82 lines
2.1 KiB
Python
82 lines
2.1 KiB
Python
import threading
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from typing import Any, List, TypeVar
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from reactivex import abc, typing
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from reactivex.disposable import SerialDisposable
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from .observer import Observer
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_T_in = TypeVar("_T_in", contravariant=True)
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class ScheduledObserver(Observer[_T_in]):
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def __init__(
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self, scheduler: abc.SchedulerBase, observer: abc.ObserverBase[_T_in]
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) -> None:
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super().__init__()
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self.scheduler = scheduler
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self.observer = observer
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self.lock = threading.RLock()
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self.is_acquired = False
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self.has_faulted = False
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self.queue: List[typing.Action] = []
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self.disposable = SerialDisposable()
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# Note to self: list append is thread safe
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# http://effbot.org/pyfaq/what-kinds-of-global-value-mutation-are-thread-safe.htm
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def _on_next_core(self, value: Any) -> None:
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def action() -> None:
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self.observer.on_next(value)
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self.queue.append(action)
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def _on_error_core(self, error: Exception) -> None:
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def action() -> None:
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self.observer.on_error(error)
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self.queue.append(action)
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def _on_completed_core(self) -> None:
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def action() -> None:
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self.observer.on_completed()
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self.queue.append(action)
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def ensure_active(self) -> None:
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is_owner = False
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with self.lock:
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if not self.has_faulted and self.queue:
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is_owner = not self.is_acquired
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self.is_acquired = True
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if is_owner:
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self.disposable.disposable = self.scheduler.schedule(self.run)
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def run(self, scheduler: abc.SchedulerBase, state: Any) -> None:
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parent = self
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with self.lock:
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if parent.queue:
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work = parent.queue.pop(0)
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else:
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parent.is_acquired = False
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return
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try:
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work()
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except Exception:
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with self.lock:
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parent.queue = []
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parent.has_faulted = True
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raise
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self.scheduler.schedule(self.run)
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def dispose(self) -> None:
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super().dispose()
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self.disposable.dispose()
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