mirror of https://github.com/vector-im/riot-web
130 lines
3.6 KiB
TypeScript
130 lines
3.6 KiB
TypeScript
/*
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Copyright 2018, 2021 The Matrix.org Foundation C.I.C.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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/**
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A countdown timer, exposing a promise api.
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A timer starts in a non-started state,
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and needs to be started by calling `start()`` on it first.
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Timers can be `abort()`-ed which makes the promise reject prematurely.
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Once a timer is finished or aborted, it can't be started again
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(because the promise should not be replaced). Instead, create
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a new one through `clone()` or `cloneIfRun()`.
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*/
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export default class Timer {
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private timerHandle: number;
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private startTs: number;
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private promise: Promise<void>;
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private resolve: () => void;
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private reject: (Error) => void;
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constructor(private timeout: number) {
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this.setNotStarted();
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}
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private setNotStarted() {
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this.timerHandle = null;
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this.startTs = null;
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this.promise = new Promise<void>((resolve, reject) => {
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this.resolve = resolve;
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this.reject = reject;
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}).finally(() => {
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this.timerHandle = null;
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});
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}
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private onTimeout = () => {
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const now = Date.now();
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const elapsed = now - this.startTs;
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if (elapsed >= this.timeout) {
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this.resolve();
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this.setNotStarted();
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} else {
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const delta = this.timeout - elapsed;
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this.timerHandle = setTimeout(this.onTimeout, delta);
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}
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};
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changeTimeout(timeout: number) {
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if (timeout === this.timeout) {
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return;
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}
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const isSmallerTimeout = timeout < this.timeout;
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this.timeout = timeout;
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if (this.isRunning() && isSmallerTimeout) {
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clearTimeout(this.timerHandle);
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this.onTimeout();
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}
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}
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/**
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* if not started before, starts the timer.
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* @returns {Timer} the same timer
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*/
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start() {
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if (!this.isRunning()) {
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this.startTs = Date.now();
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this.timerHandle = setTimeout(this.onTimeout, this.timeout);
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}
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return this;
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}
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/**
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* (re)start the timer. If it's running, reset the timeout. If not, start it.
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* @returns {Timer} the same timer
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*/
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restart() {
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if (this.isRunning()) {
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// don't clearTimeout here as this method
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// can be called in fast succession,
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// instead just take note and compare
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// when the already running timeout expires
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this.startTs = Date.now();
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return this;
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} else {
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return this.start();
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}
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}
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/**
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* if the timer is running, abort it,
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* and reject the promise for this timer.
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* @returns {Timer} the same timer
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*/
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abort() {
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if (this.isRunning()) {
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clearTimeout(this.timerHandle);
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this.reject(new Error("Timer was aborted."));
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this.setNotStarted();
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}
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return this;
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}
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/**
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*promise that will resolve when the timer elapses,
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*or is rejected when abort is called
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*@return {Promise}
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*/
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finished() {
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return this.promise;
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}
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isRunning() {
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return this.timerHandle !== null;
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}
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}
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