Merge "Add CancellationSignalBeamer" into udc-dev
This commit is contained in:
Adrian Roos
325
core/java/android/os/CancellationSignalBeamer.java
Normal file
325
core/java/android/os/CancellationSignalBeamer.java
Normal file
@@ -0,0 +1,325 @@
|
||||
/*
|
||||
* 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 android.os;
|
||||
|
||||
import android.annotation.NonNull;
|
||||
import android.annotation.Nullable;
|
||||
import android.system.SystemCleaner;
|
||||
|
||||
import java.lang.ref.Cleaner;
|
||||
import java.lang.ref.Reference;
|
||||
import java.util.HashMap;
|
||||
|
||||
/**
|
||||
* A transport for {@link CancellationSignal}, but unlike
|
||||
* {@link CancellationSignal#createTransport()} doesn't require pre-creating the transport in the
|
||||
* target process. Instead, cancellation is forwarded over the same IPC surface as the cancellable
|
||||
* request.
|
||||
*
|
||||
* <p><strong>Important:</strong> For this to work, the following invariants must be held up:
|
||||
* <ul>
|
||||
* <li>A call to beam() <strong>MUST</strong> result in a call to close() on the result
|
||||
* (otherwise, the token will be leaked and cancellation isn't propagated), and that call
|
||||
* must happen after the call using the
|
||||
* token is sent (otherwise, any concurrent cancellation may be lost). It is strongly
|
||||
* recommended to use try-with-resources on the token.
|
||||
* <li>The cancel(), forget() and cancellable operations transporting the token must either
|
||||
* all be oneway on the same binder, or all be non-oneway to guarantee proper ordering.
|
||||
* <li>A {@link CancellationSignal} <strong>SHOULD</strong> be used only once, as there
|
||||
* can only be a single {@link android.os.CancellationSignal.OnCancelListener OnCancelListener}.
|
||||
*
|
||||
* </ul>
|
||||
* <p>Caveats:
|
||||
* <ul>
|
||||
* <li>Cancellation is only ever dispatched after the token is closed, and thus after the
|
||||
* call performing the cancellable operation (if the invariants are followed). The operation
|
||||
* must therefore not block the incoming binder thread, or cancellation won't be possible.
|
||||
* <li>Consequently, in the unlikely event that the sender dies right after beaming an already
|
||||
* cancelled {@link CancellationSignal}, the cancellation may be lost (unlike with
|
||||
* {@link CancellationSignal#createTransport()}).
|
||||
* <li>The forwarding OnCancelListener is set in the implied finally phase of try-with-resources
|
||||
* / when closing the token. If the receiver is in the same process, and the signal is
|
||||
* already cancelled, this may invoke the target's OnCancelListener during that phase.
|
||||
* </ul>
|
||||
*
|
||||
*
|
||||
* <p>Usage:
|
||||
* <pre>
|
||||
* // Sender:
|
||||
*
|
||||
* class FooManager {
|
||||
* var mCancellationSignalSender = new CancellationSignalBeamer.Sender() {
|
||||
* @Override
|
||||
* public void onCancel(IBinder token) { remoteIFooService.onCancelToken(token); }
|
||||
*
|
||||
* @Override
|
||||
* public void onForget(IBinder token) { remoteIFooService.onForgetToken(token); }
|
||||
* };
|
||||
*
|
||||
* public void doCancellableOperation(..., CancellationSignal cs) {
|
||||
* try (var csToken = mCancellationSignalSender.beam(cs)) {
|
||||
* remoteIFooService.doCancellableOperation(..., csToken);
|
||||
* }
|
||||
* }
|
||||
* }
|
||||
*
|
||||
* // Receiver:
|
||||
*
|
||||
* class FooManagerService extends IFooService.Stub {
|
||||
* var mCancellationSignalReceiver = new CancellationSignalBeamer.Receiver();
|
||||
*
|
||||
* @Override
|
||||
* public void doCancellableOperation(..., IBinder csToken) {
|
||||
* CancellationSignal cs = mCancellationSignalReceiver.unbeam(csToken))
|
||||
* // ...
