1 /**
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing, software
13 * distributed under the License is distributed on an "AS IS" BASIS,
14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15 * See the License for the specific language governing permissions and
16 * limitations under the License.
17 */
18 package org.apache.hadoop.hbase.regionserver;
19
20 import org.apache.hadoop.hbase.classification.InterfaceAudience;
21 import org.apache.hadoop.hbase.Cell;
22
23 /**
24 * This interface is used for the tracking and enforcement of Deletes during the course of a Get or
25 * Scan operation.
26 * <p>
27 * This class is utilized through three methods:
28 * <ul>
29 * <li>{@link #add} when encountering a Delete</li>
30 * <li>{@link #isDeleted} when checking if a Put KeyValue has been deleted</li>
31 * <li>{@link #update} when reaching the end of a StoreFile</li>
32 * </ul>
33 */
34 @InterfaceAudience.Private
35 public interface DeleteTracker {
36
37 /**
38 * Add the specified cell to the list of deletes to check against for this row operation.
39 * <p>
40 * This is called when a Delete is encountered in a StoreFile.
41 * @param cell - the delete cell
42 */
43 void add(Cell cell);
44
45 /**
46 * Check if the specified cell buffer has been deleted by a previously seen delete.
47 * @param cell - current cell to check if deleted by a previously seen delete
48 * @return deleteResult The result tells whether the KeyValue is deleted and why
49 */
50 DeleteResult isDeleted(Cell cell);
51
52 /**
53 * @return true if there are no current delete, false otherwise
54 */
55 boolean isEmpty();
56
57 /**
58 * Called at the end of every StoreFile.
59 * <p>
60 * Many optimized implementations of Trackers will require an update at when the end of each
61 * StoreFile is reached.
62 */
63 void update();
64
65 /**
66 * Called between rows.
67 * <p>
68 * This clears everything as if a new DeleteTracker was instantiated.
69 */
70 void reset();
71
72 /**
73 * Return codes for comparison of two Deletes.
74 * <p>
75 * The codes tell the merging function what to do.
76 * <p>
77 * INCLUDE means add the specified Delete to the merged list. NEXT means move to the next element
78 * in the specified list(s).
79 */
80 enum DeleteCompare {
81 INCLUDE_OLD_NEXT_OLD,
82 INCLUDE_OLD_NEXT_BOTH,
83 INCLUDE_NEW_NEXT_NEW,
84 INCLUDE_NEW_NEXT_BOTH,
85 NEXT_OLD,
86 NEXT_NEW
87 }
88
89 /**
90 * Returns codes for delete result. The codes tell the ScanQueryMatcher whether the kv is deleted
91 * and why. Based on the delete result, the ScanQueryMatcher will decide the next operation
92 */
93 enum DeleteResult {
94 FAMILY_DELETED, // The KeyValue is deleted by a delete family.
95 FAMILY_VERSION_DELETED, // The KeyValue is deleted by a delete family version.
96 COLUMN_DELETED, // The KeyValue is deleted by a delete column.
97 VERSION_DELETED, // The KeyValue is deleted by a version delete.
98 NOT_DELETED
99 }
100
101 }