#-----------------------------------------------------------------------------
# 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.
#-----------------------------------------------------------------------------
'''
'''
#-----------------------------------------------------------------------------
# Boilerplate
#-----------------------------------------------------------------------------
from __future__ import annotations
import logging # isort:skip
log = logging.getLogger(__name__)
#-----------------------------------------------------------------------------
# Imports
#-----------------------------------------------------------------------------
# Standard library imports
from functools import wraps
from typing import (
TYPE_CHECKING,
Any,
Callable,
TypeVar,
cast,
)
# External imports
from typing_extensions import Literal, Protocol
## Bokeh imports
if TYPE_CHECKING:
from ..server.callbacks import NextTickCallback
from .document import Callback, Document
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# Globals and constants
#-----------------------------------------------------------------------------
__all__ = (
'UnlockedDocumentProxy',
'without_document_lock',
)
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# General API
#-----------------------------------------------------------------------------
F = TypeVar("F", bound=Callable[..., Any])
class NoLockCallback(Protocol[F]):
__call__: F
nolock: Literal[True]
[docs]def without_document_lock(func: F) -> NoLockCallback[F]:
''' Wrap a callback function to execute without first obtaining the
document lock.
Args:
func (callable) : The function to wrap
Returns:
callable : a function wrapped to execute without a |Document| lock.
While inside an unlocked callback, it is completely *unsafe* to modify
``curdoc()``. The value of ``curdoc()`` inside the callback will be a
specially wrapped version of |Document| that only allows safe operations,
which are:
* :func:`~bokeh.document.Document.add_next_tick_callback`
* :func:`~bokeh.document.Document.remove_next_tick_callback`
Only these may be used safely without taking the document lock. To make
other changes to the document, you must add a next tick callback and make
your changes to ``curdoc()`` from that second callback.
Attempts to otherwise access or change the Document will result in an
exception being raised.
'''
@wraps(func)
def _wrapper(*args: Any, **kw: Any) -> None:
func(*args, **kw)
wrapper = cast(NoLockCallback[F], _wrapper)
wrapper.nolock = True
return wrapper
UNSAFE_DOC_ATTR_USAGE_MSG = (
"Only 'add_next_tick_callback' may be used safely without taking the document lock; "
"to make other changes to the document, add a next tick callback and make your changes "
"from that callback."
)
[docs]class UnlockedDocumentProxy:
''' Wrap a Document object so that only methods that can safely be used
from unlocked callbacks or threads are exposed. Attempts to otherwise
access or change the Document results in an exception.
'''
[docs] def __init__(self, doc: Document) -> None:
'''
'''
self._doc = doc
def __getattr__(self, attr: str) -> Any:
'''
'''
raise AttributeError(UNSAFE_DOC_ATTR_USAGE_MSG)
[docs] def add_next_tick_callback(self, callback: Callback) -> NextTickCallback:
''' Add a "next tick" callback.
Args:
callback (callable) :
'''
return self._doc.add_next_tick_callback(callback)
[docs] def remove_next_tick_callback(self, callback: NextTickCallback) -> None:
''' Remove a "next tick" callback.
Args:
callback (callable) :
'''
self._doc.remove_next_tick_callback(callback)
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# Dev API
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# Private API
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#-----------------------------------------------------------------------------
# Code
#-----------------------------------------------------------------------------