001/* 002 * Licensed to the Apache Software Foundation (ASF) under one 003 * or more contributor license agreements. See the NOTICE file 004 * distributed with this work for additional information 005 * regarding copyright ownership. The ASF licenses this file 006 * to you under the Apache License, Version 2.0 (the 007 * "License"); you may not use this file except in compliance 008 * with the License. You may obtain a copy of the License at 009 * 010 * http://www.apache.org/licenses/LICENSE-2.0 011 * 012 * Unless required by applicable law or agreed to in writing, software 013 * distributed under the License is distributed on an "AS IS" BASIS, 014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 015 * See the License for the specific language governing permissions and 016 * limitations under the License. 017 */ 018package org.apache.hadoop.hbase.io; 019 020import java.io.IOException; 021import java.io.OutputStream; 022import java.nio.ByteBuffer; 023import org.apache.hadoop.hbase.io.util.StreamUtils; 024import org.apache.hadoop.hbase.util.ByteBufferUtils; 025import org.apache.yetus.audience.InterfaceAudience; 026 027/** 028 * When deal with OutputStream which is not ByteBufferWriter type, wrap it with this class. We will 029 * have to write offheap ByteBuffer (DBB) data into the OS. This class is having a temp byte array 030 * to which we can copy the DBB data for writing to the OS. <br> 031 * This is used while writing Cell data to WAL. In case of AsyncWAL, the OS created there is 032 * ByteBufferWriter. But in case of FSHLog, the OS passed by DFS client, is not of type 033 * ByteBufferWriter. We will need this temp solution until DFS client supports writing ByteBuffer 034 * directly to the OS it creates. <br> 035 * Note: This class is not thread safe. 036 */ 037@InterfaceAudience.Private 038public class ByteBufferWriterOutputStream extends OutputStream implements ByteBufferWriter { 039 040 private static final int DEFAULT_BUFFER_SIZE = 4096; 041 042 private final OutputStream os; 043 private final int bufSize; 044 private byte[] buf; 045 046 public ByteBufferWriterOutputStream(OutputStream os) { 047 this(os, DEFAULT_BUFFER_SIZE); 048 } 049 050 public ByteBufferWriterOutputStream(OutputStream os, int size) { 051 this.os = os; 052 this.bufSize = size; 053 this.buf = null; 054 } 055 056 /** 057 * Writes len bytes from the specified ByteBuffer starting at offset off to this OutputStream. If 058 * b is null, a NullPointerException is thrown. If off is negative or larger than the ByteBuffer 059 * then an ArrayIndexOutOfBoundsException is thrown. If len is greater than the length of the 060 * ByteBuffer, then an ArrayIndexOutOfBoundsException is thrown. This method does not change the 061 * position of the ByteBuffer. 062 * @param b the ByteBuffer 063 * @param off the start offset in the data 064 * @param len the number of bytes to write n * if an I/O error occurs. In particular, an 065 * IOException is thrown if the output stream is closed. 066 */ 067 @Override 068 public void write(ByteBuffer b, int off, int len) throws IOException { 069 // Lazily load in the event that this version of 'write' is not invoked 070 if (this.buf == null) { 071 this.buf = new byte[this.bufSize]; 072 } 073 int totalCopied = 0; 074 while (totalCopied < len) { 075 int bytesToCopy = Math.min((len - totalCopied), this.bufSize); 076 ByteBufferUtils.copyFromBufferToArray(this.buf, b, off + totalCopied, 0, bytesToCopy); 077 this.os.write(this.buf, 0, bytesToCopy); 078 totalCopied += bytesToCopy; 079 } 080 } 081 082 @Override 083 public void writeInt(int i) throws IOException { 084 StreamUtils.writeInt(this.os, i); 085 } 086 087 @Override 088 public void write(int b) throws IOException { 089 this.os.write(b); 090 } 091 092 @Override 093 public void write(byte[] b, int off, int len) throws IOException { 094 this.os.write(b, off, len); 095 } 096 097 @Override 098 public void flush() throws IOException { 099 this.os.flush(); 100 } 101 102 @Override 103 public void close() throws IOException { 104 this.os.close(); 105 } 106}