SinkDisposer
包装了两个disposable：_sink, _disposable
维持和管理状态：disposed、sinkAndSubscriptionSet
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private final class SinkDisposer: Cancelable {
private enum DisposeState: Int32 {
case disposed = 1
case sinkAndSubscriptionSet = 2
}
private let _state = AtomicInt(0)
private var _sink: Disposable?
private var _subscription: Disposable?
var isDisposed: Bool {
return isFlagSet(self._state, DisposeState.disposed.rawValue)
}
// set sink and subscription
func setSinkAndSubscription(sink: Disposable, subscription: Disposable) {
self._sink = sink
self._subscription = subscription
// 设置状态
let previousState = fetchOr(self._state, DisposeState.sinkAndSubscriptionSet.rawValue)
if (previousState & DisposeState.sinkAndSubscriptionSet.rawValue) != 0 {
rxFatalError("Sink and subscription were already set")
}
// 如果状态已经disposed, 那么新设置的两个disposable马上会dispose
if (previousState & DisposeState.disposed.rawValue) != 0 {
// dispose 并 置空
sink.dispose()
subscription.dispose()
self._sink = nil
self._subscription = nil
}
}
func dispose() {
// 设置状态
let previousState = fetchOr(self._state, DisposeState.disposed.rawValue)
if (previousState & DisposeState.disposed.rawValue) != 0 {
return
}
// dispose: _sink and _subscription
if (previousState & DisposeState.sinkAndSubscriptionSet.rawValue) != 0 {
guard let sink = self._sink else {
rxFatalError("Sink not set")
}
guard let subscription = self._subscription else {
rxFatalError("Subscription not set")
}
// dispose 并 置空
sink.dispose()
subscription.dispose()
self._sink = nil
self._subscription = nil
}
}
}
注：文中源码来自RxSwift