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ChannelSubscriber

faststream.redis.subscriber.usecases.ChannelSubscriber #

ChannelSubscriber(
    config: RedisSubscriberConfig,
    specification: SubscriberSpecification[Any, Any],
    calls: CallsCollection[Any],
)

Bases: LogicSubscriber

Source code in faststream/redis/subscriber/usecases/channel_subscriber.py
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def __init__(
    self,
    config: "RedisSubscriberConfig",
    specification: "SubscriberSpecification[Any, Any]",
    calls: "CallsCollection[Any]",
) -> None:
    assert config.channel_sub
    parser = RedisPubSubParser(config, pattern=config.channel_sub.path_regex)
    config.decoder = parser.decode_message
    config.parser = parser.parse_message
    super().__init__(config, specification, calls)

    self._channel = config.channel_sub
    self.subscription: RPubSub | None = None

lock instance-attribute #

lock: AbstractContextManager[Any] = FakeContext()

extra_watcher_options instance-attribute #

extra_watcher_options: dict[str, Any] = {}

graceful_timeout instance-attribute #

graceful_timeout: float | None

calls instance-attribute #

calls = calls

specification instance-attribute #

specification = specification

ack_policy instance-attribute #

ack_policy = config.ack_policy

running instance-attribute #

running = False

tasks instance-attribute #

tasks: list[Task[Any]] = []

config instance-attribute #

config = config

subscription instance-attribute #

subscription: PubSub | None = None

channel property #

channel: PubSub

add_call #

add_call(
    *,
    parser_: Optional[CustomCallable],
    decoder_: Optional[CustomCallable],
    dependencies_: Sequence[Dependant],
    codec_: Optional[CodecProto] = None,
) -> Self
Source code in faststream/_internal/endpoint/subscriber/usecase.py
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def add_call(
    self,
    *,
    parser_: Optional["CustomCallable"],
    decoder_: Optional["CustomCallable"],
    dependencies_: Sequence["Dependant"],
    codec_: Optional["CodecProto"] = None,
) -> Self:
    self._call_options = _CallOptions(
        parser=parser_,
        decoder=decoder_,
        dependencies=dependencies_,
        codec=codec_,
    )
    return self

consume async #

consume(msg: MsgType) -> Any

Consume a message asynchronously.

Source code in faststream/_internal/endpoint/subscriber/usecase.py
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async def consume(self, msg: MsgType) -> Any:
    """Consume a message asynchronously."""
    if not self.running:
        return None

    try:
        return await self.process_message(msg)

    except StopConsume:
        # Stop handler at StopConsume exception
        await self.stop()

    except SystemExit:
        # Stop handler at `exit()` call
        await self.stop()

        if app := self._outer_config.context.get("app"):
            app.exit()

    except Exception:  # nosec B110  # noqa: S110
        # All other exceptions were logged by CriticalLogMiddleware
        pass

process_message async #

process_message(msg: MsgType) -> Response

Execute all message processing stages.

Source code in faststream/_internal/endpoint/subscriber/usecase.py
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async def process_message(self, msg: MsgType) -> "Response":
    """Execute all message processing stages."""
    context = self._outer_config.context
    logger_state = self._outer_config.logger

    async with AsyncExitStack() as stack:
        stack.enter_context(self.lock)

        # Enter context before middlewares
        stack.enter_context(
            context.scopes(
                (
                    ("handler_", self),
                    ("logger", logger_state.logger.logger),
                    *self._outer_config.extra_context.items(),
                ),
            ),
        )

        # enter all middlewares
        middlewares: list[BaseMiddleware] = []
        for base_m in self.__build__middlewares_stack():
            middleware = base_m(msg, context=context)
            middlewares.append(middleware)
            await middleware.__aenter__()

        cache: dict[Any, Any] = {}
        parsing_error: Exception | None = None
        for h in self.calls:
            try:
                message = await h.is_suitable(msg, cache)
            except Exception as e:
                parsing_error = e
                break

            if message is not None:
                stack.enter_context(
                    context.scopes(
                        (
                            ("log_context", self.get_log_context(message)),
                            ("message", message),
                        ),
                    ),
                )

                # Middlewares should be exited before scope release
                for m in middlewares:
                    stack.push_async_exit(m.__aexit__)

                result_msg = ensure_response(
                    await h.call(
                        message=message,
                        # consumer middlewares
                        _extra_middlewares=(
                            m.consume_scope for m in middlewares[::-1]
                        ),
                    ),
                )

                if not result_msg.correlation_id:
                    result_msg.correlation_id = message.correlation_id

                for p in chain(
                    self.__get_response_publisher(message),
                    h.handler._publishers,
                ):
                    await p._publish(
                        result_msg.as_publish_command(),
                        _extra_middlewares=(
                            m.publish_scope for m in middlewares[::-1]
                        ),
                    )

