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1   /*
2    * Copyright 2012 The Netty Project
3    *
4    * The Netty Project licenses this file to you under the Apache License,
5    * version 2.0 (the "License"); you may not use this file except in compliance
6    * with the License. You may obtain a copy of the License at:
7    *
8    *   http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13   * License for the specific language governing permissions and limitations
14   * under the License.
15   */
16  package org.jboss.netty.util.internal;
17  
18  import java.lang.reflect.Method;
19  import java.nio.ByteBuffer;
20  
21  /**
22   * This is fork of ElasticSearch's ByteBufferAllocator.Cleaner class
23   */
24  public final class ByteBufferUtil {
25      private static final boolean CLEAN_SUPPORTED;
26      private static final Method directBufferCleaner;
27      private static final Method directBufferCleanerClean;
28  
29      static {
30          Method directBufferCleanerX = null;
31          Method directBufferCleanerCleanX = null;
32          boolean v;
33          try {
34              directBufferCleanerX = Class.forName("java.nio.DirectByteBuffer").getMethod("cleaner");
35              directBufferCleanerX.setAccessible(true);
36              directBufferCleanerCleanX = Class.forName("sun.misc.Cleaner").getMethod("clean");
37              directBufferCleanerCleanX.setAccessible(true);
38              v = true;
39          } catch (Exception e) {
40              v = false;
41          }
42          CLEAN_SUPPORTED = v;
43          directBufferCleaner = directBufferCleanerX;
44          directBufferCleanerClean = directBufferCleanerCleanX;
45      }
46  
47      /**
48       * Destroy the given {@link ByteBuffer} if possible
49       */
50      public static void destroy(ByteBuffer buffer) {
51          if (CLEAN_SUPPORTED && buffer.isDirect()) {
52              try {
53                  Object cleaner = directBufferCleaner.invoke(buffer);
54                  directBufferCleanerClean.invoke(cleaner);
55              } catch (Exception e) {
56                  // silently ignore exception
57              }
58          }
59      }
60  
61      private ByteBufferUtil() {
62          // Utility class
63      }
64  }