dinlo
71 lines
1.9 KiB
JavaScript
71 lines
1.9 KiB
JavaScript
class PromiseQueue {
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constructor({ concurrency = 1 } = {}) {
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this.options = { concurrency };
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this.running = 0;
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this.queue = [];
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this.idleCallbacks = [];
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}
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clear() {
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this.queue = [];
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}
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onIdle(callback) {
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this.idleCallbacks.push(callback);
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return () => {
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const index = this.idleCallbacks.indexOf(callback);
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if (index !== -1) {
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this.idleCallbacks.splice(index, 1);
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}
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};
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}
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waitTillIdle() {
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return new Promise((resolve) => {
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if (this.running === 0) {
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resolve();
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return;
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}
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const dispose = this.onIdle(() => {
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dispose();
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resolve();
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});
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});
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}
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add(callback) {
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return new Promise((resolve, reject) => {
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const runCallback = () => {
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this.running += 1;
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try {
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Promise.resolve(callback()).then((val) => {
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resolve(val);
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this.processNext();
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}, (err) => {
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reject(err);
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this.processNext();
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});
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}
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catch (err) {
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reject(err);
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this.processNext();
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}
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};
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if (this.running >= this.options.concurrency) {
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this.queue.push(runCallback);
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}
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else {
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runCallback();
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}
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});
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}
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// Internal function, don't use
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processNext() {
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this.running -= 1;
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const callback = this.queue.shift();
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if (callback) {
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callback();
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}
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else if (this.running === 0) {
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this.idleCallbacks.forEach((item) => item());
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}
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}
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}
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export { PromiseQueue };
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