001/* 002 * The contents of this file are subject to the terms of the Common Development and 003 * Distribution License (the License). You may not use this file except in compliance with the 004 * License. 005 * 006 * You can obtain a copy of the License at legal/CDDLv1.0.txt. See the License for the 007 * specific language governing permission and limitations under the License. 008 * 009 * When distributing Covered Software, include this CDDL Header Notice in each file and include 010 * the License file at legal/CDDLv1.0.txt. If applicable, add the following below the CDDL 011 * Header, with the fields enclosed by brackets [] replaced by your own identifying 012 * information: "Portions Copyright [year] [name of copyright owner]". 013 * 014 * Copyright 2010–2011 ApexIdentity Inc. 015 * Portions Copyright 2011-2014 ForgeRock AS. 016 */ 017 018package org.forgerock.openig.io; 019 020import java.io.File; 021import java.io.IOException; 022 023/** 024 * A buffer that fist uses memory, then a temporary file for data storage. Initially, a 025 * {@link MemoryBuffer} is used; when the memory buffer limit is exceeded it promotes to 026 * the use of a {@link FileBuffer}. 027 */ 028public class TemporaryBuffer implements Buffer { 029 030 /** File used for temporary storage. */ 031 private File file = null; 032 033 /** The directory where temporary files are created. */ 034 private File directory; 035 036 /** The length limit of the file buffer. */ 037 private int fileLimit; 038 039 /** The buffer currently in use. */ 040 private Buffer buffer; 041 042 /** 043 * Constructs a new temporary buffer. 044 * 045 * @param initialLength the initial length of memory buffer byte array. 046 * @param memoryLimit the length limit of the memory buffer. 047 * @param fileLimit the length limit of the file buffer. 048 * @param directory the directory where temporary files are created, or {@code null} to use the system-dependent 049 * default temporary directory. 050 */ 051 public TemporaryBuffer(int initialLength, int memoryLimit, int fileLimit, File directory) { 052 buffer = new MemoryBuffer(initialLength, memoryLimit); 053 this.fileLimit = fileLimit; 054 this.directory = directory; 055 } 056 057 @Override 058 public int read(int pos, byte[] b, int off, int len) throws IOException { 059 notClosed(); 060 return buffer.read(pos, b, off, len); 061 } 062 063 @Override 064 public void append(byte[] b, int off, int len) throws IOException, OverflowException { 065 notClosed(); 066 try { 067 buffer.append(b, off, len); 068 } catch (OverflowException oe) { 069 // may throw OverflowException to indicate no promotion possible 070 promote(); 071 // recursively retry after promotion 072 append(b, off, len); 073 } 074 } 075 076 @Override 077 public int length() throws IOException { 078 notClosed(); 079 return buffer.length(); 080 } 081 082 @Override 083 public void close() throws IOException { 084 if (buffer != null) { 085 try { 086 buffer.close(); 087 } finally { 088 buffer = null; 089 if (file != null) { 090 file.delete(); 091 } 092 file = null; 093 } 094 } 095 } 096 097 /** 098 * Throws an {@link IOException} if the buffer is closed. 099 */ 100 private void notClosed() throws IOException { 101 if (buffer == null) { 102 throw new IOException("buffer is closed"); 103 } 104 } 105 106 private void promote() throws IOException, OverflowException { 107 if (buffer instanceof MemoryBuffer) { 108 MemoryBuffer membuf = (MemoryBuffer) buffer; 109 file = File.createTempFile("buf", null, directory); 110 buffer = new FileBuffer(file, fileLimit); 111 // accesses byte array directly 112 buffer.append(membuf.data, 0, membuf.length()); 113 membuf.close(); 114 } else { 115 // no further promotion possible 116 throw new OverflowException(); 117 } 118 } 119}