GeezerVison is showing github.com — Semaphore/JavaScript/5-atomics.js at master · HowProgrammingWorks/Semaphore

Expand file tree

5-atomics.js

Copy path

More file actions

Latest commit

History

52 lines (45 loc) · 1.33 KB

5-atomics.js

Copy path

File metadata and controls

52 lines (45 loc) · 1.33 KB

Raw

Copy raw file

Download raw file

Open symbols panel

Edit and raw actions

'use strict';

const fs = require('node:fs');

const threads = require('node:worker_threads');

const { Worker, isMainThread } = threads;

class CountingSemaphore {

constructor(shared, offset = 0, initial) {

this.counter = new Int32Array(shared, offset, 1);

if (typeof initial === 'number') {

Atomics.store(this.counter, 0, initial);

}

enter(callback) {

Atomics.wait(this.counter, 0, 0);

Atomics.sub(this.counter, 0, 1);

setTimeout(callback, 0);

}

leave() {

Atomics.add(this.counter, 0, 1);

Atomics.notify(this.counter, 0, 1);

}

// Usage

if (isMainThread) {

const buffer = new SharedArrayBuffer(4);

// Try to change 10 to 2 at next line to check solution

const semaphore = new CountingSemaphore(buffer, 0, 10);

console.dir({ semaphore: semaphore.counter[0] });

for (let i = 0; i < 20; i++) {

new Worker(__filename, { workerData: buffer });

}

} else {

const { threadId, workerData } = threads;

const semaphore = new CountingSemaphore(workerData);

console.dir({ threadId, semaphore: semaphore.counter[0] });

const REPEAT_COUNT = 1000000;

const file = `file-${threadId}.dat`;

semaphore.enter(() => {

const data = `Data from ${threadId}`.repeat(REPEAT_COUNT);

fs.writeFile(file, data, () => {

fs.unlink(file, () => {

semaphore.leave();

});

}