org.xmlBlaster.util.recorder.file
Class FileIO

java.lang.Object
  org.xmlBlaster.util.recorder.file.FileIO

public class FileIO

extends java.lang.Object

This is the generic interface to the harddisk.

It recovers on restart as the current situation is stored as well.

To use this, you supply an implementation of

Performance is on a standard harddisk and 600 MHz intel server:

• With SYNC mode: 90 write/sec or 90 reads/sec
• None SYNC mode: 7000 write/sec or 5000 reads/sec

In SYNC mode, the harddisk is synced after any data written. SYNC is usually left off, as an application crash can be recovered without.

You can call readNext(false) and need to commit when you have processed the retrieved data successully with saveCurrReadPos(). If your processing fails without a saveCurrReadPos() call the subsequent readNext() gets the same data again.

File Format: "data....."

TODO:
- If the file is never read empty it grows and grows ...
- The mode DISCARD_OLDEST does not shrink the file size

See the util.recorder requirement.

See Also:

FileIOTest

Field Summary

private long	currReadPos
private java.io.File	file
private java.lang.String	fileName
private boolean	firstLost
private boolean	firstUnread
private Global	glob
private long	lastReadPos
private static java.util.logging.Logger	log
private long	LOST_POS
private long	maxEntries
private java.lang.String	ME
private int	mode
private int	modeDiscard
private int	modeDiscardOldest
private int	modeException
private long	numFileDeleteLost Remember number of lost data when file was killed by somebody
private long	numLost
private long	numUnread
private java.io.RandomAccessFile	ra
private long	UNREAD_POS
private I_UserDataHandler	userDataHandler
private boolean	useSync

Constructor Summary

FileIO(Global glob, java.lang.String fileName, I_UserDataHandler userDataHandler, long maxEntries, boolean useSync)

Method Summary

void	destroy() Destroy data
long	getCurrReadPos() Read the first 8 bytes contain the offset to data to be read
long	getNumFileDeleteLost() Returns the number of lost data objects when the file was deleted by somebody.
long	getNumLost() Counter for lost messages in 'discard' or 'discardOldest' mode
long	getNumUnread() The number of unread data entities.
void	initialize() Initializes on first startup or reloads an existing file.
java.io.File	mkfile(java.lang.String fullName) Creates recursive all directories, assuming file name is the last part of the path
java.lang.Object	readNext(boolean autoCommit) You can call readNext(false) and need to commit when you have processed the retrieved data successully with saveCurrReadPos().
void	saveCurrReadPos() Write the first 8 bytes containing the offset to data to be read
void	setModeDiscard() Throw the message away if queue is full - the message is silently lost!
void	setModeDiscardOldest() Throw the oldest message away if queue is full - the message is silently lost!
void	setModeException() Default you get an Exception if queue is full
void	shutdown() Don't loose data
boolean	undo() Undo the last read, not that this is not thread save! Only one single undo is supported
void	writeNext(java.lang.Object data) Write more data.

Methods inherited from class java.lang.Object

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

Field Detail

log

private static java.util.logging.Logger log

ME

private final java.lang.String ME

See Also:

Constant Field Values

glob

private final Global glob

currReadPos

private long currReadPos

lastReadPos

private long lastReadPos

file

private java.io.File file

ra

private java.io.RandomAccessFile ra

numUnread

private long numUnread

firstUnread

private boolean firstUnread

UNREAD_POS

private final long UNREAD_POS

See Also:

Constant Field Values

firstLost

private boolean firstLost

numLost

private long numLost

LOST_POS

private final long LOST_POS

See Also:

Constant Field Values

numFileDeleteLost

private long numFileDeleteLost

Remember number of lost data when file was killed by somebody

useSync

private boolean useSync

userDataHandler

private final I_UserDataHandler userDataHandler

fileName

private java.lang.String fileName

maxEntries

private long maxEntries

modeException

private final int modeException

See Also:

Constant Field Values

modeDiscardOldest

private final int modeDiscardOldest

See Also:

Constant Field Values

modeDiscard

private final int modeDiscard

See Also:

Constant Field Values

mode

private int mode

Constructor Detail

FileIO

public FileIO(Global glob,
              java.lang.String fileName,
              I_UserDataHandler userDataHandler,
              long maxEntries,
              boolean useSync)
       throws java.io.IOException

Parameters:

maxEntries - < 0 sets it to unlimited

userDataHandler - Your implementation of your data format marshalling

Method Detail

initialize

public void initialize()
                throws java.io.IOException

Initializes on first startup or reloads an existing file.

Throws:

java.io.IOException

mkfile

public java.io.File mkfile(java.lang.String fullName)
                    throws java.io.IOException

Creates recursive all directories, assuming file name is the last part of the path

Returns:

The new file handle

Throws:

java.io.IOException

readNext

public java.lang.Object readNext(boolean autoCommit)
                          throws java.io.IOException,
                                 XmlBlasterException

You can call readNext(false) and need to commit when you have processed the retrieved data successully with saveCurrReadPos(). If your processing fails without a saveCurrReadPos() call the subsequent readNext() gets the same data again.

Throws:

XmlBlasterException - /> "FileRecorder.FileLost" If file disappeared, you can proceed
Of an XmlBlasterExeption from the user data handler

java.io.IOException

XmlBlasterException

undo

public boolean undo()

Undo the last read, not that this is not thread save!

Only one single undo is supported

Returns:

true if undo was possible

writeNext

public void writeNext(java.lang.Object data)
               throws java.io.IOException,
                      XmlBlasterException

Write more data.

Throws:

XmlBlasterException - /> "ErrorCode.FileRecorder.FileLost" If file disappeared, we create a new and store the message
"ErrorCode.RESOURCE_OVERFLOW_QUEUE_ENTRIES" Maximum size reached in Exception mode
Of an XmlBlasterExeption from the user data handler

java.io.IOException

XmlBlasterException

saveCurrReadPos

public final void saveCurrReadPos()
                           throws java.io.IOException

Write the first 8 bytes containing the offset to data to be read

Throws:

java.io.IOException

getCurrReadPos

public final long getCurrReadPos()
                          throws java.io.IOException

Read the first 8 bytes contain the offset to data to be read

Throws:

java.io.IOException

getNumUnread

public final long getNumUnread()

The number of unread data entities.

getNumLost

public long getNumLost()

Counter for lost messages in 'discard' or 'discardOldest' mode

getNumFileDeleteLost

public final long getNumFileDeleteLost()

Returns the number of lost data objects when the file was deleted by somebody.

setModeDiscard

public void setModeDiscard()

Throw the message away if queue is full - the message is silently lost!

setModeDiscardOldest

public void setModeDiscardOldest()

Throw the oldest message away if queue is full - the message is silently lost!

setModeException

public void setModeException()

Default you get an Exception if queue is full

shutdown

public void shutdown()

Don't loose data

destroy

public void destroy()

Destroy data