Merge "[Magnifier-38] Avoid deadlock causing ANR" into pi-dev

am: 285797a45a

Change-Id: I81474f04a8d33d2cf063aa0d89b7abca255d3864

core/java/android/widget/Magnifier.java

@@ -393,6 +393,12 @@ public final class Magnifier {
         private int mWindowPositionY;
         private boolean mPendingWindowPositionUpdate;
 
+        // The lock used to synchronize the UI and render threads when a #destroy
+        // is performed on the UI thread and a frame callback on the render thread.
+        // When both mLock and mDestroyLock need to be held at the same time,
+        // mDestroyLock should be acquired before mLock in order to avoid deadlocks.
+        private final Object mDestroyLock = new Object();
+
         InternalPopupWindow(final Context context, final Display display,
                 final Surface parentSurface,
                 final int width, final int height, final float elevation, final float cornerRadius,
@@ -517,9 +523,11 @@ public final class Magnifier {
          * Destroys this instance.
          */
         public void destroy() {
+            synchronized (mDestroyLock) {
+                mSurface.destroy();
+            }
             synchronized (mLock) {
                 mRenderer.destroy();
-                mSurface.destroy();
                 mSurfaceControl.destroy();
                 mSurfaceSession.kill();
                 mBitmapRenderNode.destroy();
@@ -567,10 +575,11 @@ public final class Magnifier {
                     final int pendingY = mWindowPositionY;
 
                     callback = frame -> {
-                        synchronized (mLock) {
+                        synchronized (mDestroyLock) {
                             if (!mSurface.isValid()) {
                                 return;
                             }
+                            synchronized (mLock) {
                                 mRenderer.setLightCenter(mDisplay, pendingX, pendingY);
                                 // Show or move the window at the content draw frame.
                                 SurfaceControl.openTransaction();
@@ -583,6 +592,7 @@ public final class Magnifier {
                                 }
                                 SurfaceControl.closeTransaction();
                             }
+                        }
                     };
                 } else {
                     callback = null;