org.apache.spark.io

Class ReadAheadInputStream

Object

java.io.InputStream

org.apache.spark.io.ReadAheadInputStream

All Implemented Interfaces:

java.io.Closeable, AutoCloseable

public class ReadAheadInputStream
extends java.io.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 and Description
ReadAheadInputStream(java.io.InputStream inputStream, int bufferSizeInBytes, int readAheadThresholdInBytes) Creates a ReadAheadInputStream with the specified buffer size and read-ahead threshold

Method Summary

Modifier and Type	Method and 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, read, reset

Methods inherited from class Object

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

Constructor Detail

ReadAheadInputStream

public ReadAheadInputStream(java.io.InputStream inputStream,
                            int bufferSizeInBytes,
                            int readAheadThresholdInBytes)

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

Parameters:

inputStream - The underlying input stream.

bufferSizeInBytes - The buffer size.

readAheadThresholdInBytes - If the active buffer has less data than the read-ahead threshold, an async read is triggered.

Method Detail

read

public int read()
         throws java.io.IOException

Specified by:

read in class java.io.InputStream

Throws:

java.io.IOException

read

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

Overrides:

read in class java.io.InputStream

Throws:

java.io.IOException

available

public int available()
              throws java.io.IOException

Overrides:

available in class java.io.InputStream

Throws:

java.io.IOException

skip

public long skip(long n)
          throws java.io.IOException

Overrides:

skip in class java.io.InputStream

Throws:

java.io.IOException

close

public void close()
           throws java.io.IOException

Specified by:

close in interface java.io.Closeable

Specified by:

close in interface AutoCloseable

Overrides:

close in class java.io.InputStream

Throws:

java.io.IOException