org.apache.excalibur.store.impl

Class StoreJanitorImpl

java.lang.Object

org.apache.avalon.framework.logger.AbstractLogEnabled

org.apache.excalibur.store.impl.StoreJanitorImpl

All Implemented Interfaces:

java.lang.Runnable, org.apache.avalon.framework.activity.Startable, org.apache.avalon.framework.logger.LogEnabled, org.apache.avalon.framework.parameters.Parameterizable, org.apache.avalon.framework.thread.ThreadSafe, StoreJanitor

public class StoreJanitorImpl
extends org.apache.avalon.framework.logger.AbstractLogEnabled
implements StoreJanitor, org.apache.avalon.framework.parameters.Parameterizable, org.apache.avalon.framework.thread.ThreadSafe, java.lang.Runnable, org.apache.avalon.framework.activity.Startable

This class is a implentation of a StoreJanitor. Store classes can register to the StoreJanitor. When memory is too low, the StoreJanitor frees the registered caches until memory is normal.

A few parameters can be used:

• freememory: How many bytes shall be always free in the JVM (Default: 1mb)
• heapsize: Maximum possible size of the JVM memory consumption (Default: 66600000b)
• cleanupthreadinterval: How often (sec) shall run the cleanup thread (Default: 10s)
• adaptivethreadinterval (experimental): Enable adaptive algorithm to determine thread interval (Default: false) When true, cleanupthreadinterval defines the maximum cleanup interval. Cleanup interval then is determined based on the memory fill rate: the faster memory is filled in, and the less free memory is left, the shorter is the cleanup time.
• threadpriority: Priority of the thread (1-10). (Default: 10)
• percent_to_free: What fraction of the store to free when memory is low (1-100). (Default: 10%)
• invokegc: Invoke the gc on low memory first (true|false; default: false)

Version:

CVS $Id: StoreJanitorImpl.java,v 1.4 2004/02/28 11:47:31 cziegeler Exp $

Author:

Avalon Development Team

Field Summary

Fields

Modifier and Type	Field and Description
private boolean	adaptiveThreadInterval
private boolean	doRun
private boolean	firstRun Flag to ignore memory bursts during startup (1st janitor run)
private double	fraction
private int	index
protected long	interval The calculated delay for the next checker run in ms
protected long	inUse Amount of memory in use before sleep().
protected boolean	invokeGC Should the gc be called on low memory?
private java.lang.Runtime	jvm
private int	maxHeapSize
private long	maxRateOfChange Used memory change rate in bytes per second
private int	minFreeMemory
private int	minThreadInterval
private int	priority
private boolean	secondRun Flag to ignore memory bursts during startup (2nd janitor run)
private java.util.ArrayList	storelist
private int	threadInterval

Fields inherited from interface org.apache.excalibur.store.StoreJanitor

ROLE

Constructor Summary

Constructors

Constructor and Description
StoreJanitorImpl()

Method Summary

Methods

Modifier and Type	Method and Description
private int	calcToFree(Store store) This method claculates the number of Elements to be freememory out of the Cache.
protected void	checkMemory() The "checker" thread checks if memory is running low in the jvm.
private void	freeMemory() Round Robin alghorithm for freeing the registered caches.
private void	freePhysicalMemory() This method forces the garbage collector
private boolean	getAdaptiveThreadInterval()
private int	getIndex()
private java.lang.Runtime	getJVM()
private int	getMaxHeapSize()
private int	getMinFreeMemory()
private int	getPriority()
private java.util.ArrayList	getStoreList()
private int	getThreadInterval()
java.util.Iterator	iterator() This method return a java.util.Iterator of every registered stores The iterators returned is fail-fast: if list is structurally modified at any time after the iterator is created, in any way, the iterator will throw a ConcurrentModificationException.
private long	longDiv(long top, long bottom)
protected long	memoryInUse() Calculate the JVM memory in use now.
private boolean	memoryLow() Method to check if memory is running low in the JVM.
private long	minTimeToFill(long rate) Calculate amount of time needed to fill all free memory with given fill rate.
void	parameterize(org.apache.avalon.framework.parameters.Parameters params) Parameterize the StoreJanitorImpl.
void	register(Store store) This method register the stores
void	run() The "checker" thread loop.
private void	setIndex(int _index)
void	start()
void	stop()
void	unregister(Store store) This method unregister the stores

