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 java.io.Closeable;
22 import java.io.IOException;
23 import java.util.List;
24
25 import org.apache.hadoop.hbase.Cell;
26 import org.apache.hadoop.hbase.classification.InterfaceAudience;
27
28 /**
29 * Internal scanners differ from client-side scanners in that they operate on
30 * HStoreKeys and byte[] instead of RowResults. This is because they are
31 * actually close to how the data is physically stored, and therefore it is more
32 * convenient to interact with them that way. It is also much easier to merge
33 * the results across SortedMaps than RowResults.
34 *
35 * <p>Additionally, we need to be able to determine if the scanner is doing
36 * wildcard column matches (when only a column family is specified or if a
37 * column regex is specified) or if multiple members of the same column family
38 * were specified. If so, we need to ignore the timestamp to ensure that we get
39 * all the family members, as they may have been last updated at different
40 * times.
41 */
42 @InterfaceAudience.Private
43 public interface InternalScanner extends Closeable {
44 /**
45 * Grab the next row's worth of values.
46 * @param results return output array
47 * @return true if more rows exist after this one, false if scanner is done
48 * @throws IOException e
49 */
50 boolean next(List<Cell> results) throws IOException;
51
52 /**
53 * Grab the next row's worth of values.
54 * @param result return output array
55 * @param scannerContext
56 * @return true if more rows exist after this one, false if scanner is done
57 * @throws IOException e
58 */
59 boolean next(List<Cell> result, ScannerContext scannerContext) throws IOException;
60
61 /**
62 * Closes the scanner and releases any resources it has allocated
63 * @throws IOException
64 */
65 void close() throws IOException;
66 }