|
||||
* }
|
||||
*
|
||||
* @Override
|
||||
* public void onCancelToken(..., IBinder csToken) {
|
||||
* mCancellationSignalReceiver.cancelToken(csToken))
|
||||
* }
|
||||
*
|
||||
* @Override
|
||||
* public void onForgetToken(..., IBinder csToken) {
|
||||
* mCancellationSignalReceiver.forgetToken(csToken))
|
||||
* }
|
||||
* }
|
||||
*
|
||||
* </pre>
|
||||
*
|
||||
* @hide
|
||||
*/
|
||||
public class CancellationSignalBeamer {
|
||||
|
||||
static final Cleaner sCleaner = SystemCleaner.cleaner();
|
||||
|
||||
/** The sending side of an {@link CancellationSignalBeamer} */
|
||||
public abstract static class Sender {
|
||||
|
||||
/**
|
||||
* Beams a {@link CancellationSignal} through an existing Binder interface.
|
||||
*
|
||||
* @param cs the {@code CancellationSignal} to beam, or {@code null}.
|
||||
* @return an {@link IBinder} token. MUST be {@link CloseableToken#close}d <em>after</em>
|
||||
* the binder call transporting it to the remote process, best with
|
||||
* try-with-resources. {@code null} if {@code cs} was {@code null}.
|
||||
*/
|
||||
// TODO(b/254888024): @MustBeClosed
|
||||
@Nullable
|
||||
public CloseableToken beam(@Nullable CancellationSignal cs) {
|
||||
if (cs == null) {
|
||||
return null;
|
||||
}
|
||||
return new Token(this, cs);
|
||||
}
|
||||
|
||||
/**
|
||||
* A {@link #beam}ed {@link CancellationSignal} was closed.
|
||||
*
|
||||
* MUST be forwarded to {@link Receiver#cancel} with proper ordering. See
|
||||
* {@link CancellationSignalBeamer} for details.
|
||||
*/
|
||||
public abstract void onCancel(IBinder token);
|
||||
|
||||
/**
|
||||
* A {@link #beam}ed {@link CancellationSignal} was GC'd.
|
||||
*
|
||||
* MUST be forwarded to {@link Receiver#forget} with proper ordering. See
|
||||
* {@link CancellationSignalBeamer} for details.
|
||||
*/
|
||||
public abstract void onForget(IBinder token);
|
||||
|
||||
private static class Token extends Binder implements CloseableToken, Runnable {
|
||||
|
||||
private final Sender mSender;
|
||||
private Preparer mPreparer;
|
||||
|
||||
private Token(Sender sender, CancellationSignal signal) {
|
||||
mSender = sender;
|
||||
mPreparer = new Preparer(sender, signal, this);
|
||||
}
|
||||
|
||||
@Override
|
||||
public void close() {
|
||||
Preparer preparer = mPreparer;
|
||||
mPreparer = null;
|
||||
if (preparer != null) {
|
||||
preparer.setup();
|
||||
}
|
||||
}
|
||||
|
||||
@Override
|
||||
public void run() {
|
||||
mSender.onForget(this);
|
||||
}
|
||||
|
||||
private static class Preparer implements CancellationSignal.OnCancelListener {
|
||||
private final Sender mSender;
|
||||
private final CancellationSignal mSignal;
|
||||
private final Token mToken;
|
||||
|
||||
private Preparer(Sender sender, CancellationSignal signal, Token token) {
|
||||
mSender = sender;
|
||||
mSignal = signal;
|
||||
mToken = token;
|
||||
}
|
||||
|
||||
void setup() {
|
||||
sCleaner.register(this, mToken);
|
||||
mSignal.setOnCancelListener(this);
|
||||
}
|
||||
|
||||
@Override
|
||||
public void onCancel() {
|
||||
try {
|
||||
mSender.onCancel(mToken);
|
||||
} finally {
|
||||
// Make sure we dispatch onCancel before the cleaner can run.
|
||||
Reference.reachabilityFence(this);
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/**
|
||||
* A {@link #beam}ed {@link CancellationSignal} ready for sending over Binder.
|
||||
*
|
||||
* MUST be closed <em>after</em> it is sent over binder, ideally through try-with-resources.
|
||||
*/
|
||||
public interface CloseableToken extends IBinder, AutoCloseable {
|
||||
@Override
|
||||
void close(); // No throws
|
||||
}
|
||||
}
|
||||
|
||||
/** The receiving side of a {@link CancellationSignalBeamer}. */
|
||||
public static class Receiver implements IBinder.DeathRecipient {
|
||||
private final HashMap<IBinder, CancellationSignal> mTokenMap = new HashMap<>();
|
||||
private final boolean mCancelOnSenderDeath;
|
||||
|
||||
/**
|
||||
* Constructs a new {@code Receiver}.
