bsv/lib/workers.js

/**
 * Workers
 * =======
 *
 * Workers manages either processes (in node) or threads (in a browser). The
 * workers are intended to handle CPU-heavy tasks that block IO. This class is
 * a little unusual in that it must use different interfaces whether in node or
 * in the browser. In node, we use node's build-in child_process fork to create
 * new workers we can communicate with. In the browser, we use web workers.
 * Unfortunately, node and web browsers do not have a common interface for
 * workers. There is a node module called webworker-threads for node that
 * mimics the browser's web workers, but unfortunately it does not support
 * require(), and thus isn't very useful in our case. Therefore we fall back to
 * process forks.
 *
 * You probably don't need to use this class directly. Use Work, which will
 * automatically spawn new workers if needed.
 */
'use strict'

import { WorkersResult } from './workers-result'

let globalWorkers

class Workers {
  constructor (
    nativeWorkers = [],
    lastid = 0,
    incompconsteRes = [],
    promisemap = new Map()
  ) {
    this.nativeWorkers = nativeWorkers
    this.lastid = lastid
    this.incompconsteRes = incompconsteRes
    this.promisemap = promisemap
  }

  asyncObjectMethod (obj, methodname, args, id = this.lastid + 1) {
    if (!args) {
      throw new Error('must specify args')
    }
    const result = obj[methodname](...args)
    const workersResult = new WorkersResult().fromResult(result, id)
    return workersResult
  }

  static asyncObjectMethod (obj, methodname, args, id) {
    if (!globalWorkers) {
      globalWorkers = new Workers()
    }
    return globalWorkers.asyncObjectMethod(obj, methodname, args, id)
  }

  asyncClassMethod (classObj, methodname, args, id = this.lastid + 1) {
    if (!args) {
      throw new Error('must specify args')
    }
    const result = classObj[methodname](...args)
    const workersResult = new WorkersResult().fromResult(result, id)
    return workersResult
  }

  static asyncClassMethod (classObj, methodname, args, id) {
    if (!globalWorkers) {
      globalWorkers = new Workers()
    }
    return globalWorkers.asyncClassMethod(classObj, methodname, args, id)
  }

  static endGlobalWorkers () {
    if (globalWorkers && !process.browser) {
      globalWorkers = undefined
    }
  }
}

export { Workers }