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1-mutex.js
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55 lines (48 loc) · 1.28 KB
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'use strict';
const threads = require('node:worker_threads');
const { Worker, isMainThread } = threads;
const LOCKED = 0;
const UNLOCKED = 1;
class Mutex {
constructor(shared, offset = 0, initial = false) {
this.lock = new Int32Array(shared, offset, 1);
if (initial) Atomics.store(this.lock, 0, UNLOCKED);
this.owner = false;
}
enter(callback) {
Atomics.wait(this.lock, 0, LOCKED);
Atomics.store(this.lock, 0, LOCKED);
this.owner = true;
setTimeout(callback, 0);
}
leave() {
if (!this.owner) return false;
Atomics.store(this.lock, 0, UNLOCKED);
Atomics.notify(this.lock, 0, 1);
this.owner = false;
return true;
}
}
// Usage
if (isMainThread) {
const buffer = new SharedArrayBuffer(4);
const mutex = new Mutex(buffer, 0, true);
console.dir({ mutex });
new Worker(__filename, { workerData: buffer });
new Worker(__filename, { workerData: buffer });
} else {
const { threadId, workerData } = threads;
const mutex = new Mutex(workerData);
if (threadId === 1) {
mutex.enter(() => {
console.log('Entered mutex');
setTimeout(() => {
if (mutex.leave()) {
console.log('Left mutex');
}
}, 100);
});
} else if (!mutex.leave()) {
console.log('Can not leave mutex: not owner');
}
}