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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  
21  package org.apache.hadoop.hbase.filter;
22  
23  import java.io.DataInput;
24  import java.io.DataOutput;
25  import java.io.IOException;
26  import java.util.ArrayList;
27  
28  import org.apache.hadoop.hbase.KeyValue;
29  import org.apache.hadoop.hbase.util.Bytes;
30  
31  import com.google.common.base.Preconditions;
32  
33  /**
34   * Pass results that have same row prefix.
35   */
36  public class PrefixFilter extends FilterBase {
37    protected byte [] prefix = null;
38    protected boolean passedPrefix = false;
39    protected boolean filterRow = true;
40  
41    public PrefixFilter(final byte [] prefix) {
42      this.prefix = prefix;
43    }
44  
45    public PrefixFilter() {
46      super();
47    }
48  
49    public byte[] getPrefix() {
50      return prefix;
51    }
52  
53    public boolean filterRowKey(byte[] buffer, int offset, int length) {
54      if (buffer == null || this.prefix == null)
55        return true;
56      if (length < prefix.length)
57        return true;
58      // if they are equal, return false => pass row
59      // else return true, filter row
60      // if we are passed the prefix, set flag
61      int cmp = Bytes.compareTo(buffer, offset, this.prefix.length, this.prefix, 0,
62          this.prefix.length);
63      if(cmp > 0) {
64        passedPrefix = true;
65      }
66      filterRow = (cmp != 0);
67      return filterRow;
68    }
69  
70    @Override
71    public ReturnCode filterKeyValue(KeyValue ignored) {
72      return filterRow ? ReturnCode.NEXT_ROW : ReturnCode.INCLUDE;
73    }
74  
75    public boolean filterRow() {
76      return filterRow;
77    }
78  
79    public void reset() {
80      filterRow = true;
81    }
82  
83    public boolean filterAllRemaining() {
84      return passedPrefix;
85    }
86  
87    public static Filter createFilterFromArguments(ArrayList<byte []> filterArguments) {
88      Preconditions.checkArgument(filterArguments.size() == 1,
89                                  "Expected 1 but got: %s", filterArguments.size());
90      byte [] prefix = ParseFilter.removeQuotesFromByteArray(filterArguments.get(0));
91      return new PrefixFilter(prefix);
92    }
93  
94    public void write(DataOutput out) throws IOException {
95      Bytes.writeByteArray(out, this.prefix);
96    }
97  
98    public void readFields(DataInput in) throws IOException {
99      this.prefix = Bytes.readByteArray(in);
100   }
101 
102   @Override
103   public String toString() {
104     return this.getClass().getSimpleName() + " " + Bytes.toStringBinary(this.prefix);
105   }
106 }