| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF 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 |
| * |
| * 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 org.apache.commons.io.input; |
| |
| import java.lang.reflect.Field; |
| import java.lang.reflect.Method; |
| import java.nio.ByteBuffer; |
| |
| /** |
| * Cleans a direct {@link ByteBuffer}. Without manual intervention, direct ByteBuffers will be cleaned eventually upon |
| * garbage collection. However, this should not be relied upon since it may not occur in a timely fashion - |
| * especially since off heap ByeBuffers don't put pressure on the garbage collector. |
| * <p> |
| * <b>Warning:</b> Do not attempt to use a direct {@link ByteBuffer} that has been cleaned or bad things will happen. |
| * Don't use this class unless you can ensure that the cleaned buffer will not be accessed anymore. |
| * </p> |
| * <p> |
| * See <a href=https://bugs.openjdk.java.net/browse/JDK-4724038>JDK-4724038</a> |
| * </p> |
| */ |
| final class ByteBufferCleaner { |
| |
| private interface Cleaner { |
| void clean(ByteBuffer buffer) throws ReflectiveOperationException; |
| } |
| |
| private static final class Java8Cleaner implements Cleaner { |
| |
| private final Method cleanerMethod; |
| private final Method cleanMethod; |
| |
| private Java8Cleaner() throws ReflectiveOperationException, SecurityException { |
| cleanMethod = Class.forName("sun.misc.Cleaner").getMethod("clean"); |
| cleanerMethod = Class.forName("sun.nio.ch.DirectBuffer").getMethod("cleaner"); |
| } |
| |
| @Override |
| public void clean(final ByteBuffer buffer) throws ReflectiveOperationException { |
| final Object cleaner = cleanerMethod.invoke(buffer); |
| if (cleaner != null) { |
| cleanMethod.invoke(cleaner); |
| } |
| } |
| } |
| |
| private static final class Java9Cleaner implements Cleaner { |
| |
| private final Object theUnsafe; |
| private final Method invokeCleaner; |
| |
| private Java9Cleaner() throws ReflectiveOperationException, SecurityException { |
| final Class<?> unsafeClass = Class.forName("sun.misc.Unsafe"); |
| final Field field = unsafeClass.getDeclaredField("theUnsafe"); |
| field.setAccessible(true); |
| theUnsafe = field.get(null); |
| invokeCleaner = unsafeClass.getMethod("invokeCleaner", ByteBuffer.class); |
| } |
| |
| @Override |
| public void clean(final ByteBuffer buffer) throws ReflectiveOperationException { |
| invokeCleaner.invoke(theUnsafe, buffer); |
| } |
| } |
| |
| private static final Cleaner INSTANCE = getCleaner(); |
| |
| /** |
| * Releases memory held by the given {@link ByteBuffer}. |
| * |
| * @param buffer to release. |
| * @throws IllegalStateException on internal failure. |
| */ |
| static void clean(final ByteBuffer buffer) { |
| try { |
| INSTANCE.clean(buffer); |
| } catch (final Exception e) { |
| throw new IllegalStateException("Failed to clean direct buffer.", e); |
| } |
| } |
| |
| private static Cleaner getCleaner() { |
| try { |
| return new Java8Cleaner(); |
| } catch (final Exception e) { |
| try { |
| return new Java9Cleaner(); |
| } catch (final Exception e1) { |
| throw new IllegalStateException("Failed to initialize a Cleaner.", e); |
| } |
| } |
| } |
| |
| /** |
| * Tests if were able to load a suitable cleaner for the current JVM. Attempting to call |
| * {@code ByteBufferCleaner#clean(ByteBuffer)} when this method returns false will result in an exception. |
| * |
| * @return {@code true} if cleaning is supported, {@code false} otherwise. |
| */ |
| static boolean isSupported() { |
| return INSTANCE != null; |
| } |
| } |