View Javadoc

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.regionserver;
20  
21  import org.apache.hadoop.classification.InterfaceAudience;
22  
23  /**
24   * This interface is used for the tracking and enforcement of Deletes
25   * during the course of a Get or Scan operation.
26   * <p>
27   * This class is utilized through three methods:
28   * <ul><li>{@link #add} when encountering a Delete
29   * <li>{@link #isDeleted} when checking if a Put KeyValue has been deleted
30   * <li>{@link #update} when reaching the end of a StoreFile
31   */
32  @InterfaceAudience.Private
33  public interface DeleteTracker {
34  
35    /**
36     * Add the specified KeyValue to the list of deletes to check against for
37     * this row operation.
38     * <p>
39     * This is called when a Delete is encountered in a StoreFile.
40     * @param buffer KeyValue buffer
41     * @param qualifierOffset column qualifier offset
42     * @param qualifierLength column qualifier length
43     * @param timestamp timestamp
44     * @param type delete type as byte
45     */
46    void add(
47      byte[] buffer, int qualifierOffset, int qualifierLength, long timestamp, byte type
48    );
49  
50    /**
51     * Check if the specified KeyValue buffer has been deleted by a previously
52     * seen delete.
53     * @param buffer KeyValue buffer
54     * @param qualifierOffset column qualifier offset
55     * @param qualifierLength column qualifier length
56     * @param timestamp timestamp
57     * @return deleteResult The result tells whether the KeyValue is deleted and why
58     */
59    DeleteResult isDeleted(
60      byte[] buffer, int qualifierOffset, int qualifierLength, long timestamp
61    );
62  
63    /**
64     * @return true if there are no current delete, false otherwise
65     */
66    boolean isEmpty();
67  
68    /**
69     * Called at the end of every StoreFile.
70     * <p>
71     * Many optimized implementations of Trackers will require an update at
72     * when the end of each StoreFile is reached.
73     */
74    void update();
75  
76    /**
77     * Called between rows.
78     * <p>
79     * This clears everything as if a new DeleteTracker was instantiated.
80     */
81    void reset();
82  
83  
84    /**
85     * Return codes for comparison of two Deletes.
86     * <p>
87     * The codes tell the merging function what to do.
88     * <p>
89     * INCLUDE means add the specified Delete to the merged list.
90     * NEXT means move to the next element in the specified list(s).
91     */
92    enum DeleteCompare {
93      INCLUDE_OLD_NEXT_OLD,
94      INCLUDE_OLD_NEXT_BOTH,
95      INCLUDE_NEW_NEXT_NEW,
96      INCLUDE_NEW_NEXT_BOTH,
97      NEXT_OLD,
98      NEXT_NEW
99    }
100 
101   /**
102    * Returns codes for delete result.
103    * The codes tell the ScanQueryMatcher whether the kv is deleted and why.
104    * Based on the delete result, the ScanQueryMatcher will decide the next
105    * operation
106    */
107   enum DeleteResult {
108     FAMILY_DELETED, // The KeyValue is deleted by a delete family.
109     FAMILY_VERSION_DELETED, // The KeyValue is deleted by a delete family version.
110     COLUMN_DELETED, // The KeyValue is deleted by a delete column.
111     VERSION_DELETED, // The KeyValue is deleted by a version delete.
112     NOT_DELETED
113   }
114 
115 }