Reduce LocationManager memory usage (204b1338) · Commits · e / os / android_frameworks_base

core/java/com/android/internal/listeners/ListenerTransport.java

+14 −36

Original line number	Diff line number	Diff line
		@@ -16,54 +16,43 @@

		package com.android.internal.listeners;


		import android.annotation.NonNull;
		import android.annotation.Nullable;

		import com.android.internal.util.Preconditions;

		import java.util.Objects;
		import java.util.concurrent.Executor;
		import java.util.function.Consumer;

		/**
		* A listener registration object which holds data associated with a listener, such the executor
		* the listener should run on.
		* A listener transport object which can run listener operations on an executor.
		*
		* @param <TListener> listener type
		*/
		public class ListenerTransport<TListener> {

		private final Executor mExecutor;
		public interface ListenerTransport<TListener> {

		private volatile @Nullable TListener mListener;

		protected ListenerTransport(@NonNull Executor executor, @NonNull TListener listener) {
		Preconditions.checkArgument(executor != null, "invalid null executor");
		Preconditions.checkArgument(listener != null, "invalid null listener/callback");
		mExecutor = executor;
		mListener = listener;
		}
		/**
		* Should return a valid listener until {@link #unregister()} is invoked, and must return
		* null after that. Recommended (but not required) that this is implemented via a volatile
		* variable.
		*/
		@Nullable TListener getListener();

		/**
		* Prevents any listener invocations that happen-after this call.
		* Must be implemented so that {@link #getListener()} returns null after this is invoked.
		*/
		public final void unregister() {
		mListener = null;
		}
		void unregister();

		/**
		* Executes the given operation for the listener.
		*/
		public final void execute(@NonNull Consumer<TListener> operation) {
		default void execute(Executor executor, Consumer<TListener> operation) {
		Objects.requireNonNull(operation);

		if (mListener == null) {
		if (getListener() == null) {
		return;
		}

		mExecutor.execute(() -> {
		TListener listener = mListener;
		executor.execute(() -> {
		TListener listener = getListener();
		if (listener == null) {
		return;
		}
		@@ -71,15 +60,4 @@ public class ListenerTransport<TListener> {
		operation.accept(listener);
		});
		}

		@Override
		public final boolean equals(Object obj) {
		// intentionally bound to reference equality so removal works as expected
		return this == obj;
		}

		@Override
		public final int hashCode() {
		return super.hashCode();
		}
		}

core/java/com/android/internal/listeners/ListenerTransportManager.java

0 → 100644

+97 −0

Original line number	Diff line number	Diff line
		/*
		* Copyright (C) 2020 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.internal.listeners;

		import android.os.RemoteException;

		import com.android.internal.annotations.GuardedBy;

		import java.lang.ref.WeakReference;
		import java.util.Map;
		import java.util.WeakHashMap;

		/**
		* A listener transport manager which handles mappings between the client facing listener and system
		* server facing transport. Supports transports which may be removed either from the client side or
		* from the system server side without leaking memory.
		*
		* @param <TTransport>> transport type
		*/
		public abstract class ListenerTransportManager<TTransport extends ListenerTransport<?>> {

		@GuardedBy("mRegistrations")
		private final Map<Object, WeakReference<TTransport>> mRegistrations;

		protected ListenerTransportManager() {
		// using weakhashmap means that the transport may be GCed if the server drops its reference,
		// and thus the listener may be GCed as well if the client drops that reference. if the
		// server will never drop a reference without warning (ie, transport removal may only be
		// initiated from the client side), then arraymap or similar may be used without fear of
		// memory leaks.
		mRegistrations = new WeakHashMap<>();
		}

		/**
		* Adds a new transport with the given listener key.
		*/
		public final void addListener(Object key, TTransport transport) {
		try {
		synchronized (mRegistrations) {
		// ordering of operations is important so that if an error occurs at any point we
		// are left in a reasonable state
		registerTransport(transport);
		WeakReference<TTransport> oldTransportRef = mRegistrations.put(key,
		new WeakReference<>(transport));
		if (oldTransportRef != null) {
		TTransport oldTransport = oldTransportRef.get();
		if (oldTransport != null) {
		oldTransport.unregister();
		unregisterTransport(oldTransport);
		}
		}
		}
		} catch (RemoteException e) {
		throw e.rethrowFromSystemServer();
		}
		}

