asyncstorage-down/taskqueue.js

A leveldown API implementation that maps to AsyncStorage in React Native, originally a fork of no9/localstorage-down

'use strict';

var argsarray = require('argsarray');
var Queue = require('tiny-queue');

// see http://stackoverflow.com/a/15349865/680742
var nextTick = global.setImmediate || process.nextTick;

function TaskQueue() {
  this.queue = new Queue();
  this.running = false;
}

TaskQueue.prototype.add = function (fun, callback) {
  this.queue.push({fun: fun, callback: callback});
  this.processNext();
};

TaskQueue.prototype.processNext = function () {
  var self = this;
  if (self.running || !self.queue.length) {
    return;
  }
  self.running = true;

  var task = self.queue.shift();
  nextTick(function () {
    task.fun(argsarray(function (args) {
      task.callback.apply(null, args);
      self.running = false;
      self.processNext();
    }));
  });
};

module.exports = TaskQueue;