I'll add something under the JCS util package.
The utility I'm using looks like this:
/**
* This handles dividing puts and gets.
* <p>
* There are two required properties.
* <p>
* <ol>
* <li>.numberOfPartitions</li>
* <li>.partitionRegionNamePrefix</li>
* </ol>
* System properties will override values in the properties file.
* <p>
* We use a JCS region name for each partition that looks like this:
partitionRegionNamePrefix + "_"
* + patitionNuber. The number is ) indexed based.
* <p>
* @author Aaron Smuts
*/
public class PartitionedJCSCacheImpl
extends AbstractPropertyContainer
implements Cache
{
/** the logger. */
private static final Log log = LogFactory.getLog(
PartitionedJCSCacheImpl.class );
/** The number of partitions. */
private int numberOfPartitions = 1;
/**
* We use a JCS region name for each partition that looks like this:
partitionRegionNamePrefix +
* "_" + partitionNumber
*/
private String partitionRegionNamePrefix;
/** An array of partitions built during inialization. */
private JCS[] partitions;
/** Is the class initialized. */
private boolean initialized = false;
/** Sets default properties heading and group. */
public PartitionedJCSCacheImpl()
{
setPropertiesHeading( "PartitionedJCSCache" );
setPropertiesGroup( "webservices" );
}
/**
* Puts the value into the appropriate cache partition.
* <p>
* @param key key
* @param object object
* @return true if there were no errors.
* @throws ConfigurationException on configuration problem
*/
public boolean put( Serializable key, Serializable object )
throws ConfigurationException
{
if ( key == null || object == null )
{
log.warn( "Bad input key [" + key + "]. Cannot put null into the
cache." );
return false;
}
ensureInit();
int partition = getPartitionNumberForKey( key );
try
{
partitions[partition].put( key, object );
return true;
}
catch ( CacheException e )
{
log.error( "Problem putting value for key [" + key + "] in cache ["
+ partitions[partition] + "]" );
return false;
}
}
/**
* Gets the object for the key from the desired partition.
* <p>
* @param key key
* @return result, null if not found.
* @throws ConfigurationException on configuration problem
*/
public Object get( Serializable key )
throws ConfigurationException
{
if ( key == null )
{
log.warn( "Bad input key [" + key + "]." );
return null;
}
ensureInit();
int partition = getPartitionNumberForKey( key );
return partitions[partition].get( key );
}
/**
* Gets the ICacheElement (the wrapped object) for the key from the desired
partition.
* <p>
* @param key key
* @return result, null if not found.
* @throws ConfigurationException on configuration problem
*/
public ICacheElement getCacheElement( Serializable key )
throws ConfigurationException
{
if ( key == null )
{
log.warn( "Bad input key [" + key + "]." );
return null;
}
ensureInit();
int partition = getPartitionNumberForKey( key );
return partitions[partition].getCacheElement( key );
}
/**
* This expects a numeric key. If the key cannot be converted into a
number, we wil return 0.
* TODO we could md5 it or get the hashcode.
* <p>
* We determine the partition by taking the mod of the number of partions.
* <p>
* @param key key
* @return the partition number.
*/
protected int getPartitionNumberForKey( Serializable key )
{
if ( key == null )
{
return 0;
}
long keyNum = getNumericValueForKey( key );
int partition = (int) ( keyNum % getNumberOfPartitions() );
if ( log.isDebugEnabled() )
{
log.debug( "Using partition [" + partition + "] for key [" + key +
"]" );
}
return partition;
}
/**
* This can be overridden for special purposes.
* <p>
* @param key key
* @return long
*/
public long getNumericValueForKey( Serializable key )
{
String keyString = key.toString();
long keyNum = -1;
try
{
keyNum = Long.parseLong( keyString );
}
catch ( NumberFormatException e )
{
// THIS IS UGLY, but I can't think of a better failsafe right now.
keyNum = key.hashCode();
log.warn( "Counldn't convert [" + key + "] into a number. Will use
hashcode [" + keyNum + "]" );
}
return keyNum;
}
/**
* Initialize if we haven't already.
* <p>
* @throws ConfigurationException on configuration problem
*/
protected synchronized void ensureInit()
throws ConfigurationException
{
if ( !initialized )
{
initialize();
}
}
/**
* Use the partion prefix and the number of partions to get JCS regions.
* <p>
* @throws ConfigurationException on configuration problem
*/
protected synchronized void initialize()
throws ConfigurationException
{
ensureProperties();
JCS[] tempPartitions = new JCS[this.getNumberOfPartitions()];
for ( int i = 0; i < this.getNumberOfPartitions(); i++ )
{
String regionName = this.getPartitionRegionNamePrefix() + "_" + i;
try
{
tempPartitions[i] = JCS.getInstance( regionName );
}
catch ( CacheException e )
{
log.error( "Problem getting cache for region [" + regionName +
"]" );
}
}
partitions = tempPartitions;
initialized = true;
}
/**
* Loads in the needed configuration settings. System properties are
checked first. A system
* property will override local property value.
* <p>
* Loads the following JCS Cache specific properties:
* <ul>
* <li>heading.numberOfPartitions</li>
* <li>heading.partitionRegionNamePrefix</li>
* </ul>
* @throws ConfigurationException on configuration problem
*/
protected void handleProperties()
throws ConfigurationException
{
// Number of Partitions.
String numberOfPartitionsPropertyName = this.getPropertiesHeading() +
".numberOfPartitions";
String numberOfPartitionsPropertyValue = getPropertyForName(
numberOfPartitionsPropertyName, true );
try
{
this.setNumberOfPartitions( Integer.parseInt(
numberOfPartitionsPropertyValue ) );
}
catch ( NumberFormatException e )
{
String message = "Could not convert [" +
numberOfPartitionsPropertyValue + "] into a number for ["
+ numberOfPartitionsPropertyName + "]";
log.error( message );
throw new ConfigurationException( message );
}
// Partition Name Prefix.
