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![Erik Johnston](/assets/img/avatar_default.png)
During the migration the automated script to update the copyright headers accidentally got rid of some of the existing copyright lines. Reinstate them.
150 lines
4.9 KiB
Python
150 lines
4.9 KiB
Python
#
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# This file is licensed under the Affero General Public License (AGPL) version 3.
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#
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# Copyright 2014-2016 OpenMarket Ltd
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# Copyright (C) 2023 New Vector, Ltd
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU Affero General Public License as
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# published by the Free Software Foundation, either version 3 of the
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# License, or (at your option) any later version.
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#
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# See the GNU Affero General Public License for more details:
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# <https://www.gnu.org/licenses/agpl-3.0.html>.
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#
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# Originally licensed under the Apache License, Version 2.0:
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# <http://www.apache.org/licenses/LICENSE-2.0>.
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#
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# [This file includes modifications made by New Vector Limited]
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#
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#
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import logging
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from typing import (
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Any,
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Awaitable,
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Callable,
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Dict,
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Generic,
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List,
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Optional,
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TypeVar,
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Union,
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)
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from typing_extensions import ParamSpec
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from twisted.internet import defer
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from synapse.logging.context import make_deferred_yieldable, run_in_background
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from synapse.metrics.background_process_metrics import run_as_background_process
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from synapse.types import UserID
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from synapse.util.async_helpers import maybe_awaitable
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logger = logging.getLogger(__name__)
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def user_left_room(distributor: "Distributor", user: UserID, room_id: str) -> None:
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distributor.fire("user_left_room", user=user, room_id=room_id)
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class Distributor:
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"""A central dispatch point for loosely-connected pieces of code to
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register, observe, and fire signals.
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Signals are named simply by strings.
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TODO(paul): It would be nice to give signals stronger object identities,
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so we can attach metadata, docstrings, detect typos, etc... But this
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model will do for today.
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"""
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def __init__(self) -> None:
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self.signals: Dict[str, Signal] = {}
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self.pre_registration: Dict[str, List[Callable]] = {}
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def declare(self, name: str) -> None:
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if name in self.signals:
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raise KeyError("%r already has a signal named %s" % (self, name))
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self.signals[name] = Signal(name)
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if name in self.pre_registration:
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signal = self.signals[name]
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for observer in self.pre_registration[name]:
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signal.observe(observer)
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def observe(self, name: str, observer: Callable) -> None:
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if name in self.signals:
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self.signals[name].observe(observer)
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else:
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# TODO: Avoid strong ordering dependency by allowing people to
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# pre-register observations on signals that don't exist yet.
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if name not in self.pre_registration:
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self.pre_registration[name] = []
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self.pre_registration[name].append(observer)
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def fire(self, name: str, *args: Any, **kwargs: Any) -> None:
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"""Dispatches the given signal to the registered observers.
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Runs the observers as a background process. Does not return a deferred.
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"""
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if name not in self.signals:
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raise KeyError("%r does not have a signal named %s" % (self, name))
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run_as_background_process(name, self.signals[name].fire, *args, **kwargs)
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P = ParamSpec("P")
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R = TypeVar("R")
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class Signal(Generic[P]):
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"""A Signal is a dispatch point that stores a list of callables as
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observers of it.
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Signals can be "fired", meaning that every callable observing it is
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invoked. Firing a signal does not change its state; it can be fired again
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at any later point. Firing a signal passes any arguments from the fire
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method into all of the observers.
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"""
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def __init__(self, name: str):
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self.name: str = name
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self.observers: List[Callable[P, Any]] = []
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def observe(self, observer: Callable[P, Any]) -> None:
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"""Adds a new callable to the observer list which will be invoked by
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the 'fire' method.
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Each observer callable may return a Deferred."""
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self.observers.append(observer)
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def fire(self, *args: P.args, **kwargs: P.kwargs) -> "defer.Deferred[List[Any]]":
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"""Invokes every callable in the observer list, passing in the args and
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kwargs. Exceptions thrown by observers are logged but ignored. It is
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not an error to fire a signal with no observers.
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Returns a Deferred that will complete when all the observers have
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completed."""
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async def do(observer: Callable[P, Union[R, Awaitable[R]]]) -> Optional[R]:
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try:
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return await maybe_awaitable(observer(*args, **kwargs))
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except Exception as e:
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logger.warning(
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"%s signal observer %s failed: %r",
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self.name,
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observer,
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e,
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)
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return None
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deferreds = [run_in_background(do, o) for o in self.observers]
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return make_deferred_yieldable(
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defer.gatherResults(deferreds, consumeErrors=True)
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)
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def __repr__(self) -> str:
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return "<Signal name=%r>" % (self.name,)
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