Class WebSocketProtocol

gunicorn/asgi/websocket.py:42–437

WebSocket connection handler for ASGI applications. Uses callback-based data feeding instead of StreamReader for efficiency. Data is fed via feed_data() from the parent protocol's data_received().

class WebSocketProtocol:
    """WebSocket connection handler for ASGI applications.

    Uses callback-based data feeding instead of StreamReader for efficiency.
    Data is fed via feed_data() from the parent protocol's data_received().
    """

    def __init__(self, transport, scope, app, log):
        """Initialize WebSocket protocol handler.

        Args:
            transport: asyncio transport for writing
            scope: ASGI WebSocket scope dict
            app: ASGI application callable
            log: Logger instance
        """
        self.transport = transport
        self.scope = scope
        self.app = app
        self.log = log

        self.accepted = False
        self.closed = False
        self.close_code = None
        self.close_reason = ""

        # Close handshake state (RFC 6455 Section 7.1.1)
        self._close_sent = False
        self._close_received = False
        self._close_event = asyncio.Event()

        # Message reassembly state
        self._fragments = []
        self._fragment_opcode = None

        # Receive queue for incoming messages
        self._receive_queue = asyncio.Queue()

        # Callback-based data reception (replaces StreamReader)
        self._buffer = bytearray()
        self._data_event = asyncio.Event()
        self._eof = False

    def feed_data(self, data):
        """Feed incoming data from the parent protocol's data_received().

        Args:
            data: bytes received on the connection
        """
        if data:
            self._buffer.extend(data)
            self._data_event.set()

    def feed_eof(self):
        """Signal that the connection has been closed."""
        self._eof = True
        self._data_event.set()