root
83 lines
2.4 KiB
JavaScript
Executable File
83 lines
2.4 KiB
JavaScript
Executable File
/**
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* Browser 并发槽位限流器：standard / real 各自独立队列
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*/
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const { QUEUE_TIMEOUT_MS } = require('./constants');
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class BrowserConcurrencyLimiter {
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/**
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* @param {number} max 最大并发 Browser 数
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*/
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constructor(max) {
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this.max = max;
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this.active = 0;
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this.waiters = [];
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}
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/** @returns {{ max: number, active: number, queued: number }} */
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getStats() {
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return { max: this.max, active: this.active, queued: this.waiters.length };
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}
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/**
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* @param {string} taskName
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* @param {number} [timeoutMs]
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*/
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async acquire(taskName, timeoutMs = QUEUE_TIMEOUT_MS) {
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if (this.active < this.max) {
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this.active++;
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console.log(`[并发槽位] ${taskName} 立即获取 (${this.active}/${this.max})`);
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return;
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}
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console.log(`[并发槽位] ${taskName} 排队等待 (队列 ${this.waiters.length + 1})`);
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await new Promise((resolve, reject) => {
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const entry = {
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resolve: () => {
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this.active++;
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console.log(`[并发槽位] ${taskName} 出队执行 (${this.active}/${this.max})`);
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resolve();
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},
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reject,
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};
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if (timeoutMs > 0) {
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entry.timer = setTimeout(() => {
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const idx = this.waiters.indexOf(entry);
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if (idx >= 0) {
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this.waiters.splice(idx, 1);
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reject(new Error('QUEUE_TIMEOUT'));
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}
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}, timeoutMs);
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}
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this.waiters.push(entry);
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});
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}
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/** @param {string} taskName */
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release(taskName) {
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this.active = Math.max(0, this.active - 1);
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const next = this.waiters.shift();
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if (next) {
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if (next.timer) clearTimeout(next.timer);
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next.resolve();
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} else {
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console.log(`[并发槽位] ${taskName} 释放 (${this.active}/${this.max})`);
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}
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}
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/**
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* @template T
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* @param {string} taskName
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* @param {() => Promise<T>} fn
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* @returns {Promise<T>}
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*/
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async run(taskName, fn) {
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await this.acquire(taskName);
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try {
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return await fn();
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} finally {
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this.release(taskName);
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}
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}
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}
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module.exports = { BrowserConcurrencyLimiter };
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