String prefixPropertyName = this.getPropertiesHeading() +
".partitionRegionNamePrefix";
String prefix = getPropertyForName( prefixPropertyName, true );
this.setPartitionRegionNamePrefix( prefix );
}
/**
* Checks the system properties before the properties.
* <p>
* @param propertyName name
* @param required is it required?
* @return the property value if one is found
* @throws ConfigurationException thrown if it is required and not found.
*/
protected String getPropertyForName( String propertyName, boolean required )
throws ConfigurationException
{
String propertyValue = null;
propertyValue = System.getProperty( propertyName );
if ( propertyValue != null )
{
if ( log.isInfoEnabled() )
{
log.info( "Found system property override: Name [" +
propertyName + "] Value [" + propertyValue + "]" );
}
}
else
{
propertyValue = this.getProperties().getProperty( propertyName );
if ( required && propertyValue == null )
{
String message = "Could not find required property [" +
propertyName + "] in propertiesGroup ["
+ this.getPropertiesGroup() + "]";
log.error( message );
throw new ConfigurationException( message );
}
else
{
if ( log.isInfoEnabled() )
{
log.info( "Name [" + propertyName + "] Value [" +
propertyValue + "]" );
}
}
}
return propertyValue;
}
/**
* @param numberOfPartitions The numberOfPartitions to set.
*/
protected void setNumberOfPartitions( int numberOfPartitions )
{
this.numberOfPartitions = numberOfPartitions;
}
/**
* @return Returns the numberOfPartitions.
*/
protected int getNumberOfPartitions()
{
return numberOfPartitions;
}
/**
* @param partitionRegionNamePrefix The partitionRegionNamePrefix to set.
*/
protected void setPartitionRegionNamePrefix( String
partitionRegionNamePrefix )
{
this.partitionRegionNamePrefix = partitionRegionNamePrefix;
}
/**
* @return Returns the partitionRegionNamePrefix.
*/
protected String getPartitionRegionNamePrefix()
{
return partitionRegionNamePrefix;
}
/**
* @param partitions The partitions to set.
*/
protected void setPartitions( JCS[] partitions )
{
this.partitions = partitions;
}
/**
* @return Returns the partitions.
*/
protected JCS[] getPartitions()
{
return partitions;
}
--- On Tue, 8/11/09, Aaron Smuts <asm...@yahoo.com> wrote:
> From: Aaron Smuts <asm...@yahoo.com>
> Subject: Re: JCS HA cluster, is possible?
> To: "JCS Users List" <jcs-users@jakarta.apache.org>, "rcolme...@tiscali.it"
> <rcolme...@tiscali.it>
> Date: Tuesday, August 11, 2009, 10:54 AM
>
> You can implement this very easily with a bit of client
> code. In fact, I've done just this elsewhere, or at
> least something very similar.
>
> I have an installation that handles millions of items a
> day. The items average 80k. I don't have disk
> space to keep them all on any one box. So, I
> partitioned the data. I did it this way.
>
> I took 8 boxes and setup 4 remote cache server
> primary/failover pairs. (fyi. Each is configured to
> use a jdbc disk cache backed by mysql running locally.)
>
> Every client is configured with 4 remote cache client
> auxiliaries, one for each pair.
>
> I configured 4 regions on the clients. You could have
> far more.
>
> I divided the remote clients between the regions.
> Region 1 uses p/f pair A. Region 2, B . . .
>
> (In another instance I have 180 regions divided between 4
> remote servers.)
>
> I decide what region to put the data in through a simple
> algorithm: key mod numerOfPartitions (here 4) = the
> region.
>
> I named the regions in a pattern like this:
>
> MyPartitionedData_0
> MyPartitionedData_1
> MyPartitionedData_2
> MyPartitionedData_3
>
> I take the suffic from the algorithm and put the data in
> the appropriate region. I made a simple abstraction
> that does just this.
>
> I could add more partitions and reconfigure. It can
> be scaled indefinitely. . ..
>
> Perhaps I'll put in in the JCS util package.
>
> Cheers,
>
> Aaron
>
>
>
> --- On Tue, 8/11/09, rcolme...@tiscali.it
> <rcolme...@tiscali.it>
> wrote:
>
> > From: rcolme...@tiscali.it
> <rcolme...@tiscali.it>
> > Subject: JCS HA cluster, is possible?
> > To: jcs-users@jakarta.apache.org
> > Date: Tuesday, August 11, 2009, 10:40 AM
> > Hi,
> >
> > I have a question about JCS behavior.
> >
> > Suppose this scenario:
> > -
> > four JCS server: S1,S2,S3,S4
> > - for every server a max of 10,000
> > cacheable objects
> > - a client C1
> >
> > I need that client C1 writes 40,000
> > objects to 4 JCS servers. JCS could automatic
> balance
> > the
> > objects
> > insertion between the 4 servers partitioning the
> objects
> > set (via round
> > robin, for example)?
> >
> > I need the maximum performance (availability),
> > not affordability. Substantially I need
> > that an object instance "O1"
> > is allocated _only_ in one server and that the client
> > lookup
> > is
> > executed in parallel on the four servers.
> >
> > Is this possible with JCS?
> >
> >
> > TIA
> > Roberto Colmegna
> >
> >
> >
> >
> > Torna a grande richiesta l'offerta estiva di Tiscali
> Photo
> > !! Non rinuniciare ai tuoi ricordi. Stampa le tue foto
> a
> > soli 0,09 euro
> >
> >
> >
> > http://photo.tiscali.it
> >
> >
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