/*
    * Copyright 2012 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:
    *
    *   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.jboss.netty.util.internal;
  
  import java.lang.reflect.Method;
  import java.nio.ByteBuffer;
  
  /**
   * This is fork of ElasticSearch's ByteBufferAllocator.Cleaner class
   */
  public final class ByteBufferUtil {
      private static final boolean CLEAN_SUPPORTED;
      private static final Method directBufferCleaner;
      private static final Method directBufferCleanerClean;
  
      static {
          Method directBufferCleanerX = null;
          Method directBufferCleanerCleanX = null;
          boolean v;
          try {
              directBufferCleanerX = Class.forName("java.nio.DirectByteBuffer").getMethod("cleaner");
              directBufferCleanerX.setAccessible(true);
              directBufferCleanerCleanX = Class.forName("sun.misc.Cleaner").getMethod("clean");
              directBufferCleanerCleanX.setAccessible(true);
              v = true;
          } catch (Exception e) {
              v = false;
          }
          CLEAN_SUPPORTED = v;
          directBufferCleaner = directBufferCleanerX;
          directBufferCleanerClean = directBufferCleanerCleanX;
      }
  
      /**
       * Destroy the given {@link ByteBuffer} if possible
       */
      public static void destroy(ByteBuffer buffer) {
          if (CLEAN_SUPPORTED && buffer.isDirect()) {
              try {
                  Object cleaner = directBufferCleaner.invoke(buffer);
                  directBufferCleanerClean.invoke(cleaner);
              } catch (Exception e) {
                  // silently ignore exception
              }
          }
      }
  
      private ByteBufferUtil() {
          // Utility class
      }
  }