54 lines
1.6 KiB
Python
54 lines
1.6 KiB
Python
from threading import RLock
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from typing import Optional
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from reactivex.abc import DisposableBase
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class SingleAssignmentDisposable(DisposableBase):
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"""Single assignment disposable.
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Represents a disposable resource which only allows a single
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assignment of its underlying disposable resource. If an underlying
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disposable resource has already been set, future attempts to set the
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underlying disposable resource will throw an Error."""
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def __init__(self) -> None:
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"""Initializes a new instance of the SingleAssignmentDisposable
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class.
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"""
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self.is_disposed: bool = False
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self.current: Optional[DisposableBase] = None
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self.lock = RLock()
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super().__init__()
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def get_disposable(self) -> Optional[DisposableBase]:
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return self.current
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def set_disposable(self, value: DisposableBase) -> None:
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if self.current:
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raise Exception("Disposable has already been assigned")
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with self.lock:
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should_dispose = self.is_disposed
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if not should_dispose:
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self.current = value
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if self.is_disposed and value:
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value.dispose()
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disposable = property(get_disposable, set_disposable)
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def dispose(self) -> None:
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"""Sets the status to disposed"""
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old: Optional[DisposableBase] = None
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with self.lock:
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if not self.is_disposed:
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self.is_disposed = True
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old = self.current
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self.current = None
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if old is not None:
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old.dispose()
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