101 lines
3.2 KiB
Python
101 lines
3.2 KiB
Python
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import sys
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import time
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from asyncio import AbstractEventLoop, get_event_loop
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from types import TracebackType
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from typing import Any, Awaitable, Callable, Dict, Optional, TypeVar
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try:
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import contextvars
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except ImportError:
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from . import dummy_contextvars as contextvars # type: ignore
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__all__ = [
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"run_in_executor_with_context",
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"call_soon_threadsafe",
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"get_traceback_from_context",
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]
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_T = TypeVar("_T")
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def run_in_executor_with_context(
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func: Callable[..., _T], *args: Any, loop: Optional[AbstractEventLoop] = None
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) -> Awaitable[_T]:
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"""
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Run a function in an executor, but make sure it uses the same contextvars.
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This is required so that the function will see the right application.
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See also: https://bugs.python.org/issue34014
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"""
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loop = loop or get_event_loop()
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ctx: contextvars.Context = contextvars.copy_context()
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return loop.run_in_executor(None, ctx.run, func, *args)
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def call_soon_threadsafe(
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func: Callable[[], None],
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max_postpone_time: Optional[float] = None,
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loop: Optional[AbstractEventLoop] = None,
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) -> None:
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"""
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Wrapper around asyncio's `call_soon_threadsafe`.
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This takes a `max_postpone_time` which can be used to tune the urgency of
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the method.
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Asyncio runs tasks in first-in-first-out. However, this is not what we
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want for the render function of the prompt_toolkit UI. Rendering is
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expensive, but since the UI is invalidated very often, in some situations
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we render the UI too often, so much that the rendering CPU usage slows down
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the rest of the processing of the application. (Pymux is an example where
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we have to balance the CPU time spend on rendering the UI, and parsing
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process output.)
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However, we want to set a deadline value, for when the rendering should
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happen. (The UI should stay responsive).
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"""
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loop2 = loop or get_event_loop()
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# If no `max_postpone_time` has been given, schedule right now.
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if max_postpone_time is None:
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loop2.call_soon_threadsafe(func)
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return
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max_postpone_until = time.time() + max_postpone_time
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def schedule() -> None:
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# When there are no other tasks scheduled in the event loop. Run it
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# now.
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# Notice: uvloop doesn't have this _ready attribute. In that case,
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# always call immediately.
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if not getattr(loop2, "_ready", []): # type: ignore
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func()
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return
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# If the timeout expired, run this now.
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if time.time() > max_postpone_until:
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func()
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return
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# Schedule again for later.
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loop2.call_soon_threadsafe(schedule)
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loop2.call_soon_threadsafe(schedule)
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def get_traceback_from_context(context: Dict[str, Any]) -> Optional[TracebackType]:
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"""
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Get the traceback object from the context.
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"""
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exception = context.get("exception")
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if exception:
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if hasattr(exception, "__traceback__"):
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return exception.__traceback__
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else:
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# call_exception_handler() is usually called indirectly
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# from an except block. If it's not the case, the traceback
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# is undefined...
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return sys.exc_info()[2]
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return None
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