Merge "[Settings] Code refactor for async Lifecycle listening" into tm-dev

src/com/android/settings/network/helper/LifecycleCallbackConverter.java

@@ -0,0 +1,132 @@
+/*
+ * Copyright (C) 2022 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 com.android.settings.network.helper;
+
+import androidx.annotation.AnyThread;
+import androidx.annotation.NonNull;
+import androidx.annotation.UiThread;
+import androidx.annotation.VisibleForTesting;
+import androidx.lifecycle.Lifecycle;
+
+import com.android.settingslib.utils.ThreadUtils;
+
+import java.util.concurrent.atomic.AtomicLong;
+import java.util.function.Consumer;
+
+/**
+ * A {@link LifecycleCallbackAdapter} which support carrying a result from any threads back to UI
+ * thread through {@link #postResult(T)}.
+ *
+ * A {@link Consumer<T>} would be invoked from UI thread for further processing on the result.
+ *
+ * Note: Result not in STARTED or RESUMED stage will be discarded silently.
+ *       This is to align with the criteria set within
+ *       {@link LifecycleCallbackAdapter#onStateChanged()}.
+ */
+@VisibleForTesting
+public class LifecycleCallbackConverter<T> extends LifecycleCallbackAdapter {
+    private static final String TAG = "LifecycleCallbackConverter";
+
+    private final Thread mUiThread;
+    private final Consumer<T> mResultCallback;
+
+    /**
+     * A record of number of active status change.
+     * Even numbers (0, 2, 4, 6 ...) are inactive status.
+     * Odd numbers (1, 3, 5, 7 ...) are active status.
+     */
+    private final AtomicLong mNumberOfActiveStatusChange = new AtomicLong();
+
+    /**
+     * Constructor
+     *
+     * @param lifecycle {@link Lifecycle} to monitor
+     * @param resultCallback for further processing the result
+     */
+    @VisibleForTesting
+    @UiThread
+    public LifecycleCallbackConverter(
+            @NonNull Lifecycle lifecycle, @NonNull Consumer<T> resultCallback) {
+        super(lifecycle);
+        mUiThread = Thread.currentThread();
+        mResultCallback = resultCallback;
+    }
+
+    /**
+     * Post a result (from any thread) back to UI thread.
+     *
+     * @param result the object ready to be passed back to {@link Consumer<T>}.
+     */
+    @AnyThread
+    @VisibleForTesting
+    public void postResult(T result) {
+        /**
+         * Since mNumberOfActiveStatusChange only increase, it is a concept of sequence number.
+         * Carry it when sending data in between different threads allow to verify if the data
+         * has arrived on time. And drop the data when expired.
+         */
+        long currentNumberOfChange = mNumberOfActiveStatusChange.get();
+        if (Thread.currentThread() == mUiThread) {
+            dispatchExtResult(currentNumberOfChange, result); // Dispatch directly
+        } else {
+            postResultToUiThread(currentNumberOfChange, result);
+        }
+    }
+
+    @AnyThread
+    protected void postResultToUiThread(long numberOfStatusChange, T result) {
+        ThreadUtils.postOnMainThread(() -> dispatchExtResult(numberOfStatusChange, result));
+    }
+
+    @UiThread
+    protected void dispatchExtResult(long numberOfStatusChange, T result) {
+        /**
+         * For a postResult() sending in between different threads, not only create a latency
+         * but also enqueued into main UI thread for dispatch.
+         *
+         * To align behavior within {@link LifecycleCallbackAdapter#onStateChanged()},
+         * some checking on both numberOfStatusChange and {@link Lifecycle} status are required.
+         */
+        if (isActiveStatus(numberOfStatusChange)
+                && (numberOfStatusChange == mNumberOfActiveStatusChange.get())
+                && getLifecycle().getCurrentState().isAtLeast(Lifecycle.State.STARTED)) {
+            mResultCallback.accept(result);
+        }
+    }
+
+    private static final boolean isActiveStatus(long numberOfStatusChange) {
+        return ((numberOfStatusChange & 1L) != 0L);
+    }
+
+    /* Implementation of LifecycleCallbackAdapter */
+    @UiThread
+    public boolean isCallbackActive() {
+        return isActiveStatus(mNumberOfActiveStatusChange.get());
+    }
+
+    /* Implementation of LifecycleCallbackAdapter */
+    @UiThread
+    public void setCallbackActive(boolean updatedActiveStatus) {
+        /**
+         * Make sure only increase when active status got changed.
+         * This is to implement the definition of mNumberOfActiveStatusChange.
+         */
+        if (isCallbackActive() != updatedActiveStatus) {
+            mNumberOfActiveStatusChange.getAndIncrement();
+        }
+    }
+}

tests/unit/src/com/android/settings/network/helper/LifecycleCallbackConverterTest.java

