x-mini/lib/mini/queue.js

封装小程序

// https://github.com/zhengjunxin/wx-queue-request
const checkConcurrency = (concurrency = 1) => {
  if (concurrency == null) {
    concurrency = 1
  } else if (concurrency === 0) {
    throw new Error('Concurrency must not be zero')
  }
  return concurrency
}

const onlyOnce = (fn) => (...args) => {
  if (fn === null) {
    throw new Error('Callback was already called')
  }
  const callFn = fn
  fn = null
  return callFn(...args)
}

function queue(callback, concurrency) {
  checkConcurrency(concurrency)

  // 待处理的队列
  let workers = []
  // 正在处理的队列
  const workerList = []

  return {
    concurrency,
    push(task, callback) {
      workers.push({
        task,
        callback,
      })
      setTimeout(() => {
        this.process()
      }, 0)
    },
    process() {
      while (this.concurrency > workerList.length && workers.length) {
        const worker = workers.shift()
        workerList.push(worker)
        callback(worker.task, onlyOnce((...args) => {
          this.pull(worker)
          if (typeof worker.callback === 'function') {
            worker.callback(...args)
          }
          this.process()
        }))
      }
    },
    pull(worker) {
      const index = workerList.indexOf(worker)
      if (index !== -1) {
        workerList.splice(index, 1)
      }
    }
  }
}

function queueWorker(fn, concurrency = 10) {
  if (typeof fn !== 'function') {
    throw Error('fn must be function')
  }
  const work = queue((task, callback) => task(callback), concurrency)

  return (obj) => {
    work.push((callback) => {
      const originComplete = obj.complete
      obj.complete = (...args) => {
        callback()
        if (typeof originComplete === 'function') {
          originComplete(...args)
        }
      }
      fn(obj)
    })
  }
}

// function queueRequest(concurrency) {
//   const request = wx.request

//   Object.defineProperty(wx, 'request', {
//     get() {
//       return queueWorker(request, concurrency)
//     }
//   })
// }

// exports.queueWorker = queueWorker;
// exports.queueRequest = queueRequest;
module.exports = queueWorker;