Reduce surface placement of sync group

1. setReady may be called multiples times from
WindowOrganizerController#startTransition and
DisplayContent#executeAppTransition. If the state is the same,
there is no need to request traversal.

2. When collecting a change if the group is not ready, the
visibility, config, lifecycle events and setReady=true will
trigger traversal as well.

Bug: 260059642
Test: atest SyncEngineTests
Test: Start next activity and finish current activity.
      The slice of trace "finishActivity" should not contain
      "performSurfacePlacement".
Change-Id: I8cc0c70bb8c2da504cc53379ea107c13d8bdd197

2 files changed, 15 insertions, 10 deletions

diff --git a/services/core/java/com/android/server/wm/BLASTSyncEngine.java b/services/core/java/com/android/server/wm/BLASTSyncEngine.java
index d3452277a29f..cd26e2eb9c53 100644
--- a/services/core/java/com/android/server/wm/BLASTSyncEngine.java
+++ b/services/core/java/com/android/server/wm/BLASTSyncEngine.java
@@ -226,6 +226,9 @@ class BLASTSyncEngine {
         }
 
         private void setReady(boolean ready) {
+            if (mReady == ready) {
+                return;
+            }
             ProtoLog.v(WM_DEBUG_SYNC_ENGINE, "SyncGroup %d: Set ready", mSyncId);
             mReady = ready;
             if (!ready) return;
@@ -239,7 +242,9 @@ class BLASTSyncEngine {
             ProtoLog.v(WM_DEBUG_SYNC_ENGINE, "SyncGroup %d: Adding to group: %s", mSyncId, wc);
             wc.setSyncGroup(this);
             wc.prepareSync();
-            mWm.mWindowPlacerLocked.requestTraversal();
+            if (mReady) {
+                mWm.mWindowPlacerLocked.requestTraversal();
+            }
         }
 
         void onCancelSync(WindowContainer wc) {
diff --git a/services/tests/wmtests/src/com/android/server/wm/SyncEngineTests.java b/services/tests/wmtests/src/com/android/server/wm/SyncEngineTests.java
index d3aa073c84d8..df7b3cdebe28 100644
--- a/services/tests/wmtests/src/com/android/server/wm/SyncEngineTests.java
+++ b/services/tests/wmtests/src/com/android/server/wm/SyncEngineTests.java
@@ -74,15 +74,15 @@ public class SyncEngineTests extends WindowTestsBase {
 
         int id = startSyncSet(bse, listener);
         bse.addToSyncSet(id, mockWC);
-        // Make sure a traversal is requested
-        verify(mWm.mWindowPlacerLocked, times(1)).requestTraversal();
+        // The traversal is not requested because ready is not set.
+        verify(mWm.mWindowPlacerLocked, times(0)).requestTraversal();
 
         bse.onSurfacePlacement();
         verify(listener, times(0)).onTransactionReady(anyInt(), any());
 
         bse.setReady(id);
         // Make sure a traversal is requested
-        verify(mWm.mWindowPlacerLocked, times(2)).requestTraversal();
+        verify(mWm.mWindowPlacerLocked).requestTraversal();
         bse.onSurfacePlacement();
         verify(listener, times(1)).onTransactionReady(eq(id), notNull());
 
@@ -103,14 +103,14 @@ public class SyncEngineTests extends WindowTestsBase {
         int id = startSyncSet(bse, listener);
         bse.addToSyncSet(id, mockWC);
         bse.setReady(id);
-        // Make sure traversals requested (one for add and another for setReady)
-        verify(mWm.mWindowPlacerLocked, times(2)).requestTraversal();
+        // Make sure traversals requested.
+        verify(mWm.mWindowPlacerLocked).requestTraversal();
         bse.onSurfacePlacement();
         verify(listener, times(0)).onTransactionReady(anyInt(), any());
 
         mockWC.onSyncFinishedDrawing();
-        // Make sure a (third) traversal is requested.
-        verify(mWm.mWindowPlacerLocked, times(3)).requestTraversal();
+        // Make sure the second traversal is requested.
+        verify(mWm.mWindowPlacerLocked, times(2)).requestTraversal();
         bse.onSurfacePlacement();
         verify(listener, times(1)).onTransactionReady(eq(id), notNull());
     }
@@ -127,8 +127,8 @@ public class SyncEngineTests extends WindowTestsBase {
         int id = startSyncSet(bse, listener);
         bse.addToSyncSet(id, mockWC);
         bse.setReady(id);
-        // Make sure traversals requested (one for add and another for setReady)
-        verify(mWm.mWindowPlacerLocked, times(2)).requestTraversal();
+        // Make sure traversals requested.
+        verify(mWm.mWindowPlacerLocked).requestTraversal();
         bse.onSurfacePlacement();
         verify(listener, times(0)).onTransactionReady(anyInt(), any());