A resource pool e.g. for projects. Inspired by https://www.npmjs.com/package/generic-pool

parallelPool.js

/**
 * parallelPool module
 * @description A resource pool e.g. for projects. Inspired by https://www.npmjs.com/package/generic-pool
 * @module parallelPool
 * @author Tom Söderlund
 */

// Private functions

/* const projectPool = new ParallelPool({}) */
function ParallelPool ({ create, destroy }, { idleTimeoutMillis = 30000 } = {}) {
  // Private
  const items = {}
  const timerId = setInterval(() => {
    Object.keys(items).forEach(itemId => {
      if ((Date.now() - items[itemId].time) > idleTimeoutMillis) {
        this.release(itemId)
      }
    })
  }, idleTimeoutMillis / 2)

  // Get an instance e.g. a project
  this.acquire = itemId => {
    if (!items[itemId]) {
      items[itemId] = { payload: create && create(itemId) }
    }
    items[itemId].time = Date.now()
    return items[itemId].payload
  }

  // Release an instance e.g. a project
  this.release = itemId => {
    destroy && destroy(itemId)
    delete items[itemId]
  }
}

// Public API

module.exports = ParallelPool