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.IOException; 021import java.util.Arrays; 022 023/** 024 * A buffer that uses a byte array for data storage. The byte array starts at a prescribed 025 * initial length, and grows exponentially up to the prescribed limit. 026 * <p> 027 * <strong>Note:</strong> This implementation is not synchronized. If multiple threads access 028 * a buffer concurrently, threads that append to the buffer should synchronize on the instance 029 * of this object. 030 */ 031public class MemoryBuffer implements Buffer { 032 033 /** The byte array storing buffer data. */ 034 byte[] data; // package scope to give TemporaryBuffer access without intermediate copy 035 036 /** The current length of the buffer. */ 037 private final int limit; 038 039 /** Current length of the buffer. */ 040 private int length = 0; 041 042 /** 043 * Constructs a new memory buffer. 044 * 045 * @param initial the initial size of the byte array to create. 046 * @param limit the buffer length limit, after which an {@link OverflowException} will be thrown. 047 */ 048 public MemoryBuffer(int initial, int limit) { 049 data = new byte[initial]; 050 this.limit = limit; 051 } 052 053 @Override 054 public int read(int pos, byte[] b, int off, int len) throws IOException { 055 if (off < 0 || len < 0 || len > b.length - off) { 056 throw new IndexOutOfBoundsException(); 057 } 058 notClosed(); 059 int n = 0; 060 if (pos < length) { 061 n = Math.min(len, length - pos); 062 System.arraycopy(data, pos, b, off, n); 063 } 064 return n; 065 } 066 067 @Override 068 public void append(byte[] b, int off, int len) throws IOException { 069 if (off < 0 || len < 0 || len > b.length - off) { 070 throw new IndexOutOfBoundsException(); 071 } 072 notClosed(); 073 int end = this.length + len; 074 if (end > limit) { 075 throw new OverflowException(); 076 } 077 if (data.length < end) { 078 // buffer grows exponentially (up to limit) 079 data = Arrays.copyOf(data, Math.max(end, Math.min(limit, data.length << 1))); 080 } 081 System.arraycopy(b, off, data, this.length, len); 082 this.length += len; 083 } 084 085 @Override 086 public int length() { 087 return length; 088 } 089 090 @Override 091 public void close() { 092 data = null; 093 } 094 095 @Override 096 public void finalize() throws Throwable { 097 close(); 098 super.finalize(); 099 } 100 101 /** 102 * Throws an {@link IOException} if the buffer is closed. 103 */ 104 private void notClosed() throws IOException { 105 if (data == null) { 106 throw new IOException("buffer is closed"); 107 } 108 } 109}