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1   /**
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   *     http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing, software
13   * distributed under the License is distributed on an "AS IS" BASIS,
14   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15   * See the License for the specific language governing permissions and
16   * limitations under the License.
17   */
18  package org.apache.hadoop.hbase.util;
19  
20  import org.apache.commons.logging.Log;
21  import org.apache.commons.logging.LogFactory;
22  
23  import com.google.protobuf.ByteString;
24  import com.google.protobuf.HBaseZeroCopyByteString;
25  
26  /**
27   * Hack to workaround HBASE-1304 issue that keeps bubbling up when a mapreduce context.
28   */
29  public class ByteStringer {
30    private static final Log LOG = LogFactory.getLog(ByteStringer.class);
31  
32    /**
33     * Flag set at class loading time.
34     */
35    private static boolean USE_ZEROCOPYBYTESTRING = true;
36  
37    // Can I classload HBaseZeroCopyByteString without IllegalAccessError?
38    // If we can, use it passing ByteStrings to pb else use native ByteString though more costly
39    // because it makes a copy of the passed in array.
40    static {
41      try {
42        HBaseZeroCopyByteString.wrap(new byte [0]);
43      } catch (IllegalAccessError iae) {
44        USE_ZEROCOPYBYTESTRING = false;
45        LOG.debug("Failed to classload HBaseZeroCopyByteString: " + iae.toString());
46      }
47    }
48  
49    private ByteStringer() {
50      super();
51    }
52  
53    /**
54     * Wraps a byte array in a {@link ByteString} without copying it.
55     */
56    public static ByteString wrap(final byte[] array) {
57      return USE_ZEROCOPYBYTESTRING? HBaseZeroCopyByteString.wrap(array): ByteString.copyFrom(array);
58    }
59  
60    /**
61     * Wraps a subset of a byte array in a {@link ByteString} without copying it.
62     */
63    public static ByteString wrap(final byte[] array, int offset, int length) {
64      return USE_ZEROCOPYBYTESTRING? HBaseZeroCopyByteString.wrap(array, offset, length):
65        ByteString.copyFrom(array, offset, length);
66    }
67  }