Synchronize window config updates (2/n)

Introduce ClientTransactionListenerController to keep track of the
registered listeners.

Bug: 260873529
Test: ClientTransactionListenerControllerTest
Change-Id: I98a7fddda24ef74a5f894e9d769456e0ba1993d0

3 files changed, 222 insertions, 1 deletions

diff --git a/core/java/android/app/servertransaction/ClientTransactionListenerController.java b/core/java/android/app/servertransaction/ClientTransactionListenerController.java
new file mode 100644
index 000000000000..e2aee839b0c3
--- /dev/null
+++ b/core/java/android/app/servertransaction/ClientTransactionListenerController.java
@@ -0,0 +1,142 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.app.servertransaction;
+
+import static com.android.window.flags.Flags.syncWindowConfigUpdateFlag;
+
+import static java.util.Objects.requireNonNull;
+
+import android.annotation.CallbackExecutor;
+import android.annotation.NonNull;
+import android.os.Process;
+import android.util.ArrayMap;
+
+import com.android.internal.annotations.GuardedBy;
+import com.android.internal.annotations.VisibleForTesting;
+
+import java.util.ArrayList;
+import java.util.concurrent.Executor;
+import java.util.function.IntConsumer;
+
+/**
+ * Singleton controller to manage listeners to individual {@link ClientTransaction}.
+ *
+ * TODO(b/260873529) make as TestApi to allow CTS.
+ * @hide
+ */
+public class ClientTransactionListenerController {
+
+    private static ClientTransactionListenerController sController;
+
+    private final Object mLock = new Object();
+
+    /**
+     * Mapping from client registered listener for display change to the corresponding
+     * {@link Executor} to invoke the listener on.
+     * @see #registerDisplayChangeListener(IntConsumer, Executor)
+     */
+    @GuardedBy("mLock")
+    private final ArrayMap<IntConsumer, Executor> mDisplayChangeListeners = new ArrayMap<>();
+
+    private final ArrayList<IntConsumer> mTmpDisplayChangeListeners = new ArrayList<>();
+
+    /** Gets the singleton controller. */
+    @NonNull
+    public static ClientTransactionListenerController getInstance() {
+        synchronized (ClientTransactionListenerController.class) {
+            if (sController == null) {
+                sController = new ClientTransactionListenerController();
+            }
+            return sController;
+        }
+    }
+
+    /** Creates a new instance for test only. */
+    @VisibleForTesting
+    @NonNull
+    public static ClientTransactionListenerController createInstanceForTesting() {
+        return new ClientTransactionListenerController();
+    }
+
+    private ClientTransactionListenerController() {}
+
+    /**
+     * Registers a new listener for display change. It will be invoked when receives a
+     * {@link ClientTransaction} that is updating display-related window configuration, such as
+     * bounds and rotation.
+     *
+     * WHen triggered, the listener will be invoked with the logical display id that was changed.
+     *
+     * @param listener the listener to invoke when receives a transaction with Display change.
+     * @param executor the executor on which callback method will be invoked.
+     */
+    public void registerDisplayChangeListener(@NonNull IntConsumer listener,
+            @NonNull @CallbackExecutor Executor executor) {
+        if (!isSyncWindowConfigUpdateFlagEnabled()) {
+            return;
+        }
+        requireNonNull(listener);
+        requireNonNull(executor);
+        synchronized (mLock) {
+            mDisplayChangeListeners.put(listener, executor);
+        }
+    }
+
+    /**
+     * Unregisters the listener for display change that was previously registered through
+     * {@link #registerDisplayChangeListener}.
+     */
+    public void unregisterDisplayChangeListener(@NonNull IntConsumer listener) {
+        if (!isSyncWindowConfigUpdateFlagEnabled()) {
+            return;
+        }
+        synchronized (mLock) {
+            mDisplayChangeListeners.remove(listener);
+        }
+    }
+
+    /**
+     * Called when receives a {@link ClientTransaction} that is updating display-related
+     * window configuration.
+     */
+    public void onDisplayChanged(int displayId) {
+        if (!isSyncWindowConfigUpdateFlagEnabled()) {
+            return;
+        }
+        synchronized (mLock) {
+            // Make a copy of the list to avoid listener removal during callback.
+            mTmpDisplayChangeListeners.addAll(mDisplayChangeListeners.keySet());
+            final int num = mTmpDisplayChangeListeners.size();
+            try {
+                for (int i = 0; i < num; i++) {
+                    final IntConsumer listener = mTmpDisplayChangeListeners.get(i);
+                    final Executor executor = mDisplayChangeListeners.get(listener);
+                    executor.execute(() -> listener.accept(displayId));
+                }
+            } finally {
+                mTmpDisplayChangeListeners.clear();
+            }
+        }
+    }
+
+    /** Whether {@link #syncWindowConfigUpdateFlag} feature flag is enabled. */
+    @VisibleForTesting
+    public boolean isSyncWindowConfigUpdateFlagEnabled() {
+        // Can't read flag from isolated process.
+        return !Process.isIsolated() && syncWindowConfigUpdateFlag();
+    }
+}
diff --git a/core/java/android/app/servertransaction/TransactionExecutor.java b/core/java/android/app/servertransaction/TransactionExecutor.java
index 09a9ab326ef7..d080162e4b8c 100644
--- a/core/java/android/app/servertransaction/TransactionExecutor.java
+++ b/core/java/android/app/servertransaction/TransactionExecutor.java
@@ -184,9 +184,12 @@ public class TransactionExecutor {
         }
 
