stable/freqtrade/rpc/api_server/api_ws.py

import logging
from typing import Any, Dict

from fastapi import APIRouter, Depends, WebSocketDisconnect
from fastapi.websockets import WebSocket, WebSocketState
from pydantic import ValidationError
from websockets.exceptions import WebSocketException

from freqtrade.enums import RPCMessageType, RPCRequestType
from freqtrade.rpc.api_server.api_auth import validate_ws_token
from freqtrade.rpc.api_server.deps import get_channel_manager, get_rpc
from freqtrade.rpc.api_server.ws import WebSocketChannel
from freqtrade.rpc.api_server.ws.channel import ChannelManager
from freqtrade.rpc.api_server.ws_schemas import (WSAnalyzedDFMessage, WSMessageSchema,
                                                 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,
    channel_manager: ChannelManager
):
    """
    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
    response: WSMessageSchema

    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
        return

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

        # Format response
        response = WSWhitelistMessage(data=whitelist)
        # Send it back
        await channel_manager.send_direct(channel, 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)

        # For every pair in the generator, send a separate message
        for message in rpc._ws_request_analyzed_df(limit):
            response = WSAnalyzedDFMessage(data=message)
            await channel_manager.send_direct(channel, 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),
    token: str = Depends(validate_ws_token)
):
    """
    Message WebSocket endpoint, facilitates sending RPC messages
    """
    try:
        channel = await channel_manager.on_connect(ws)
        if await is_websocket_alive(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, channel_manager)

            except (WebSocketDisconnect, WebSocketException):
                # Handle client disconnects
                logger.info(f"Consumer disconnected - {channel}")
            except RuntimeError:
                # Handle cases like -
                # RuntimeError('Cannot call "send" once a closed message has been sent')
                pass
            except Exception as e:
                logger.info(f"Consumer connection failed - {channel}: {e}")
                logger.debug(e, exc_info=e)

    except RuntimeError:
        # WebSocket was closed
        # Do nothing
        pass
    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)
    finally:
        if channel:
            await channel_manager.on_disconnect(ws)