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Commit b39eb56d authored by Shan Huang's avatar Shan Huang
Browse files

Fix IME callback being unexpectedly garbage-collected and breaking back 

gesture.

Bug: 266528689
Test: Open GMail, Calendar, Launcher, find UI surfaces to bring up IME,
then swipe back. Repeat in different combinations of the steps and make
sure back always works.
Test: atest WindowOnBackInvokedDispatcherTest

Change-Id: I0cba6d6963c6b988f02a7baf56f2901d17b5c9b3
parent 4f767358

core/java/android/window/ImeOnBackInvokedDispatcher.java

+6 −1
Original line number Diff line number Diff line
@@ -82,8 +82,13 @@ public class ImeOnBackInvokedDispatcher implements OnBackInvokedDispatcher, Parc 
            @NonNull OnBackInvokedCallback callback) {

        final Bundle bundle = new Bundle();

        // Always invoke back for ime without checking the window focus.

        // We use strong reference in the binder wrapper to avoid accidentally GC the callback.

        // This is necessary because the callback is sent to and registered from

        // the app process, which may treat the IME callback as weakly referenced. This will not

        // cause a memory leak because the app side already clears the reference correctly.

        final IOnBackInvokedCallback iCallback =

                new WindowOnBackInvokedDispatcher.OnBackInvokedCallbackWrapper(callback);

                new WindowOnBackInvokedDispatcher.OnBackInvokedCallbackWrapper(

                        callback, false /* useWeakRef */);

        bundle.putBinder(RESULT_KEY_CALLBACK, iCallback.asBinder());

        bundle.putInt(RESULT_KEY_PRIORITY, priority);

        bundle.putInt(RESULT_KEY_ID, callback.hashCode());

core/java/android/window/WindowOnBackInvokedDispatcher.java

+29 −4
Original line number Diff line number Diff line
@@ -233,10 +233,34 @@ public class WindowOnBackInvokedDispatcher implements OnBackInvokedDispatcher { 
    }



    static class OnBackInvokedCallbackWrapper extends IOnBackInvokedCallback.Stub {

        private final WeakReference<OnBackInvokedCallback> mCallback;

        static class CallbackRef {

            final WeakReference<OnBackInvokedCallback> mWeakRef;

            final OnBackInvokedCallback mStrongRef;

            CallbackRef(@NonNull OnBackInvokedCallback callback, boolean useWeakRef) {

                if (useWeakRef) {

                    mWeakRef = new WeakReference<>(callback);

                    mStrongRef = null;

                } else {

                    mStrongRef = callback;

                    mWeakRef = null;

                }

            }



            OnBackInvokedCallback get() {

                if (mStrongRef != null) {

                    return mStrongRef;

                }

                return mWeakRef.get();

            }

        }

        final CallbackRef mCallbackRef;



        OnBackInvokedCallbackWrapper(@NonNull OnBackInvokedCallback callback) {

            mCallback = new WeakReference<>(callback);

            mCallbackRef = new CallbackRef(callback, true /* useWeakRef */);

        }



        OnBackInvokedCallbackWrapper(@NonNull OnBackInvokedCallback callback, boolean useWeakRef) {

            mCallbackRef = new CallbackRef(callback, useWeakRef);

        }



        @Override
@@ -279,8 +303,9 @@ public class WindowOnBackInvokedDispatcher implements OnBackInvokedDispatcher { 
        public void onBackInvoked() throws RemoteException {

            Handler.getMain().post(() -> {

                mProgressAnimator.reset();

                final OnBackInvokedCallback callback = mCallback.get();

                final OnBackInvokedCallback callback = mCallbackRef.get();

                if (callback == null) {

                    Log.d(TAG, "Trying to call onBackInvoked() on a null callback reference.");

                    return;

                }

                callback.onBackInvoked();
@@ -289,7 +314,7 @@ public class WindowOnBackInvokedDispatcher implements OnBackInvokedDispatcher { 


        @Nullable

        private OnBackAnimationCallback getBackAnimationCallback() {

            OnBackInvokedCallback callback = mCallback.get();

            OnBackInvokedCallback callback = mCallbackRef.get();

            return callback instanceof OnBackAnimationCallback ? (OnBackAnimationCallback) callback

                    : null;

        }