asyncc/lib/retry.js

Just asynchronous patterns

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports["default"] = retry;
var _utils = require("./_utils");
/**
* Run `task` max. `times` times. Stops at first iteration where no error is returned.
*
* Calls `callback` if `times` is reached or `task` returned no error.
*
* @name retry
* @memberOf module:serial
* @static
* @method
* @param {Number|Object} times - retry max. `times` times - default=2
* @param {Number} [times.times=2] - max. number of retries
* @param {Number} [times.lag=0] - time-lag in ms between retries
* @param {Function} task - iterator function of type `function (cb: Function, index: Number)`
* @param {Function} [callback] - optional callback `function (errors: Error, result: any)` from last callback.
* @example
* let arr = []
* retry({times: 3, lag: 100}, // max. 3 retries with 100ms time-lag between retries
*   (cb, index) => { // task
*     let err = index < 2 ? new Error() : null
*     arr.push(index)
*     cb(err, index)
*   }, (err, res) => { // callback
*     //> err = null
*     //> res = 2
*     //> arr = [0, 1, 2]
*   }
* )
*/
function retry(num, task, callback) {
  var i = 0;
  var _times2 = (0, _utils._times)(num, {
      times: 2
    }),
    times = _times2.times,
    lag = _times2.lag,
    fn = _times2.fn;
  run();
  function cb(err, res) {
    if (!err || i >= times) {
      callback && callback(err, res);
    } else {
      fn(function () {
        run();
      }, lag);
    }
  }
  function run() {
    task(cb, i++);
  }
}