firestar5683
58 lines
1.8 KiB
Python
58 lines
1.8 KiB
Python
from datetime import datetime
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from typing import Callable, Optional, TypeVar
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from reactivex import Observable, abc, typing
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from reactivex.scheduler import TimeoutScheduler
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_T = TypeVar("_T")
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def throttle_first_(
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window_duration: typing.RelativeTime, scheduler: Optional[abc.SchedulerBase] = None
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) -> Callable[[Observable[_T]], Observable[_T]]:
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def throttle_first(source: Observable[_T]) -> Observable[_T]:
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"""Returns an observable that emits only the first item emitted
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by the source Observable during sequential time windows of a
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specified duration.
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Args:
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source: Source observable to throttle.
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Returns:
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An Observable that performs the throttle operation.
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"""
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def subscribe(
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observer: abc.ObserverBase[_T],
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scheduler_: Optional[abc.SchedulerBase] = None,
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) -> abc.DisposableBase:
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_scheduler = scheduler or scheduler_ or TimeoutScheduler.singleton()
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duration = _scheduler.to_timedelta(window_duration or 0.0)
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if duration <= _scheduler.to_timedelta(0):
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raise ValueError("window_duration cannot be less or equal zero.")
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last_on_next: Optional[datetime] = None
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def on_next(x: _T) -> None:
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nonlocal last_on_next
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emit = False
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now = _scheduler.now
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with source.lock:
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if not last_on_next or now - last_on_next >= duration:
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last_on_next = now
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emit = True
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if emit:
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observer.on_next(x)
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return source.subscribe(
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on_next, observer.on_error, observer.on_completed, scheduler=_scheduler
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)
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return Observable(subscribe)
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return throttle_first
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__all__ = ["throttle_first_"]
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