Merge "[Settings] Code refactor for Lifecycle listening"

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

@@ -0,0 +1,100 @@
+/*
+ * 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.MainThread;
+import androidx.annotation.NonNull;
+import androidx.annotation.VisibleForTesting;
+import androidx.lifecycle.Lifecycle;
+import androidx.lifecycle.LifecycleEventObserver;
+import androidx.lifecycle.LifecycleOwner;
+
+import java.util.concurrent.atomic.AtomicReference;
+
+/**
+ * A {@link androidx.lifecycle.LifecycleObserver} implementation of adapter over callback.
+ *
+ * Which including:
+ * 1. Request to active callback when Lifecycle.State.STARTED
+ * 2. Request to inactive callback when Lifecycle.State.STOPPED
+ * 3. Close (no further resume) when Lifecycle.State.DESTROYED
+ */
+@VisibleForTesting
+abstract class LifecycleCallbackAdapter implements LifecycleEventObserver, AutoCloseable {
+    private static final String TAG = "LifecycleCallbackAdapter";
+    private AtomicReference<Lifecycle> mLifecycle = new AtomicReference<Lifecycle>();
+
+    /**
+     * Constructor
+     * @param lifecycle {@link Lifecycle} to monitor
+     */
+    @VisibleForTesting
+    protected LifecycleCallbackAdapter(@NonNull Lifecycle lifecycle) {
+        mLifecycle.set(lifecycle);
+        lifecycle.addObserver(this);
+    }
+
+    /**
+     * Get {@link Lifecycle} under monitor.
+     * @return {@link Lifecycle}. Return {@code null} when closed.
+     */
+    @VisibleForTesting
+    public Lifecycle getLifecycle() {
+        return mLifecycle.get();
+    }
+
+    /**
+     * Check current callback status.
+     * @return true when callback is active.
+     */
+    public abstract boolean isCallbackActive();
+
+    /**
+     * Change callback status.
+     * @param isActive true to active callback, otherwise inactive.
+     */
+    public abstract void setCallbackActive(boolean isActive);
+
+    /**
+     * Implementation of LifecycleEventObserver.
+     */
+    public void onStateChanged(LifecycleOwner source, Lifecycle.Event event) {
+        if (mLifecycle.get() == null) {
+            return;
+        }
+
+        Lifecycle.State state = event.getTargetState();
+        boolean expectCallbackActive = state.isAtLeast(Lifecycle.State.STARTED);
+        if (expectCallbackActive != isCallbackActive()) {
+            setCallbackActive(expectCallbackActive);
+        }
+        if (state == Lifecycle.State.DESTROYED) {
+            close();
+        }
+    }
+
+    /**
+     * Implementation of AutoCloseable.
+     */
+    @MainThread
+    public void close() {
+        Lifecycle lifecycle = mLifecycle.getAndSet(null);
+        if (lifecycle != null) {
+            lifecycle.removeObserver(this);
+        }
+    }
+}

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

@@ -0,0 +1,111 @@
+/*
+ * 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;
+
+@RunWith(AndroidJUnit4.class)
+public class LifecycleCallbackAdapterTest implements LifecycleOwner {
+
+    private final LifecycleRegistry mRegistry = LifecycleRegistry.createUnsafe(this);
+
+    private TestObj mTarget;
+
+    @Before
+    public void setUp() {
+        mTarget = new TestObj(getLifecycle());
+    }
+
+    public Lifecycle getLifecycle() {
+        return mRegistry;
+    }
+
+    @Test
+    public void lifecycle_get_lifecycleToMonitor() {
+        assertThat(mTarget.getLifecycle()).isEqualTo(mRegistry);
+    }
+
+    @Test
+    public void lifecycle_stateChangeToStart_callbackActive() {
+        mRegistry.handleLifecycleEvent(Lifecycle.Event.ON_CREATE);
+
+        assertThat(mTarget.getCallbackCount()).isEqualTo(0);
+        assertThat(mTarget.isCallbackActive()).isEqualTo(Boolean.FALSE);
+
+        mRegistry.handleLifecycleEvent(Lifecycle.Event.ON_START);
+
+        assertThat(mTarget.getCallbackCount()).isEqualTo(1);
+        assertThat(mTarget.isCallbackActive()).isEqualTo(Boolean.TRUE);
+    }
+
+    @Test
+    public void lifecycle_stateChangeToStop_callbackInActive() {
+        mRegistry.handleLifecycleEvent(Lifecycle.Event.ON_CREATE);
+        mRegistry.handleLifecycleEvent(Lifecycle.Event.ON_START);
+        mRegistry.handleLifecycleEvent(Lifecycle.Event.ON_STOP);
+
+        assertThat(mTarget.getCallbackCount()).isEqualTo(2);
+        assertThat(mTarget.isCallbackActive()).isEqualTo(Boolean.FALSE);
+    }
+
+    @Test
+    public void lifecycle_stateChangeToDestroy_noFurtherActive() {
+        mRegistry.handleLifecycleEvent(Lifecycle.Event.ON_CREATE);
+        mRegistry.handleLifecycleEvent(Lifecycle.Event.ON_START);
+        mRegistry.handleLifecycleEvent(Lifecycle.Event.ON_STOP);
+        mRegistry.handleLifecycleEvent(Lifecycle.Event.ON_DESTROY);
+
+        assertThat(mTarget.getCallbackCount()).isEqualTo(2);
+        assertThat(mTarget.isCallbackActive()).isEqualTo(Boolean.FALSE);
+
+        mRegistry.handleLifecycleEvent(Lifecycle.Event.ON_CREATE);
+        mRegistry.handleLifecycleEvent(Lifecycle.Event.ON_START);
+
+        assertThat(mTarget.getCallbackCount()).isEqualTo(2);
+        assertThat(mTarget.isCallbackActive()).isEqualTo(Boolean.FALSE);
+    }
+
+    public static class TestObj extends LifecycleCallbackAdapter {
+        boolean mIsActive;
+        int mNumberOfCallback;
+
+        public TestObj(Lifecycle lifecycle) {
+            super(lifecycle);
+        }
+
+        public boolean isCallbackActive() {
+            return mIsActive;
+        }
+
+        public void setCallbackActive(boolean isActive) {
+            mIsActive = isActive;
+            mNumberOfCallback ++;
+        }
+
+        protected int getCallbackCount() {
+            return mNumberOfCallback;
+        }
+    }
+}