001package org.apache.commons.jcs3.auxiliary.disk.indexed; 002 003/* 004 * Licensed to the Apache Software Foundation (ASF) under one 005 * or more contributor license agreements. See the NOTICE file 006 * distributed with this work for additional information 007 * regarding copyright ownership. The ASF licenses this file 008 * to you under the Apache License, Version 2.0 (the 009 * "License"); you may not use this file except in compliance 010 * with the License. You may obtain a copy of the License at 011 * 012 * http://www.apache.org/licenses/LICENSE-2.0 013 * 014 * Unless required by applicable law or agreed to in writing, 015 * software distributed under the License is distributed on an 016 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 017 * KIND, either express or implied. See the License for the 018 * specific language governing permissions and limitations 019 * under the License. 020 */ 021 022import java.io.Serializable; 023 024/** 025 * Disk objects are located by descriptor entries. These are saved on shutdown and loaded into 026 * memory on startup. 027 */ 028public class IndexedDiskElementDescriptor 029 implements Serializable, Comparable<IndexedDiskElementDescriptor> 030{ 031 /** Don't change */ 032 private static final long serialVersionUID = -3029163572847659450L; 033 034 /** Position of the cache data entry on disk. */ 035 long pos; 036 037 /** Number of bytes the serialized form of the cache data takes. */ 038 int len; 039 040 /** 041 * Constructs a usable disk element descriptor. 042 * <p> 043 * @param pos 044 * @param len 045 */ 046 public IndexedDiskElementDescriptor( final long pos, final int len ) 047 { 048 this.pos = pos; 049 this.len = len; 050 } 051 052 /** 053 * @return debug string 054 */ 055 @Override 056 public String toString() 057 { 058 final StringBuilder buf = new StringBuilder(); 059 buf.append( "[DED: " ); 060 buf.append( " pos = " + pos ); 061 buf.append( " len = " + len ); 062 buf.append( "]" ); 063 return buf.toString(); 064 } 065 066 /** 067 * @see Object#hashCode() 068 */ 069 @Override 070 public int hashCode() 071 { 072 return Long.valueOf(this.pos).hashCode() ^ Integer.valueOf(len).hashCode(); 073 } 074 075 /** 076 * @see Object#equals(Object) 077 */ 078 @Override 079 public boolean equals(final Object o) 080 { 081 if (o == null) 082 { 083 return false; 084 } 085 if (o instanceof IndexedDiskElementDescriptor) 086 { 087 final IndexedDiskElementDescriptor ided = (IndexedDiskElementDescriptor)o; 088 return pos == ided.pos && len == ided.len; 089 } 090 091 return false; 092 } 093 094 /** 095 * Compares based on length, then on pos descending. 096 * <p> 097 * @param o Object 098 * @return int 099 */ 100 @Override 101 public int compareTo( final IndexedDiskElementDescriptor o ) 102 { 103 if ( o == null ) 104 { 105 return 1; 106 } 107 108 int lenCompare = Integer.compare(len, o.len); 109 if (lenCompare == 0) 110 { 111 return Long.compare(o.pos, pos); 112 } 113 114 return lenCompare; 115 } 116}