Using Async.queue to queue commands

lib/devices/android/android.js

@@ -42,8 +42,7 @@ Android.prototype.init = function () {
   this.args.devicePort = 4724;
   this.appMd5Hash = null;
   this.args.avd = null;
-  this.queue = [];
-  this.progress = 0;
+  this.initQueue();
   this.implicitWaitMs = 0;
   this.shuttingDown = false;
   this.adb = null;
@@ -89,7 +88,6 @@ Android.prototype.start = function (cb, onDie) {
     this.uiautomator.setExitHandler(this.onUiautomatorExit.bind(this));
 
     logger.debug("Using fast reset? " + this.args.fastReset);
-
     async.series([
       this.prepareDevice.bind(this),
       this.packageAndLaunchActivityFromManifest.bind(this),
@@ -387,8 +385,6 @@ Android.prototype.stop = function (cb) {
 
 Android.prototype.cleanup = function () {
   logger.info("Cleaning up android objects");
-  this.queue = [];
-  this.progress = 0;
   this.adb = null;
   this.uiautomator = null;
   this.shuttingDown = false;
@@ -422,43 +418,19 @@ Android.prototype.shutdown = function (cb) {
 Android.prototype.proxy = deviceCommon.proxy;
 Android.prototype.respond = deviceCommon.respond;
 
-Android.prototype.push = function (elem) {
-  this.queue.push(elem);
-
-  var next = function () {
-    if (this.queue.length <= 0) {
-      return;
-    }
-
-    if (this.queue[0] === null) {
-      this.queue.shift();
-      return;
-    }
-
-    // Always send the command.
-    if (this.progress > 0) {
-      this.progress = 0;
-    }
-
-    var target = this.queue.shift()
-      , action = target[0][0]
-      , params = typeof target[0][1] === "undefined" ? {} : target[0][1]
-      , cb = target[1];
+Android.prototype.initQueue = function () {
+  this.queue = async.queue(function (task, cb) {
+    var action = task.action,
+        params = task.params;
 
     this.cbForCurrentCmd = cb;
 
-    this.progress++;
-
     if (this.adb && !this.shuttingDown) {
       this.uiautomator.sendAction(action, params, function (response) {
         this.cbForCurrentCmd = null;
         if (typeof cb === 'function') {
           this.respond(response, cb);
         }
-
-        // maybe there's moar work to do
-        this.progress--;
-        next();
       }.bind(this));
     } else {
       this.cbForCurrentCmd = null;
@@ -468,17 +440,16 @@ Android.prototype.push = function (elem) {
         msg = "We're in the middle of shutting down the Android device, " +
               "so your request won't be executed. Sorry!";
       }
-
       this.respond({
         status: status.codes.UnknownError.code
       , value: msg
       }, cb);
-      this.progress--;
-      next();
-    }
-  }.bind(this);
+    }    
+  }.bind(this), 1);
+};
 
-  next();
+Android.prototype.push = function (elem) {
+  this.queue.push({action:elem[0][0], params:elem[0][1] || {}}, elem[1]);
 };
 
 Android.prototype.wakeUp = function (cb) {