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- import { ReplaySubject } from '../ReplaySubject';
- import { MonoTypeOperatorFunction, SchedulerLike } from '../types';
- import { share } from './share';
- export interface ShareReplayConfig {
- bufferSize?: number;
- windowTime?: number;
- refCount: boolean;
- scheduler?: SchedulerLike;
- }
- export function shareReplay<T>(config: ShareReplayConfig): MonoTypeOperatorFunction<T>;
- export function shareReplay<T>(bufferSize?: number, windowTime?: number, scheduler?: SchedulerLike): MonoTypeOperatorFunction<T>;
- /**
- * Share source and replay specified number of emissions on subscription.
- *
- * This operator is a specialization of `replay` that connects to a source observable
- * and multicasts through a `ReplaySubject` constructed with the specified arguments.
- * A successfully completed source will stay cached in the `shareReplay`ed observable forever,
- * but an errored source can be retried.
- *
- * ## Why use `shareReplay`?
- *
- * You generally want to use `shareReplay` when you have side-effects or taxing computations
- * that you do not wish to be executed amongst multiple subscribers.
- * It may also be valuable in situations where you know you will have late subscribers to
- * a stream that need access to previously emitted values.
- * This ability to replay values on subscription is what differentiates {@link share} and `shareReplay`.
- *
- * ## Reference counting
- *
- * By default `shareReplay` will use `refCount` of false, meaning that it will _not_ unsubscribe the
- * source when the reference counter drops to zero, i.e. the inner `ReplaySubject` will _not_ be unsubscribed
- * (and potentially run for ever).
- * This is the default as it is expected that `shareReplay` is often used to keep around expensive to setup
- * observables which we want to keep running instead of having to do the expensive setup again.
- *
- * As of RXJS version 6.4.0 a new overload signature was added to allow for manual control over what
- * happens when the operators internal reference counter drops to zero.
- * If `refCount` is true, the source will be unsubscribed from once the reference count drops to zero, i.e.
- * the inner `ReplaySubject` will be unsubscribed. All new subscribers will receive value emissions from a
- * new `ReplaySubject` which in turn will cause a new subscription to the source observable.
- *
- * ## Examples
- *
- * Example with a third subscriber coming late to the party
- *
- * ```ts
- * import { interval, take, shareReplay } from 'rxjs';
- *
- * const shared$ = interval(2000).pipe(
- * take(6),
- * shareReplay(3)
- * );
- *
- * shared$.subscribe(x => console.log('sub A: ', x));
- * shared$.subscribe(y => console.log('sub B: ', y));
- *
- * setTimeout(() => {
- * shared$.subscribe(y => console.log('sub C: ', y));
- * }, 11000);
- *
- * // Logs:
- * // (after ~2000 ms)
- * // sub A: 0
- * // sub B: 0
- * // (after ~4000 ms)
- * // sub A: 1
- * // sub B: 1
- * // (after ~6000 ms)
- * // sub A: 2
- * // sub B: 2
- * // (after ~8000 ms)
- * // sub A: 3
- * // sub B: 3
- * // (after ~10000 ms)
- * // sub A: 4
- * // sub B: 4
- * // (after ~11000 ms, sub C gets the last 3 values)
- * // sub C: 2
- * // sub C: 3
- * // sub C: 4
- * // (after ~12000 ms)
- * // sub A: 5
- * // sub B: 5
- * // sub C: 5
- * ```
- *
- * Example for `refCount` usage
- *
- * ```ts
- * import { Observable, tap, interval, shareReplay, take } from 'rxjs';
- *
- * const log = <T>(name: string, source: Observable<T>) => source.pipe(
- * tap({
- * subscribe: () => console.log(`${ name }: subscribed`),
- * next: value => console.log(`${ name }: ${ value }`),
- * complete: () => console.log(`${ name }: completed`),
- * finalize: () => console.log(`${ name }: unsubscribed`)
- * })
- * );
- *
- * const obs$ = log('source', interval(1000));
- *
- * const shared$ = log('shared', obs$.pipe(
- * shareReplay({ bufferSize: 1, refCount: true }),
- * take(2)
- * ));
- *
- * shared$.subscribe(x => console.log('sub A: ', x));
- * shared$.subscribe(y => console.log('sub B: ', y));
- *
- * // PRINTS:
- * // shared: subscribed <-- reference count = 1
- * // source: subscribed
- * // shared: subscribed <-- reference count = 2
- * // source: 0
- * // shared: 0
- * // sub A: 0
- * // shared: 0
- * // sub B: 0
- * // source: 1
- * // shared: 1
- * // sub A: 1
- * // shared: completed <-- take(2) completes the subscription for sub A
- * // shared: unsubscribed <-- reference count = 1
- * // shared: 1
- * // sub B: 1
- * // shared: completed <-- take(2) completes the subscription for sub B
- * // shared: unsubscribed <-- reference count = 0
- * // source: unsubscribed <-- replaySubject unsubscribes from source observable because the reference count dropped to 0 and refCount is true
- *
- * // In case of refCount being false, the unsubscribe is never called on the source and the source would keep on emitting, even if no subscribers
- * // are listening.
- * // source: 2
- * // source: 3
- * // source: 4
- * // ...
- * ```
- *
- * @see {@link publish}
- * @see {@link share}
- * @see {@link publishReplay}
- *
- * @param configOrBufferSize Maximum element count of the replay buffer or {@link ShareReplayConfig configuration}
- * object.
- * @param windowTime Maximum time length of the replay buffer in milliseconds.
- * @param scheduler Scheduler where connected observers within the selector function
- * will be invoked on.
- * @return A function that returns an Observable sequence that contains the
- * elements of a sequence produced by multicasting the source sequence within a
- * selector function.
- */
- export function shareReplay<T>(
- configOrBufferSize?: ShareReplayConfig | number,
- windowTime?: number,
- scheduler?: SchedulerLike
- ): MonoTypeOperatorFunction<T> {
- let bufferSize: number;
- let refCount = false;
- if (configOrBufferSize && typeof configOrBufferSize === 'object') {
- ({ bufferSize = Infinity, windowTime = Infinity, refCount = false, scheduler } = configOrBufferSize);
- } else {
- bufferSize = (configOrBufferSize ?? Infinity) as number;
- }
- return share<T>({
- connector: () => new ReplaySubject(bufferSize, windowTime, scheduler),
- resetOnError: true,
- resetOnComplete: false,
- resetOnRefCountZero: refCount,
- });
- }
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