org.apache.activeio.journal.howl

Class HowlJournal

java.lang.Object

org.apache.activeio.journal.howl.HowlJournal

All Implemented Interfaces:

Journal

public class HowlJournal
extends Object
implements Journal

An implementation of the Journal interface using a HOWL logger. This is is a thin wrapper around a HOWL logger. This implementation can be used to write records but not to retreive them yet. Once the HOWL logger implements the methods needed to retreive previously stored records, this class can be completed.

Version:

$Revision: 1.2 $

Constructor Summary

Constructors

Constructor and Description
HowlJournal(Configuration configuration)

Method Summary

Modifier and Type	Method and Description
void	close() Close the Journal.
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 location) 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 recordLocator, boolean force) Informs the journal that all the journal space up to the location is no longer needed and can be reclaimed for reuse.
RecordLocation	write(Packet packet, boolean sync) Writes a Packet of data to the journal.

Methods inherited from class java.lang.Object

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

Constructor Detail

HowlJournal

public HowlJournal(Configuration configuration)
            throws InvalidFileSetException,
                   LogConfigurationException,
                   InvalidLogBufferException,
                   ClassNotFoundException,
                   IOException,
                   InterruptedException

Throws:

InvalidFileSetException

LogConfigurationException

InvalidLogBufferException

ClassNotFoundException

IOException

InterruptedException

Method Detail

write

public RecordLocation write(Packet packet,
                            boolean sync)
                     throws 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

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:

IOException - if the write failed.

See Also:

org.apache.activeio.journal.Journal#write(byte[], boolean)

setMark

public void setMark(RecordLocation recordLocator,
                    boolean force)
             throws InvalidRecordLocationException,
                    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:

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

force - if this call should block until the mark is set on the journal.

Throws:

InvalidRecordLocationException - if location parameter is out of range. It cannot be a location that is before the current mark.

IOException - if the record could not be read.

See Also:

org.apache.activeio.journal.Journal#setMark(org.codehaus.activemq.journal.RecordLocation, boolean)

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:

the mark that was set in the Journal.

See Also:

Journal.getMark()

close

public void close()
           throws IOException

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:

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

See Also:

Journal.close()

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.

See Also:

org.apache.activeio.journal.Journal#setJournalEventListener(org.codehaus.activemq.journal.JournalEventListener)

getNextRecordLocation

public RecordLocation getNextRecordLocation(RecordLocation lastLocation)
                                     throws 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 - the reference location the is used to find the next location. To get the oldest location available in the journal, location should be set to null.

Returns:

the next record location

Throws:

InvalidRecordLocationException - if location parameter is out of range. It cannot be a location that is before the current mark.

See Also:

org.apache.activeio.journal.Journal#getNextRecordLocation(org.codehaus.activemq.journal.RecordLocation)

read

public Packet read(RecordLocation location)
            throws InvalidRecordLocationException,
                   IOException

Description copied from interface: Journal

Reads a previously written record from the journal.

Specified by:

read in interface Journal

Parameters:

location - is where to read the record from.

Returns:

the data previously written at the location.

Throws:

InvalidRecordLocationException - if location parameter is out of range. It cannot be a location that is before the current mark.

IOException - if the record could not be read.

See Also:

org.apache.activeio.journal.Journal#read(org.codehaus.activemq.journal.RecordLocation)