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7-spin-lock.js
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64 lines (55 loc) · 1.4 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() {
return new Promise((resolve) => {
const tryEnter = () => {
const prev = Atomics.exchange(this.lock, 0, LOCKED);
if (prev === UNLOCKED) {
this.owner = true;
resolve();
} else {
setTimeout(tryEnter, 0);
}
};
tryEnter();
});
}
leave() {
if (!this.owner) return;
Atomics.store(this.lock, 0, UNLOCKED);
this.owner = false;
}
}
// 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);
setInterval(() => {
console.log(`Interval ${threadId}`);
}, 500);
const loop = async () => {
await mutex.enter();
console.log(`Enter ${threadId}`);
setTimeout(() => {
mutex.leave();
console.log(`Leave ${threadId}`);
setTimeout(loop, 0);
}, 5000);
};
loop();
}