1 /** 2 * Licensed to the Apache Software Foundation (ASF) under one 3 * or more contributor license agreements. See the NOTICE file 4 * distributed with this work for additional information 5 * regarding copyright ownership. The ASF licenses this file 6 * to you under the Apache License, Version 2.0 (the 7 * "License"); you may not use this file except in compliance 8 * with the License. You may obtain a copy of the License at 9 * 10 * http://www.apache.org/licenses/LICENSE-2.0 11 * 12 * Unless required by applicable law or agreed to in writing, software 13 * distributed under the License is distributed on an "AS IS" BASIS, 14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 15 * See the License for the specific language governing permissions and 16 * limitations under the License. 17 */ 18 package org.apache.hadoop.hbase.io; 19 20 import java.io.InputStream; 21 import java.nio.ByteBuffer; 22 23 import org.apache.hadoop.hbase.classification.InterfaceAudience; 24 import org.apache.hadoop.hbase.util.ByteBufferUtils; 25 26 /** 27 * Not thread safe! 28 * <p> 29 * Please note that the reads will cause position movement on wrapped ByteBuffer. 30 */ 31 @InterfaceAudience.Private 32 public class ByteBufferInputStream extends InputStream { 33 34 private ByteBuffer buf; 35 36 public ByteBufferInputStream(ByteBuffer buf) { 37 this.buf = buf; 38 } 39 40 /** 41 * Reads the next byte of data from this input stream. The value byte is returned as an 42 * <code>int</code> in the range <code>0</code> to <code>255</code>. If no byte is available 43 * because the end of the stream has been reached, the value <code>-1</code> is returned. 44 * @return the next byte of data, or <code>-1</code> if the end of the stream has been reached. 45 */ 46 @Override 47 public int read() { 48 if (this.buf.hasRemaining()) { 49 return (this.buf.get() & 0xff); 50 } 51 return -1; 52 } 53 54 /** 55 * Reads up to next <code>len</code> bytes of data from buffer into passed array(starting from 56 * given offset). 57 * @param b the array into which the data is read. 58 * @param off the start offset in the destination array <code>b</code> 59 * @param len the maximum number of bytes to read. 60 * @return the total number of bytes actually read into the buffer, or <code>-1</code> if not even 61 * 1 byte can be read because the end of the stream has been reached. 62 */ 63 @Override 64 public int read(byte[] b, int off, int len) { 65 int avail = available(); 66 if (avail <= 0) { 67 return -1; 68 } 69 70 if (len > avail) { 71 len = avail; 72 } 73 if (len <= 0) { 74 return 0; 75 } 76 77 ByteBufferUtils.copyFromBufferToArray(b, this.buf, this.buf.position(), off, len); 78 this.buf.position(this.buf.position() + len); // we should advance the buffer position 79 return len; 80 } 81 82 /** 83 * Skips <code>n</code> bytes of input from this input stream. Fewer bytes might be skipped if the 84 * end of the input stream is reached. The actual number <code>k</code> of bytes to be skipped is 85 * equal to the smaller of <code>n</code> and remaining bytes in the stream. 86 * @param n the number of bytes to be skipped. 87 * @return the actual number of bytes skipped. 88 */ 89 @Override 90 public long skip(long n) { 91 long k = Math.min(n, available()); 92 if (k < 0) { 93 k = 0; 94 } 95 this.buf.position((int) (this.buf.position() + k)); 96 return k; 97 } 98 99 /** 100 * @return the number of remaining bytes that can be read (or skipped 101 * over) from this input stream. 102 */ 103 @Override 104 public int available() { 105 return this.buf.remaining(); 106 } 107 }