#----------------------------------------------------------------------------- # 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. #----------------------------------------------------------------------------- ''' Provide a base class for all Bokeh Server Protocol message types. Boker messages are comprised of a sequence of JSON fragments. Specified as Python JSON-like data, messages have the general form: .. code-block:: python [ # these are required b'{header}', # serialized header dict b'{metadata}', # serialized metadata dict b'{content}, # serialized content dict # these are optional, and come in pairs; header contains num_buffers b'{buf_header}', # serialized buffer header dict b'array' # raw buffer payload data ... ] The ``header`` fragment will have the form: .. code-block:: python header = { # these are required 'msgid' : <str> # a unique id for the message 'msgtype' : <str> # a message type, e.g. 'ACK', 'PATCH-DOC', etc # these are optional 'num_buffers' : <int> # the number of additional buffers, if any } The ``metadata`` fragment may contain any arbitrary information. It is not processed by Bokeh for any purpose, but may be useful for external monitoring or instrumentation tools. The ``content`` fragment is defined by the specific message type. ''' #----------------------------------------------------------------------------- # Boilerplate #----------------------------------------------------------------------------- import logging # isort:skip log = logging.getLogger(__name__) #----------------------------------------------------------------------------- # Imports #----------------------------------------------------------------------------- # External imports from tornado.escape import json_decode, json_encode # Bokeh imports import bokeh.util.serialization as bkserial # Bokeh imports from .exceptions import MessageError, ProtocolError #----------------------------------------------------------------------------- # Globals and constants #----------------------------------------------------------------------------- __all__ = ( 'Message', ) #----------------------------------------------------------------------------- # General API #----------------------------------------------------------------------------- #----------------------------------------------------------------------------- # Dev API #----------------------------------------------------------------------------- [docs]class Message: ''' The Message base class encapsulates creating, assembling, and validating the integrity of Bokeh Server messages. Additionally, it provide hooks ''' [docs] def __init__(self, header, metadata, content): ''' Initialize a new message from header, metadata, and content dictionaries. To assemble a message from existing JSON fragments, use the ``assemble`` method. To create new messages with automatically generated headers, use subclass ``create`` methods. Args: header (JSON-like) : metadata (JSON-like) : content (JSON-like) : ''' self.header = header self.metadata = metadata self.content = content self._buffers = [] def __repr__(self): return "Message %r content: %r" % (self.msgtype, self.content) [docs] @classmethod def assemble(cls, header_json, metadata_json, content_json): ''' Creates a new message, assembled from JSON fragments. Args: header_json (``JSON``) : metadata_json (``JSON``) : content_json (``JSON``) : Returns: Message subclass Raises: MessageError ''' try: header = json_decode(header_json) except ValueError: raise MessageError("header could not be decoded") try: metadata = json_decode(metadata_json) except ValueError: raise MessageError("metadata could not be decoded") try: content = json_decode(content_json) except ValueError: raise MessageError("content could not be decoded") msg = cls(header, metadata, content) msg._header_json = header_json msg._metadata_json = metadata_json msg._content_json = content_json return msg [docs] def add_buffer(self, buf_header, buf_payload): ''' Associate a buffer header and payload with this message. Args: buf_header (``JSON``) : a buffer header buf_payload (``JSON`` or bytes) : a buffer payload Returns: None Raises: MessageError ''' if 'num_buffers' in self._header: self._header['num_buffers'] += 1 else: self._header['num_buffers'] = 1 self._header_json = None self._buffers.append((buf_header, buf_payload)) [docs] def assemble_buffer(self, buf_header, buf_payload): ''' Add a buffer header and payload that we read from the socket. This differs from add_buffer() because we're validating vs. the header's num_buffers, instead of filling in the header. Args: buf_header (``JSON``) : a buffer header buf_payload (``JSON`` or bytes) : a buffer payload Returns: None Raises: ProtocolError ''' if self.header.get('num_buffers', 0) <= len(self._buffers): raise ProtocolError("too many buffers received expecting " + str(self.header['num_buffers'])) self._buffers.append((buf_header, buf_payload)) [docs] async def write_buffers(self, conn, locked=True): ''' Write any buffer headers and payloads to the given connection. Args: conn (object) : May be any object with a ``write_message`` method. Typically, a Tornado ``WSHandler`` or ``WebSocketClientConnection`` locked (bool) : Returns: int : number of bytes sent ''' if conn is None: raise ValueError("Cannot write_buffers to connection None") sent = 0 for header, payload in self._buffers: await conn.write_message(header, locked=locked) await conn.write_message(payload, binary=True, locked=locked) sent += (len(header) + len(payload)) return sent [docs] @classmethod def create_header(cls, request_id=None): ''' Return a message header fragment dict. Args: request_id (str or None) : Message ID of the message this message replies to Returns: dict : a message header ''' header = { 'msgid' : bkserial.make_id(), 'msgtype' : cls.msgtype } if request_id is not None: header['reqid'] = request_id return header [docs] async def send(self, conn): ''' Send the message on the given connection. Args: conn (WebSocketHandler) : a WebSocketHandler to send messages Returns: int : number of bytes sent ''' if conn is None: raise ValueError("Cannot send to connection None") with await conn.write_lock.acquire(): sent = 0 await conn.write_message(self.header_json, locked=False) sent += len(self.header_json) # uncomment this to make it a lot easier to reproduce lock-related bugs #await asyncio.sleep(0.1) await conn.write_message(self.metadata_json, locked=False) sent += len(self.metadata_json) # uncomment this to make it a lot easier to reproduce lock-related bugs #await asyncio.sleep(0.1) await conn.write_message(self.content_json, locked=False) sent += len(self.content_json) sent += await self.write_buffers(conn, locked=False) return sent @property def complete(self): ''' Returns whether all required parts of a message are present. Returns: bool : True if the message is complete, False otherwise ''' return self.header is not None and \ self.metadata is not None and \ self.content is not None and \ self.header.get('num_buffers', 0) == len(self._buffers) # header fragment properties @property def header(self): return self._header @header.setter def header(self, value): self._header = value self._header_json = None @property def header_json(self): if not self._header_json: self._header_json = json_encode(self.header) return self._header_json # content fragment properties @property def content(self): return self._content @content.setter def content(self, value): self._content = value self._content_json = None @property def content_json(self): if not self._content_json: self._content_json = json_encode(self.content) return self._content_json # metadata fragment properties @property def metadata(self): return self._metadata @metadata.setter def metadata(self, value): self._metadata = value self._metadata_json = None @property def metadata_json(self): if not self._metadata_json: self._metadata_json = json_encode(self.metadata) return self._metadata_json # buffer properties @property def buffers(self): return self._buffers #----------------------------------------------------------------------------- # Private API #----------------------------------------------------------------------------- #----------------------------------------------------------------------------- # Code #-----------------------------------------------------------------------------