CleanerJava6.java — netty Source File

Source Code

/*
* Copyright 2014 The Netty Project
*
* The Netty Project licenses this file to you 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:
*
*   https://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 io.netty.util.internal;

import io.netty.util.internal.logging.InternalLogger;
import io.netty.util.internal.logging.InternalLoggerFactory;

import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles;
import java.nio.ByteBuffer;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.Objects;

import static java.lang.invoke.MethodType.methodType;

/**
 * Allows to free direct {@link ByteBuffer} by using Cleaner. This is encapsulated in an extra class to be able
 * to use {@link PlatformDependent0} on Android without problems.
 * <p>
 * For more details see <a href="https://github.com/netty/netty/issues/2604">#2604</a>.
 */
final class CleanerJava6 implements Cleaner {
    private static final MethodHandle CLEAN_METHOD;

    private static final InternalLogger logger = InternalLoggerFactory.getInstance(CleanerJava6.class);

    static {
        MethodHandle clean;
        Throwable error = null;
        final ByteBuffer direct = ByteBuffer.allocateDirect(1);
        try {
            Object mayBeCleanerField = AccessController.doPrivileged(new PrivilegedAction<Object>() {
                @Override
                public Object run() {
                    try {
                        Class<?> cleanerClass = Class.forName("sun.misc.Cleaner");
                        Class<?> directBufClass = Class.forName("sun.nio.ch.DirectBuffer");
                        MethodHandles.Lookup lookup = MethodHandles.lookup();

                        // Call clean() on the cleaner
                        MethodHandle clean = lookup.findVirtual(
                                cleanerClass, "clean", methodType(void.class));
                        // But only if the cleaner is non-null
                        MethodHandle nullTest = lookup.findStatic(
                                Objects.class, "nonNull", methodType(boolean.class, Object.class));
                        clean = MethodHandles.guardWithTest(
// ... (107 more lines)