''' 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.
'''
from __future__ import absolute_import, print_function
import logging
log = logging.getLogger(__name__)
from tornado import gen
from tornado.httpclient import HTTPRequest
from tornado.ioloop import IOLoop
from tornado.websocket import websocket_connect, WebSocketError
from bokeh.protocol import Protocol
from bokeh.protocol.exceptions import MessageError, ProtocolError, ValidationError
from bokeh.protocol.receiver import Receiver
from .states import NOT_YET_CONNECTED, CONNECTED_BEFORE_ACK, CONNECTED_AFTER_ACK, DISCONNECTED, WAITING_FOR_REPLY
from .websocket import WebSocketClientConnectionWrapper
[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):
''' Opens a websocket connection to the server.
'''
self._url = websocket_url
self._session = session
self._protocol = Protocol("1.0")
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._protocol = Protocol("1.0")
self._server_info = None
@property
def url(self):
''' The URL of the websocket this Connection is to. '''
return self._url
@property
def io_loop(self):
''' The Tornado ``IOLoop`` this connection is using. '''
return self._loop
@property
def connected(self):
''' Whether we've connected the Websocket and have exchanged initial
handshake messages.
'''
return isinstance(self._state, CONNECTED_AFTER_ACK)
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 loop_until_closed(self):
''' Execute a blocking loop that runs and exectutes 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)
@gen.coroutine
def send_message(self, message):
if self._socket is None:
log.info("We're disconnected, so not sending message %r", message)
else:
try:
sent = yield 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.
raise gen.Return(None)
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.send_message(msg)
def _send_message_wait_for_reply(self, message):
waiter = WAITING_FOR_REPLY(message.header['msgid'])
self._state = waiter
send_result = []
def message_sent(future):
send_result.append(future)
self._loop.add_future(self.send_message(message), message_sent)
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
[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 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)
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
[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
[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()
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.add_callback(self._next)
self._loop.start()
except KeyboardInterrupt:
self.close("user interruption")
@gen.coroutine
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()
raise gen.Return(None)
else:
log.debug("Running state " + self._state.__class__.__name__)
yield self._state.run(self)
@gen.coroutine
def _transition(self, new_state):
log.debug("transitioning to state " + new_state.__class__.__name__)
self._state = new_state
yield self._next()
@gen.coroutine
def _transition_to_disconnected(self):
self._tell_session_about_disconnect()
yield self._transition(DISCONNECTED())
@gen.coroutine
def _connect_async(self):
versioned_url = "%s?bokeh-protocol-version=1.0&bokeh-session-id=%s" % (self._url, self._session.id)
request = HTTPRequest(versioned_url)
try:
socket = yield websocket_connect(request)
self._socket = WebSocketClientConnectionWrapper(socket)
except Exception as e:
log.info("Failed to connect to server: %r", e)
if self._socket is None:
yield self._transition_to_disconnected()
else:
yield self._transition(CONNECTED_BEFORE_ACK())
@gen.coroutine
def _wait_for_ack(self):
message = yield self._pop_message()
if message and message.msgtype == 'ACK':
log.debug("Received %r", message)
yield self._transition(CONNECTED_AFTER_ACK())
elif message is None:
yield self._transition_to_disconnected()
else:
raise ProtocolError("Received %r instead of ACK" % message)
@gen.coroutine
def _handle_messages(self):
message = yield self._pop_message()
if message is None:
yield 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.
yield self._next()
@gen.coroutine
def _pop_message(self):
while True:
if self._socket is None:
raise gen.Return(None)
# log.debug("Waiting for fragment...")
fragment = None
try:
fragment = yield 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")
raise gen.Return(None)
try:
message = yield self._receiver.consume(fragment)
if message is not None:
log.debug("Received message %r" % message)
raise gen.Return(message)
except (MessageError, ProtocolError, ValidationError) as e:
log.error("%r", e, exc_info=True)
self.close(why="error parsing message from server")
def _tell_session_about_disconnect(self):
if self._session:
self._session._notify_disconnected()
