Module com.aoapps.hodgepodge

Package com.aoapps.hodgepodge.io

Class FifoFile

java.lang.Object

com.aoapps.hodgepodge.io.FifoFile

public class FifoFile
extends Object

A FifoFile allows code to read and write to an on-disk managed FIFO. Objects of this class provide InputStream and OutputStream implementations that may be used by any number of concurrent threads. If using this class to access a single file from multiple instances of FifoFile, whether in a single JVM or different JVMs, due to limitations of the underlying RandomAccessFile, only one instance may read and one instance may write. However, race conditions still exists in this scenario, and it is strongly advised to access a file through a single instance of FifoFile.

This class is best used for persistence or management of large FIFO data sets.

Author:

AO Industries, Inc.

Constructor Summary

Constructors

Constructor	Description
FifoFile(File file, long maxFifoLength)
FifoFile(String filename, long maxFifoLength)

Method Summary

Modifier and Type	Method	Description
void	close()
void	flush()	Flushes all updates to this file to the underlying storage device.
int	getBlockSize()
long	getFileLength()
protected long	getFirstIndex()	Gets the data index of the next value that will be read.
FifoFileInputStream	getInputStream()
long	getLength()	Gets the number of bytes currently contained by the FIFO.
long	getMaximumFifoLength()
FifoFileOutputStream	getOutputStream()
void	reset()	Resets this FifoFile to contain no contents and start writing at the beginning of the file.
protected void	setFirstIndex(long index)	Sets the data index of the next value that will be read.
protected void	setLength(long length)	Sets the number of bytes currently contained by the FIFO.

Methods inherited from class java.lang.Object

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

Constructor Details

FifoFile

public FifoFile(String filename,
 long maxFifoLength)
         throws IOException

Throws:

IOException

FifoFile

public FifoFile(File file,
 long maxFifoLength)
         throws IOException

Throws:

IOException

Method Details

getInputStream

public FifoFileInputStream getInputStream()

getOutputStream

public FifoFileOutputStream getOutputStream()

getMaximumFifoLength

public long getMaximumFifoLength()

getFileLength

public long getFileLength()

getBlockSize

public int getBlockSize()

reset

public void reset()
           throws IOException

Resets this FifoFile to contain no contents and start writing at the beginning of the file.

Throws:

IOException

close

public void close()
           throws IOException

Throws:

IOException

getFirstIndex

protected long getFirstIndex()
                      throws IOException

Gets the data index of the next value that will be read.

Throws:

IOException

setFirstIndex

protected void setFirstIndex(long index)
                      throws IOException

Sets the data index of the next value that will be read.

Throws:

IOException

getLength

public long getLength()
               throws IOException

Gets the number of bytes currently contained by the FIFO.

Throws:

IOException

setLength

protected void setLength(long length)
                  throws IOException

Sets the number of bytes currently contained by the FIFO.

Throws:

IOException

flush

public void flush()
           throws IOException

Flushes all updates to this file to the underlying storage device. This is performed by RandomAccessFile.getChannel().force(true).

Throws:

IOException

See Also:

• FifoFileOutputStream.flush()