Package org.apache.spark.io

Class ReadAheadInputStream

Object

java.io.InputStream

org.apache.spark.io.ReadAheadInputStream

All Implemented Interfaces:

Closeable, AutoCloseable

public class ReadAheadInputStream
extends InputStream

InputStream implementation which asynchronously reads ahead from the underlying input stream when specified amount of data has been read from the current buffer. It does it by maintaining two buffers - active buffer and read ahead buffer. Active buffer contains data which should be returned when a read() call is issued. The read ahead buffer is used to asynchronously read from the underlying input stream and once the current active buffer is exhausted, we flip the two buffers so that we can start reading from the read ahead buffer without being blocked in disk I/O.

Constructor Summary

Constructors

Constructor	Description
ReadAheadInputStream(InputStream inputStream, int bufferSizeInBytes)	Creates a ReadAheadInputStream with the specified buffer size and read-ahead threshold

Method Summary

Modifier and Type	Method	Description
int	available()
void	close()
int	read()
int	read(byte[] b, int offset, int len)
long	skip(long n)

Methods inherited from class java.io.InputStream

mark, markSupported, nullInputStream, read, readAllBytes, readNBytes, readNBytes, reset, skipNBytes, transferTo

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

ReadAheadInputStream

public ReadAheadInputStream(InputStream inputStream,
 int bufferSizeInBytes)

Creates a ReadAheadInputStream with the specified buffer size and read-ahead threshold

Parameters:

inputStream - The underlying input stream.

bufferSizeInBytes - The buffer size.

Method Details

read

public int read()
         throws IOException

Specified by:

read in class InputStream

Throws:

IOException

read

public int read(byte[] b,
 int offset,
 int len)
         throws IOException

Overrides:

read in class InputStream

Throws:

IOException

available

public int available()
              throws IOException

Overrides:

available in class InputStream

Throws:

IOException

skip

public long skip(long n)
          throws IOException

Overrides:

skip in class InputStream

Throws:

IOException

close

public void close()
           throws IOException

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Overrides:

close in class InputStream

Throws:

IOException