|
||||
*
|
||||
* @param cancelOnSenderDeath if true, {@link CancellationSignal}s obtained from
|
||||
* {@link #unbeam} are automatically {@link #cancel}led if the sender token
|
||||
* {@link Binder#linkToDeath dies}; otherwise they are simnply dropped. Note: if the
|
||||
* sending process drops all references to the {@link CancellationSignal} before
|
||||
* process death, the cancellation is not guaranteed.
|
||||
*/
|
||||
public Receiver(boolean cancelOnSenderDeath) {
|
||||
mCancelOnSenderDeath = cancelOnSenderDeath;
|
||||
}
|
||||
|
||||
/**
|
||||
* Unbeams a token that was obtained via {@link Sender#beam} and turns it back into a
|
||||
* {@link CancellationSignal}.
|
||||
*
|
||||
* A subsequent call to {@link #cancel} with the same token will cancel the returned
|
||||
* {@code CancellationSignal}.
|
||||
*
|
||||
* @param token a token that was obtained from {@link Sender}, possibly in a remote process.
|
||||
* @return a {@link CancellationSignal} linked to the given token.
|
||||
*/
|
||||
@Nullable
|
||||
public CancellationSignal unbeam(@Nullable IBinder token) {
|
||||
if (token == null) {
|
||||
return null;
|
||||
}
|
||||
synchronized (this) {
|
||||
CancellationSignal cs = mTokenMap.get(token);
|
||||
if (cs != null) {
|
||||
return cs;
|
||||
}
|
||||
|
||||
cs = new CancellationSignal();
|
||||
mTokenMap.put(token, cs);
|
||||
try {
|
||||
token.linkToDeath(this, 0);
|
||||
} catch (RemoteException e) {
|
||||
dead(token);
|
||||
}
|
||||
return cs;
|
||||
}
|
||||
}
|
||||
|
||||
/**
|
||||
* Forgets state associated with the given token (if any).
|
||||
*
|
||||
* Subsequent calls to {@link #cancel} or binder death notifications on the token will not
|
||||
* have any effect.
|
||||
*
|
||||
* This MUST be invoked when forwarding {@link Sender#onForget}, otherwise the token and
|
||||
* {@link CancellationSignal} will leak if the token was ever {@link #unbeam}ed.
|
||||
*
|
||||
* Optionally, the receiving service logic may also invoke this if it can guarantee that
|
||||
* the unbeamed CancellationSignal isn't needed anymore (i.e. the cancellable operation
|
||||
* using the CancellationSignal has been fully completed).
|
||||
*
|
||||
* @param token the token to forget. No-op if {@code null}.
|
||||
*/
|
||||
public void forget(@Nullable IBinder token) {
|
||||
synchronized (this) {
|
||||
if (mTokenMap.remove(token) != null) {
|
||||
token.unlinkToDeath(this, 0);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/**
|
||||
* Cancels the {@link CancellationSignal} associated with the given token (if any).
|
||||
*
|
||||
* This MUST be invoked when forwarding {@link Sender#onCancel}, otherwise the token and
|
||||
* {@link CancellationSignal} will leak if the token was ever {@link #unbeam}ed.
|
||||
*
|
||||
* Optionally, the receiving service logic may also invoke this if it can guarantee that
|
||||
* the unbeamed CancellationSignal isn't needed anymore (i.e. the cancellable operation
|
||||
* using the CancellationSignal has been fully completed).
|
||||
*
|
||||
* @param token the token to forget. No-op if {@code null}.
