staggerjs/lib/index.js

Light utility to stagger a stack of async methods

'use strict';

Object.defineProperty(exports, "__esModule", {
  value: true
});

var _extends = Object.assign || function (target) { for (var i = 1; i < arguments.length; i++) { var source = arguments[i]; for (var key in source) { if (Object.prototype.hasOwnProperty.call(source, key)) { target[key] = source[key]; } } } return target; };

var _tcomb = require('tcomb');

var _tcomb2 = _interopRequireDefault(_tcomb);

var _throttleFunction = require('throttle-function');

var _throttleFunction2 = _interopRequireDefault(_throttleFunction);

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }

var InfinityType = _tcomb2.default.irreducible('InfinityType', function (x) {
  return typeof x === 'number' && x === Infinity;
});

var Methods = _tcomb2.default.list(_tcomb2.default.Function);
var Settings = _tcomb2.default.interface({
  perSecond: _tcomb2.default.union([_tcomb2.default.Number, InfinityType]),
  maxOngoingMethods: _tcomb2.default.union([_tcomb2.default.Integer, InfinityType])
}, { strict: true });

var defaultSettings = {
  perSecond: 20,
  maxOngoingMethods: 5
};

exports.default = function (_methods, _settings) {
  var methods = Methods(_methods);
  var settings = Settings(_extends({}, defaultSettings, _settings));

  var maxOngoingMethods = settings.maxOngoingMethods,
      perSecond = settings.perSecond;


  var throttle = (0, _throttleFunction2.default)(function (method) {
    return method();
  }, {
    window: 1, // window is in seconds
    limit: perSecond
  });

  return new Promise(function (resolve) {
    var queue = [];

    var onDone = function onDone(res) {
      throttle(function () {
        return runMethod(methods[queue.length]);
      });

      return res;
    };

    var runMethod = function runMethod(method) {
      if (queue.length !== methods.length) {
        queue.push(method().then(onDone).catch(onDone));
      } else {
        resolve(Promise.all(queue));
      }
    };

    methods.slice(0, maxOngoingMethods).forEach(function (m, i) {
      return i === 0 ? runMethod(m) : throttle(function () {
        return runMethod(m);
      });
    });
  });
};