java/pig-galago/src/com/yahoo/pig/impl/io/InputStreamPosition.java

   1 /*
   2  * Copyright (c) 2007 Yahoo! Inc.  All rights reserved.
   3  * See accompanying LICENSE file.
   4  */
   5 package com.yahoo.pig.impl.io;
   6
   7 import java.io.FilterInputStream;
   8 import java.io.IOException;
   9 import java.io.InputStream;
  10
  11 /**
  12  * A simple filter stream that keeps track of the position. It is not at
  13  * all specific to Pig, but the need for it arises when implementing LoadFuncs.
  14  *
  15  * @author breed
  16  *
  17  */
  18 public class InputStreamPosition extends FilterInputStream {
  19     long pos;
  20     long markedPos;
  21     /**
  22      * Creates a InputStream filter for the given InputStream with
  23      * the given initial position.
  24      */
  25     public InputStreamPosition(InputStream in, long pos) {
  26        super(in);
  27        this.pos = pos;
  28     }
  29     public synchronized void mark(int readlimit) {
  30         super.mark(readlimit);
  31         markedPos = pos;
  32     }
  33     public int read() throws IOException {
  34         int c = super.read();
  35         pos++;
  36         return c;
  37     }
  38     public int read(byte[] b, int off, int len) throws IOException {
  39         int rc = super.read(b, off, len);
  40         if (rc > 0) {
  41             pos += rc;
  42         }
  43         return rc;
  44     }
  45     public synchronized void reset() throws IOException {
  46         super.reset();
  47         pos = markedPos;
  48     }
  49     public long skip(long n) throws IOException {
  50         long rc = super.skip(n);
  51         pos += rc;
  52         return rc;
  53     }
  54
  55     /**
  56      * Returns the current position in the tracked InputStream.
  57      */
  58     public long getPosition() {
  59         return pos;
  60     }
  61 }