Methods inherited from class org.apache.avalon.framework.logger.AbstractLogEnabled

enableLogging, getLogger, setupLogger, setupLogger, setupLogger

Methods inherited from class java.lang.Object

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

Field Detail

minFreeMemory

private int minFreeMemory

maxHeapSize

private int maxHeapSize

threadInterval

private int threadInterval

minThreadInterval

private int minThreadInterval

adaptiveThreadInterval

private boolean adaptiveThreadInterval

priority

private int priority

fraction

private double fraction

invokeGC

protected boolean invokeGC

Should the gc be called on low memory?

jvm

private java.lang.Runtime jvm

storelist

private java.util.ArrayList storelist

index

private int index

doRun

private boolean doRun

inUse

protected long inUse

Amount of memory in use before sleep(). Must be initially set a resonable value; ie. memoryInUse()

firstRun

private boolean firstRun

Flag to ignore memory bursts during startup (1st janitor run)

secondRun

private boolean secondRun

Flag to ignore memory bursts during startup (2nd janitor run)

interval

protected long interval

The calculated delay for the next checker run in ms

maxRateOfChange

private long maxRateOfChange

Used memory change rate in bytes per second

Constructor Detail

StoreJanitorImpl

public StoreJanitorImpl()

Method Detail

parameterize

public void parameterize(org.apache.avalon.framework.parameters.Parameters params)
                  throws org.apache.avalon.framework.parameters.ParameterException

Parameterize the StoreJanitorImpl.

Specified by:

parameterize in interface org.apache.avalon.framework.parameters.Parameterizable

Parameters:

params - the Configuration of the application

Throws:

org.apache.avalon.framework.parameters.ParameterException

start

public void start()

Specified by:

start in interface org.apache.avalon.framework.activity.Startable

stop

public void stop()

Specified by:

stop in interface org.apache.avalon.framework.activity.Startable

run

public void run()

The "checker" thread loop.

Specified by:

run in interface java.lang.Runnable

checkMemory

protected void checkMemory()

The "checker" thread checks if memory is running low in the jvm.

memoryLow

private boolean memoryLow()

Method to check if memory is running low in the JVM.

Returns:

true if memory is low

memoryInUse

protected long memoryInUse()

Calculate the JVM memory in use now.

Returns:

memory in use.

minTimeToFill

private long minTimeToFill(long rate)

Calculate amount of time needed to fill all free memory with given fill rate.

Parameters:

rate - memory fill rate in time per bytes

Returns:

amount of time to fill all the memory with given fill rate

longDiv

private long longDiv(long top,
           long bottom)

register

public void register(Store store)

This method register the stores

Specified by:

register in interface StoreJanitor

Parameters:

store - the store to be registered

unregister

public void unregister(Store store)

This method unregister the stores

Specified by:

unregister in interface StoreJanitor

Parameters:

store - the store to be unregistered

iterator

public java.util.Iterator iterator()

This method return a java.util.Iterator of every registered stores The iterators returned is fail-fast: if list is structurally modified at any time after the iterator is created, in any way, the iterator will throw a ConcurrentModificationException. Thus, in the face of concurrent modification, the iterator fails quickly and cleanly, rather than risking arbitrary, non-deterministic behavior at an undetermined time in the future.

Specified by:

iterator in interface StoreJanitor

Returns:

a java.util.Iterator

freeMemory

private void freeMemory()

Round Robin alghorithm for freeing the registered caches.

calcToFree

private int calcToFree(Store store)

This method claculates the number of Elements to be freememory out of the Cache.

Parameters:

store - the Store which was selected as victim

Returns:

number of elements to be removed!

freePhysicalMemory

private void freePhysicalMemory()

This method forces the garbage collector

getMinFreeMemory

private int getMinFreeMemory()

getMaxHeapSize

private int getMaxHeapSize()

getPriority

private int getPriority()

getThreadInterval

private int getThreadInterval()

getAdaptiveThreadInterval

private boolean getAdaptiveThreadInterval()

getJVM

private java.lang.Runtime getJVM()

getStoreList

private java.util.ArrayList getStoreList()

setIndex

private void setIndex(int _index)

getIndex

private int getIndex()