465 lines
12 KiB
Python
465 lines
12 KiB
Python
# 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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"""Defines the various valid commands
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The VALID_SERVER_COMMANDS and VALID_CLIENT_COMMANDS define which commands are
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allowed to be sent by which side.
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"""
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import abc
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import logging
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from typing import Optional, Tuple, Type, TypeVar
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from synapse.replication.tcp.streams._base import StreamRow
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from synapse.util import json_decoder, json_encoder
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logger = logging.getLogger(__name__)
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T = TypeVar("T", bound="Command")
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class Command(metaclass=abc.ABCMeta):
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"""The base command class.
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All subclasses must set the NAME variable which equates to the name of the
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command on the wire.
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A full command line on the wire is constructed from `NAME + " " + to_line()`
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"""
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NAME: str
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@classmethod
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@abc.abstractmethod
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def from_line(cls: Type[T], line: str) -> T:
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"""Deserialises a line from the wire into this command. `line` does not
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include the command.
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"""
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@abc.abstractmethod
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def to_line(self) -> str:
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"""Serialises the command for the wire. Does not include the command
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prefix.
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"""
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def get_logcontext_id(self) -> str:
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"""Get a suitable string for the logcontext when processing this command"""
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# by default, we just use the command name.
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return self.NAME
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SC = TypeVar("SC", bound="_SimpleCommand")
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class _SimpleCommand(Command):
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"""An implementation of Command whose argument is just a 'data' string."""
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def __init__(self, data: str):
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self.data = data
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@classmethod
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def from_line(cls: Type[SC], line: str) -> SC:
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return cls(line)
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def to_line(self) -> str:
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return self.data
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class ServerCommand(_SimpleCommand):
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"""Sent by the server on new connection and includes the server_name.
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Format::
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SERVER <server_name>
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"""
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NAME = "SERVER"
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class RdataCommand(Command):
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"""Sent by server when a subscribed stream has an update.
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Format::
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RDATA <stream_name> <instance_name> <token> <row_json>
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The `<token>` may either be a numeric stream id OR "batch". The latter case
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is used to support sending multiple updates with the same stream ID. This
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is done by sending an RDATA for each row, with all but the last RDATA having
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a token of "batch" and the last having the final stream ID.
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The client should batch all incoming RDATA with a token of "batch" (per
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stream_name) until it sees an RDATA with a numeric stream ID.
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The `<instance_name>` is the source of the new data (usually "master").
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`<token>` of "batch" maps to the instance variable `token` being None.
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An example of a batched series of RDATA::
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RDATA presence master batch ["@foo:example.com", "online", ...]
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RDATA presence master batch ["@bar:example.com", "online", ...]
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RDATA presence master 59 ["@baz:example.com", "online", ...]
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"""
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NAME = "RDATA"
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def __init__(
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self, stream_name: str, instance_name: str, token: Optional[int], row: StreamRow
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):
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self.stream_name = stream_name
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self.instance_name = instance_name
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self.token = token
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self.row = row
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@classmethod
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def from_line(cls: Type["RdataCommand"], line: str) -> "RdataCommand":
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stream_name, instance_name, token, row_json = line.split(" ", 3)
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return cls(
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stream_name,
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instance_name,
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None if token == "batch" else int(token),
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json_decoder.decode(row_json),
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)
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def to_line(self) -> str:
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return " ".join(
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(
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self.stream_name,
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self.instance_name,
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str(self.token) if self.token is not None else "batch",
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json_encoder.encode(self.row),
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)
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)
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def get_logcontext_id(self) -> str:
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return "RDATA-" + self.stream_name
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class PositionCommand(Command):
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"""Sent by an instance to tell others the stream position without needing to
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send an RDATA.
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Two tokens are sent, the new position and the last position sent by the
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instance (in an RDATA or other POSITION). The tokens are chosen so that *no*
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rows were written by the instance between the `prev_token` and `new_token`.