|
||||
*/
|
||||
public void cancel(@Nullable IBinder token) {
|
||||
CancellationSignal cs;
|
||||
synchronized (this) {
|
||||
cs = mTokenMap.get(token);
|
||||
if (cs != null) {
|
||||
forget(token);
|
||||
} else {
|
||||
return;
|
||||
}
|
||||
}
|
||||
cs.cancel();
|
||||
}
|
||||
|
||||
private void dead(@NonNull IBinder token) {
|
||||
if (mCancelOnSenderDeath) {
|
||||
cancel(token);
|
||||
} else {
|
||||
forget(token);
|
||||
}
|
||||
}
|
||||
|
||||
@Override
|
||||
public void binderDied(@NonNull IBinder who) {
|
||||
dead(who);
|
||||
}
|
||||
|
||||
@Override
|
||||
public void binderDied() {
|
||||
throw new RuntimeException("unreachable");
|
||||
}
|
||||
}
|
||||
}
|
||||
@@ -0,0 +1,224 @@
|
||||
/*
|
||||
* 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 android.os;
|
||||
|
||||
import static android.os.CancellationSignalBeamer.Sender;
|
||||
|
||||
import static com.google.common.truth.Truth.assertThat;
|
||||
|
||||
import android.content.Context;
|
||||
import android.os.CancellationSignalBeamer.Receiver;
|
||||
import android.util.PollingCheck;
|
||||
import android.util.PollingCheck.PollingCheckCondition;
|
||||
|
||||
import androidx.test.filters.SmallTest;
|
||||
import androidx.test.platform.app.InstrumentationRegistry;
|
||||
import androidx.test.runner.AndroidJUnit4;
|
||||
|
||||
import org.junit.Test;
|
||||
import org.junit.runner.RunWith;
|
||||
|
||||
import java.io.File;
|
||||
import java.io.IOException;
|
||||
import java.lang.ref.Cleaner;
|
||||
import java.lang.ref.Reference;
|
||||
import java.util.concurrent.CountDownLatch;
|
||||
|
||||
@RunWith(AndroidJUnit4.class)
|
||||
@SmallTest
|
||||
public class CancellationSignalBeamerTest {
|
||||
|
||||
private CancellationSignal mSenderSignal = new CancellationSignal();
|
||||
private CancellationSignal mReceivedSignal;
|
||||
private Context mContext = InstrumentationRegistry.getInstrumentation().getContext();
|
||||
|
||||
@Test
|
||||
public void testBeam_null() {
|
||||
try (var token = mSender.beam(null)) {
|
||||
assertThat(token).isNull();
|
||||
invokeGenericService(token);
|
||||
}
|
||||
assertThat(mReceivedSignal).isNull();
|
||||
}
|
||||
|
||||
@Test
|
||||
public void testBeam_nonNull() {
|
||||
try (var token = mSender.beam(mSenderSignal)) {
|
||||
assertThat(token).isNotNull();
|
||||
invokeGenericService(token);
|
||||
}
|
||||
assertThat(mReceivedSignal).isNotNull();
|
||||
}
|
||||
|
||||
@Test
|
||||
public void testBeam_async() {
|
||||
IBinder outerToken;
|
||||
try (var token = mSender.beam(mSenderSignal)) {
|
||||
assertThat(token).isNotNull();
|
||||
outerToken = token;
|
||||
}
|
||||
invokeGenericService(outerToken);
|
||||
assertThat(mReceivedSignal).isNotNull();
|
||||
}
|
||||
|
||||
@Test
|
||||
public void testCancelOnSentSignal_cancelsReceivedSignal() {
|
||||
try (var token = mSender.beam(mSenderSignal)) {
|
||||
invokeGenericService(token);
|
||||
}
|
||||
mSenderSignal.cancel();
|
||||
assertThat(mReceivedSignal.isCanceled()).isTrue();
|
||||
}
|
||||
|
||||
@Test
|
||||
public void testSendingCancelledSignal_cancelsReceivedSignal() {
|
||||
mSenderSignal.cancel();
|
||||
try (var token = mSender.beam(mSenderSignal)) {
|
||||
invokeGenericService(token);
|
||||
}
|
||||
assertThat(mReceivedSignal.isCanceled()).isTrue();
|
||||
}
|
||||
|
||||
@Test
|
||||
public void testUnbeam_null() {
|
||||
assertThat(mReceiver.unbeam(null)).isNull();
|
||||
}
|
||||
|
||||
@Test
|
||||
public void testForget_null() {
|
||||
mReceiver.forget(null);
|
||||
}
|
||||
|
||||
@Test
|
||||
public void testCancel_null() {
|
||||
mReceiver.cancel(null);
|
||||
}
|
||||
|
||||
@Test
|
||||
public void testForget_withUnknownToken() {
|
||||
mReceiver.forget(new Binder());
|
||||
}
|
||||
|
||||
@Test
|
||||
public void testCancel_withUnknownToken() {
|
||||
mReceiver.cancel(new Binder());
|
||||
}
|
||||
|
||||
@Test
|
||||
public void testBinderDied_withUnknownToken() {
|
||||
mReceiver.binderDied(new Binder());
|
||||
}
|
||||
|
||||
@Test
|
||||
public void testReceiverWithCancelOnSenderDead_cancelsOnSenderDeath() {
|
||||
var receiver = new Receiver(true /* cancelOnSenderDeath */);
|
||||
var token = new Binder();
|
||||
var signal = receiver.unbeam(token);
|
||||
receiver.binderDied(token);
|
||||
assertThat(signal.isCanceled()).isTrue();
|
||||
}
|
||||
|
||||
@Test
|
||||
public void testReceiverWithoutCancelOnSenderDead_doesntCancelOnSenderDeath() {
|
||||
var receiver = new Receiver(false /* cancelOnSenderDeath */);
|
||||
var token = new Binder();
|
||||
var signal = receiver.unbeam(token);
|
||||
receiver.binderDied(token);
|
||||
assertThat(signal.isCanceled()).isFalse();
|
||||
}
|
||||
|
||||
@Test
|
||||
public void testDroppingSentSignal_dropsReceivedSignal() throws Exception {
|
||||
// In a multiprocess scenario, sending token over Binder might leak the token
|
||||
// on both ends if we create a reference cycle. Simulate that worst-case scenario
|
||||
// here by leaking it directly, then test that cleanup of the signals still works.
