97 lines
3.0 KiB
Python
97 lines
3.0 KiB
Python
from threading import Lock
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from typing import MutableMapping, Optional, TypeVar
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from weakref import WeakKeyDictionary
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from reactivex import abc, typing
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from reactivex.internal.constants import DELTA_ZERO
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from reactivex.internal.exceptions import WouldBlockException
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from .scheduler import Scheduler
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_TState = TypeVar("_TState")
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class ImmediateScheduler(Scheduler):
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"""Represents an object that schedules units of work to run immediately,
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on the current thread. You're not allowed to schedule timeouts using the
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ImmediateScheduler since that will block the current thread while waiting.
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Attempts to do so will raise a :class:`WouldBlockException`.
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"""
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_lock = Lock()
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_global: MutableMapping[type, "ImmediateScheduler"] = WeakKeyDictionary()
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@classmethod
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def singleton(cls) -> "ImmediateScheduler":
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with ImmediateScheduler._lock:
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try:
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self = ImmediateScheduler._global[cls]
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except KeyError:
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self = super().__new__(cls)
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ImmediateScheduler._global[cls] = self
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return self
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def __new__(cls) -> "ImmediateScheduler":
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return cls.singleton()
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def schedule(
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self, action: typing.ScheduledAction[_TState], state: Optional[_TState] = None
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) -> abc.DisposableBase:
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"""Schedules an action to be executed.
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Args:
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action: Action to be executed.
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state: [Optional] state to be given to the action function.
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Returns:
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The disposable object used to cancel the scheduled action
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(best effort).
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"""
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return self.invoke_action(action, state)
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def schedule_relative(
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self,
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duetime: typing.RelativeTime,
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action: typing.ScheduledAction[_TState],
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state: Optional[_TState] = None,
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) -> abc.DisposableBase:
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"""Schedules an action to be executed after duetime.
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Args:
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duetime: Relative time after which to execute the action.
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action: Action to be executed.
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state: [Optional] state to be given to the action function.
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Returns:
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The disposable object used to cancel the scheduled action
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(best effort).
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"""
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duetime = self.to_timedelta(duetime)
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if duetime > DELTA_ZERO:
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raise WouldBlockException()
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return self.invoke_action(action, state)
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def schedule_absolute(
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self,
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duetime: typing.AbsoluteTime,
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action: typing.ScheduledAction[_TState],
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state: Optional[_TState] = None,
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) -> abc.DisposableBase:
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"""Schedules an action to be executed at duetime.
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Args:
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duetime: Absolute time at which to execute the action.
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action: Action to be executed.
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state: [Optional] state to be given to the action function.
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Returns:
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The disposable object used to cancel the scheduled action
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(best effort).
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"""
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duetime = self.to_datetime(duetime)
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return self.schedule_relative(duetime - self.now, action, state)
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