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
19 package org.apache.hadoop.hbase.codec.prefixtree.scanner;
20
21 import org.apache.hadoop.hbase.classification.InterfaceAudience;
22
23 /**
24 * An indicator of the state of the scanner after an operation such as nextCell() or
25 * positionAt(..). For example:
26 * <ul>
27 * <li>In a DataBlockScanner, the AFTER_LAST position indicates to the parent StoreFileScanner that
28 * it should load the next block.</li>
29 * <li>In a StoreFileScanner, the AFTER_LAST position indicates that the file has been exhausted.
30 * </li>
31 * <li>In a RegionScanner, the AFTER_LAST position indicates that the scanner should move to the
32 * next region.</li>
33 * </ul>
34 */
35 @InterfaceAudience.Private
36 public enum CellScannerPosition {
37
38 /**
39 * getCurrentCell() will NOT return a valid cell. Calling nextCell() will advance to the first
40 * cell.
41 */
42 BEFORE_FIRST,
43
44 /**
45 * getCurrentCell() will return a valid cell, but it is not the cell requested by positionAt(..),
46 * rather it is the nearest cell before the requested cell.
47 */
48 BEFORE,
49
50 /**
51 * getCurrentCell() will return a valid cell, and it is exactly the cell that was requested by
52 * positionAt(..).
53 */
54 AT,
55
56 /**
57 * getCurrentCell() will return a valid cell, but it is not the cell requested by positionAt(..),
58 * rather it is the nearest cell after the requested cell.
59 */
60 AFTER,
61
62 /**
63 * getCurrentCell() will NOT return a valid cell. Calling nextCell() will have no effect.
64 */
65 AFTER_LAST
66
67 }