Package org.apache.jena.dboe.transaction.txn.journal

Class Journal

java.lang.Object

org.apache.jena.dboe.transaction.txn.journal.Journal

All Implemented Interfaces:

org.apache.jena.atlas.lib.Closeable, org.apache.jena.atlas.lib.Sync

public final class Journal
extends Object
implements org.apache.jena.atlas.lib.Sync, org.apache.jena.atlas.lib.Closeable

A transaction journal. The journal is append-only for writes, with truncation of the file every so often. It is read during recovery. The size of entries depends on per-component redo/undo records; the control records like COMMIT are quite small. Entries have a CRC to ensure that part-entries are not acted on.

Method Summary

Modifier and Type	Method	Description
void	abortWrite()
void	close()
void	commitWrite()
static Journal	create(BufferChannel chan)
static Journal	create(Location location)
void	endWrite()
Iterator<JournalEntry>	entries()
Iterator<JournalEntry>	entries(long startPosition)
static boolean	exists(Location location)
String	getFilename()
Location	getLocation()
boolean	isEmpty()
long	position()
JournalEntry	readJournal(long id)
void	reopen()	Forced reopen - Thread.interrupt causes java to close file.
void	reset()
long	size()
void	startWrite()
void	sync()
void	truncate(long size)
long	write(JournalEntryType type, ComponentId componentId, ByteBuffer buffer)	Write an entry and return it's location in the journal
long	write(PrepareState prepareState)
long	writeJournal(JournalEntry entry)
long	writeStartPosn()

Methods inherited from class java.lang.Object

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

Method Details

exists

public static boolean exists(Location location)

create

public static Journal create(BufferChannel chan)

create

public static Journal create(Location location)

reopen

public void reopen()

Forced reopen - Thread.interrupt causes java to close file. Attempt to close, open, and position.

writeJournal

public long writeJournal(JournalEntry entry)

write

public long write(PrepareState prepareState)

write

public long write(JournalEntryType type,
 ComponentId componentId,
 ByteBuffer buffer)

Write an entry and return it's location in the journal

readJournal

public JournalEntry readJournal(long id)

startWrite

public void startWrite()

writeStartPosn

public long writeStartPosn()

commitWrite

public void commitWrite()

abortWrite

public void abortWrite()

endWrite

public void endWrite()

entries

public Iterator<JournalEntry> entries()

entries

public Iterator<JournalEntry> entries(long startPosition)

sync

public void sync()

Specified by:

sync in interface org.apache.jena.atlas.lib.Sync

close

public void close()

Specified by:

close in interface org.apache.jena.atlas.lib.Closeable

size

public long size()

isEmpty

public boolean isEmpty()

truncate

public void truncate(long size)

reset

public void reset()

position

public long position()

getLocation

public Location getLocation()

getFilename

public String getFilename()