130 lines
5.7 KiB
JavaScript
130 lines
5.7 KiB
JavaScript
import { async } from '../scheduler/async';
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import { isDate } from '../util/isDate';
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import { Subscriber } from '../Subscriber';
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import { TimeoutError } from '../util/TimeoutError';
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/**
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*
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* Errors if Observable does not emit a value in given time span.
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*
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* <span class="informal">Timeouts on Observable that doesn't emit values fast enough.</span>
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*
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* <img src="./img/timeout.png" width="100%">
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*
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* `timeout` operator accepts as an argument either a number or a Date.
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*
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* If number was provided, it returns an Observable that behaves like a source
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* Observable, unless there is a period of time where there is no value emitted.
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* So if you provide `100` as argument and first value comes after 50ms from
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* the moment of subscription, this value will be simply re-emitted by the resulting
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* Observable. If however after that 100ms passes without a second value being emitted,
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* stream will end with an error and source Observable will be unsubscribed.
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* These checks are performed throughout whole lifecycle of Observable - from the moment
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* it was subscribed to, until it completes or errors itself. Thus every value must be
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* emitted within specified period since previous value.
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*
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* If provided argument was Date, returned Observable behaves differently. It throws
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* if Observable did not complete before provided Date. This means that periods between
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* emission of particular values do not matter in this case. If Observable did not complete
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* before provided Date, source Observable will be unsubscribed. Other than that, resulting
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* stream behaves just as source Observable.
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*
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* `timeout` accepts also a Scheduler as a second parameter. It is used to schedule moment (or moments)
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* when returned Observable will check if source stream emitted value or completed.
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*
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* @example <caption>Check if ticks are emitted within certain timespan</caption>
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* const seconds = Rx.Observable.interval(1000);
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*
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* seconds.timeout(1100) // Let's use bigger timespan to be safe,
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* // since `interval` might fire a bit later then scheduled.
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* .subscribe(
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* value => console.log(value), // Will emit numbers just as regular `interval` would.
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* err => console.log(err) // Will never be called.
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* );
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*
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* seconds.timeout(900).subscribe(
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* value => console.log(value), // Will never be called.
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* err => console.log(err) // Will emit error before even first value is emitted,
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* // since it did not arrive within 900ms period.
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* );
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*
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* @example <caption>Use Date to check if Observable completed</caption>
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* const seconds = Rx.Observable.interval(1000);
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*
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* seconds.timeout(new Date("December 17, 2020 03:24:00"))
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* .subscribe(
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* value => console.log(value), // Will emit values as regular `interval` would
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* // until December 17, 2020 at 03:24:00.
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* err => console.log(err) // On December 17, 2020 at 03:24:00 it will emit an error,
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* // since Observable did not complete by then.
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* );
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*
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* @see {@link timeoutWith}
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*
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* @param {number|Date} due Number specifying period within which Observable must emit values
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* or Date specifying before when Observable should complete
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* @param {Scheduler} [scheduler] Scheduler controlling when timeout checks occur.
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* @return {Observable<T>} Observable that mirrors behaviour of source, unless timeout checks fail.
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* @method timeout
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* @owner Observable
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*/
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export function timeout(due, scheduler = async) {
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const absoluteTimeout = isDate(due);
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const waitFor = absoluteTimeout ? (+due - scheduler.now()) : Math.abs(due);
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return (source) => source.lift(new TimeoutOperator(waitFor, absoluteTimeout, scheduler, new TimeoutError()));
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}
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class TimeoutOperator {
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constructor(waitFor, absoluteTimeout, scheduler, errorInstance) {
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this.waitFor = waitFor;
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this.absoluteTimeout = absoluteTimeout;
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this.scheduler = scheduler;
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this.errorInstance = errorInstance;
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}
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call(subscriber, source) {
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return source.subscribe(new TimeoutSubscriber(subscriber, this.absoluteTimeout, this.waitFor, this.scheduler, this.errorInstance));
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}
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}
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/**
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* We need this JSDoc comment for affecting ESDoc.
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* @ignore
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* @extends {Ignored}
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*/
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class TimeoutSubscriber extends Subscriber {
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constructor(destination, absoluteTimeout, waitFor, scheduler, errorInstance) {
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super(destination);
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this.absoluteTimeout = absoluteTimeout;
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this.waitFor = waitFor;
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this.scheduler = scheduler;
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this.errorInstance = errorInstance;
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this.action = null;
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this.scheduleTimeout();
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}
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static dispatchTimeout(subscriber) {
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subscriber.error(subscriber.errorInstance);
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}
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scheduleTimeout() {
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const { action } = this;
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if (action) {
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// Recycle the action if we've already scheduled one. All the production
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// Scheduler Actions mutate their state/delay time and return themeselves.
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// VirtualActions are immutable, so they create and return a clone. In this
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// case, we need to set the action reference to the most recent VirtualAction,
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// to ensure that's the one we clone from next time.
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this.action = action.schedule(this, this.waitFor);
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}
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else {
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this.add(this.action = this.scheduler.schedule(TimeoutSubscriber.dispatchTimeout, this.waitFor, this));
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}
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}
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_next(value) {
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if (!this.absoluteTimeout) {
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this.scheduleTimeout();
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}
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super._next(value);
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}
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/** @deprecated internal use only */ _unsubscribe() {
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this.action = null;
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this.scheduler = null;
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this.errorInstance = null;
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}
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}
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//# sourceMappingURL=timeout.js.map
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