Source code for bokeh.server.callbacks

#-----------------------------------------------------------------------------
# Copyright (c) 2012 - 2021, Anaconda, Inc., and Bokeh Contributors.
# All rights reserved.
#
# The full license is in the file LICENSE.txt, distributed with this software.
#-----------------------------------------------------------------------------
''' Provide classes to represent callback code that can be associate with
Bokeh Documents and Sessions.

'''

#-----------------------------------------------------------------------------
# Boilerplate
#-----------------------------------------------------------------------------
from __future__ import annotations

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

#-----------------------------------------------------------------------------
# Imports
#-----------------------------------------------------------------------------

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

# Bokeh imports
from ..core.types import ID
from ..util.tornado import _CallbackGroup

if TYPE_CHECKING:
    from tornado.ioloop import IOLoop

#-----------------------------------------------------------------------------
# Globals and constants
#-----------------------------------------------------------------------------

__all__ = (
    'NextTickCallback',
    'PeriodicCallback',
    'SessionCallback',
    'TimeoutCallback',
)

#-----------------------------------------------------------------------------
# Dev API
#-----------------------------------------------------------------------------

Callback = Callable[[], None]

[docs]class SessionCallback: ''' A base class for callback objects associated with Bokeh Documents and Sessions. ''' _id: ID
[docs] def __init__(self, callback: Callback, *, callback_id: ID) -> None: ''' Args: callback (callable) : id (ID) : ''' self._id = callback_id # specify type here until this is released: https://github.com/python/mypy/pull/10548 self._callback: Callback = callback
@property def id(self) -> ID: ''' A unique ID for this callback ''' return self._id @property def callback(self) -> Callback: ''' The callable that this callback wraps. ''' return self._callback
#----------------------------------------------------------------------------- # General API #-----------------------------------------------------------------------------
[docs]class NextTickCallback(SessionCallback): ''' Represent a callback to execute on the next ``IOLoop`` "tick". '''
[docs] def __init__(self, callback: Callback, *, callback_id: ID) -> None: ''' Args: callback (callable) : id (ID) : ''' super().__init__(callback=callback, callback_id=callback_id)
[docs]class PeriodicCallback(SessionCallback): ''' Represent a callback to execute periodically on the ``IOLoop`` at a specified periodic time interval. ''' _period: int
[docs] def __init__(self, callback: Callback, period: int, *, callback_id: ID) -> None: ''' Args: callback (callable) : period (int) : id (ID) : ''' super().__init__(callback=callback, callback_id=callback_id) self._period = period
@property def period(self) -> int: ''' The period time (in milliseconds) that this callback should repeat execution at. ''' return self._period
[docs]class TimeoutCallback(SessionCallback): ''' Represent a callback to execute once on the ``IOLoop`` after a specified time interval passes. ''' _timeout: int
[docs] def __init__(self, callback: Callback, timeout: int, *, callback_id: ID) -> None: ''' Args: callback (callable) : timeout (int) : id (ID) : ''' super().__init__(callback=callback, callback_id=callback_id) self._timeout = timeout
@property def timeout(self) -> int: ''' The timeout (in milliseconds) that the callback should run after. ''' return self._timeout
#----------------------------------------------------------------------------- # Dev API #----------------------------------------------------------------------------- class DocumentCallbackGroup: ''' ''' def __init__(self, io_loop: IOLoop) -> None: ''' ''' self._group = _CallbackGroup(io_loop) def remove_all_callbacks(self) -> None: ''' ''' self._group.remove_all_callbacks() def add_session_callbacks(self, callbacks: Sequence[SessionCallback]) -> None: ''' ''' for cb in callbacks: self.add_session_callback(cb) def add_session_callback(self, callback_obj: SessionCallback) -> None: ''' ''' if isinstance(callback_obj, PeriodicCallback): self._group.add_periodic_callback(callback_obj.callback, callback_obj.period, callback_obj.id) elif isinstance(callback_obj, TimeoutCallback): self._group.add_timeout_callback(callback_obj.callback, callback_obj.timeout, callback_obj.id) elif isinstance(callback_obj, NextTickCallback): self._group.add_next_tick_callback(callback_obj.callback, callback_obj.id) else: raise ValueError(f"Expected callback of type PeriodicCallback, TimeoutCallback, NextTickCallback, got: {callback_obj.callback}") def remove_session_callback(self, callback_obj: SessionCallback) -> None: ''' ''' # we may be called multiple times because of multiple # views on a document - the document has to notify that # the callback was removed even if only one view invoked # it. So we need to silently no-op if we're already # removed. try: if isinstance(callback_obj, PeriodicCallback): self._group.remove_periodic_callback(callback_obj.id) elif isinstance(callback_obj, TimeoutCallback): self._group.remove_timeout_callback(callback_obj.id) elif isinstance(callback_obj, NextTickCallback): self._group.remove_next_tick_callback(callback_obj.id) except ValueError: pass #----------------------------------------------------------------------------- # Private API #----------------------------------------------------------------------------- #----------------------------------------------------------------------------- # Code #-----------------------------------------------------------------------------