Handling configuration changes at runtime instead of killing the process

Change-Id: I0c7f7e58ddb690f371c257b6142a4e918e9acb7f

src/com/android/launcher3/util/ConfigMonitor.java

@@ -29,9 +29,12 @@ import android.util.Log;
 import android.view.Display;
 import android.view.WindowManager;
 
+import com.android.launcher3.MainThreadExecutor;
+import com.android.launcher3.Utilities.Consumer;
+
 /**
  * {@link BroadcastReceiver} which watches configuration changes and
- * restarts the process in case changes which affect the device profile occur.
+ * notifies the callback in case changes which affect the device profile occur.
  */
 public class ConfigMonitor extends BroadcastReceiver implements DisplayListener {
 
@@ -48,7 +51,9 @@ public class ConfigMonitor extends BroadcastReceiver implements DisplayListener
     private final Point mRealSize;
     private final Point mSmallestSize, mLargestSize;
 
-    public ConfigMonitor(Context context) {
+    private Consumer<Context> mCallback;
+
+    public ConfigMonitor(Context context, Consumer<Context> callback) {
         mContext = context;
 
         Configuration config = context.getResources().getConfiguration();
@@ -64,6 +69,12 @@ public class ConfigMonitor extends BroadcastReceiver implements DisplayListener
         mSmallestSize = new Point();
         mLargestSize = new Point();
         display.getCurrentSizeRange(mSmallestSize, mLargestSize);
+
+        mCallback = callback;
+
+        mContext.registerReceiver(this, new IntentFilter(Intent.ACTION_CONFIGURATION_CHANGED));
+        mContext.getSystemService(DisplayManager.class)
+                .registerDisplayListener(this, new Handler(UiThreadHelper.getBackgroundLooper()));
     }
 
     @Override
@@ -71,16 +82,10 @@ public class ConfigMonitor extends BroadcastReceiver implements DisplayListener
         Configuration config = context.getResources().getConfiguration();
         if (mFontScale != config.fontScale || mDensity != config.densityDpi) {
             Log.d(TAG, "Configuration changed");
-            killProcess();
+            notifyChange();
         }
     }
 
-    public void register() {
-        mContext.registerReceiver(this, new IntentFilter(Intent.ACTION_CONFIGURATION_CHANGED));
-        mContext.getSystemService(DisplayManager.class)
-                .registerDisplayListener(this, new Handler(UiThreadHelper.getBackgroundLooper()));
-    }
-
     @Override
     public void onDisplayAdded(int displayId) { }
 
@@ -97,7 +102,7 @@ public class ConfigMonitor extends BroadcastReceiver implements DisplayListener
 
         if (!mRealSize.equals(mTmpPoint1) && !mRealSize.equals(mTmpPoint1.y, mTmpPoint1.x)) {
             Log.d(TAG, String.format("Display size changed from %s to %s", mRealSize, mTmpPoint1));
-            killProcess();
+            notifyChange();
             return;
         }
 
@@ -105,22 +110,28 @@ public class ConfigMonitor extends BroadcastReceiver implements DisplayListener
         if (!mSmallestSize.equals(mTmpPoint1) || !mLargestSize.equals(mTmpPoint2)) {
             Log.d(TAG, String.format("Available size changed from [%s, %s] to [%s, %s]",
                     mSmallestSize, mLargestSize, mTmpPoint1, mTmpPoint2));
-            killProcess();
+            notifyChange();
         }
     }
 
-    private void killProcess() {
-        Log.d(TAG, "restarting launcher");
-        try {
-            mContext.unregisterReceiver(this);
-            mContext.getSystemService(DisplayManager.class).unregisterDisplayListener(this);
-        } catch (Exception e) {
-            // We are going to die anyway, ignore any error die to race condition in registering.
+    private synchronized void notifyChange() {
+        if (mCallback != null) {
+            Consumer<Context> callback = mCallback;
+            mCallback = null;
+            new MainThreadExecutor().execute(() -> callback.accept(mContext));
         }
-        android.os.Process.killProcess(android.os.Process.myPid());
     }
 
     private Display getDefaultDisplay(Context context) {
         return context.getSystemService(WindowManager.class).getDefaultDisplay();
     }
+
+    public void unregister() {
+        try {
+            mContext.unregisterReceiver(this);
+            mContext.getSystemService(DisplayManager.class).unregisterDisplayListener(this);
+        } catch (Exception e) {
+            Log.e(TAG, "Failed to unregister config monitor", e);
+        }
+    }
 }