Signal dream end to overlay in finish().

Originally, the dream service signaled its exit to the overlay when
the window detaches. However, there are other flows where it's possible
for the dream to initiate exiting before this point. In this case, the
teardown will begin and a race condition will exist between signaling
to the overlay and stopping the dream process.

This changelist addresses this by placing the exit signal to the
overlay in finish. Proceeding through finish is deferred until this
signal is sent, ensuring the overlay is always informed.

Fixes: 265920994
Test: atest DreamOverlayTest
Change-Id: I1a07d3839979d37599c1e053d8715340b5c4830c

1 files changed, 22 insertions, 15 deletions

diff --git a/core/java/android/service/dreams/DreamService.java b/core/java/android/service/dreams/DreamService.java
index d3788862b6c0..cbe1ded3b2df 100644
--- a/core/java/android/service/dreams/DreamService.java
+++ b/core/java/android/service/dreams/DreamService.java
@@ -1050,6 +1050,24 @@ public class DreamService extends Service implements Window.Callback {
      * </p>
      */
     public final void finish() {
+        // If there is an active overlay connection, signal that the dream is ending before
+        // continuing. Note that the overlay cannot rely on the unbound state, since another dream
+        // might have bound to it in the meantime.
+        if (mOverlayConnection != null) {
+            mOverlayConnection.addConsumer(overlay -> {
+                try {
+                    overlay.endDream();
+                    mOverlayConnection.unbind();
+                    mOverlayConnection = null;
+                    finish();
+                } catch (RemoteException e) {
+                    Log.e(mTag, "could not inform overlay of dream end:" + e);
+                }
+            });
+            mOverlayConnection.clearConsumers();
+            return;
+        }
+
         if (mDebug) Slog.v(mTag, "finish(): mFinished=" + mFinished);
 
         Activity activity = mActivity;
@@ -1066,10 +1084,6 @@ public class DreamService extends Service implements Window.Callback {
         }
         mFinished = true;
 
-        if (mOverlayConnection != null) {
-            mOverlayConnection.unbind();
-        }
-
         if (mDreamToken == null) {
             if (mDebug) Slog.v(mTag, "finish() called when not attached.");
             stopSelf();
@@ -1389,17 +1403,6 @@ public class DreamService extends Service implements Window.Callback {
 
                     @Override
                     public void onViewDetachedFromWindow(View v) {
-                        if (mOverlayConnection != null) {
-                            mOverlayConnection.addConsumer(overlay -> {
-                                try {
-                                    overlay.endDream();
-                                } catch (RemoteException e) {
-                                    Log.e(mTag, "could not inform overlay of dream end:" + e);
-                                }
-                            });
-                            mOverlayConnection.clearConsumers();
-                        }
-
                         if (mActivity == null || !mActivity.isChangingConfigurations()) {
                             // Only stop the dream if the view is not detached by relaunching
                             // activity for configuration changes. It is important to also clear
@@ -1408,6 +1411,10 @@ public class DreamService extends Service implements Window.Callback {
                             mActivity = null;
                             finish();
                         }
+
+                        if (mOverlayConnection != null && mDreamStartOverlayConsumer != null) {
+                            mOverlayConnection.removeConsumer(mDreamStartOverlayConsumer);
+                        }
                     }
                 });
     }