#----------------------------------------------------------------------------- # Copyright (c) 2012 - 2020, 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 #----------------------------------------------------------------------------- import logging # isort:skip log = logging.getLogger(__name__) #----------------------------------------------------------------------------- # Imports #----------------------------------------------------------------------------- # External imports from tornado.httpclient import HTTPRequest from tornado.ioloop import IOLoop from tornado.websocket import WebSocketError, websocket_connect # Bokeh imports from ..protocol import Protocol from ..protocol.exceptions import MessageError, ProtocolError, ValidationError from ..protocol.receiver import Receiver from ..util.string import format_url_query_arguments from .states import ( CONNECTED_AFTER_ACK, CONNECTED_BEFORE_ACK, DISCONNECTED, NOT_YET_CONNECTED, WAITING_FOR_REPLY, ) from .websocket import WebSocketClientConnectionWrapper #----------------------------------------------------------------------------- # Globals and constants #----------------------------------------------------------------------------- __all__ = ( 'ClientConnection', ) #----------------------------------------------------------------------------- # General API #----------------------------------------------------------------------------- #----------------------------------------------------------------------------- # Dev API #----------------------------------------------------------------------------- [docs]class ClientConnection(object): ''' A Bokeh low-level class used to implement ``ClientSession``; use ``ClientSession`` to connect to the server. ''' [docs] def __init__(self, session, websocket_url, io_loop=None, arguments=None): ''' Opens a websocket connection to the server. ''' self._url = websocket_url self._session = session self._arguments = arguments self._protocol = Protocol() self._receiver = Receiver(self._protocol) self._socket = None self._state = NOT_YET_CONNECTED() if io_loop is None: # We can't use IOLoop.current because then we break # when running inside a notebook since ipython also uses it io_loop = IOLoop() self._loop = io_loop self._until_predicate = None self._server_info = None # Properties -------------------------------------------------------------- @property def connected(self): ''' Whether we've connected the Websocket and have exchanged initial handshake messages. ''' return isinstance(self._state, CONNECTED_AFTER_ACK) @property def io_loop(self): ''' The Tornado ``IOLoop`` this connection is using. ''' return self._loop @property def url(self): ''' The URL of the websocket this Connection is to. ''' return self._url # Internal methods -------------------------------------------------------- def connect(self): def connected_or_closed(): # 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) or isinstance(self._state, DISCONNECTED) self._loop_until(connected_or_closed) [docs] def close(self, why="closed"): ''' Close the Websocket connection. ''' if self._socket is not None: self._socket.close(1000, why) [docs] def force_roundtrip(self): ''' 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): ''' 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(): return isinstance(self._state, DISCONNECTED) self._loop_until(closed) [docs] def pull_doc(self, document): ''' 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): ''' 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): ''' 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): 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): 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]) self._socket = WebSocketClientConnectionWrapper(socket) except Exception as e: log.info("Failed to connect to server: %r", e) if self._socket is None: await self._transition_to_disconnected() else: await self._transition(CONNECTED_BEFORE_ACK()) async def _handle_messages(self): message = await self._pop_message() if message is None: await self._transition_to_disconnected() 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): 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.spawn_callback(self._next) self._loop.start() except KeyboardInterrupt: self.close("user interruption") async def _next(self): 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): 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): waiter = WAITING_FOR_REPLY(message.header['msgid']) self._state = waiter send_result = [] async def handle_message(message, send_result): result = await self.send_message(message) send_result.append(result) self._loop.spawn_callback(handle_message, message, send_result) def have_send_result_or_disconnected(): return len(send_result) > 0 or self._state != waiter self._loop_until(have_send_result_or_disconnected) def have_reply_or_disconnected(): 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, event): # XXX This will cause the client to always send all columns when a CDS # is mutated in place. Additionally we set use_buffers=False below as # well, to suppress using the binary array transport. Real Bokeh server # apps running inside a server can handle these updates much more # efficiently from bokeh.document.events import ColumnDataChangedEvent if hasattr(event, 'hint') and isinstance(event.hint, ColumnDataChangedEvent): event.hint.cols = None msg = self._protocol.create('PATCH-DOC', [event], use_buffers=False) self._loop.spawn_callback(self.send_message, msg) def _send_request_server_info(self): 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): if self._session: self._session._notify_disconnected() async def _transition(self, new_state): log.debug("transitioning to state " + new_state.__class__.__name__) self._state = new_state await self._next() async def _transition_to_disconnected(self): self._tell_session_about_disconnect() await self._transition(DISCONNECTED()) async def _wait_for_ack(self): message = await self._pop_message() if message and message.msgtype == 'ACK': log.debug("Received %r", message) await self._transition(CONNECTED_AFTER_ACK()) elif message is None: await self._transition_to_disconnected() else: raise ProtocolError("Received %r instead of ACK" % message) #----------------------------------------------------------------------------- # Private API #----------------------------------------------------------------------------- #----------------------------------------------------------------------------- # Code #-----------------------------------------------------------------------------