import { Subject, SubjectSubscriber } from '../Subject';
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import { Operator } from '../Operator';
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import { Observable } from '../Observable';
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import { Subscriber } from '../Subscriber';
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import { Subscription } from '../Subscription';
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import { TeardownLogic } from '../types';
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import { refCount as higherOrderRefCount } from '../operators/refCount';
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/**
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* @class ConnectableObservable<T>
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*/
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export class ConnectableObservable<T> extends Observable<T> {
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protected _subject: Subject<T>;
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protected _refCount: number = 0;
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protected _connection: Subscription;
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/** @internal */
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_isComplete = false;
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constructor(public source: Observable<T>,
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protected subjectFactory: () => Subject<T>) {
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super();
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}
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/** @deprecated This is an internal implementation detail, do not use. */
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_subscribe(subscriber: Subscriber<T>) {
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return this.getSubject().subscribe(subscriber);
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}
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protected getSubject(): Subject<T> {
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const subject = this._subject;
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if (!subject || subject.isStopped) {
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this._subject = this.subjectFactory();
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}
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return this._subject;
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}
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connect(): Subscription {
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let connection = this._connection;
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if (!connection) {
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this._isComplete = false;
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connection = this._connection = new Subscription();
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connection.add(this.source
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.subscribe(new ConnectableSubscriber(this.getSubject(), this)));
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if (connection.closed) {
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this._connection = null;
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connection = Subscription.EMPTY;
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}
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}
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return connection;
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}
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refCount(): Observable<T> {
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return higherOrderRefCount()(this) as Observable<T>;
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}
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}
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export const connectableObservableDescriptor: PropertyDescriptorMap = (() => {
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const connectableProto = <any>ConnectableObservable.prototype;
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return {
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operator: { value: null as null },
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_refCount: { value: 0, writable: true },
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_subject: { value: null as null, writable: true },
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_connection: { value: null as null, writable: true },
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_subscribe: { value: connectableProto._subscribe },
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_isComplete: { value: connectableProto._isComplete, writable: true },
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getSubject: { value: connectableProto.getSubject },
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connect: { value: connectableProto.connect },
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refCount: { value: connectableProto.refCount }
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};
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})();
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class ConnectableSubscriber<T> extends SubjectSubscriber<T> {
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constructor(destination: Subject<T>,
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private connectable: ConnectableObservable<T>) {
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super(destination);
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}
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protected _error(err: any): void {
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this._unsubscribe();
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super._error(err);
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}
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protected _complete(): void {
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this.connectable._isComplete = true;
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this._unsubscribe();
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super._complete();
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}
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protected _unsubscribe() {
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const connectable = <any>this.connectable;
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if (connectable) {
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this.connectable = null;
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const connection = connectable._connection;
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connectable._refCount = 0;
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connectable._subject = null;
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connectable._connection = null;
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if (connection) {
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connection.unsubscribe();
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}
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}
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}
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}
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class RefCountOperator<T> implements Operator<T, T> {
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constructor(private connectable: ConnectableObservable<T>) {
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}
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call(subscriber: Subscriber<T>, source: any): TeardownLogic {
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const { connectable } = this;
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(<any> connectable)._refCount++;
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const refCounter = new RefCountSubscriber(subscriber, connectable);
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const subscription = source.subscribe(refCounter);
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if (!refCounter.closed) {
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(<any> refCounter).connection = connectable.connect();
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}
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return subscription;
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}
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}
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class RefCountSubscriber<T> extends Subscriber<T> {
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private connection: Subscription;
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constructor(destination: Subscriber<T>,
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private connectable: ConnectableObservable<T>) {
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super(destination);
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}
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protected _unsubscribe() {
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const { connectable } = this;
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if (!connectable) {
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this.connection = null;
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return;
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}
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this.connectable = null;
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const refCount = (<any> connectable)._refCount;
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if (refCount <= 0) {
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this.connection = null;
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return;
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}
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(<any> connectable)._refCount = refCount - 1;
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if (refCount > 1) {
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this.connection = null;
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return;
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}
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///
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// Compare the local RefCountSubscriber's connection Subscription to the
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// connection Subscription on the shared ConnectableObservable. In cases
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// where the ConnectableObservable source synchronously emits values, and
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// the RefCountSubscriber's downstream Observers synchronously unsubscribe,
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// execution continues to here before the RefCountOperator has a chance to
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// supply the RefCountSubscriber with the shared connection Subscription.
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// For example:
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// ```
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// range(0, 10).pipe(
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// publish(),
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// refCount(),
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// take(5),
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// ).subscribe();
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// ```
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// In order to account for this case, RefCountSubscriber should only dispose
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// the ConnectableObservable's shared connection Subscription if the
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// connection Subscription exists, *and* either:
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// a. RefCountSubscriber doesn't have a reference to the shared connection
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// Subscription yet, or,
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// b. RefCountSubscriber's connection Subscription reference is identical
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// to the shared connection Subscription
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///
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const { connection } = this;
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const sharedConnection = (<any> connectable)._connection;
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this.connection = null;
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if (sharedConnection && (!connection || sharedConnection === connection)) {
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sharedConnection.unsubscribe();
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}
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}
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}
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