_token = yield self.streamer.get_stream_updates( + stream_name, token, + ) + + # Send all the missing updates + for update in updates: + token, row = update[0], update[1] + self.send_command(RdataCommand(stream_name, token, row)) + + # Now we can send any updates that came in while we were subscribing + pending_rdata = self.pending_rdata.pop(stream_name, []) + for token, update in pending_rdata: + self.send_command(RdataCommand(stream_name, token, update)) + + # We send a POSITION command to ensure that they have an up to + # date token (especially useful if we didn't send any updates + # above) + self.send_command(PositionCommand(stream_name, current_token)) + + # They're now fully subscribed + self.replication_streams.add(stream_name) + except Exception as e: + logger.exception("[%s] Failed to handle REPLICATE command", self.id()) + self.send_error("failed to handle replicate: %r", e) + finally: + self.connecting_streams.discard(stream_name) + + 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 + """ + if stream_name in self.replication_streams: + # The client is subscribed to the stream + self.send_command(RdataCommand(stream_name, token, data)) + elif stream_name in self.connecting_streams: + # The client is being subscribed to the stream + logger.info("[%s] Queuing RDATA %r %r", self.id(), stream_name, token) + self.pending_rdata.setdefault(stream_name, []).append((token, data)) + else: + # The client isn't subscribed + logger.debug("[%s] Dropping RDATA %r %r", self.id(), stream_name, token) + + def send_sync(self, data): + self.send_command(SyncCommand(data)) + + def on_connection_closed(self): + BaseReplicationStreamProtocol.on_connection_closed(self) + logger.info("[%s] Replication connection closed", self.id()) + self.streamer.lost_connection(self) + + +class ClientReplicationStreamProtocol(BaseReplicationStreamProtocol): + VALID_INBOUND_COMMANDS = VALID_SERVER_COMMANDS + VALID_OUTBOUND_COMMANDS = VALID_CLIENT_COMMANDS + + def __init__(self, client_name, server_name, clock, handler): + BaseReplicationStreamProtocol.__init__(self, clock) + + self.client_name = client_name + self.server_name = server_name + self.handler = handler + + # Map of stream to batched updates. See RdataCommand for info on how + # batching works. + self.pending_batches = {} + + def connectionMade(self): + self.send_command(NameCommand(self.client_name)) + BaseReplicationStreamProtocol.connectionMade(self) + + # Once we've connected subscribe to the necessary streams + for stream_name, token in self.handler.get_streams_to_replicate().iteritems(): + self.replicate(stream_name, token) + + # Tell the server if we have any users currently syncing (should only + # happen on synchrotrons) + currently_syncing = self.handler.get_currently_syncing_users() + for user_id in currently_syncing: + self.send_command(UserSyncCommand(user_id, True)) + + # We've now finished connecting to so inform the client handler + self.handler.update_connection(self) + + def on_SERVER(self, cmd): + if cmd.data != self.server_name: + logger.error("[%s] Connected to wrong remote: %r", self.id(), cmd.data) + self.transport.abortConnection() + + def on_RDATA(self, cmd): + try: + row = STREAMS_MAP[cmd.stream_name].ROW_TYPE(*cmd.row) + except Exception: + logger.exception( + "[%s] Failed to parse RDATA: %r %r", + self.id(), cmd.stream_name, cmd.row + ) + raise + + if cmd.token is None: + # I.e. this is part of a batch of updates for this stream. Batch + # until we get an update for the stream with a non None token + self.pending_batches.setdefault(cmd.stream_name, []).append(row) + else: + # Check if this is the last of a batch of updates + rows = self.pending_batches.pop(cmd.stream_name, []) + rows.append(row) + + self.handler.on_rdata(cmd.stream_name, cmd.token, rows) + + def on_POSITION(self, cmd): + self.handler.on_position(cmd.stream_name, cmd.token) + + def on_SYNC(self, cmd): + self.handler.on_sync(cmd.data) + + def replicate(self, stream_name, token): + """Send the subscription request to the server + """ + if stream_name not in STREAMS_MAP: + raise Exception("Invalid stream name %r" % (stream_name,)) + + logger.info( + "[%s] Subscribing to replication stream: %r from %r", + self.id(), stream_name, token + ) + + self.send_command(ReplicateCommand(stream_name, token)) + + def on_connection_closed(self): + BaseReplicationStreamProtocol.on_connection_closed(self) + self.handler.update_connection(None) + + +# The following simply registers metrics for the replication connections + +metrics.register_callback( + "pending_commands", + lambda: { + (p.name, p.conn_id): len(p.pending_commands) + for p in connected_connections + }, + labels=["name", "conn_id"], +) + + +def transport_buffer_size(protocol): + if protocol.transport: + size = len(protocol.transport.dataBuffer) + protocol.transport._tempDataLen + return size + return 0 + + +metrics.register_callback( + "transport_send_buffer", + lambda: { + (p.name, p.conn_id): transport_buffer_size(p) + for p in connected_connections + }, + labels=["name", "conn_id"], +) + + +def transport_kernel_read_buffer_size(protocol, read=True): + SIOCINQ = 0x541B + SIOCOUTQ = 0x5411 + + if protocol.transport: + fileno = protocol.transport.getHandle().fileno() + if read: + op = SIOCINQ + else: + op = SIOCOUTQ + size = struct.unpack("I", fcntl.ioctl(fileno, op, '\0\0\0\0'))[0] + return size + return 0 + + +metrics.register_callback( + "transport_kernel_send_buffer", + lambda: { + (p.name, p.conn_id): transport_kernel_read_buffer_size(p, False) + for p in connected_connections + }, + labels=["name", "conn_id"], +) + + +metrics.register_callback( + "transport_kernel_read_buffer", + lambda: { + (p.name, p.conn_id): transport_kernel_read_buffer_size(p, True) + for p in connected_connections + }, + labels=["name", "conn_id"], +)