three-stdlib/utils/WorkerPool.js

stand-alone library of threejs examples

class WorkerPool {
  constructor(pool = 4) {
    this.pool = pool;
    this.queue = [];
    this.workers = [];
    this.workersResolve = [];
    this.workerStatus = 0;
  }
  _initWorker(workerId) {
    if (!this.workers[workerId]) {
      const worker = this.workerCreator();
      worker.addEventListener("message", this._onMessage.bind(this, workerId));
      this.workers[workerId] = worker;
    }
  }
  _getIdleWorker() {
    for (let i = 0; i < this.pool; i++)
      if (!(this.workerStatus & 1 << i))
        return i;
    return -1;
  }
  _onMessage(workerId, msg) {
    const resolve = this.workersResolve[workerId];
    resolve && resolve(msg);
    if (this.queue.length) {
      const { resolve: resolve2, msg: msg2, transfer } = this.queue.shift();
      this.workersResolve[workerId] = resolve2;
      this.workers[workerId].postMessage(msg2, transfer);
    } else {
      this.workerStatus ^= 1 << workerId;
    }
  }
  setWorkerCreator(workerCreator) {
    this.workerCreator = workerCreator;
  }
  setWorkerLimit(pool) {
    this.pool = pool;
  }
  postMessage(msg, transfer) {
    return new Promise((resolve) => {
      const workerId = this._getIdleWorker();
      if (workerId !== -1) {
        this._initWorker(workerId);
        this.workerStatus |= 1 << workerId;
        this.workersResolve[workerId] = resolve;
        this.workers[workerId].postMessage(msg, transfer);
      } else {
        this.queue.push({ resolve, msg, transfer });
      }
    });
  }
  dispose() {
    this.workers.forEach((worker) => worker.terminate());
    this.workersResolve.length = 0;
    this.workers.length = 0;
    this.queue.length = 0;
    this.workerStatus = 0;
  }
}
export {
  WorkerPool
};
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