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(If an instance hasn't sent a position before then the new position can be
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used for both.)
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Format::
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POSITION <stream_name> <instance_name> <prev_token> <new_token>
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On receipt of a POSITION command instances should check if they have missed
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any updates, and if so then fetch them out of band. Instances can check this
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by comparing their view of the current token for the sending instance with
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the included `prev_token`.
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The `<instance_name>` is the process that sent the command and is the source
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of the stream.
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"""
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NAME = "POSITION"
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def __init__(
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self, stream_name: str, instance_name: str, prev_token: int, new_token: int
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):
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self.stream_name = stream_name
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self.instance_name = instance_name
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self.prev_token = prev_token
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self.new_token = new_token
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@classmethod
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def from_line(cls: Type["PositionCommand"], line: str) -> "PositionCommand":
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stream_name, instance_name, prev_token, new_token = line.split(" ", 3)
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return cls(stream_name, instance_name, int(prev_token), int(new_token))
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def to_line(self) -> str:
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return " ".join(
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(
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self.stream_name,
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self.instance_name,
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str(self.prev_token),
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str(self.new_token),
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)
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)
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class ErrorCommand(_SimpleCommand):
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"""Sent by either side if there was an ERROR. The data is a string describing
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the error.
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"""
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NAME = "ERROR"
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class PingCommand(_SimpleCommand):
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"""Sent by either side as a keep alive. The data is arbitrary (often timestamp)"""
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NAME = "PING"
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class NameCommand(_SimpleCommand):
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"""Sent by client to inform the server of the client's identity. The data
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is the name
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"""
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NAME = "NAME"
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class ReplicateCommand(Command):
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"""Sent by the client to subscribe to streams.
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Format::
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REPLICATE
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"""
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NAME = "REPLICATE"
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def __init__(self) -> None:
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pass
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@classmethod
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def from_line(cls: Type[T], line: str) -> T:
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return cls()
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def to_line(self) -> str:
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return ""
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class UserSyncCommand(Command):
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"""Sent by the client to inform the server that a user has started or
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stopped syncing on this process.
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This is used by the process handling presence (typically the master) to
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calculate who is online and who is not.
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Includes a timestamp of when the last user sync was.
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Format::
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USER_SYNC <instance_id> <user_id> <state> <last_sync_ms>
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Where <state> is either "start" or "end"
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"""
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NAME = "USER_SYNC"
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def __init__(
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self, instance_id: str, user_id: str, is_syncing: bool, last_sync_ms: int
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):
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self.instance_id = instance_id
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self.user_id = user_id
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self.is_syncing = is_syncing
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self.last_sync_ms = last_sync_ms
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@classmethod
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def from_line(cls: Type["UserSyncCommand"], line: str) -> "UserSyncCommand":
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instance_id, user_id, state, last_sync_ms = line.split(" ", 3)
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if state not in ("start", "end"):
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raise Exception("Invalid USER_SYNC state %r" % (state,))
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return cls(instance_id, user_id, state == "start", int(last_sync_ms))
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def to_line(self) -> str:
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return " ".join(
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(
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self.instance_id,
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self.user_id,
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"start" if self.is_syncing else "end",
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str(self.last_sync_ms),
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)
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)
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class ClearUserSyncsCommand(Command):
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"""Sent by the client to inform the server that it should drop all
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information about syncing users sent by the client.
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Mainly used when client is about to shut down.
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Format::
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CLEAR_USER_SYNC <instance_id>
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"""
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NAME = "CLEAR_USER_SYNC"
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def __init__(self, instance_id: str):
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self.instance_id = instance_id
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@classmethod
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def from_line(
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cls: Type["ClearUserSyncsCommand"], line: str
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) -> "ClearUserSyncsCommand":
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return cls(line)
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def to_line(self) -> str:
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return self.instance_id
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class FederationAckCommand(Command):
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"""Sent by the client when it has processed up to a given point in the
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federation stream. This allows the master to drop in-memory caches of the
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federation stream.
