CB-8119 Restart adb when we detect it's hung

bin/templates/cordova/lib/build.js

@@ -398,6 +398,7 @@ module.exports.run = function(options, optResolvedTarget) {
  * Returns "arm" or "x86".
  */
 module.exports.detectArchitecture = function(target) {
+    function helper() {
         return exec('adb -s ' + target + ' shell cat /proc/cpuinfo')
         .then(function(output) {
             if (/intel/i.exec(output)) {
@@ -405,6 +406,37 @@ module.exports.detectArchitecture = function(target) {
             }
             return 'arm';
         });
+    }
+    // It sometimes happens (at least on OS X), that this command will hang forever.
+    // To fix it, either unplug & replug device, or restart adb server.
+    return helper().timeout(1000, 'Device communication timed out. Try unplugging & replugging the device.')
+    .then(null, function(err) {
+        if (/timed out/.exec('' + err)) {
+            // adb kill-server doesn't seem to do the trick.
+            // Could probably find a x-platform version of killall, but I'm not actually
+            // sure that this scenario even happens on non-OSX machines.
+            return exec('killall adb')
+            .then(function() {
+                console.log('adb seems hung. retrying.');
+                return helper()
+                .then(null, function() {
+                    // The double kill is sadly often necessary, at least on mac.
+                    console.log('Now device not found... restarting adb again.');
+                    return exec('killall adb')
+                    .then(function() {
+                        return helper()
+                        .then(null, function() {
+                            return Q.reject('USB is flakey. Try unplugging & replugging the device.');
+                        });
+                    });
+                });
+            }, function() {
+                // For non-killall OS's.
+                return Q.reject(err);
+            })
+        }
+        throw err;
+    });
 };
 
 module.exports.findBestApkForArchitecture = function(buildResults, arch) {

bin/templates/cordova/lib/device.js

@@ -28,8 +28,10 @@ var exec  = require('./exec'),
 
 /**
  * Returns a promise for the list of the device ID's found
+ * @param lookHarder When true, try restarting adb if no devices are found.
  */
-module.exports.list = function() {
+module.exports.list = function(lookHarder) {
+    function helper() {
         return exec('adb devices')
         .then(function(output) {
             var response = output.split('\n');
@@ -42,9 +44,27 @@ module.exports.list = function() {
             return device_list;
         });
     }
+    return helper()
+    .then(function(list) {
+        if (list.length === 0 && lookHarder) {
+            // adb kill-server doesn't seem to do the trick.
+            // Could probably find a x-platform version of killall, but I'm not actually
+            // sure that this scenario even happens on non-OSX machines.
+            return exec('killall adb')
+            .then(function() {
+                console.log('Restarting adb to see if more devices are detected.');
+                return helper();
+            }, function() {
+                // For non-killall OS's.
+                return list;
+            });
+        }
+        return list;
+    });
+}
 
 module.exports.resolveTarget = function(target) {
-    return this.list()
+    return this.list(true)
     .then(function(device_list) {
         if (!device_list || !device_list.length) {
             return Q.reject('ERROR: Failed to deploy to device, no devices found.');