| /** |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.hadoop.fs; |
| |
| import java.io.BufferedInputStream; |
| import java.io.IOException; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| |
| |
| /** |
| * A class optimizes reading from FSInputStream by bufferring |
| */ |
| |
| @InterfaceAudience.Private |
| @InterfaceStability.Unstable |
| public class BufferedFSInputStream extends BufferedInputStream |
| implements Seekable, PositionedReadable { |
| /** |
| * Creates a <code>BufferedFSInputStream</code> |
| * with the specified buffer size, |
| * and saves its argument, the input stream |
| * <code>in</code>, for later use. An internal |
| * buffer array of length <code>size</code> |
| * is created and stored in <code>buf</code>. |
| * |
| * @param in the underlying input stream. |
| * @param size the buffer size. |
| * @exception IllegalArgumentException if size <= 0. |
| */ |
| public BufferedFSInputStream(FSInputStream in, int size) { |
| super(in, size); |
| } |
| |
| public long getPos() throws IOException { |
| return ((FSInputStream)in).getPos()-(count-pos); |
| } |
| |
| public long skip(long n) throws IOException { |
| if (n <= 0) { |
| return 0; |
| } |
| |
| seek(getPos()+n); |
| return n; |
| } |
| |
| public void seek(long pos) throws IOException { |
| if( pos<0 ) { |
| return; |
| } |
| // optimize: check if the pos is in the buffer |
| long end = ((FSInputStream)in).getPos(); |
| long start = end - count; |
| if( pos>=start && pos<end) { |
| this.pos = (int)(pos-start); |
| return; |
| } |
| |
| // invalidate buffer |
| this.pos = 0; |
| this.count = 0; |
| |
| ((FSInputStream)in).seek(pos); |
| } |
| |
| public boolean seekToNewSource(long targetPos) throws IOException { |
| pos = 0; |
| count = 0; |
| return ((FSInputStream)in).seekToNewSource(targetPos); |
| } |
| |
| public int read(long position, byte[] buffer, int offset, int length) throws IOException { |
| return ((FSInputStream)in).read(position, buffer, offset, length) ; |
| } |
| |
| public void readFully(long position, byte[] buffer, int offset, int length) throws IOException { |
| ((FSInputStream)in).readFully(position, buffer, offset, length); |
| } |
| |
| public void readFully(long position, byte[] buffer) throws IOException { |
| ((FSInputStream)in).readFully(position, buffer); |
| } |
| } |