Package edu.stanford.slac.archiverappliance.PB.utils

Class LineByteStream

java.lang.Object

edu.stanford.slac.archiverappliance.PB.utils.LineByteStream

All Implemented Interfaces:

Closeable, AutoCloseable

public class LineByteStream
extends Object
implements Closeable

This class wraps a RandomAccessFile and returns byte arrays separated by lines. In addition it also maintains a count of the bytes read. We expect the file channel to be positioned correctly for the initial read. After each read, the channel is positioned just after the newline.

Author:

mshankar

Field Summary

Fields

Modifier and Type	Field	Description
static int	MAX_ITERATIONS_TO_DETERMINE_LINE
static int	MAX_LINE_SIZE

Constructor Summary

Constructors

Constructor	Description
LineByteStream(Path path)
LineByteStream(Path path, long startPosition)
LineByteStream(Path path, long startPosition, long endPosition)

Method Summary

Modifier and Type	Method	Description
void	close()
String	getAbsolutePath()
long	getCurrentPosition()
byte[]	readLine()
ByteArray	readLine(ByteArray bar)	Optimize the readline by offering the abilty to reuse the same memory allocation.
void	safeClose()
void	seekToBeforeLastLine()	Seeks and positions the pointer to to the last line in the file.
void	seekToBeforePreviousLine(long posn)	Seeks and positions the pointer to line previous to the specified position.
void	seekToFirstNewLine()	Seeks to the first new line after the current position in the rndAccFile.

Methods inherited from class java.lang.Object

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

Field Detail

MAX_LINE_SIZE

public static int MAX_LINE_SIZE

MAX_ITERATIONS_TO_DETERMINE_LINE

public static int MAX_ITERATIONS_TO_DETERMINE_LINE

Constructor Detail

LineByteStream

public LineByteStream(Path path)
               throws IOException

Throws:

IOException

LineByteStream

public LineByteStream(Path path,
                      long startPosition)
               throws IOException

Throws:

IOException

LineByteStream

public LineByteStream(Path path,
                      long startPosition,
                      long endPosition)
               throws IOException

Throws:

IOException

Method Detail

readLine

public byte[] readLine()
                throws IOException

Throws:

IOException

readLine

public ByteArray readLine(ByteArray bar)
                   throws IOException

Optimize the readline by offering the abilty to reuse the same memory allocation. This does not escape the bytes as it is reading the line. While this is optimal to do, it means for raw responses, we'll be redoing some of the work and raw responses are 90% of the requests. If in future, we determine that unescaping here is more optimal, this method has an unescape version in version control history. Returns the same byte array as the input.

Parameters:

bar - ByteArray

Returns:

bar ByteArray

Throws:

IOException -  

seekToFirstNewLine

public void seekToFirstNewLine()
                        throws IOException

Seeks to the first new line after the current position in the rndAccFile. The file pointer is located just after the first newline.

Throws:

IOException -  

seekToBeforeLastLine

public void seekToBeforeLastLine()
                          throws IOException

Seeks and positions the pointer to to the last line in the file. The file pointer is located just before the last line so that readLine gets a valid line. About the only thing once can do after this is to read a line and stop...

Throws:

IOException -  

seekToBeforePreviousLine

public void seekToBeforePreviousLine(long posn)
                              throws IOException

Seeks and positions the pointer to line previous to the specified position. The file pointer is located just so that one can do a readline. Note that this method is not efficient at all; so use with care.

Parameters:

posn -  

Throws:

IOException -  

getCurrentPosition

public long getCurrentPosition()
                        throws IOException

Throws:

IOException

safeClose

public void safeClose()

getAbsolutePath

public String getAbsolutePath()

close

public void close()
           throws IOException

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Throws:

IOException