         if (configUpdatedDisplays != null) {
+            final ClientTransactionListenerController controller =
+                    ClientTransactionListenerController.getInstance();
             final int displayCount = configUpdatedDisplays.size();
             for (int i = 0; i < displayCount; i++) {
-                // TODO(b/260873529): trigger onDisplayChanged.
+                final int displayId = configUpdatedDisplays.valueAt(i);
+                controller.onDisplayChanged(displayId);
             }
         }
     }
diff --git a/core/tests/coretests/src/android/app/servertransaction/ClientTransactionListenerControllerTest.java b/core/tests/coretests/src/android/app/servertransaction/ClientTransactionListenerControllerTest.java
new file mode 100644
index 000000000000..0f62b1c23ab4
--- /dev/null
+++ b/core/tests/coretests/src/android/app/servertransaction/ClientTransactionListenerControllerTest.java
@@ -0,0 +1,76 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.app.servertransaction;
+
+import static org.mockito.ArgumentMatchers.anyInt;
+import static org.mockito.Mockito.clearInvocations;
+import static org.mockito.Mockito.doReturn;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.spy;
+import static org.mockito.Mockito.verify;
+
+import android.platform.test.annotations.Presubmit;
+
+import androidx.test.filters.SmallTest;
+import androidx.test.runner.AndroidJUnit4;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+
+import java.util.function.IntConsumer;
+
+/**
+ * Tests for {@link ClientTransactionListenerController}.
+ *
+ * Build/Install/Run:
+ *  atest FrameworksCoreTests:ClientTransactionListenerControllerTest
+ */
+@RunWith(AndroidJUnit4.class)
+@SmallTest
+@Presubmit
+public class ClientTransactionListenerControllerTest {
+    @Mock
+    private IntConsumer mDisplayChangeListener;
+
+    private ClientTransactionListenerController mController;
+
+    @Before
+    public void setup() {
+        MockitoAnnotations.initMocks(this);
+        mController = spy(ClientTransactionListenerController.createInstanceForTesting());
+        doReturn(true).when(mController).isSyncWindowConfigUpdateFlagEnabled();
+    }
+
+    @Test
+    public void testRegisterDisplayChangeListener() {
+        mController.registerDisplayChangeListener(mDisplayChangeListener, Runnable::run);
+
+        mController.onDisplayChanged(123);
+
+        verify(mDisplayChangeListener).accept(123);
+
+        clearInvocations(mDisplayChangeListener);
+        mController.unregisterDisplayChangeListener(mDisplayChangeListener);
+
+        mController.onDisplayChanged(321);
+
+        verify(mDisplayChangeListener, never()).accept(anyInt());
+    }
+}