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1   /*
2    *
3    * Licensed to the Apache Software Foundation (ASF) under one
4    * or more contributor license agreements.  See the NOTICE file
5    * distributed with this work for additional information
6    * regarding copyright ownership.  The ASF licenses this file
7    * to you under the Apache License, Version 2.0 (the
8    * "License"); you may not use this file except in compliance
9    * with the License.  You may obtain a copy of the License at
10   *
11   *     http://www.apache.org/licenses/LICENSE-2.0
12   *
13   * Unless required by applicable law or agreed to in writing, software
14   * distributed under the License is distributed on an "AS IS" BASIS,
15   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16   * See the License for the specific language governing permissions and
17   * limitations under the License.
18   */
19  package org.apache.hadoop.hbase.util;
20  
21  import java.nio.ByteBuffer;
22  
23  import org.apache.hadoop.classification.InterfaceAudience;
24  
25  /**
26   * Defines the general behavior of a bloom filter.
27   *
28   * <p>
29   * The Bloom filter is a data structure that was introduced in 1970 and that
30   * has been adopted by the networking research community in the past decade
31   * thanks to the bandwidth efficiencies that it offers for the transmission of
32   * set membership information between networked hosts. A sender encodes the
33   * information into a bit vector, the Bloom filter, that is more compact than a
34   * conventional representation. Computation and space costs for construction
35   * are linear in the number of elements. The receiver uses the filter to test
36   * whether various elements are members of the set. Though the filter will
37   * occasionally return a false positive, it will never return a false negative.
38   * When creating the filter, the sender can choose its desired point in a
39   * trade-off between the false positive rate and the size.
40   *
41   * @see BloomFilterWriter for the ability to add elements to a Bloom filter
42   */
43  @InterfaceAudience.Private
44  public interface BloomFilter extends BloomFilterBase {
45  
46    /**
47     * Check if the specified key is contained in the bloom filter.
48     *
49     * @param buf data to check for existence of
50     * @param offset offset into the data
51     * @param length length of the data
52     * @param bloom bloom filter data to search. This can be null if auto-loading
53     *        is supported.
54     * @return true if matched by bloom, false if not
55     */
56    boolean contains(byte [] buf, int offset, int length, ByteBuffer bloom);
57  
58    /**
59     * @return true if this Bloom filter can automatically load its data
60     *         and thus allows a null byte buffer to be passed to contains()
61     */
62    boolean supportsAutoLoading();
63  }