#-----------------------------------------------------------------------------
# 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
Server.
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 (
CONNECTED_AFTER_ACK,
CONNECTED_BEFORE_ACK,
DISCONNECTED,
NOT_YET_CONNECTED,
WAITING_FOR_REPLY,
ErrorReason,
State,
)
from .websocket import WebSocketClientConnectionWrapper
if TYPE_CHECKING:
from ..document import Document
from ..document.events import DocumentChangedEvent
from ..protocol.message import Message
from ..protocol.messages.server_info_reply import ServerInfo
from .session import ClientSession
#-----------------------------------------------------------------------------
# Globals and constants
#-----------------------------------------------------------------------------
__all__ = (
'ClientConnection',
)
#-----------------------------------------------------------------------------
# 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:
log.info("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:
log.info("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 self._state.run(self)
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
log.info("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()
