stable/freqtrade/rpc/api_server/ws/channel.py

import asyncio
import logging
import time
from threading import RLock
from typing import Any, Dict, List, Optional, Type, Union
from uuid import uuid4

from fastapi import WebSocket as FastAPIWebSocket

from freqtrade.rpc.api_server.ws.proxy import WebSocketProxy
from freqtrade.rpc.api_server.ws.serializer import (HybridJSONWebSocketSerializer,
                                                    WebSocketSerializer)
from freqtrade.rpc.api_server.ws.types import WebSocketType
from freqtrade.rpc.api_server.ws_schemas import WSMessageSchemaType


logger = logging.getLogger(__name__)


class WebSocketChannel:
    """
    Object to help facilitate managing a websocket connection
    """

    def __init__(
        self,
        websocket: WebSocketType,
        channel_id: Optional[str] = None,
        drain_timeout: int = 3,
        throttle: float = 0.01,
        serializer_cls: Type[WebSocketSerializer] = HybridJSONWebSocketSerializer
    ):

        self.channel_id = channel_id if channel_id else uuid4().hex[:8]

        # The WebSocket object
        self._websocket = WebSocketProxy(websocket)

        self.drain_timeout = drain_timeout
        self.throttle = throttle

        self._subscriptions: List[str] = []
        # 32 is the size of the receiving queue in websockets package
        self.queue: asyncio.Queue[Dict[str, Any]] = asyncio.Queue(maxsize=32)
        self._relay_task = asyncio.create_task(self.relay())

        # Internal event to signify a closed websocket
        self._closed = asyncio.Event()

        # Wrap the WebSocket in the Serializing class
        self._wrapped_ws = serializer_cls(self._websocket)

    def __repr__(self):
        return f"WebSocketChannel({self.channel_id}, {self.remote_addr})"

    @property
    def raw_websocket(self):
        return self._websocket.raw_websocket

    @property
    def remote_addr(self):
        return self._websocket.remote_addr

    async def _send(self, data):
        """
        Send data on the wrapped websocket
        """
        await self._wrapped_ws.send(data)

    async def send(self, data) -> bool:
        """
        Add the data to the queue to be sent.
        :returns: True if data added to queue, False otherwise
        """

        # This block only runs if the queue is full, it will wait
        # until self.drain_timeout for the relay to drain the outgoing queue
        # We can't use asyncio.wait_for here because the queue may have been created with a
        # different eventloop
        start = time.time()
        while self.queue.full():
            await asyncio.sleep(1)
            if (time.time() - start) > self.drain_timeout:
                return False

        # If for some reason the queue is still full, just return False
        try:
            self.queue.put_nowait(data)
        except asyncio.QueueFull:
            return False

        # If we got here everything is ok
        return True

    async def recv(self):
        """
        Receive data on the wrapped websocket
        """
        return await self._wrapped_ws.recv()

    async def ping(self):
        """
        Ping the websocket
        """
        return await self._websocket.ping()

    async def close(self):
        """
        Close the WebSocketChannel
        """

        try:
            await self.raw_websocket.close()
        except Exception:
            pass

        self._closed.set()
        self._relay_task.cancel()

    def is_closed(self) -> bool:
        """
        Closed flag
        """
        return self._closed.is_set()

    def set_subscriptions(self, subscriptions: List[str] = []) -> None:
        """
        Set which subscriptions this channel is subscribed to

        :param subscriptions: List of subscriptions, List[str]
        """
        self._subscriptions = subscriptions

    def subscribed_to(self, message_type: str) -> bool:
        """
        Check if this channel is subscribed to the message_type

        :param message_type: The message type to check
        """
        return message_type in self._subscriptions

    async def relay(self):
        """
        Relay messages from the channel's queue and send them out. This is started
        as a task.
        """
        while not self._closed.is_set():
            message = await self.queue.get()
            try:
                await self._send(message)
                self.queue.task_done()

                # Limit messages per sec.
                # Could cause problems with queue size if too low, and
                # problems with network traffik if too high.
                # 0.01 = 100/s
                await asyncio.sleep(self.throttle)
            except RuntimeError:
                # The connection was closed, just exit the task
                return


class ChannelManager:
    def __init__(self):
        self.channels = dict()
        self._lock = RLock()  # Re-entrant Lock

    async def on_connect(self, websocket: WebSocketType):
        """
        Wrap websocket connection into Channel and add to list

        :param websocket: The WebSocket object to attach to the Channel
        """
        if isinstance(websocket, FastAPIWebSocket):
            try:
                await websocket.accept()
            except RuntimeError:
                # The connection was closed before we could accept it
                return

        ws_channel = WebSocketChannel(websocket)

        with self._lock:
            self.channels[websocket] = ws_channel

        return ws_channel

    async def on_disconnect(self, websocket: WebSocketType):
        """
        Call close on the channel if it's not, and remove from channel list

        :param websocket: The WebSocket objet attached to the Channel
        """
        with self._lock:
            channel = self.channels.get(websocket)
            if channel:
                logger.info(f"Disconnecting channel {channel}")
                if not channel.is_closed():
                    await channel.close()

                del self.channels[websocket]

    async def disconnect_all(self):
        """
        Disconnect all Channels
        """
        with self._lock:
            for websocket in self.channels.copy().keys():
                await self.on_disconnect(websocket)

    async def broadcast(self, message: WSMessageSchemaType):
        """
        Broadcast a message on all Channels

        :param message: The message to send
        """
        with self._lock:
            for channel in self.channels.copy().values():
                if channel.subscribed_to(message.get('type')):
                    await self.send_direct(channel, message)

    async def send_direct(
            self, channel: WebSocketChannel, message: Union[WSMessageSchemaType, Dict[str, Any]]):
        """
        Send a message directly through direct_channel only

        :param direct_channel: The WebSocketChannel object to send the message through
        :param message: The message to send
        """
        if not await channel.send(message):
            await self.on_disconnect(channel.raw_websocket)

    def has_channels(self):
        """
        Flag for more than 0 channels
        """
        return len(self.channels) > 0