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

java.lang.Object
  org.apache.cocoon.components.store.impl.StoreJanitorImpl

All Implemented Interfaces:

Runnable, StoreJanitor

Direct Known Subclasses:

CocoonStoreJanitor

public class StoreJanitorImpl

extends Object

implements StoreJanitor, Runnable

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 1304280 2012-03-23 11:18:01Z ilgrosso $

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.
void	destroy()
Log	getLogger()
void	init() Initialize the StoreJanitorImpl.
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	register(Store store) This method register the stores
void	run() The "checker" thread loop.
void	setAdaptiveThreadInterval(boolean adaptiveThreadInterval) Experimental adaptive algorithm for cleanup interval
void	setCleanupThreadInterval(int cleanupThreadInterval) How often shall the cleanup thread check memory? If not specified, defaults to 10 seconds.
void	setFreeingAlgorithm(String algorithm)
void	setFreeMemory(int freeMemory) How much free memory shall be available in the jvm? If not specified, defaults to 1Mb.
void	setHeapSize(int heapSize) How much memory at max jvm can consume? The default max heapsize for Sun's JVM is (almost) 64Mb, can be increased by specifying -Xmx command line parameter.
void	setInvokeGC(boolean invokeGC) Shall garbage collector be invoked on low memory? If not specified, defaults to false.
void	setLogger(Log l)
void	setPercentToFree(double percentToFree) What percent of the store elements shall be dropped on low memory? If not specified, defaults to 10%
void	setThreadPriority(int threadPriority) What should be the priority of the cleanup thread? This property is used only by older implementation of the janitor.
void	unregister(Store store) This method unregister the stores

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

setFreeMemory

public void setFreeMemory(int freeMemory)

How much free memory shall be available in the jvm? If not specified, defaults to 1Mb.

Parameters:

freeMemory -

setHeapSize

public void setHeapSize(int heapSize)

How much memory at max jvm can consume? The default max heapsize for Sun's JVM is (almost) 64Mb, can be increased by specifying -Xmx command line parameter. If not specified, defaults to 66600000 bytes.

Parameters:

heapSize -

setCleanupThreadInterval

public void setCleanupThreadInterval(int cleanupThreadInterval)

How often shall the cleanup thread check memory? If not specified, defaults to 10 seconds.

Parameters:

cleanupThreadInterval -

setAdaptiveThreadInterval

public void setAdaptiveThreadInterval(boolean adaptiveThreadInterval)

Experimental adaptive algorithm for cleanup interval

Parameters:

adaptiveThreadInterval -

setPercentToFree

public void setPercentToFree(double percentToFree)

What percent of the store elements shall be dropped on low memory? If not specified, defaults to 10%

Parameters:

percentToFree -

setInvokeGC

public void setInvokeGC(boolean invokeGC)

Shall garbage collector be invoked on low memory? If not specified, defaults to false.

Parameters:

invokeGC -

setThreadPriority

public void setThreadPriority(int threadPriority)

What should be the priority of the cleanup thread? This property is used only by older implementation of the janitor. New implementation uses centrally configured thread pool (see thread-pools element below).

Parameters:

threadPriority -

setFreeingAlgorithm

public void setFreeingAlgorithm(String algorithm)

getLogger

public Log getLogger()

setLogger

public void setLogger(Log l)

init

public void init()
          throws Exception

Initialize the StoreJanitorImpl.

Throws:

Exception

destroy

public void destroy()

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