		/**
		* Removes the transport with the given listener key.
		*/
		public final void removeListener(Object key) {
		try {
		synchronized (mRegistrations) {
		// ordering of operations is important so that if an error occurs at any point we
		// are left in a reasonable state
		WeakReference<TTransport> transportRef = mRegistrations.remove(key);
		if (transportRef != null) {
		TTransport transport = transportRef.get();
		if (transport != null) {
		transport.unregister();
		unregisterTransport(transport);
		}
		}
		}
		} catch (RemoteException e) {
		throw e.rethrowFromSystemServer();
		}
		}

		protected abstract void registerTransport(TTransport transport) throws RemoteException;

		protected abstract void unregisterTransport(TTransport transport) throws RemoteException;
		}

core/java/com/android/internal/listeners/ListenerTransportMultiplexer.java

deleted100644 → 0

+0 −258

Original line number	Diff line number	Diff line
		/*
		* Copyright (C) 2020 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.internal.listeners;

		import android.annotation.NonNull;
		import android.annotation.Nullable;
		import android.os.Build;
		import android.os.RemoteException;
		import android.util.ArrayMap;
		import android.util.IndentingPrintWriter;

		import com.android.internal.annotations.GuardedBy;
		import com.android.internal.util.Preconditions;

		import java.io.FileDescriptor;
		import java.util.ArrayList;
		import java.util.Collection;
		import java.util.Objects;
		import java.util.concurrent.Executor;
		import java.util.function.Consumer;

		/**
		* A listener multiplexer designed for use by client-side code. This class ensures that listeners
		* are never invoked while a lock is held. This class is only useful for multiplexing listeners -
		* if all client listeners can be combined into a single server request, and all server results will
		* be delivered to all clients.
		*
		* By default, the multiplexer will replace requests on the server simply by registering the new
		* request and trusting the server to know this is replacing the old request. If the server needs to
		* have the old request unregistered first, subclasses should override
		* {@link #reregisterWithServer(Object, Object)}.
		*
		* @param <TRequest> listener request type, may be Void
		* @param <TListener> listener type
		*/
		public abstract class ListenerTransportMultiplexer<TRequest, TListener> {

		private final Object mLock = new Object();

		@GuardedBy("mLock")
		private ArrayMap<Object, RequestListenerTransport<TRequest, TListener>> mRegistrations =
		new ArrayMap<>();

		@GuardedBy("mLock")
		private boolean mServiceRegistered = false;

		@GuardedBy("mLock")
		private TRequest mCurrentRequest;

		/**
		* Should be implemented to register the given merged request with the server.
		*
		* @see #reregisterWithServer(Object, Object)
		*/
		protected abstract void registerWithServer(TRequest mergedRequest) throws RemoteException;

		/**
		* Invoked when the server already has a request registered, and it is being replaced with a new
		* request. The default implementation simply registers the new request, trusting the server to
		* overwrite the old request.
		*/
		protected void reregisterWithServer(TRequest oldMergedRequest, TRequest mergedRequest)
		throws RemoteException {
		registerWithServer(mergedRequest);
		}

		/**
		* Should be implemented to unregister from the server.
		*/
		protected abstract void unregisterWithServer() throws RemoteException;

		/**
		* Called in order to generate a merged request from the given requests. The list of requests
		* will never be empty.
		*/
		protected @Nullable TRequest mergeRequests(Collection<TRequest> requests) {
		if (Build.IS_DEBUGGABLE) {
		for (TRequest request : requests) {
		// if using non-null requests then implementations must override this method
		Preconditions.checkState(request == null);
		}
		}

		return null;
		}

		/**
		* Adds a new listener with no request, using the listener as the key.
		*/
		public void addListener(@NonNull TListener listener, @NonNull Executor executor) {
		addListener(listener, null, listener, executor);
		}

		/**
		* Adds a new listener with the given request, using the listener as the key.
		*/
		public void addListener(@Nullable TRequest request, @NonNull TListener listener,
		@NonNull Executor executor) {
		addListener(listener, request, listener, executor);
		}

		/**
		* Adds a new listener with the given request using a custom key.
		*/
		public void addListener(@NonNull Object key, @Nullable TRequest request,
		@NonNull TListener listener, @NonNull Executor executor) {
		Objects.requireNonNull(key);
		RequestListenerTransport<TRequest, TListener> registration =
		new RequestListenerTransport<>(request, executor, listener);

		synchronized (mLock) {
		ArrayMap<Object, RequestListenerTransport<TRequest, TListener>> newRegistrations =
		new ArrayMap<>(mRegistrations.size() + 1);
		newRegistrations.putAll(mRegistrations);
		RequestListenerTransport<TRequest, TListener> old = newRegistrations.put(key,
		registration);
		mRegistrations = newRegistrations;

		if (old != null) {
		old.unregister();
		}

		updateService();
		}
		}

		/**
		* Removes the listener with the given key.
		*/
		public void removeListener(@NonNull Object key) {
		Objects.requireNonNull(key);

		synchronized (mLock) {
		if (!mRegistrations.containsKey(key)) {
		return;
		}

		ArrayMap<Object, RequestListenerTransport<TRequest, TListener>> newRegistrations =
		new ArrayMap<>(mRegistrations);
		RequestListenerTransport<TRequest, TListener> old = newRegistrations.remove(key);
		mRegistrations = newRegistrations;

		if (old != null) {
		old.unregister();
		updateService();
		}
		}
		}

		private void updateService() {
		synchronized (mLock) {
		if (mRegistrations.isEmpty()) {
		mCurrentRequest = null;
		if (mServiceRegistered) {
		try {
		mServiceRegistered = false;
		unregisterWithServer();
		} catch (RemoteException e) {
		throw e.rethrowFromSystemServer();
		}
		}
		return;
		}

