001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.apache.wicket.pageStore.disk; 018 019import java.io.File; 020import java.util.Collections; 021import java.util.HashSet; 022import java.util.Set; 023 024import org.apache.wicket.util.file.Files; 025import org.apache.wicket.util.lang.Args; 026 027/** 028 * Keep files in a nested filed structure to minimize amount of directory entries (inodes) in a single directory. 029 * 030 * @author svenmeier 031 */ 032public class NestedFolders 033{ 034 private final File base; 035 036 /** 037 * Create folders in the given base folder. 038 * 039 * @param base base has to be a folder 040 */ 041 public NestedFolders(File base) 042 { 043 this.base = Args.notNull(base, "base"); 044 } 045 046 public File getBase() 047 { 048 return base; 049 } 050 051 /** 052 * Get a nested folder for the given name. 053 * 054 * @param name name 055 * @param create 056 * @return 057 */ 058 public File get(String name, final boolean create) 059 { 060 name = name.replace('*', '_'); 061 name = name.replace('/', '_'); 062 name = name.replace(':', '_'); 063 064 String path = createPathFrom(name); 065 066 File folder = new File(base, path); 067 if (create && folder.exists() == false) 068 { 069 Files.mkdirs(folder); 070 } 071 return folder; 072 } 073 074 private String createPathFrom(final String name) 075 { 076 int hash = Math.abs(name.hashCode()); 077 String low = String.valueOf(hash % 9973); 078 String high = String.valueOf((hash / 9973) % 9973); 079 StringBuilder bs = new StringBuilder(name.length() + 10); 080 bs.append(low); 081 bs.append(File.separator); 082 bs.append(high); 083 bs.append(File.separator); 084 bs.append(name); 085 086 return bs.toString(); 087 } 088 089 /** 090 * Remove a nested folder. 091 * 092 * @param name name of folder 093 */ 094 public void remove(String name) 095 { 096 File folder = get(name, false); 097 if (folder.exists()) 098 { 099 Files.removeFolder(folder); 100 101 File high = folder.getParentFile(); 102 final String[] highChildren = high.list(); 103 if (highChildren != null && highChildren.length == 0 && Files.removeFolder(high)) 104 { 105 File low = high.getParentFile(); 106 final String[] lowChildren = low.list(); 107 if (lowChildren != null && lowChildren.length == 0) 108 { 109 Files.removeFolder(low); 110 } 111 } 112 } 113 } 114 115 /** 116 * Get all files inside. 117 * 118 * @return files 119 */ 120 public Set<File> getAll() 121 { 122 Set<File> files = new HashSet<>(); 123 124 if (base.exists()) 125 { 126 for (File low : Files.list(base)) 127 { 128 for (File high: Files.list(low)) 129 { 130 Collections.addAll(files, Files.list(high)); 131 } 132 } 133 } 134 135 return files; 136 } 137}