A lock designed for multi-threaded browser environments.
(we are not on npm yet)npm install @mogoe1/reentrant-lock
npm install --save git+https://github.com/mogoe1/reentrant-lock.git
- The implementation relies on SharedArrayBuffers. Make sure your site meets the security requirements.
- The implementation relies on Atomics.waitAsync which is implemented by v8 but not documented at mdn yet. You might want to proivide a polyfill.
The following example shows how a reentrant-lock can be used to make sure only one thrad at a time has access to a shared ressource.
// file: main.js
import { ReentrantLock } from "@mogoe1/reentrant-lock";
const lock = ReentrantLock.create();
const worker = new Worker("worker.js", { type: "module" });
lock.lockAsync().then(_ => {
worker.postMessage(lock.buffer);
// exclusive access to resource
console.log("locked!");
lock.unlock();
console.log("unlocked");
});// file: worker.js
import { ReentrantLock } from "@mogoe1/reentrant-lock";
self.addEventListener("message", message => {
const buffer = message.data;
const lock = new ReentrantLock(new Int32Array(buffer));
let newlyLocked = lock.lock(); // this blocks the worker thread untill the main thread unlocks it's ReentrantLock instance!
console.log(newlyLocked); // true
newlyLocked = lock.lock(); // lock can be called multiple times without blocking more than once
console.log(newlyLocked); // false
// exclusive access to resource here
let stillOwned = lock.unlock();
console.log(stillOwned); // true, because lock was called twice without unlock
stillOwned = lock.unlock();
console.log(stillOwned); // false, because unlock was called as often as lock
});The API is documented at https://mogoe1.github.io/reentrant-lock/classes/ReentrantLock.html.