bitronix.tm.journal

Class TransactionLogAppender

java.lang.Object

bitronix.tm.journal.TransactionLogAppender

public class TransactionLogAppender
extends Object

Used to write TransactionLogRecord objects to a log file.

Author:

Ludovic Orban, Brett Wooldridge

Field Summary

Fields

Modifier and Type	Field and Description
static int	END_RECORD int-encoded "xntB" ASCII string.

Constructor Summary

Constructors

Constructor and Description
TransactionLogAppender(File file, long maxFileLength) Create an appender that will write to specified file up to the specified maximum length.

Method Summary

Modifier and Type	Method and Description
protected void	clearDanglingLogs()
protected void	close() Close the appender and the underlying file.
protected void	force() Force flushing the logs to disk
protected TransactionLogCursor	getCursor() Creates a cursor on this journal file allowing iteration of its records.
protected List<TransactionLogRecord>	getDanglingLogs()
long	getPosition() Get the current file position.
byte	getState() Get STATE_HEADER.
protected boolean	setPositionAndAdvance(TransactionLogRecord tlog) Get the current file position and advance the position by recordSize if the maximum file length won't be exceeded.
void	setState(byte state) Set STATE_HEADER.
String	toString()
protected void	writeLog(TransactionLogRecord tlog) Write a TransactionLogRecord to disk.

Methods inherited from class java.lang.Object

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

Field Detail

END_RECORD

public static final int END_RECORD

int-encoded "xntB" ASCII string. This will be useful after swapping log files since we will potentially overwrite old logs not necessarily of the same size. Very useful when debugging and eventually restoring broken log files.

See Also:

Constant Field Values

Constructor Detail

TransactionLogAppender

public TransactionLogAppender(File file,
                              long maxFileLength)
                       throws IOException

Create an appender that will write to specified file up to the specified maximum length.

Parameters:

file - the underlying File used to write to disk.

maxFileLength - size of the file on disk that can never be bypassed.

Throws:

IOException - if an I/O error occurs.

Method Detail

setPositionAndAdvance

protected boolean setPositionAndAdvance(TransactionLogRecord tlog)
                                 throws IOException

Get the current file position and advance the position by recordSize if the maximum file length won't be exceeded. Callers to this method are synchronized within the DiskJournal and it is guaranteed there will never be two callers to this method. This creates a Java memory barrier that guarantees that 'position' will never be viewed inconsistently between threads.

Parameters:

tlog - the TransactionLogRecord

Returns:

true if the log should rollover, false otherwise

Throws:

IOException - if an I/O error occurs

writeLog

protected void writeLog(TransactionLogRecord tlog)
                 throws IOException

Write a TransactionLogRecord to disk.

Parameters:

tlog - the record to write to disk.

Throws:

IOException - if an I/O error occurs.

getDanglingLogs

protected List<TransactionLogRecord> getDanglingLogs()

clearDanglingLogs

protected void clearDanglingLogs()

getState

public byte getState()

Get STATE_HEADER.

Returns:

the STATE_HEADER value.

setState

public void setState(byte state)
              throws IOException

Set STATE_HEADER.

Parameters:

state - the STATE_HEADER value.

Throws:

IOException - if an I/O error occurs.

getPosition

public long getPosition()

Get the current file position.

Returns:

the file position

close

protected void close()
              throws IOException

Close the appender and the underlying file.

Throws:

IOException - if an I/O error occurs.

getCursor

protected TransactionLogCursor getCursor()
                                  throws IOException

Creates a cursor on this journal file allowing iteration of its records. This opens a new read-only file descriptor independent of the write-only one still used for writing transaction logs.

Returns:

a TransactionLogCursor.

Throws:

IOException - if an I/O error occurs.

force

protected void force()
              throws IOException

Force flushing the logs to disk

Throws:

IOException - if an I/O error occurs.

toString

public String toString()

Overrides:

toString in class Object