/** | |
* Licensed to the Apache Software Foundation (ASF) under one | |
* or more contributor license agreements. See the NOTICE file | |
* distributed with this work for additional information | |
* regarding copyright ownership. The ASF licenses this file | |
* to you under the Apache License, Version 2.0 (the | |
* "License"); you may not use this file except in compliance | |
* with the License. You may obtain a copy of the License at | |
* | |
* http://www.apache.org/licenses/LICENSE-2.0 | |
* | |
* Unless required by applicable law or agreed to in writing, software | |
* distributed under the License is distributed on an "AS IS" BASIS, | |
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
* See the License for the specific language governing permissions and | |
* limitations under the License. | |
*/ | |
package org.apache.hadoop.contrib.index.lucene; | |
import java.io.IOException; | |
import org.apache.lucene.store.Directory; | |
/** | |
* This class copies some methods from Lucene's SegmentInfos since that class | |
* is not public. | |
*/ | |
public final class LuceneUtil { | |
static final class IndexFileNames { | |
/** Name of the index segment file */ | |
static final String SEGMENTS = "segments"; | |
/** Name of the generation reference file name */ | |
static final String SEGMENTS_GEN = "segments.gen"; | |
} | |
/** | |
* Check if the file is a segments_N file | |
* @param name | |
* @return true if the file is a segments_N file | |
*/ | |
public static boolean isSegmentsFile(String name) { | |
return name.startsWith(IndexFileNames.SEGMENTS) | |
&& !name.equals(IndexFileNames.SEGMENTS_GEN); | |
} | |
/** | |
* Check if the file is the segments.gen file | |
* @param name | |
* @return true if the file is the segments.gen file | |
*/ | |
public static boolean isSegmentsGenFile(String name) { | |
return name.equals(IndexFileNames.SEGMENTS_GEN); | |
} | |
/** | |
* Get the generation (N) of the current segments_N file in the directory. | |
* | |
* @param directory -- directory to search for the latest segments_N file | |
*/ | |
public static long getCurrentSegmentGeneration(Directory directory) | |
throws IOException { | |
String[] files = directory.list(); | |
if (files == null) | |
throw new IOException("cannot read directory " + directory | |
+ ": list() returned null"); | |
return getCurrentSegmentGeneration(files); | |
} | |
/** | |
* Get the generation (N) of the current segments_N file from a list of | |
* files. | |
* | |
* @param files -- array of file names to check | |
*/ | |
public static long getCurrentSegmentGeneration(String[] files) { | |
if (files == null) { | |
return -1; | |
} | |
long max = -1; | |
for (int i = 0; i < files.length; i++) { | |
String file = files[i]; | |
if (file.startsWith(IndexFileNames.SEGMENTS) | |
&& !file.equals(IndexFileNames.SEGMENTS_GEN)) { | |
long gen = generationFromSegmentsFileName(file); | |
if (gen > max) { | |
max = gen; | |
} | |
} | |
} | |
return max; | |
} | |
/** | |
* Parse the generation off the segments file name and return it. | |
*/ | |
public static long generationFromSegmentsFileName(String fileName) { | |
if (fileName.equals(IndexFileNames.SEGMENTS)) { | |
return 0; | |
} else if (fileName.startsWith(IndexFileNames.SEGMENTS)) { | |
return Long.parseLong( | |
fileName.substring(1 + IndexFileNames.SEGMENTS.length()), | |
Character.MAX_RADIX); | |
} else { | |
throw new IllegalArgumentException("fileName \"" + fileName | |
+ "\" is not a segments file"); | |
} | |
} | |
} |