76 lines
1.4 KiB
JavaScript
76 lines
1.4 KiB
JavaScript
/**
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* 一个非常普通的“锁”
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*/
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export class Mutex {
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/**
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* 锁目前的状态，只有“unlocked”和“locked”两种情况
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*
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* @type {'locked' | 'unlocked'}
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*/
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#status;
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/**
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* 上锁后用于等待的锁Promise
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*
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* @type {null | Promise<void>}
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*/
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#promise;
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/**
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* 上锁后用于触发锁Promise的resolve函数
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*
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* @type {null | function(): void}
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*/
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#resolve;
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constructor() {
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this.#status = "unlocked";
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this.#promise = null;
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this.#resolve = null;
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}
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/**
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* 上锁
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*
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* 请时刻记住使用`await Mutex#lock()`来使锁正常工作
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*/
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async lock() {
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switch (this.#status) {
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case "locked":
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await this.#promise;
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case "unlocked":
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this.#status = "locked";
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// @ts-ignore
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({ promise: this.#promise, resolve: this.#resolve } = Promise.withResolvers());
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break;
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}
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}
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/**
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* 解锁
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*
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* 请不要在未上锁的情况下解锁
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*/
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unlock() {
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if (this.#status === "unlocked") throw new Error("This Mutex is not locked.");
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this.#status = "unlocked";
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if (this.#resolve) this.#resolve();
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}
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/**
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* 启用锁的try-finally封装，用于在函数执行完后自动解放锁的控制权（就算发生错误）
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*
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* @param {function(): void | Promise<void>} content
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*/
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async scoped(content) {
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try {
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await this.lock();
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await content();
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} finally {
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this.unlock();
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}
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}
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}
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