Source code for bokeh.client.connection

# Copyright (c) 2012 - 2024, Anaconda, Inc., and Bokeh Contributors.
# All rights reserved.
# The full license is in the file LICENSE.txt, distributed with this software.
''' Implements a very low level facility for communicating with a Bokeh

Users will always want to use :class:`~bokeh.client.session.ClientSession`
instead for standard usage.


# Boilerplate
from __future__ import annotations

import logging # isort:skip
log = logging.getLogger(__name__)

# Imports

# Standard library imports
from typing import TYPE_CHECKING, Any, Callable

# External imports
from tornado.httpclient import HTTPClientError, HTTPRequest
from tornado.ioloop import IOLoop
from tornado.websocket import WebSocketError, websocket_connect

# Bokeh imports
from ..core.types import ID
from ..protocol import Protocol
from ..protocol.exceptions import MessageError, ProtocolError, ValidationError
from ..protocol.receiver import Receiver
from ..util.strings import format_url_query_arguments
from ..util.tornado import fixup_windows_event_loop_policy
from .states import (
from .websocket import WebSocketClientConnectionWrapper

    from ..document import Document
    from import DocumentChangedEvent
    from ..protocol.message import Message
    from ..protocol.messages.server_info_reply import ServerInfo
    from .session import ClientSession

