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
24 import org.apache.hadoop.hbase.classification.InterfaceAudience;
25
26 /**
27 * Utility functions for region server storage layer.
28 */
29 @InterfaceAudience.Private
30 public class StoreUtils {
31 /**
32 * Creates a deterministic hash code for store file collection.
33 */
34 public static Integer getDeterministicRandomSeed(final Collection<StoreFile> files) {
35 if (files != null && !files.isEmpty()) {
36 return files.iterator().next().getPath().getName().hashCode();
37 }
38 return null;
39 }
40
41 /**
42 * Determines whether any files in the collection are references.
43 * @param files The files.
44 */
45 public static boolean hasReferences(final Collection<StoreFile> files) {
46 if (files != null) {
47 for (StoreFile hsf: files) {
48 if (hsf.isReference()) {
49 return true;
50 }
51 }
52 }
53 return false;
54 }
55
56 /**
57 * Gets lowest timestamp from candidate StoreFiles
58 */
59 public static long getLowestTimestamp(final Collection<StoreFile> candidates)
60 throws IOException {
61 long minTs = Long.MAX_VALUE;
62 for (StoreFile storeFile : candidates) {
63 minTs = Math.min(minTs, storeFile.getModificationTimeStamp());
64 }
65 return minTs;
66 }
67
68 /**
69 * Gets the largest file (with reader) out of the list of files.
70 * @param candidates The files to choose from.
71 * @return The largest file; null if no file has a reader.
72 */
73 static StoreFile getLargestFile(final Collection<StoreFile> candidates) {
74 long maxSize = -1L;
75 StoreFile largestSf = null;
76 for (StoreFile sf : candidates) {
77 StoreFile.Reader r = sf.getReader();
78 if (r == null) continue;
79 long size = r.length();
80 if (size > maxSize) {
81 maxSize = size;
82 largestSf = sf;
83 }
84 }
85 return largestSf;
86 }
87 }