| /* |
| * 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.lucene.index; |
| |
| |
| import java.util.regex.Pattern; |
| |
| import org.apache.lucene.codecs.Codec; |
| |
| /** |
| * This class contains useful constants representing filenames and extensions |
| * used by lucene, as well as convenience methods for querying whether a file |
| * name matches an extension ({@link #matchesExtension(String, String) |
| * matchesExtension}), as well as generating file names from a segment name, |
| * generation and extension ( |
| * {@link #fileNameFromGeneration(String, String, long) fileNameFromGeneration}, |
| * {@link #segmentFileName(String, String, String) segmentFileName}). |
| * |
| * <p><b>NOTE</b>: extensions used by codecs are not |
| * listed here. You must interact with the {@link Codec} |
| * directly. |
| * |
| * @lucene.internal |
| */ |
| |
| public final class IndexFileNames { |
| |
| /** No instance */ |
| private IndexFileNames() {} |
| |
| /** Name of the index segment file */ |
| public static final String SEGMENTS = "segments"; |
| |
| /** Name of pending index segment file */ |
| public static final String PENDING_SEGMENTS = "pending_segments"; |
| |
| /** Name of the generation reference file name */ |
| public static final String OLD_SEGMENTS_GEN = "segments.gen"; |
| |
| /** |
| * Computes the full file name from base, extension and generation. If the |
| * generation is -1, the file name is null. If it's 0, the file name is |
| * <base>.<ext>. If it's > 0, the file name is |
| * <base>_<gen>.<ext>.<br> |
| * <b>NOTE:</b> .<ext> is added to the name only if <code>ext</code> is |
| * not an empty string. |
| * |
| * @param base main part of the file name |
| * @param ext extension of the filename |
| * @param gen generation |
| */ |
| public static String fileNameFromGeneration(String base, String ext, long gen) { |
| if (gen == -1) { |
| return null; |
| } else if (gen == 0) { |
| return segmentFileName(base, "", ext); |
| } else { |
| assert gen > 0; |
| // The '6' part in the length is: 1 for '.', 1 for '_' and 4 as estimate |
| // to the gen length as string (hopefully an upper limit so SB won't |
| // expand in the middle. |
| StringBuilder res = new StringBuilder(base.length() + 6 + ext.length()) |
| .append(base).append('_').append(Long.toString(gen, Character.MAX_RADIX)); |
| if (ext.length() > 0) { |
| res.append('.').append(ext); |
| } |
| return res.toString(); |
| } |
| } |
| |
| /** |
| * Returns a file name that includes the given segment name, your own custom |
| * name and extension. The format of the filename is: |
| * <segmentName>(_<name>)(.<ext>). |
| * <p> |
| * <b>NOTE:</b> .<ext> is added to the result file name only if |
| * <code>ext</code> is not empty. |
| * <p> |
| * <b>NOTE:</b> _<segmentSuffix> is added to the result file name only if |
| * it's not the empty string |
| * <p> |
| * <b>NOTE:</b> all custom files should be named using this method, or |
| * otherwise some structures may fail to handle them properly (such as if they |
| * are added to compound files). |
| */ |
| public static String segmentFileName(String segmentName, String segmentSuffix, String ext) { |
| if (ext.length() > 0 || segmentSuffix.length() > 0) { |
| assert !ext.startsWith("."); |
| StringBuilder sb = new StringBuilder(segmentName.length() + 2 + segmentSuffix.length() + ext.length()); |
| sb.append(segmentName); |
| if (segmentSuffix.length() > 0) { |
| sb.append('_').append(segmentSuffix); |
| } |
| if (ext.length() > 0) { |
| sb.append('.').append(ext); |
| } |
| return sb.toString(); |
| } else { |
| return segmentName; |
| } |
| } |
| |
| /** |
| * Returns true if the given filename ends with the given extension. One |
| * should provide a <i>pure</i> extension, without '.'. |
| */ |
| public static boolean matchesExtension(String filename, String ext) { |
| // It doesn't make a difference whether we allocate a StringBuilder ourself |
| // or not, since there's only 1 '+' operator. |
| return filename.endsWith("." + ext); |
| } |
| |
| /** locates the boundary of the segment name, or -1 */ |
| private static int indexOfSegmentName(String filename) { |
| // If it is a .del file, there's an '_' after the first character |
| int idx = filename.indexOf('_', 1); |
| if (idx == -1) { |
| // If it's not, strip everything that's before the '.' |
| idx = filename.indexOf('.'); |
| } |
| return idx; |
| } |
| |
| /** |
| * Strips the segment name out of the given file name. If you used |
| * {@link #segmentFileName} or {@link #fileNameFromGeneration} to create your |
| * files, then this method simply removes whatever comes before the first '.', |
| * or the second '_' (excluding both). |
| * |
| * @return the filename with the segment name removed, or the given filename |
| * if it does not contain a '.' and '_'. |
| */ |
| public static String stripSegmentName(String filename) { |
| int idx = indexOfSegmentName(filename); |
| if (idx != -1) { |
| filename = filename.substring(idx); |
| } |
| return filename; |
| } |
| |
| /** Returns the generation from this file name, or 0 if there is no |
| * generation. */ |
| public static long parseGeneration(String filename) { |
| assert filename.startsWith("_"); |
| String parts[] = stripExtension(filename).substring(1).split("_"); |
| // 4 cases: |
| // segment.ext |
| // segment_gen.ext |
| // segment_codec_suffix.ext |
| // segment_gen_codec_suffix.ext |
| if (parts.length == 2 || parts.length == 4) { |
| return Long.parseLong(parts[1], Character.MAX_RADIX); |
| } else { |
| return 0; |
| } |
| } |
| |
| /** |
| * Parses the segment name out of the given file name. |
| * |
| * @return the segment name only, or filename |
| * if it does not contain a '.' and '_'. |
| */ |
| public static String parseSegmentName(String filename) { |
| int idx = indexOfSegmentName(filename); |
| if (idx != -1) { |
| filename = filename.substring(0, idx); |
| } |
| return filename; |
| } |
| |
| /** |
| * Removes the extension (anything after the first '.'), |
| * otherwise returns the original filename. |
| */ |
| public static String stripExtension(String filename) { |
| int idx = filename.indexOf('.'); |
| if (idx != -1) { |
| filename = filename.substring(0, idx); |
| } |
| return filename; |
| } |
| |
| /** |
| * Return the extension (anything after the first '.'), |
| * or null if there is no '.' in the file name. |
| */ |
| public static String getExtension(String filename) { |
| final int idx = filename.indexOf('.'); |
| if (idx == -1) { |
| return null; |
| } else { |
| return filename.substring(idx + 1, filename.length()); |
| } |
| } |
| |
| /** |
| * All files created by codecs much match this pattern (checked in |
| * SegmentInfo). |
| */ |
| public static final Pattern CODEC_FILE_PATTERN = Pattern.compile("_[a-z0-9]+(_.*)?\\..*"); |
| |
| } |