@thi.ng/rstream/tunnel.js

Reactive streams & subscription primitives for constructing dataflow graphs / pipelines

import { State } from "./api.js";
import { __nextID } from "./idgen.js";
import { LOGGER } from "./logger.js";
import { Subscription } from "./subscription.js";
import { defWorker } from "./defworker.js";
const tunnel = (opts) => new Tunnel(opts);
class Tunnel extends Subscription {
  workers;
  src;
  transferables;
  terminate;
  interrupt;
  index;
  constructor(opts) {
    super(void 0, { id: opts.id || `tunnel-${__nextID()}` });
    this.src = opts.src;
    this.workers = new Array(opts.maxWorkers || 1);
    this.transferables = opts.transferables;
    this.terminate = opts.terminate || 1e3;
    this.interrupt = opts.interrupt || false;
    this.index = 0;
  }
  next(x) {
    if (this.state < State.DONE) {
      let tx;
      if (this.transferables) {
        tx = this.transferables(x);
      }
      let worker = this.workers[this.index];
      if (this.interrupt && worker) {
        worker.terminate();
        worker = null;
      }
      if (!worker) {
        this.workers[this.index++] = worker = defWorker(this.src);
        this.index %= this.workers.length;
        worker.addEventListener(
          "message",
          (e) => this.dispatch(e.data)
        );
        worker.addEventListener(
          "error",
          (e) => this.error(e)
        );
      }
      worker.postMessage(x, tx || []);
    }
  }
  done() {
    super.done();
    if (this.terminate > 0) {
      setTimeout(() => {
        LOGGER.info("terminating workers...");
        this.workers.forEach((worker) => worker?.terminate());
        delete this.workers;
      }, this.terminate);
    }
  }
}
export {
  Tunnel,
  tunnel
};