		ArrayList<TRequest> requests = new ArrayList<>(mRegistrations.size());
		for (int i = 0; i < mRegistrations.size(); i++) {
		requests.add(mRegistrations.valueAt(i).getRequest());
		}

		TRequest merged = mergeRequests(requests);
		if (!mServiceRegistered \|\| !Objects.equals(merged, mCurrentRequest)) {
		TRequest old = mCurrentRequest;
		mCurrentRequest = null;
		try {
		if (mServiceRegistered) {
		// if a remote exception is thrown the service should not be registered
		mServiceRegistered = false;
		reregisterWithServer(old, merged);
		} else {
		registerWithServer(merged);
		}
		mCurrentRequest = merged;
		mServiceRegistered = true;
		} catch (RemoteException e) {
		throw e.rethrowFromSystemServer();
		}
		}
		}
		}

		protected final void deliverToListeners(Consumer<TListener> operation) {
		ArrayMap<Object, RequestListenerTransport<TRequest, TListener>> registrations;
		synchronized (mLock) {
		registrations = mRegistrations;
		}

		try {
		for (int i = 0; i < registrations.size(); i++) {
		registrations.valueAt(i).execute(operation);
		}
		} finally {
		onOperationFinished(operation);
		}
		}

		/**
		* Invoked when an operation is finished. This method will always be called once for every call
		* to {@link #deliverToListeners(Consumer)}, regardless of whether the operation encountered any
		* error or failed to execute in any way for any listeners.
		*/
		protected void onOperationFinished(@NonNull Consumer<TListener> operation) {}

		/**
		* Dumps debug information.
		*/
		public void dump(FileDescriptor fd, IndentingPrintWriter ipw, String[] args) {
		ArrayMap<Object, RequestListenerTransport<TRequest, TListener>> registrations;
		synchronized (mLock) {
		registrations = mRegistrations;

		ipw.print("service: ");
		if (mServiceRegistered) {
		if (mCurrentRequest == null) {
		ipw.print("request registered");
		} else {
		ipw.print("request registered - " + mCurrentRequest);
		}
		} else {
		ipw.print("unregistered");
		}
		ipw.println();
		}

		if (!registrations.isEmpty()) {
		ipw.println("listeners:");

		ipw.increaseIndent();
		for (int i = 0; i < registrations.size(); i++) {
		ipw.print(registrations.valueAt(i));
		}
		ipw.decreaseIndent();
		}
		}
		}

core/java/com/android/internal/listeners/RequestListenerTransport.java

deleted100644 → 0

+0 −45

Original line number	Diff line number	Diff line
		/*
		* Copyright (C) 2020 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.internal.listeners;

		import android.annotation.Nullable;

		import java.util.concurrent.Executor;

		/**
		* A listener transport with an associated request.
		*
		* @param <TRequest> request type
		* @param <TListener> listener type
		*/
		public class RequestListenerTransport<TRequest, TListener> extends ListenerTransport<TListener> {

		private final @Nullable TRequest mRequest;

		protected RequestListenerTransport(@Nullable TRequest request, Executor executor,
		TListener listener) {
		super(executor, listener);
		mRequest = request;
		}

		/**
		* Returns the request associated with this transport.
		*/
		public final @Nullable TRequest getRequest() {
		return mRequest;
		}
		}

core/tests/coretests/src/com/android/internal/listeners/ListenerTransportMultiplexerTest.java

deleted100644 → 0

+0 −194

Original line number	Diff line number	Diff line
		/*
		* Copyright (C) 2020 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.internal.listeners;

		import static com.google.common.truth.Truth.assertThat;

		import static org.mockito.Mockito.mock;
		import static org.mockito.Mockito.never;
		import static org.mockito.Mockito.times;
		import static org.mockito.Mockito.verify;

		import android.os.Handler;
		import android.os.Looper;

		import androidx.test.filters.SmallTest;
		import androidx.test.runner.AndroidJUnit4;

		import junit.framework.TestCase;

		import org.junit.Before;
		import org.junit.Test;
		import org.junit.runner.RunWith;

		import java.util.Collection;
		import java.util.Comparator;
		import java.util.concurrent.CountDownLatch;
		import java.util.concurrent.atomic.AtomicReference;

