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4-callback.js
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60 lines (53 loc) · 1.46 KB
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'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') {
this.counter[0] = initial;
}
this.queue = [];
}
enter(callback) {
if (this.counter[0] > 0) {
this.counter[0]--;
setTimeout(callback, 0);
} else {
this.queue.push(callback);
}
}
leave() {
this.counter[0]++;
if (this.queue.length > 0) {
const callback = this.queue.shift();
this.counter[0]--;
setTimeout(callback, 0);
}
}
}
// 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();
});
});
});
}