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1   /*
2    * Copyright 2010 The Apache Software Foundation
3    *
4    * Licensed to the Apache Software Foundation (ASF) under one
5    * or more contributor license agreements.  See the NOTICE file
6    * distributed with this work for additional information
7    * regarding copyright ownership.  The ASF licenses this file
8    * to you under the Apache License, Version 2.0 (the
9    * "License"); you may not use this file except in compliance
10   * with the License.  You may obtain a copy of the License at
11   *
12   *     http://www.apache.org/licenses/LICENSE-2.0
13   *
14   * Unless required by applicable law or agreed to in writing, software
15   * distributed under the License is distributed on an "AS IS" BASIS,
16   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
17   * See the License for the specific language governing permissions and
18   * limitations under the License.
19   */
20  package org.apache.hadoop.hbase.client.coprocessor;
21  
22  import org.apache.hadoop.hbase.HConstants;
23  import org.apache.hadoop.hbase.io.HbaseObjectWritable;
24  import org.apache.hadoop.hbase.util.Bytes;
25  import org.apache.hadoop.hbase.util.Classes;
26  import org.apache.hadoop.io.Writable;
27  
28  import java.io.DataInput;
29  import java.io.DataOutput;
30  import java.io.IOException;
31  import java.io.Serializable;
32  
33  /**
34   * Represents the return value from a
35   * {@link org.apache.hadoop.hbase.client.coprocessor.Exec} invocation.
36   * This simply wraps the value for easier
37   * {@link org.apache.hadoop.hbase.io.HbaseObjectWritable}
38   * serialization.
39   *
40   * <p>
41   * This class is used internally by the HBase client code to properly serialize
42   * responses from {@link org.apache.hadoop.hbase.ipc.CoprocessorProtocol}
43   * method invocations.  It should not be used directly by clients.
44   * </p>
45   *
46   * @see Exec
47   * @see org.apache.hadoop.hbase.client.HTable#coprocessorExec(Class, byte[], byte[], org.apache.hadoop.hbase.client.coprocessor.Batch.Call)
48   * @see org.apache.hadoop.hbase.client.HTable#coprocessorExec(Class, byte[], byte[], org.apache.hadoop.hbase.client.coprocessor.Batch.Call, org.apache.hadoop.hbase.client.coprocessor.Batch.Callback)
49   */
50  public class ExecResult implements Writable {
51    private byte[] regionName;
52    private Object value;
53  
54    public ExecResult() {
55    }
56  
57    public ExecResult(Object value) {
58      this(HConstants.EMPTY_BYTE_ARRAY, value);
59    }
60    public ExecResult(byte[] region, Object value) {
61      this.regionName = region;
62      this.value = value;
63    }
64  
65    public byte[] getRegionName() {
66      return regionName;
67    }
68  
69    public Object getValue() {
70      return value;
71    }
72  
73    @Override
74    public void write(DataOutput out) throws IOException {
75      Bytes.writeByteArray(out, regionName);
76      HbaseObjectWritable.writeObject(out, value,
77          value != null ? value.getClass() : Writable.class, null);
78    }
79  
80    @Override
81    public void readFields(DataInput in) throws IOException {
82      regionName = Bytes.readByteArray(in);
83      value = HbaseObjectWritable.readObject(in, null);
84    }
85  }