@jsreport/jsreport-core/lib/main/store/queue.js

javascript based business reporting

module.exports = () => {
  const items = []
  let busy = false

  function execute () {
    if (items.length < 1 || busy) {
      return
    }

    busy = true
    const item = items.shift()
    item.busy = true

    Promise.resolve(item.fn()).then((res) => {
      item.resolve(res)
      busy = false
      execute()
      return null
    }).catch((err) => {
      item.reject(err)
      busy = false
      execute()
      return null
    })
  }

  return {
    push (fn) {
      let _resolve, _reject

      const result = new Promise((resolve, reject) => {
        _resolve = resolve
        _reject = reject
      })

      items.push({
        fn,
        resolve: _resolve,
        reject: _reject,
        submittedOn: new Date().getTime()
      })

      execute()
      return result
    }
  }
}