org.apache.marmotta.kiwi.persistence

Class KiWiGarbageCollector

java.lang.Object

java.lang.Thread

org.apache.marmotta.kiwi.persistence.KiWiGarbageCollector

All Implemented Interfaces:

Runnable

public class KiWiGarbageCollector
extends Thread

This class implements a garbage collector for the database that cleans up deleted triples and nodes when they are no longer referenced. It runs from time to time (default: on startup and every hour) and executes a complex SQL query, checking for all tables referencing rows in the triples and nodes tables. References need to be registered by other components via the addTripleTableDependency and addNodeTableDependency methods.

Author: Sebastian Schaffert (sschaffert@apache.org)

Nested Class Summary

Nested classes/interfaces inherited from class java.lang.Thread

Thread.State, Thread.UncaughtExceptionHandler

Field Summary

Fields inherited from class java.lang.Thread

MAX_PRIORITY, MIN_PRIORITY, NORM_PRIORITY

Constructor Summary

Constructors

Constructor and Description
KiWiGarbageCollector(KiWiPersistence persistence)

Method Summary

Methods

Modifier and Type	Method and Description
void	addNodeTableDependency(String tableName, String columnName) Add information about a dependency of a column in some table to the "nodes" table; this information is used when cleaning up unreferenced deleted entries in the nodes table.
void	addTripleTableDependency(String tableName, String columnName) Add information about a dependency of a column in some table to the "triples" table; this information is used when cleaning up unreferenced deleted entries in the triples table.
protected boolean	checkConsistency()
protected void	fixConsistency()
protected int	garbageCollect()
long	getInterval() Get the interval to wait between garbage collections (milliseconds)
void	run() Run the garbage collector thread.
void	setInterval(long interval) Set the interval to wait between garbage collections (milliseconds)
void	shutdown()

Methods inherited from class java.lang.Thread

activeCount, checkAccess, clone, countStackFrames, currentThread, destroy, dumpStack, enumerate, getAllStackTraces, getContextClassLoader, getDefaultUncaughtExceptionHandler, getId, getName, getPriority, getStackTrace, getState, getThreadGroup, getUncaughtExceptionHandler, holdsLock, interrupt, interrupted, isAlive, isDaemon, isInterrupted, join, join, join, resume, setContextClassLoader, setDaemon, setDefaultUncaughtExceptionHandler, setName, setPriority, setUncaughtExceptionHandler, sleep, sleep, start, stop, stop, suspend, toString, yield

Methods inherited from class java.lang.Object

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

Constructor Detail

KiWiGarbageCollector

public KiWiGarbageCollector(KiWiPersistence persistence)

Method Detail

getInterval

public long getInterval()

Get the interval to wait between garbage collections (milliseconds)

setInterval

public void setInterval(long interval)

Set the interval to wait between garbage collections (milliseconds)

Parameters:

interval -

addTripleTableDependency

public void addTripleTableDependency(String tableName,
                            String columnName)

Add information about a dependency of a column in some table to the "triples" table; this information is used when cleaning up unreferenced deleted entries in the triples table. In theory, we could get this information from the database, but each database has a very different way of doing this, so it is easier to simply let dependent modules register this information.

Parameters:

tableName -

columnName -

addNodeTableDependency

public void addNodeTableDependency(String tableName,
                          String columnName)

Add information about a dependency of a column in some table to the "nodes" table; this information is used when cleaning up unreferenced deleted entries in the nodes table. In theory, we could get this information from the database, but each database has a very different way of doing this, so it is easier to simply let dependent modules register this information.

Parameters:

tableName -

columnName -

checkConsistency

protected boolean checkConsistency()
                            throws SQLException

Throws:

SQLException

fixConsistency

protected void fixConsistency()
                       throws SQLException

Throws:

SQLException

garbageCollect

protected int garbageCollect()
                      throws SQLException

Throws:

SQLException

run

public void run()

Run the garbage collector thread. The thread will run garbage collection on startup, and then in a loop wait for one hour before running again.

Specified by:

run in interface Runnable

Overrides:

run in class Thread

See Also:

Thread.start(), Thread.stop()

shutdown

public void shutdown()