stable/freqtrade/rpc/api_server/api_ws.py

import logging
from typing import Any, Dict

from fastapi import APIRouter, Depends, WebSocket, WebSocketDisconnect
# fastapi does not make this available through it, so import directly from starlette
from starlette.websockets import WebSocketState

from freqtrade.enums import RPCMessageType, RPCRequestType
from freqtrade.rpc.api_server.deps import get_channel_manager, get_rpc
from freqtrade.rpc.api_server.ws.channel import WebSocketChannel
from freqtrade.rpc.api_server.ws.schema import (ValidationError, WSAnalyzedDFMessage,
                                                WSRequestSchema, WSWhitelistMessage)
from freqtrade.rpc.rpc import RPC


logger = logging.getLogger(__name__)

# Private router, protected by API Key authentication
router = APIRouter()


async def is_websocket_alive(ws: WebSocket) -> bool:
    """
    Check if a FastAPI Websocket is still open
    """
    if (
        ws.application_state == WebSocketState.CONNECTED and
        ws.client_state == WebSocketState.CONNECTED
    ):
        return True
    return False


async def _process_consumer_request(
    request: Dict[str, Any],
    channel: WebSocketChannel,
    rpc: RPC
):
    """
    Validate and handle a request from a websocket consumer
    """
    # Validate the request, makes sure it matches the schema
    try:
        websocket_request = WSRequestSchema.parse_obj(request)
    except ValidationError as e:
        logger.error(f"Invalid request from {channel}: {e}")
        return

    type, data = websocket_request.type, websocket_request.data

    logger.debug(f"Request of type {type} from {channel}")

    # If we have a request of type SUBSCRIBE, set the topics in this channel
    if type == RPCRequestType.SUBSCRIBE:
        # If the request is empty, do nothing
        if not data:
            return

        # If all topics passed are a valid RPCMessageType, set subscriptions on channel
        if all([any(x.value == topic for x in RPCMessageType) for topic in data]):
            channel.set_subscriptions(data)

        # We don't send a response for subscriptions

    elif type == RPCRequestType.WHITELIST:
        # Get whitelist
        whitelist = rpc._ws_request_whitelist()

        # Format response
        response = WSWhitelistMessage(data=whitelist)
        # Send it back
        await channel.send(response.dict(exclude_none=True))

    elif type == RPCRequestType.ANALYZED_DF:
        limit = None

        if data:
            # Limit the amount of candles per dataframe to 'limit' or 1500
            limit = max(data.get('limit', 1500), 1500)

        # They requested the full historical analyzed dataframes
        analyzed_df = rpc._ws_request_analyzed_df(limit)

        # For every dataframe, send as a separate message
        for _, message in analyzed_df.items():
            response = WSAnalyzedDFMessage(data=message)
            await channel.send(response.dict(exclude_none=True))


@router.websocket("/message/ws")
async def message_endpoint(
    ws: WebSocket,
    rpc: RPC = Depends(get_rpc),
    channel_manager=Depends(get_channel_manager),
):
    """
    Message WebSocket endpoint, facilitates sending RPC messages
    """
    try:
        if is_websocket_alive(ws):
            # TODO:
            # Return a channel ID, pass that instead of ws to the rest of the methods
            channel = await channel_manager.on_connect(ws)

            logger.info(f"Consumer connected - {channel}")

            # Keep connection open until explicitly closed, and process requests
            try:
                while not channel.is_closed():
                    request = await channel.recv()

                    # Process the request here
                    await _process_consumer_request(request, channel, rpc)

            except WebSocketDisconnect:
                # Handle client disconnects
                logger.info(f"Consumer disconnected - {channel}")
                await channel_manager.on_disconnect(ws)
            except Exception as e:
                logger.info(f"Consumer connection failed - {channel}")
                logger.exception(e)
                # Handle cases like -
                # RuntimeError('Cannot call "send" once a closed message has been sent')
                await channel_manager.on_disconnect(ws)

    except Exception as e:
        logger.error(f"Failed to serve - {ws.client}")
        # Log tracebacks to keep track of what errors are happening
        logger.exception(e)
        await channel_manager.on_disconnect(ws)