		@RunWith(AndroidJUnit4.class)
		@SmallTest
		public class ListenerTransportMultiplexerTest extends TestCase {

		TestMultiplexer mMultiplexer;

		@Before
		public void setUp() {
		mMultiplexer = new TestMultiplexer();
		}

		@Test
		public void testAdd() {
		Runnable runnable = mock(Runnable.class);

		mMultiplexer.addListener(0, runnable, Runnable::run);
		assertThat(mMultiplexer.mRegistered).isTrue();
		assertThat(mMultiplexer.mMergedRequest).isEqualTo(0);

		mMultiplexer.notifyListeners();
		verify(runnable, times(1)).run();
		}

		@Test
		public void testAdd_Multiple() {
		Runnable runnable1 = mock(Runnable.class);
		Runnable runnable2 = mock(Runnable.class);

		mMultiplexer.addListener(0, runnable1, Runnable::run);
		mMultiplexer.addListener(0, runnable2, Runnable::run);

		mMultiplexer.notifyListeners();
		verify(runnable1).run();
		verify(runnable2).run();
		}

		@Test
		public void testRemove() {
		Runnable runnable = mock(Runnable.class);

		mMultiplexer.addListener(0, runnable, Runnable::run);
		mMultiplexer.removeListener(runnable);
		assertThat(mMultiplexer.mRegistered).isFalse();

		mMultiplexer.notifyListeners();
		verify(runnable, never()).run();
		}

		@Test
		public void testRemove_Multiple() {
		Runnable runnable1 = mock(Runnable.class);
		Runnable runnable2 = mock(Runnable.class);

		mMultiplexer.addListener(0, runnable1, Runnable::run);
		mMultiplexer.addListener(1, runnable2, Runnable::run);
		mMultiplexer.removeListener(runnable1);

		mMultiplexer.notifyListeners();
		verify(runnable1, never()).run();
		verify(runnable2).run();
		}

		@Test
		public void testMergeMultiple() {
		Runnable runnable1 = mock(Runnable.class);
		Runnable runnable2 = mock(Runnable.class);
		Runnable runnable3 = mock(Runnable.class);

		mMultiplexer.addListener(0, runnable1, Runnable::run);
		mMultiplexer.addListener(1, runnable2, Runnable::run);
		assertThat(mMultiplexer.mMergedRequest).isEqualTo(1);

		mMultiplexer.notifyListeners();
		verify(runnable1, times(1)).run();
		verify(runnable2, times(1)).run();
		verify(runnable3, times(0)).run();

		mMultiplexer.addListener(0, runnable3, Runnable::run);
		assertThat(mMultiplexer.mMergedRequest).isEqualTo(1);

		mMultiplexer.notifyListeners();
		verify(runnable1, times(2)).run();
		verify(runnable2, times(2)).run();
		verify(runnable3, times(1)).run();

		mMultiplexer.removeListener(runnable2);
		assertThat(mMultiplexer.mMergedRequest).isEqualTo(0);

		mMultiplexer.notifyListeners();
		verify(runnable1, times(3)).run();
		verify(runnable2, times(2)).run();
		verify(runnable3, times(2)).run();

		mMultiplexer.removeListener(runnable1);
		mMultiplexer.removeListener(runnable3);
		mMultiplexer.notifyListeners();
		verify(runnable1, times(3)).run();
		verify(runnable2, times(2)).run();
		verify(runnable3, times(2)).run();
		}

		@Test(timeout = 5000)
		public void testReentrancy() {
		AtomicReference<Runnable> runnable = new AtomicReference<>();
		runnable.set(() -> mMultiplexer.removeListener(runnable.get()));

		mMultiplexer.addListener(0, runnable.get(), command -> {
		CountDownLatch latch = new CountDownLatch(1);
		new Handler(Looper.getMainLooper()).post(() -> {
		command.run();
		latch.countDown();
		});
		try {
		latch.await();
		} catch (InterruptedException e) {
		throw new AssertionError(e);
		}
		});

		mMultiplexer.notifyListeners();
		assertThat(mMultiplexer.mRegistered).isFalse();
		}

		private static class TestMultiplexer extends ListenerTransportMultiplexer<Integer, Runnable> {

		boolean mRegistered;
		int mMergedRequest;

		TestMultiplexer() {
		}

		public void notifyListeners() {
		deliverToListeners(Runnable::run);
		}

		@Override
		protected void registerWithServer(Integer mergedRequest) {
		mRegistered = true;
		mMergedRequest = mergedRequest;
		}

		@Override
		protected void unregisterWithServer() {
		mRegistered = false;
		}

		@Override
		protected Integer mergeRequests(Collection<Integer> requests) {
		return requests.stream().max(Comparator.naturalOrder()).get();
		}
		}
		}