~naglis/aio_mpv_ipc

ref: bbe711ecc59e228938048c353217b0293c6e6403 aio_mpv_ipc/aio_mpv_ipc/_client.py -rw-r--r-- 7.1 KiB
bbe711ecNaglis Jonaitis Revert weakref usage 11 months ago
                                                                                
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import asyncio
import collections
import contextlib
import json
import logging
import pathlib
import typing

from aio_mpv_ipc.exceptions import (
    AioMpvIPCException,
    IPCConnectionException,
    IPCException,
    MpvStartException,
)

logger = logging.getLogger("aio_mpv_ipc")

IPC_ENCODING = "utf-8"
NEWLINE = b"\n"


@contextlib.asynccontextmanager
async def start_mpv(
    socket_path: typing.Union[pathlib.Path, str],
    *mpv_args: str,
    mpv_path: typing.Union[pathlib.Path, str] = "mpv",
    terminate: bool = False,
):
    if isinstance(socket_path, pathlib.Path):
        socket_path = str(socket_path.resolve(strict=False))
    if isinstance(mpv_path, pathlib.Path):
        mpv_path = str(mpv_path)

    mpv = await asyncio.create_subprocess_exec(
        mpv_path, f"--input-ipc-server={socket_path}", *mpv_args
    )
    logger.debug("Started mpv process with PID: %d", mpv.pid)

    try:
        yield mpv
    except IPCConnectionException as exc:
        if mpv.returncode is not None:
            raise MpvStartException(
                f"mpv exited with status code: {mpv.returncode}"
            ) from exc
        else:
            raise
    except asyncio.CancelledError:
        raise
    except Exception:
        logger.exception("An unexpected error occurred while executing mpv")
        raise
    finally:
        if terminate and mpv.returncode is None:
            mpv.terminate()
        await mpv.wait()


class MpvClient:
    def __init__(
        self,
        socket_path: pathlib.Path,
        *,
        max_connect_attempts: int = 5,
        connect_sleep_timeout: float = 0.5,
        event_queue_timeout: float = 1.0,
        json_loads=json.loads,
        json_dumps=json.dumps,
    ) -> None:
        self._socket_path = socket_path
        self._reader, self._writer = None, None
        self._writer_lock = asyncio.Lock()
        self._max_connect_attempts = max_connect_attempts
        self._connect_sleep_timeout = connect_sleep_timeout
        self._event_queue_timeout = event_queue_timeout
        self._json_loads, self._json_dumps = json_loads, json_dumps
        self._poll_task = None

        self._request_counter = 0

        self._futures: typing.Dict[str, asyncio.Future] = {}
        self._event_subscribers: typing.Dict[
            str, typing.Set[asyncio.Queue]
        ] = collections.defaultdict(set)

    @property
    def socket_path(self) -> pathlib.Path:
        return self._socket_path

    def subscribe(self, event_name: str, queue: asyncio.Queue):
        self._event_subscribers[event_name].add(queue)

    def unsubscribe(self, event_name: str, queue: asyncio.Queue):
        self._event_subscribers[event_name].remove(queue)

    async def __aenter__(self):
        attempt = 0
        while True:
            attempt += 1
            try:
                self._reader, self._writer = await asyncio.open_unix_connection(
                    self.socket_path
                )
                break
            except (ConnectionRefusedError, FileNotFoundError) as exc:
                if attempt >= self._max_connect_attempts:
                    raise IPCConnectionException("Failed to connect to mpv") from exc
                logger.debug(
                    "%d connection attempt failed, will retry after %f seconds",
                    attempt,
                    self._connect_sleep_timeout,
                )
                await asyncio.sleep(self._connect_sleep_timeout)

        self._poll_task = asyncio.create_task(
            self._poll(), name="Poll mpv JSON IPC socket"
        )

        return self

    async def __aexit__(self, _, __, ___):
        if self._poll_task is not None:
            logger.debug("Cancelling mpv polling task")
            self._poll_task.cancel()
            try:
                await self._poll_task
            except asyncio.CancelledError:
                pass
            self._poll_task = None

        if self._futures:
            logger.debug("Cancelling pending futures")
            for request_id in list(self._futures):
                self._futures.pop(request_id).cancel()

        if self._writer is not None:
            logger.debug("Closing mpv JSON IPC socket writer")
            self._writer.close()

    async def _poll(self):
        while not self._reader.at_eof():
            data = await self._reader.readline()
            if not data:
                continue

            response = self._json_loads(data.rstrip(NEWLINE))

            logger.debug("Response from mpv: %r", response)

            event_name = response.get("event")
            if event_name is not None:
                # This is an event notification, notify subscribers (if any).
                if event_name in self._event_subscribers:
                    for queue in self._event_subscribers[event_name]:
                        try:
                            await asyncio.wait_for(
                                queue.put(response), timeout=self._event_queue_timeout
                            )
                        except asyncio.TimeoutError:
                            logger.warning(
                                'Timeout while adding event "%s" response "%s" '
                                "to queue: %s. The event will be dropped",
                                event_name,
                                response,
                                queue,
                            )

            else:
                status = response.get("error")
                is_error = status and status != "success"
                if is_error:
                    logger.debug("mpv returned an error: %r", response)

                request_id = response.get("request_id")
                if request_id:
                    fut = self._futures.pop(request_id)
                    if not fut.cancelled():
                        if is_error:
                            fut.set_exception(IPCException(status, response))
                        else:
                            fut.set_result(response.get("data"))

        logger.debug("EOF received, stopping polling")

    async def ipc(
        self, command_name: str, *params, nowait: bool = False
    ) -> typing.Optional[typing.Any]:
        if self._writer is None:
            raise AioMpvIPCException("mpv JSON IPC socket writer was not initialized")

        self._request_counter += 1

        payload = {"command": [command_name, *params]}

        fut = None
        if not nowait:
            request_id = self._request_counter
            fut = asyncio.get_running_loop().create_future()
            payload.update(request_id=request_id)
            self._futures.update({request_id: fut})

        logger.debug("mpv IPC payload (nowait=%r): %s", nowait, payload)

        data = self._json_dumps(payload)

        async with self._writer_lock:
            self._writer.write(data.encode(encoding=IPC_ENCODING))
            self._writer.write(NEWLINE)

            try:
                await self._writer.drain()
            except ConnectionError as exc:
                raise IPCConnectionException("IPC connection to mpv failed") from exc

        if not nowait:
            return await fut