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This must only be sent from one worker (i.e. the one sending federation)
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Format::
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FEDERATION_ACK <instance_name> <token>
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"""
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NAME = "FEDERATION_ACK"
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def __init__(self, instance_name: str, token: int):
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self.instance_name = instance_name
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self.token = token
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@classmethod
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def from_line(
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cls: Type["FederationAckCommand"], line: str
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) -> "FederationAckCommand":
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instance_name, token = line.split(" ")
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return cls(instance_name, int(token))
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def to_line(self) -> str:
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return "%s %s" % (self.instance_name, self.token)
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class UserIpCommand(Command):
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"""Sent periodically when a worker sees activity from a client.
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Format::
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USER_IP <user_id>, <access_token>, <ip>, <device_id>, <last_seen>, <user_agent>
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"""
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NAME = "USER_IP"
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def __init__(
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self,
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user_id: str,
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access_token: str,
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ip: str,
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user_agent: str,
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device_id: str,
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last_seen: int,
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):
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self.user_id = user_id
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self.access_token = access_token
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self.ip = ip
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self.user_agent = user_agent
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self.device_id = device_id
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self.last_seen = last_seen
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@classmethod
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def from_line(cls: Type["UserIpCommand"], line: str) -> "UserIpCommand":
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user_id, jsn = line.split(" ", 1)
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access_token, ip, user_agent, device_id, last_seen = json_decoder.decode(jsn)
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return cls(user_id, access_token, ip, user_agent, device_id, last_seen)
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def to_line(self) -> str:
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return (
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self.user_id
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+ " "
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+ json_encoder.encode(
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(
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self.access_token,
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self.ip,
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self.user_agent,
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self.device_id,
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self.last_seen,
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)
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)
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)
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class RemoteServerUpCommand(_SimpleCommand):
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"""Sent when a worker has detected that a remote server is no longer
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"down" and retry timings should be reset.
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If sent from a client the server will relay to all other workers.
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Format::
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REMOTE_SERVER_UP <server>
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"""
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NAME = "REMOTE_SERVER_UP"
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_COMMANDS: Tuple[Type[Command], ...] = (
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ServerCommand,
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RdataCommand,
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PositionCommand,
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ErrorCommand,
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PingCommand,
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NameCommand,
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ReplicateCommand,
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UserSyncCommand,
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FederationAckCommand,
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UserIpCommand,
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RemoteServerUpCommand,
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ClearUserSyncsCommand,
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)
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# Map of command name to command type.
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COMMAND_MAP = {cmd.NAME: cmd for cmd in _COMMANDS}
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# The commands the server is allowed to send
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VALID_SERVER_COMMANDS = (
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ServerCommand.NAME,
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RdataCommand.NAME,
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PositionCommand.NAME,
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ErrorCommand.NAME,
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PingCommand.NAME,
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RemoteServerUpCommand.NAME,
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)
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# The commands the client is allowed to send
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VALID_CLIENT_COMMANDS = (
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NameCommand.NAME,
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ReplicateCommand.NAME,
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PingCommand.NAME,
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UserSyncCommand.NAME,
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ClearUserSyncsCommand.NAME,
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FederationAckCommand.NAME,
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UserIpCommand.NAME,
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ErrorCommand.NAME,
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RemoteServerUpCommand.NAME,
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)
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def parse_command_from_line(line: str) -> Command:
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"""Parses a command from a received line.
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Line should already be stripped of whitespace and be checked if blank.
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"""
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idx = line.find(" ")
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if idx >= 0:
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cmd_name = line[:idx]
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rest_of_line = line[idx + 1 :]
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else:
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cmd_name = line
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rest_of_line = ""
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cmd_cls = COMMAND_MAP[cmd_name]
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return cmd_cls.from_line(rest_of_line)
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