Reduce battery usage - Unregister callbacks onStop

src/main/scala/com/github/shadowsocks/ProfileManagerActivity.scala

@@ -218,6 +218,15 @@ class ProfileManagerActivity extends AppCompatActivity with OnMenuItemClickListe
     }
   }
 
+  override def onStart() {
+    super.onStart()
+    registerCallback
+  }
+  override def onStop() {
+    super.onStop()
+    unregisterCallback
+  }
+
   override def onDestroy {
     deattachService()
     super.onDestroy

src/main/scala/com/github/shadowsocks/ServiceBoundContext.scala

@@ -13,20 +13,12 @@ trait ServiceBoundContext extends Context {
   class ShadowsocksServiceConnection extends ServiceConnection {
     override def onServiceConnected(name: ComponentName, service: IBinder) {
       bgService = IShadowsocksService.Stub.asInterface(service)
-      if (callback != null) try {
-        bgService.registerCallback(callback)
-      } catch {
-        case ignored: RemoteException => // Nothing
-      }
+      registerCallback
       ServiceBoundContext.this.onServiceConnected()
     }
     override def onServiceDisconnected(name: ComponentName) {
       if (callback != null) {
-        try {
-          if (bgService != null) bgService.unregisterCallback(callback)
-        } catch {
-          case ignored: RemoteException => // Nothing
-        }
+        unregisterCallback
         callback = null
       }
       ServiceBoundContext.this.onServiceDisconnected()
@@ -34,11 +26,25 @@ trait ServiceBoundContext extends Context {
     }
   }
 
+  def registerCallback = if (bgService != null && callback != null && !callbackRegistered) try {
+    bgService.registerCallback(callback)
+    callbackRegistered = true
+  } catch {
+    case ignored: RemoteException => // Nothing
+  }
+  def unregisterCallback = if (bgService != null && callback != null && callbackRegistered) try {
+    bgService.unregisterCallback(callback)
+    callbackRegistered = false
+  } catch {
+    case ignored: RemoteException => // Nothing
+  }
+
   def onServiceConnected() = ()
   def onServiceDisconnected() = ()
 
   private var callback: IShadowsocksServiceCallback.Stub = _
   private var connection: ShadowsocksServiceConnection = _
+  private var callbackRegistered: Boolean = _
 
   // Variables
   var bgService: IShadowsocksService = _
@@ -60,11 +66,7 @@ trait ServiceBoundContext extends Context {
   def deattachService() {
     if (bgService != null) {
       if (callback != null) {
-        try {
-          bgService.unregisterCallback(callback)
-        } catch {
-          case ignored: RemoteException => // Nothing
-        }
+        unregisterCallback
         callback = null
       }
       if (connection != null) {

src/main/scala/com/github/shadowsocks/Shadowsocks.scala

@@ -461,8 +461,13 @@ class Shadowsocks
     preferences.update(profile)
   }
 
+  override def onStart() {
+    super.onStart()
+    registerCallback
+  }
   override def onStop() {
     super.onStop()
+    unregisterCallback
     clearDialog()
   }