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PublishSubject.swift
140 lines (117 loc) · 4.16 KB
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PublishSubject.swift
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//
// PublishSubject.swift
// RxSwift
//
// Created by Krunoslav Zaher on 2/11/15.
// Copyright © 2015 Krunoslav Zaher. All rights reserved.
//
/// Represents an object that is both an observable sequence as well as an observer.
///
/// Each notification is broadcasted to all subscribed observers.
public final class PublishSubject<Element>
: Observable<Element>
, SubjectType
, Cancelable
, ObserverType
, SynchronizedUnsubscribeType {
public typealias SubjectObserverType = PublishSubject<Element>
typealias Observers = AnyObserver<Element>.s
typealias DisposeKey = Observers.KeyType
/// Indicates whether the subject has any observers
public var hasObservers: Bool {
self.lock.performLocked { self.observers.count > 0 }
}
private let lock = RecursiveLock()
// state
private var disposed = false
private var observers = Observers()
private var stopped = false
private var stoppedEvent = nil as Event<Element>?
#if DEBUG
private let synchronizationTracker = SynchronizationTracker()
#endif
/// Indicates whether the subject has been isDisposed.
public var isDisposed: Bool {
self.disposed
}
/// Creates a subject.
public override init() {
super.init()
#if TRACE_RESOURCES
_ = Resources.incrementTotal()
#endif
}
/// Notifies all subscribed observers about next event.
///
/// - parameter event: Event to send to the observers.
public func on(_ event: Event<Element>) {
#if DEBUG
self.synchronizationTracker.register(synchronizationErrorMessage: .default)
defer { self.synchronizationTracker.unregister() }
#endif
dispatch(self.synchronized_on(event), event)
}
func synchronized_on(_ event: Event<Element>) -> Observers {
self.lock.lock(); defer { self.lock.unlock() }
switch event {
case .next:
if self.isDisposed || self.stopped {
return Observers()
}
return self.observers
case .completed, .error:
if self.stoppedEvent == nil {
self.stoppedEvent = event
self.stopped = true
let observers = self.observers
self.observers.removeAll()
return observers
}
return Observers()
}
}
/**
Subscribes an observer to the subject.
- parameter observer: Observer to subscribe to the subject.
- returns: Disposable object that can be used to unsubscribe the observer from the subject.
*/
public override func subscribe<Observer: ObserverType>(_ observer: Observer) -> Disposable where Observer.Element == Element {
self.lock.performLocked { self.synchronized_subscribe(observer) }
}
func synchronized_subscribe<Observer: ObserverType>(_ observer: Observer) -> Disposable where Observer.Element == Element {
if let stoppedEvent = self.stoppedEvent {
observer.on(stoppedEvent)
return Disposables.create()
}
if self.isDisposed {
observer.on(.error(RxError.disposed(object: self)))
return Disposables.create()
}
let key = self.observers.insert(observer.on)
return SubscriptionDisposable(owner: self, key: key)
}
func synchronizedUnsubscribe(_ disposeKey: DisposeKey) {
self.lock.performLocked { self.synchronized_unsubscribe(disposeKey) }
}
func synchronized_unsubscribe(_ disposeKey: DisposeKey) {
_ = self.observers.removeKey(disposeKey)
}
/// Returns observer interface for subject.
public func asObserver() -> PublishSubject<Element> {
self
}
/// Unsubscribe all observers and release resources.
public func dispose() {
self.lock.performLocked { self.synchronized_dispose() }
}
final func synchronized_dispose() {
self.disposed = true
self.observers.removeAll()
self.stoppedEvent = nil
}
#if TRACE_RESOURCES
deinit {
_ = Resources.decrementTotal()
}
#endif
}