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org.apache.cocoon.components.store.impl
Class StoreJanitorImpl

java.lang.Object
  org.apache.avalon.framework.logger.AbstractLogEnabled
      org.apache.cocoon.components.store.impl.StoreJanitorImpl

All Implemented Interfaces:

Runnable, Startable, Component, LogEnabled, Parameterizable, ThreadSafe, StoreJanitor

Direct Known Subclasses:

CocoonStoreJanitor

public class StoreJanitorImpl
extends AbstractLogEnabled
implements StoreJanitor, Parameterizable, ThreadSafe, Runnable, 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: 64mb)
• 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: current thread's priority)
• 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)
• freeingalgorithm: Currently there are two algorithms available. (Default: round-robun)

  round-robin

  The registered caches are cycled through, and each time there is a low memory situation one of the registered caches has objects freed from it.

  all-stores

  All registered stores have objects removed from them each time there is a low memory situation.

Version:

$Id: StoreJanitorImpl.html 1304258 2012-03-23 10:09:27Z ilgrosso $

Avalon component

Implements service:

type=StoreJanitor

Field Summary

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?

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

ROLE

Constructor Summary

StoreJanitorImpl()

Method Summary

protected void	checkMemory() The "checker" thread checks if memory is running low in the jvm.
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.
protected long	memoryInUse() Calculate the JVM memory in use now.
void	parameterize(Parameters params) Parameterize the StoreJanitorImpl.
void	register(Store store) This method register the stores
void	run() The "checker" thread loop.
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

invokeGC

protected boolean invokeGC

Should the gc be called on low memory?

inUse

protected long inUse

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

interval

protected long interval

The calculated delay for the next checker run in ms

Constructor Detail

StoreJanitorImpl

public StoreJanitorImpl()

Method Detail

parameterize

public void parameterize(Parameters params)
                  throws ParameterException

Parameterize the StoreJanitorImpl.

Specified by:

parameterize in interface Parameterizable

Throws:

ParameterException

start

public void start()
           throws Exception

Specified by:

start in interface Startable

Throws:

Exception

stop

public void stop()

Specified by:

stop in interface Startable

run

public void run()

The "checker" thread loop.

Specified by:

run in interface Runnable

checkMemory

protected void checkMemory()

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

memoryInUse

protected long memoryInUse()

Calculate the JVM memory in use now.

Returns:

memory in use.

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 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