@@ -0,0 +1,120 @@
+/*
+ * Copyright (C) 2022 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 com.android.settings.network.helper;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import androidx.lifecycle.Lifecycle;
+import androidx.lifecycle.LifecycleOwner;
+import androidx.lifecycle.LifecycleRegistry;
+import androidx.test.ext.junit.runners.AndroidJUnit4;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import java.util.concurrent.Phaser;
+import java.util.concurrent.atomic.AtomicReference;
+import java.util.function.Consumer;
+
+@RunWith(AndroidJUnit4.class)
+public class LifecycleCallbackConverterTest implements LifecycleOwner {
+
+    private final LifecycleRegistry mRegistry = LifecycleRegistry.createUnsafe(this);
+
+    private Object mTestData;
+    private TestConsumer mConsumer;
+    private LifecycleCallbackConverter<Object> mConverter;
+
+    @Before
+    public void setUp() {
+        mTestData = new Object();
+        mConsumer = new TestConsumer();
+        mConverter = new LifecycleCallbackConverter<Object>(getLifecycle(), mConsumer);
+    }
+
+    public Lifecycle getLifecycle() {
+        return mRegistry;
+    }
+
+    @Test
+    public void converter_dropResult_whenInActive() {
+        mConverter.postResult(mTestData);
+
+        assertThat(mConsumer.getCallbackCount()).isEqualTo(0);
+    }
+
+    @Test
+    public void converter_callbackResult_whenActive() {
+        mRegistry.handleLifecycleEvent(Lifecycle.Event.ON_CREATE);
+        mRegistry.handleLifecycleEvent(Lifecycle.Event.ON_START);
+
+        mConverter.postResult(mTestData);
+        assertThat(mConsumer.getCallbackCount()).isEqualTo(1);
+        assertThat(mConsumer.getData()).isEqualTo(mTestData);
+    }
+
+    @Test
+    public void converter_dropResult_whenBackToInActive() {
+        mRegistry.handleLifecycleEvent(Lifecycle.Event.ON_CREATE);
+        mRegistry.handleLifecycleEvent(Lifecycle.Event.ON_START);
+        mRegistry.handleLifecycleEvent(Lifecycle.Event.ON_STOP);
+
+        mConverter.postResult(mTestData);
+        assertThat(mConsumer.getCallbackCount()).isEqualTo(0);
+    }
+
+    @Test
+    public void converter_passResultToUiThread_whenActive() {
+        mRegistry.handleLifecycleEvent(Lifecycle.Event.ON_CREATE);
+        mRegistry.handleLifecycleEvent(Lifecycle.Event.ON_START);
+
+        final Phaser phaser = new Phaser(1);
+        Thread executionThread = new Thread(() -> {
+            mConverter.postResult(phaser);
+        });
+        executionThread.start();
+        phaser.awaitAdvance(0);
+
+        assertThat(mConsumer.getData()).isEqualTo(phaser);
+        assertThat(mConsumer.getCallbackCount()).isEqualTo(1);
+    }
+
+    public static class TestConsumer implements Consumer<Object> {
+        long mNumberOfCallback;
+        AtomicReference<Object> mLatestData;
+
+        public TestConsumer() {
+            mLatestData = new AtomicReference<Object>();
+        }
+
+        public void accept(Object data) {
+            mLatestData.set(data);
+            mNumberOfCallback ++;
+            if ((data != null) && (data instanceof Phaser)) {
+                ((Phaser)data).arrive();
+            }
+        }
+
+        protected long getCallbackCount() {
+            return mNumberOfCallback;
+        }
+
+        protected Object getData() {
+            return mLatestData.get();
+        }
+    }
+}