CloseGuardHelper.java
/*
* Copyright 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 androidx.javascriptengine;
import android.os.Build;
import android.util.CloseGuard;
import androidx.annotation.NonNull;
import androidx.annotation.RequiresApi;
import androidx.core.util.Preconditions;
/**
* Helper for accessing CloseGuard on API levels that support it.
*
* <p>All operations are no-ops on non-supported API levels.
*/
@SuppressWarnings("NotCloseable")
final class CloseGuardHelper {
private final CloseGuardImpl mImpl;
private CloseGuardHelper(CloseGuardImpl impl) {
mImpl = impl;
}
/**
* Returns a {@link CloseGuardHelper} which defers to the platform close guard if it is
* available.
*/
@NonNull
public static CloseGuardHelper create() {
if (Build.VERSION.SDK_INT >= 30) {
return new CloseGuardHelper(new CloseGuardApi30Impl());
}
return new CloseGuardHelper(new CloseGuardNoOpImpl());
}
/**
* Initializes the instance with a warning that the caller should have explicitly called the
* {@code closeMethodName} method instead of relying on finalization.
*
* @param closeMethodName non-null name of explicit termination method. Printed by
* warnIfOpen.
* @throws NullPointerException if closeMethodName is null.
*/
public void open(@NonNull String closeMethodName) {
mImpl.open(closeMethodName);
}
/** Marks this CloseGuard instance as closed to avoid warnings on finalization. */
public void close() {
mImpl.close();
}
/**
* Logs a warning if the caller did not properly cleanup by calling an explicit close method
* before finalization.
*/
public void warnIfOpen() {
mImpl.warnIfOpen();
}
private interface CloseGuardImpl {
void open(@NonNull String closeMethodName);
void close();
void warnIfOpen();
}
@RequiresApi(30)
static final class CloseGuardApi30Impl implements CloseGuardImpl {
private final CloseGuard mPlatformImpl = new CloseGuard();
@Override
public void open(@NonNull String closeMethodName) {
mPlatformImpl.open(closeMethodName);
}
@Override
public void close() {
mPlatformImpl.close();
}
@Override
public void warnIfOpen() {
mPlatformImpl.warnIfOpen();
}
}
static final class CloseGuardNoOpImpl implements CloseGuardImpl {
@Override
public void open(@NonNull String closeMethodName) {
Preconditions.checkNotNull(closeMethodName, "CloseMethodName must not be null.");
}
@Override
public void close() {}
@Override
public void warnIfOpen() {}
}
}