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Copy patha-lock.js
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61 lines (51 loc) · 1.12 KB
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'use strict';
const timers = require('node:timers/promises');
class Lock {
#release = null;
constructor(release) {
this.#release = release;
}
[Symbol.dispose]() {
if (!this.#release) return;
const release = this.#release;
this.#release = null;
release();
}
}
class Mutex {
#locked = false;
#waiters = [];
#release() {
const resolve = this.#waiters.shift();
if (resolve) {
resolve(new Lock(() => this.#release()));
return;
}
this.#locked = false;
}
async acquire() {
if (!this.#locked) {
this.#locked = true;
return new Lock(() => this.#release());
}
return new Promise((resolve) => {
this.#waiters.push(resolve);
});
}
}
const critical = async (mutex, name) => {
using lock = await mutex.acquire();
if (!lock) throw new ReferenceError('Lock not acquired');
console.log(`Enter: ${name}`);
await timers.setTimeout(20);
console.log(`Leave: ${name}`);
};
const main = async () => {
const mutex = new Mutex();
await Promise.all([
critical(mutex, 'A'),
critical(mutex, 'B'),
critical(mutex, 'C'),
]);
};
main();