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.regionserver;
21
22 /**
23 * This interface is used for the tracking and enforcement of Deletes
24 * during the course of a Get or Scan operation.
25 * <p>
26 * This class is utilized through three methods:
27 * <ul><li>{@link #add} when encountering a Delete
28 * <li>{@link #isDeleted} when checking if a Put KeyValue has been deleted
29 * <li>{@link #update} when reaching the end of a StoreFile
30 */
31 public interface DeleteTracker {
32
33 /**
34 * Add the specified KeyValue to the list of deletes to check against for
35 * this row operation.
36 * <p>
37 * This is called when a Delete is encountered in a StoreFile.
38 * @param buffer KeyValue buffer
39 * @param qualifierOffset column qualifier offset
40 * @param qualifierLength column qualifier length
41 * @param timestamp timestamp
42 * @param type delete type as byte
43 */
44 public void add(byte [] buffer, int qualifierOffset, int qualifierLength,
45 long timestamp, byte type);
46
47 /**
48 * Check if the specified KeyValue buffer has been deleted by a previously
49 * seen delete.
50 * @param buffer KeyValue buffer
51 * @param qualifierOffset column qualifier offset
52 * @param qualifierLength column qualifier length
53 * @param timestamp timestamp
54 * @return true is the specified KeyValue is deleted, false if not
55 */
56 public boolean isDeleted(byte [] buffer, int qualifierOffset,
57 int qualifierLength, long timestamp);
58
59 /**
60 * @return true if there are no current delete, false otherwise
61 */
62 public boolean isEmpty();
63
64 /**
65 * Called at the end of every StoreFile.
66 * <p>
67 * Many optimized implementations of Trackers will require an update at
68 * when the end of each StoreFile is reached.
69 */
70 public void update();
71
72 /**
73 * Called between rows.
74 * <p>
75 * This clears everything as if a new DeleteTracker was instantiated.
76 */
77 public void reset();
78
79
80 /**
81 * Return codes for comparison of two Deletes.
82 * <p>
83 * The codes tell the merging function what to do.
84 * <p>
85 * INCLUDE means add the specified Delete to the merged list.
86 * NEXT means move to the next element in the specified list(s).
87 */
88 enum DeleteCompare {
89 INCLUDE_OLD_NEXT_OLD,
90 INCLUDE_OLD_NEXT_BOTH,
91 INCLUDE_NEW_NEXT_NEW,
92 INCLUDE_NEW_NEXT_BOTH,
93 NEXT_OLD,
94 NEXT_NEW
95 }
96
97 }