# Globals and constants

__all__ = (

# General API

# Dev API

[docs] class ClientConnection: ''' A low-level class used to connect to a Bokeh server. ''' _state: State _loop: IOLoop _until_predicate: Callable[[], bool] | None
[docs] def __init__(self, session: ClientSession, websocket_url: str, io_loop: IOLoop | None = None, arguments: dict[str, str] | None = None, max_message_size: int = 20*1024*1024) -> None: ''' Opens a websocket connection to the server. ''' self._url = websocket_url self._session = session self._arguments = arguments self._max_message_size = max_message_size self._protocol = Protocol() self._receiver = Receiver(self._protocol) self._socket = None self._state = NOT_YET_CONNECTED() # We can't use IOLoop.current because then we break # when running inside a notebook since ipython also uses it self._loop = io_loop if io_loop is not None else IOLoop() self._until_predicate = None self._server_info = None
# Properties -------------------------------------------------------------- @property def connected(self) -> bool: ''' Whether we've connected the Websocket and have exchanged initial handshake messages. ''' return isinstance(self._state, CONNECTED_AFTER_ACK) @property def io_loop(self) -> IOLoop: ''' The Tornado ``IOLoop`` this connection is using. ''' return self._loop @property def url(self) -> str: ''' The URL of the websocket this Connection is to. ''' return self._url @property def error_reason(self) -> ErrorReason | None: ''' The reason of the connection loss encoded as a ``DISCONNECTED.ErrorReason`` enum value ''' if not isinstance(self._state, DISCONNECTED): return None return self._state.error_reason @property def error_code(self) -> int | None: ''' If there was an error that caused a disconnect, this property holds the error code. None otherwise. ''' if not isinstance(self._state, DISCONNECTED): return 0 return self._state.error_code @property def error_detail(self) -> str: ''' If there was an error that caused a disconnect, this property holds the error detail. Empty string otherwise. ''' if not isinstance(self._state, DISCONNECTED): return "" return self._state.error_detail # Internal methods -------------------------------------------------------- def connect(self) -> None: def connected_or_closed() -> bool: # we should be looking at the same state here as the 'connected' property above, so connected # means both connected and that we did our initial message exchange return isinstance(self._state, (CONNECTED_AFTER_ACK, DISCONNECTED)) self._loop_until(connected_or_closed)
[docs] def close(self, why: str = "closed") -> None: ''' Close the Websocket connection. ''' if self._socket is not None: self._socket.close(1000, why)
[docs] def force_roundtrip(self) -> None: ''' Force a round-trip request/reply to the server, sometimes needed to avoid race conditions. Mostly useful for testing. Outside of test suites, this method hurts performance and should not be needed. Returns: None ''' self._send_request_server_info()
[docs] def loop_until_closed(self) -> None: ''' Execute a blocking loop that runs and executes event callbacks until the connection is closed (e.g. by hitting Ctrl-C). While this method can be used to run Bokeh application code "outside" the Bokeh server, this practice is HIGHLY DISCOURAGED for any real use case. ''' if isinstance(self._state, NOT_YET_CONNECTED): # we don't use self._transition_to_disconnected here # because _transition is a coroutine self._tell_session_about_disconnect() self._state = DISCONNECTED() else: def closed() -> bool: return isinstance(self._state, DISCONNECTED) self._loop_until(closed)
[docs] def pull_doc(self, document: Document) -> None: ''' Pull a document from the server, overwriting the passed-in document Args: document : (Document) The document to overwrite with server content. Returns: None ''' msg = self._protocol.create('PULL-DOC-REQ') reply = self._send_message_wait_for_reply(msg) if reply is None: raise RuntimeError("Connection to server was lost") elif reply.header['msgtype'] == 'ERROR': raise RuntimeError("Failed to pull document: " + reply.content['text']) else: reply.push_to_document(document)
[docs] def push_doc(self, document: Document) -> Message[Any]: ''' Push a document to the server, overwriting any existing server-side doc. Args: document : (Document) A Document to push to the server Returns: The server reply ''' msg = self._protocol.create('PUSH-DOC', document) reply = self._send_message_wait_for_reply(msg) if reply is None: raise RuntimeError("Connection to server was lost") elif reply.header['msgtype'] == 'ERROR': raise RuntimeError("Failed to push document: " + reply.content['text']) else: return reply
[docs] def request_server_info(self) -> ServerInfo: ''' Ask for information about the server. Returns: A dictionary of server attributes. ''' if self._server_info is None: self._server_info = self._send_request_server_info() return self._server_info
async def send_message(self, message: Message[Any]) -> None: if self._socket is None:"We're disconnected, so not sending message %r", message) else: try: sent = await message.send(self._socket) log.debug("Sent %r [%d bytes]", message, sent) except WebSocketError as e: # A thing that happens is that we detect the # socket closing by getting a None from # read_message, but the network socket can be down # with many messages still in the read buffer, so # we'll process all those incoming messages and # get write errors trying to send change # notifications during that processing. # this is just debug level because it's completely normal # for it to happen when the socket shuts down. log.debug("Error sending message to server: %r", e) # error is almost certainly because # socket is already closed, but be sure, # because once we fail to send a message # we can't recover self.close(why="received error while sending") # don't re-throw the error - there's nothing to # do about it. return None # Private methods --------------------------------------------------------- async def _connect_async(self) -> None: formatted_url = format_url_query_arguments(self._url, self._arguments) request = HTTPRequest(formatted_url) try: socket = await websocket_connect(request, subprotocols=["bokeh", self._session.token], max_message_size=self._max_message_size) self._socket = WebSocketClientConnectionWrapper(socket) except HTTPClientError as e: await self._transition_to_disconnected(DISCONNECTED(ErrorReason.HTTP_ERROR, e.code, e.message)) return except Exception as e:"Failed to connect to server: %r", e) if self._socket is None: await self._transition_to_disconnected(DISCONNECTED(ErrorReason.NETWORK_ERROR, None, "Socket invalid.")) else: await self._transition(CONNECTED_BEFORE_ACK()) async def _handle_messages(self) -> None: message = await self._pop_message() if message is None: await self._transition_to_disconnected(DISCONNECTED(ErrorReason.HTTP_ERROR, 500, "Internal server error.")) else: if message.msgtype == 'PATCH-DOC': log.debug("Got PATCH-DOC, applying to session") self._session._handle_patch(message) else: log.debug("Ignoring %r", message) # we don't know about whatever message we got, ignore it. await self._next() def _loop_until(self, predicate: Callable[[], bool]) -> None: self._until_predicate = predicate try: # this runs self._next ONE time, but # self._next re-runs itself until # the predicate says to quit. self._loop.add_callback(self._next) self._loop.start() except KeyboardInterrupt: self.close("user interruption") async def _next(self) -> None: if self._until_predicate is not None and self._until_predicate(): log.debug("Stopping client loop in state %s due to True from %s", self._state.__class__.__name__, self._until_predicate.__name__) self._until_predicate = None self._loop.stop() return None else: log.debug("Running state " + self._state.__class__.__name__) await async def _pop_message(self) -> Message[Any] | None: while True: if self._socket is None: return None # log.debug("Waiting for fragment...") fragment = None try: fragment = await self._socket.read_message() except Exception as e: # this happens on close, so debug level since it's "normal" log.debug("Error reading from socket %r", e) # log.debug("... got fragment %r", fragment) if fragment is None: # XXX Tornado doesn't give us the code and reason"Connection closed by server") return None try: message = await self._receiver.consume(fragment) if message is not None: log.debug("Received message %r" % message) return message except (MessageError, ProtocolError, ValidationError) as e: log.error("%r", e, exc_info=True) self.close(why="error parsing message from server") def _send_message_wait_for_reply(self, message: Message[Any]) -> Message[Any] | None: waiter = WAITING_FOR_REPLY(message.header['msgid']) self._state = waiter send_result: list[None] = [] async def handle_message(message: Message[Any], send_result: list[None]) -> None: result = await self.send_message(message) send_result.append(result) self._loop.add_callback(handle_message, message, send_result) def have_send_result_or_disconnected() -> bool: return len(send_result) > 0 or self._state != waiter self._loop_until(have_send_result_or_disconnected) def have_reply_or_disconnected() -> bool: return self._state != waiter or waiter.reply is not None self._loop_until(have_reply_or_disconnected) return waiter.reply def _send_patch_document(self, session_id: ID, event: DocumentChangedEvent) -> None: msg = self._protocol.create('PATCH-DOC', [event]) self._loop.add_callback(self.send_message, msg) def _send_request_server_info(self) -> ServerInfo: msg = self._protocol.create('SERVER-INFO-REQ') reply = self._send_message_wait_for_reply(msg) if reply is None: raise RuntimeError("Did not get a reply to server info request before disconnect") return reply.content def _tell_session_about_disconnect(self) -> None: if self._session: self._session._notify_disconnected() async def _transition(self, new_state: State) -> None: log.debug(f"transitioning to state {new_state.__class__.__name__}") self._state = new_state await self._next() async def _transition_to_disconnected(self, dis_state: DISCONNECTED) -> None: self._tell_session_about_disconnect() await self._transition(dis_state) async def _wait_for_ack(self) -> None: message = await self._pop_message() if message and message.msgtype == 'ACK': log.debug(f"Received {message!r}") await self._transition(CONNECTED_AFTER_ACK()) elif message is None: await self._transition_to_disconnected(DISCONNECTED(ErrorReason.HTTP_ERROR, 500, "Internal server error.")) else: raise ProtocolError(f"Received {message!r} instead of ACK")
#----------------------------------------------------------------------------- # Private API #----------------------------------------------------------------------------- #----------------------------------------------------------------------------- # Code #----------------------------------------------------------------------------- fixup_windows_event_loop_policy()