|
||||
var receivedSignalCleaned = new CountDownLatch(1);
|
||||
var tokenRef = new Object[1];
|
||||
// Reference the cancellation signals in a separate method scope, so we don't
|
||||
// accidentally leak them on the stack / in a register.
|
||||
Runnable r = () -> {
|
||||
try (var token = mSender.beam(mSenderSignal)) {
|
||||
tokenRef[0] = token;
|
||||
invokeGenericService(token);
|
||||
}
|
||||
mSenderSignal = null;
|
||||
|
||||
Cleaner.create().register(mReceivedSignal, receivedSignalCleaned::countDown);
|
||||
mReceivedSignal = null;
|
||||
};
|
||||
r.run();
|
||||
|
||||
waitForWithGc(() -> receivedSignalCleaned.getCount() == 0);
|
||||
|
||||
Reference.reachabilityFence(tokenRef[0]);
|
||||
}
|
||||
|
||||
@Test
|
||||
public void testRepeatedBeaming_doesntLeak() throws Exception {
|
||||
var receivedSignalCleaned = new CountDownLatch(1);
|
||||
var tokenRef = new Object[1];
|
||||
// Reference the cancellation signals in a separate method scope, so we don't
|
||||
// accidentally leak them on the stack / in a register.
|
||||
Runnable r = () -> {
|
||||
try (var token = mSender.beam(mSenderSignal)) {
|
||||
tokenRef[0] = token;
|
||||
invokeGenericService(token);
|
||||
}
|
||||
// Beaming again leaves mReceivedSignal dangling, so it should be collected.
|
||||
mSender.beam(mSenderSignal).close();
|
||||
|
||||
Cleaner.create().register(mReceivedSignal, receivedSignalCleaned::countDown);
|
||||
mReceivedSignal = null;
|
||||
};
|
||||
r.run();
|
||||
|
||||
waitForWithGc(() -> receivedSignalCleaned.getCount() == 0);
|
||||
|
||||
Reference.reachabilityFence(tokenRef[0]);
|
||||
}
|
||||
|
||||
private void waitForWithGc(PollingCheckCondition condition) throws IOException {
|
||||
try {
|
||||
PollingCheck.waitFor(() -> {
|
||||
Runtime.getRuntime().gc();
|
||||
return condition.canProceed();
|
||||
});
|
||||
} catch (AssertionError e) {
|
||||
File heap = new File(mContext.getExternalFilesDir(null), "dump.hprof");
|
||||
Debug.dumpHprofData(heap.getAbsolutePath());
|
||||
throw e;
|
||||
}
|
||||
}
|
||||
|
||||
private void invokeGenericService(IBinder cancellationSignalToken) {
|
||||
mReceivedSignal = mReceiver.unbeam(cancellationSignalToken);
|
||||
}
|
||||
|
||||
private final Sender mSender = new Sender() {
|
||||
@Override
|
||||
public void onCancel(IBinder token) {
|
||||
mReceiver.cancel(token);
|
||||
}
|
||||
|
||||
@Override
|
||||
public void onForget(IBinder token) {
|
||||
mReceiver.forget(token);
|
||||
}
|
||||
};
|
||||
|
||||
private final Receiver mReceiver = new Receiver(false);
|
||||
}
|
||||
Reference in New Issue
Block a user