                # Return data for tests
                return result_msg

        # Suitable handler was not found or
        # parsing/decoding exception occurred
        for m in middlewares:
            stack.push_async_exit(m.__aexit__)

        # Reraise it to catch in tests
        if parsing_error:
            raise parsing_error

        error_msg = f"There is no suitable handler for {msg=}"
        raise SubscriberNotFound(error_msg)

    # An error was raised and processed by some middleware
    return ensure_response(None)

schema #

schema() -> dict[str, SubscriberSpec]
Source code in faststream/_internal/endpoint/subscriber/usecase.py
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def schema(self) -> dict[str, "SubscriberSpec"]:
    self._build_fastdepends_model()
    return self.specification.get_schema()

add_task #

add_task(
    func: Callable[..., Coroutine[Any, Any, Any]],
    func_args: tuple[Any, ...] | None = None,
    func_kwargs: dict[str, Any] | None = None,
    *,
    restart_on_failure: bool = True,
) -> None
Source code in faststream/_internal/endpoint/subscriber/mixins.py
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def add_task(
    self,
    func: Callable[..., Coroutine[Any, Any, Any]],
    func_args: tuple[Any, ...] | None = None,
    func_kwargs: dict[str, Any] | None = None,
    *,
    restart_on_failure: bool = True,
) -> None:
    args = func_args or ()
    kwargs = func_kwargs or {}
    task = asyncio.create_task(func(*args, **kwargs))
    callback = TaskCallbackSupervisor(
        func,
        func_args,
        func_kwargs,
        self,
        restart_on_failure=restart_on_failure,
    )
    task.add_done_callback(callback)
    self.tasks.append(task)

build_log_context staticmethod #

build_log_context(
    message: Optional[StreamMessage[Any]], channel: str = ""
) -> dict[str, str]
Source code in faststream/redis/subscriber/usecases/basic.py
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@staticmethod
def build_log_context(
    message: Optional["BrokerStreamMessage[Any]"],
    channel: str = "",
) -> dict[str, str]:
    return {
        "channel": channel,
        "message_id": getattr(message, "message_id", ""),
    }

consume_one async #

consume_one(msg: Any) -> None
Source code in faststream/redis/subscriber/usecases/basic.py
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async def consume_one(self, msg: Any) -> None:
    await self.consume(msg)

get_log_context #

get_log_context(
    message: Optional[StreamMessage[Any]],
) -> dict[str, str]
Source code in faststream/redis/subscriber/usecases/channel_subscriber.py
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def get_log_context(
    self,
    message: Optional["BrokerStreamMessage[Any]"],
) -> dict[str, str]:
    return self.build_log_context(
        message=message,
        channel=self.channel.name,
    )

start async #

start() -> None
Source code in faststream/redis/subscriber/usecases/channel_subscriber.py
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@override
async def start(self) -> None:
    if self.subscription:
        return

    self.subscription = psub = self._client.pubsub()

    if self.channel.pattern:
        await psub.psubscribe(self.channel.name)
    else:
        await psub.subscribe(self.channel.name)

    await super().start(psub)

stop async #

stop() -> None
Source code in faststream/redis/subscriber/usecases/channel_subscriber.py
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async def stop(self) -> None:
    await super().stop()

    if self.subscription is not None:
        await self.subscription.unsubscribe()
        await self.subscription.aclose()  # type: ignore[attr-defined]
        self.subscription = None

get_one async #

get_one(
    *, timeout: float = 5.0
) -> RedisChannelMessage | None
Source code in faststream/redis/subscriber/usecases/channel_subscriber.py
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@override
async def get_one(
    self,
    *,
    timeout: float = 5.0,
) -> "RedisChannelMessage | None":
    assert self.subscription, "You should start subscriber at first."
    assert not self.calls, (
        "You can't use `get_one` method if subscriber has registered handlers."
    )

    sleep_interval = timeout / 10

    raw_message: PubSubMessage | None = None

    with anyio.move_on_after(timeout):
        while (raw_message := await self._get_message(self.subscription)) is None:  # noqa: ASYNC110
            await anyio.sleep(sleep_interval)

    context = self._outer_config.context
    async_parser, async_decoder = self._get_parser_and_decoder()

    msg: RedisChannelMessage | None = await process_msg(  # type: ignore[assignment]
        msg=raw_message,
        middlewares=(
            m(raw_message, context=context) for m in self._broker_middlewares
        ),
        parser=async_parser,
        decoder=async_decoder,
    )
    return msg