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.IOException;
22 import java.util.Collection;
23 import java.util.List;
24
25 /**
26 * Utility functions for region server storage layer.
27 */
28 public class StoreUtils {
29 /**
30 * Creates a deterministic hash code for store file collection.
31 */
32 public static Integer getDeterministicRandomSeed(final Collection<StoreFile> files) {
33 if (files != null && !files.isEmpty()) {
34 return files.iterator().next().getPath().getName().hashCode();
35 }
36 return null;
37 }
38
39 /**
40 * Determines whether any files in the collection are references.
41 * @param files The files.
42 */
43 public static boolean hasReferences(final Collection<StoreFile> files) {
44 if (files != null) {
45 for (StoreFile hsf: files) {
46 if (hsf.isReference()) {
47 return true;
48 }
49 }
50 }
51 return false;
52 }
53
54 /**
55 * Gets lowest timestamp from candidate StoreFiles
56 */
57 public static long getLowestTimestamp(final Collection<StoreFile> candidates)
58 throws IOException {
59 long minTs = Long.MAX_VALUE;
60 for (StoreFile storeFile : candidates) {
61 minTs = Math.min(minTs, storeFile.getModificationTimeStamp());
62 }
63 return minTs;
64 }
65
66 /**
67 * Gets the largest file (with reader) out of the list of files.
68 * @param candidates The files to choose from.
69 * @return The largest file; null if no file has a reader.
70 */
71 static StoreFile getLargestFile(final Collection<StoreFile> candidates) {
72 long maxSize = -1L;
73 StoreFile largestSf = null;
74 for (StoreFile sf : candidates) {
75 StoreFile.Reader r = sf.getReader();
76 if (r == null) continue;
77 long size = r.length();
78 if (size > maxSize) {
79 maxSize = size;
80 largestSf = sf;
81 }
82 }
83 return largestSf;
84 }
85 }