bitronix.tm.journal

Class DiskJournal

java.lang.Object

bitronix.tm.journal.DiskJournal

All Implemented Interfaces:

Journal, MigratableJournal, ReadableJournal, Service

public class DiskJournal
extends Object
implements Journal, MigratableJournal, ReadableJournal

Simple implementation of a journal that writes on a two-files disk log.

Files are pre-allocated in size, never grow and when the first one is full, dangling records are copied to the second file and logging starts again on the latter.

This implementation is not highly efficient but quite robust and simple. It is based on one of the implementations proposed by Mike Spille.

Configurable properties are all starting with bitronix.tm.journal.disk.

Author:

Ludovic Orban, Brett Wooldridge

See Also:

Configuration, XA Exposed, Part III: The Implementor's Notebook

Constructor Summary

Constructors

Constructor and Description
DiskJournal() Create an uninitialized disk journal.

Method Summary

Modifier and Type	Method and Description
void	close() Close the disk journal and the underlying files.
Map<Uid,JournalRecord>	collectDanglingRecords() Collect all dangling records of the active log file.
void	force() Force active log file to synchronize with the underlying disk device.
void	log(int status, Uid gtrid, Set<String> uniqueNames) Log a new transaction status to journal.
void	migrateTo(Journal other) Can be called at any point in time to migrate all unfinished transactions into the given journal.
void	open() Open the disk journal.
void	shutdown() Shutdown the service and free all held resources.
void	unsafeReadRecordsInto(Collection<JournalRecord> target, boolean includeInvalid) Reads all raw journal records and and adds them to the given collection.

Methods inherited from class java.lang.Object

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

Constructor Detail

DiskJournal

public DiskJournal()

Create an uninitialized disk journal. You must call open() prior you can use it.

Method Detail

log

public void log(int status,
                Uid gtrid,
                Set<String> uniqueNames)
         throws IOException

Log a new transaction status to journal. Note that the DiskJournal will not check the flow of the transaction. If you call this method with erroneous data, it will be added to the journal anyway.

Specified by:

log in interface Journal

Parameters:

status - transaction status to log. See Status constants.

gtrid - raw GTRID of the transaction.

uniqueNames - unique names of the ResourceBeans participating in this transaction.

Throws:

IOException - in case of disk IO failure or if the disk journal is not open.

force

public void force()
           throws IOException

Force active log file to synchronize with the underlying disk device.

Specified by:

force in interface Journal

Throws:

IOException - in case of disk IO failure or if the disk journal is not open.

open

public void open()
          throws IOException

Open the disk journal. Files are checked for integrity and DiskJournal will refuse to open corrupted log files. If files are not present on disk, this method will create and pre-allocate them.

Specified by:

open in interface Journal

Throws:

IOException - in case of disk IO failure.

close

public void close()
           throws IOException

Close the disk journal and the underlying files.

Specified by:

close in interface Journal

Throws:

IOException - in case of disk IO failure.

shutdown

public void shutdown()

Description copied from interface: Service

Shutdown the service and free all held resources.

Specified by:

shutdown in interface Service

collectDanglingRecords

public Map<Uid,JournalRecord> collectDanglingRecords()
                                              throws IOException

Collect all dangling records of the active log file.

Specified by:

collectDanglingRecords in interface Journal

Returns:

a Map using Uid objects GTRID as key and TransactionLogRecord as value

Throws:

IOException - in case of disk IO failure or if the disk journal is not open.

migrateTo

public void migrateTo(Journal other)
               throws IOException,
                      IllegalArgumentException

Can be called at any point in time to migrate all unfinished transactions into the given journal.

Specified by:

migrateTo in interface MigratableJournal

Parameters:

other - the journal to migrate all unfinished transactions to.

Throws:

IOException - In case of not all entries could be written into the other journal.

IllegalArgumentException - If other is the same instance as 'this'.

unsafeReadRecordsInto

public void unsafeReadRecordsInto(Collection<JournalRecord> target,
                                  boolean includeInvalid)
                           throws IOException

Reads all raw journal records and and adds them to the given collection.

Notes:

• This implementation does not guarantee to return valid results if the journal is in use. The caller is responsible to control this state.
• The journal is read from the beginning to end with the oldest entry being first. If only a subset of data is required, the given collection should take care to capture the required data.

Specified by:

unsafeReadRecordsInto in interface ReadableJournal

Parameters:

target - the target collection to read the records into.

includeInvalid - specified whether broken records are attempted to be included.

Throws:

IOException - In case of reading the first record fails.