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from threading import RLock
from typing import Optional
from reactivex.abc import DisposableBase
from .disposable import Disposable
class RefCountDisposable(DisposableBase):
"""Represents a disposable resource that only disposes its underlying
disposable resource when all dependent disposable objects have been
disposed."""
class InnerDisposable(DisposableBase):
def __init__(self, parent: "RefCountDisposable") -> None:
self.parent: Optional[RefCountDisposable] = parent
self.is_disposed = False
self.lock = RLock()
def dispose(self) -> None:
with self.lock:
parent = self.parent
self.parent = None
if parent is not None:
parent.release()
def __init__(self, disposable: DisposableBase) -> None:
"""Initializes a new instance of the RefCountDisposable class with the
specified disposable."""
self.underlying_disposable = disposable
self.is_primary_disposed = False
self.is_disposed = False
self.lock = RLock()
self.count = 0
super().__init__()
def dispose(self) -> None:
"""Disposes the underlying disposable only when all dependent
disposable have been disposed."""
if self.is_disposed:
return
underlying_disposable = None
with self.lock:
if not self.is_primary_disposed:
self.is_primary_disposed = True
if not self.count:
self.is_disposed = True
underlying_disposable = self.underlying_disposable
if underlying_disposable is not None:
underlying_disposable.dispose()
def release(self) -> None:
if self.is_disposed:
return
should_dispose = False
with self.lock:
self.count -= 1
if not self.count and self.is_primary_disposed:
self.is_disposed = True
should_dispose = True
if should_dispose:
self.underlying_disposable.dispose()
@property
def disposable(self) -> DisposableBase:
"""Returns a dependent disposable that when disposed decreases the
refcount on the underlying disposable."""
with self.lock:
if self.is_disposed:
return Disposable()
self.count += 1
return self.InnerDisposable(self)
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