org.activeio.journal.active
Class JournalImpl

java.lang.Object
  org.activeio.journal.active.JournalImpl

All Implemented Interfaces:

Disposable, Journal

public final class JournalImpl

extends java.lang.Object

implements Journal, Disposable

A high speed Journal implementation. Inspired by the ideas of the Howl project but tailored to the needs of ActiveMQ.

This Journal provides the following features:

• Conncurrent writes are batched into a single write/force done by a background thread.
• Uses preallocated logs to avoid disk fragmentation and performance degregation.
• The number and size of the preallocated logs are configurable.
• Uses direct ByteBuffers to write data to log files.
• Allows logs to grow in case of an overflow condition so that overflow exceptions are not not thrown. Grown logs that are inactivated (due to a new mark) are resized to thier original size.
• No limit on the size of the record written to the journal
• Should be possible to extend so that multiple physical disk are used concurrently to increase throughput and decrease latency.

Version:

$Revision: 1.1 $

Field Summary

static int	DEFAULT_PACKET_SIZE
static int	DEFAULT_POOL_SIZE

Constructor Summary

JournalImpl(java.io.File logDirectory)

JournalImpl(java.io.File logDirectory, int logFileCount, int logFileSize)

JournalImpl(LogFileManager logFile)

Method Summary

void	close() Close the Journal.
void	dispose() This method should not throw any exceptions.
int	getInitialLogFileSize()
java.io.File	getLogDirectory()
RecordLocation	getMark() Obtains the mark that was set in the Journal.
RecordLocation	getNextRecordLocation(RecordLocation lastLocation) Allows you to get the next RecordLocation after the location that is in the journal.
Packet	read(RecordLocation l) Reads a previously written record from the journal.
void	setJournalEventListener(JournalEventListener eventListener) Registers a JournalEventListener that will receive notifications from the Journal.
void	setMark(RecordLocation l, boolean force) Informs the journal that all the journal space up to the location is no longer needed and can be reclaimed for reuse.
java.lang.String	toString()
RecordLocation	write(Packet data, boolean sync) Writes a Packet of data to the journal.

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_POOL_SIZE

public static final int DEFAULT_POOL_SIZE

DEFAULT_PACKET_SIZE

public static final int DEFAULT_PACKET_SIZE

Constructor Detail

JournalImpl

public JournalImpl(java.io.File logDirectory)
            throws java.io.IOException

JournalImpl

public JournalImpl(java.io.File logDirectory,
                   int logFileCount,
                   int logFileSize)
            throws java.io.IOException

JournalImpl

public JournalImpl(LogFileManager logFile)

Method Detail

write

public RecordLocation write(Packet data,
                            boolean sync)
                     throws java.io.IOException

Description copied from interface: Journal

Writes a Packet of data to the journal. If sync is true, then this call blocks until the data has landed on the physical disk. Otherwise, this enqueues the write request and returns.

Specified by:

write in interface Journal

Parameters:

sync - - If this call should block until the data lands on disk.

Returns:

RecordLocation the location where the data will be written to on disk.

Throws:

java.io.IOException - if the write failed.

setMark

public void setMark(RecordLocation l,
                    boolean force)
             throws InvalidRecordLocationException,
                    java.io.IOException

Description copied from interface: Journal

Informs the journal that all the journal space up to the location is no longer needed and can be reclaimed for reuse.

Specified by:

setMark in interface Journal

Parameters:

force -

l - the location of the record to mark. All record locations before the marked location will no longger be vaild.

Returns:

Throws:

InvalidRecordLocationException

java.io.IOException

java.lang.InterruptedException

getMark

public RecordLocation getMark()

Description copied from interface: Journal

Obtains the mark that was set in the Journal.

Specified by:

getMark in interface Journal

Returns:

See Also:

read(RecordLocation location);

getNextRecordLocation

public RecordLocation getNextRecordLocation(RecordLocation lastLocation)
                                     throws java.io.IOException,
                                            InvalidRecordLocationException

Description copied from interface: Journal

Allows you to get the next RecordLocation after the location that is in the journal.

Specified by:

getNextRecordLocation in interface Journal

Parameters:

lastLocation -

Returns:

Throws:

java.io.IOException

InvalidRecordLocationException

read

public Packet read(RecordLocation l)
            throws java.io.IOException,
                   InvalidRecordLocationException

Description copied from interface: Journal

Reads a previously written record from the journal.

Specified by:

read in interface Journal

Parameters:

l - is where to read the record from.

Returns:

Throws:

InvalidRecordLocationException

java.io.IOException

setJournalEventListener

public void setJournalEventListener(JournalEventListener eventListener)

Description copied from interface: Journal

Registers a JournalEventListener that will receive notifications from the Journal.

Specified by:

setJournalEventListener in interface Journal

Parameters:

eventListener - object that will receive journal events.

close

public void close()
           throws java.io.IOException

Deprecated. @see #dispose()

Description copied from interface: Journal

Close the Journal. This is blocking operation that waits for any pending put opperations to be forced to disk. Once the Journal is closed, all other methods of the journal should throw IllegalStateException.

Specified by:

close in interface Journal

Throws:

java.io.IOException - if an error occurs while the journal is being closed.

dispose

public void dispose()

Description copied from interface: Disposable

This method should not throw any exceptions. Cleaning up a Disposable object should be easy of an end user therefore do not make him have to handle an Exception.

Specified by:

dispose in interface Disposable

getLogDirectory

public java.io.File getLogDirectory()

Returns:

getInitialLogFileSize

public int getInitialLogFileSize()

toString

public java.lang.String toString()