Make StateMachine#handle call handler defined in root state.

Bug: 242545520
Test: atest com.android.server.wm.utils.StateMachineTest
Change-Id: I6f85afa75e30d41dfd8ed90106ce5edd819b02b9

2 files changed, 19 insertions, 6 deletions

diff --git a/services/core/java/com/android/server/wm/utils/StateMachine.java b/services/core/java/com/android/server/wm/utils/StateMachine.java
index 91a5dc43a69d..350784e64799 100644
--- a/services/core/java/com/android/server/wm/utils/StateMachine.java
+++ b/services/core/java/com/android/server/wm/utils/StateMachine.java
@@ -177,19 +177,18 @@ public class StateMachine {
     }
 
     /**
-     * Process an event. Search handler for a given event and {@link Handler#handle(int)}. If the
-     * handler cannot handle the event, delegate it to a handler for a parent of the given state.
+     * Process an event. Search handler for a given event and {@link Handler#handle(int, Object)}.
+     * If the handler cannot handle the event, delegate it to a handler for a parent of the given
+     * state.
      *
      * @param event Type of an event.
      */
     public void handle(int event, @Nullable Object param) {
-        int state = mState;
-        while (state != 0) {
+        for (int state = mState;; state >>= 4) {
             final Handler h = mStateHandlers.get(state);
-            if (h != null && h.handle(event, param)) {
+            if ((h != null && h.handle(event, param)) || state == 0) {
                 return;
             }
-            state >>= 4;
         }
     }
 
diff --git a/services/tests/wmtests/src/com/android/server/wm/utils/StateMachineTest.java b/services/tests/wmtests/src/com/android/server/wm/utils/StateMachineTest.java
index e82a7c222b8f..fb0ce56ddd2c 100644
--- a/services/tests/wmtests/src/com/android/server/wm/utils/StateMachineTest.java
+++ b/services/tests/wmtests/src/com/android/server/wm/utils/StateMachineTest.java
@@ -215,6 +215,20 @@ public class StateMachineTest {
     }
 
     @Test
+    public void testStateMachineTriggerStateActionDelegateRoot() {
+        final StringBuffer log = new StringBuffer();
+
+        StateMachine stateMachine = new StateMachine(0x2);
+        stateMachine.addStateHandler(0x0, new LoggingHandler(0x0, log));
+        stateMachine.addStateHandler(0x2,
+                new LoggingHandler(0x2, log, false /* handleSelf */));
+
+        // state 0x2 delegate the message handling to its parent state
+        stateMachine.handle(0, null);
+        assertEquals("h0;", log.toString());
+    }
+
+    @Test
     public void testStateMachineNestedTransition() {
         final StringBuffer log = new StringBuffer();