I think I may have found a bug in JCS with regards to the
IdleTime element attribute. Either that
or I don't understand how this setting works.
If something is put in the
cache and not retrieved until after more than IdleTime seconds, then JCS is
supposed to throw the item out of the cache and return null when asked to get()
the item right?
Below is a sample JUnit test
that shows five items being put in JCS and not accessed again until long after
the IdleTime interval has passed. The
items are still accessible and the CompositeCache's getMissCountExpired()
method returns zero when I think it should return five.
Is this a bug?
I am using JCS 1.2.7.9 to do this test.
======================================================================================
package bugtest;
import java.util.Properties;
import org.apache.jcs.JCS;
import org.apache.jcs.engine.behavior.IElementAttributes;
import org.apache.jcs.engine.control.CompositeCache;
import org.apache.jcs.engine.control.CompositeCacheManager;
import junit.framework.TestCase;
public class TestMissCountExpiredBug extends TestCase
{
public void testSomething()
throws Exception
{
// setup JCS
CompositeCacheManager mgr = CompositeCacheManager.getUnconfiguredInstance();
mgr.configure( setupProperties() );
// get access to bug test cache region
JCS jcs = JCS.getInstance( "BugTest" );
CompositeCache cache = mgr.getCache( "BugTest" );
// put five items in cache
for ( int i = 0; i < 5; i++ )
{
String key = "key" + i;
String value = "value" + i;
jcs.put( key, value );
}
// sleep for twice the length of the max idle time of items in the cache
// region
IElementAttributes attrs = cache.getElementAttributes();
long idleTimeSeconds = attrs.getIdleTime();
assertEquals( 5L, idleTimeSeconds );
System.out.println( "idle time seconds=" + idleTimeSeconds );
long sleepTime = 1000 * 2 * idleTimeSeconds;
System.out.println( "sleeping for " + sleepTime
+ " millis to allow cache elements to be flagged as idle for too long" );
Thread.sleep( sleepTime );
// try to access the five items - they should have expired so this should
// fail
for ( int i = 0; i < 5; i++ )
{
String key = "key" + i;
Object value = jcs.get( key );
if ( value != null )
{
System.out.println( "found a value for key " + key + ": " + value );
}
}
// check miss count expired - should be five
int missCountExpired = cache.getMissCountExpired();
System.out.println( "miss count expired: " + missCountExpired );
assertEquals( 5, missCountExpired );
}
private Properties setupProperties()
{
Properties answer = new Properties();
// defaults
answer.setProperty( "jcs.default", "" );
answer.setProperty( "jcs.default.cacheattributes",
"org.apache.jcs.engine.CompositeCacheAttributes" );
answer.setProperty( "jcs.default.cacheattributes.MemoryCacheName",
"org.apache.jcs.engine.memory.lru.LRUMemoryCache" );
answer.setProperty( "jcs.default.cacheattributes.MaxObjects", "100000" );
// bug test region - elements won't go to disk, but should be marked as
expired after five seconds of non-use
answer.setProperty( "jcs.region.BugTest", "" );
answer.setProperty( "jcs.region.BugTest.cacheattributes",
"org.apache.jcs.engine.CompositeCacheAttributes" );
answer.setProperty( "jcs.region.BugTest.cacheattributes.MemoryCacheName",
"org.apache.jcs.engine.memory.lru.LRUMemoryCache" );
answer.setProperty( "jcs.region.BugTest.cacheattributes.MaxObjects", "1000"
);
answer.setProperty( "jcs.region.BugTest.cacheattributes.UseMemoryShrinker",
"false" );
answer.setProperty( "jcs.region.BugTest.elementattributes",
"org.apache.jcs.engine.ElementAttributes" );
answer.setProperty( "jcs.region.BugTest.elementattributes.IsEternal",
"false" );
answer.setProperty( "jcs.region.BugTest.elementattributes.IdleTime", "5" );
return answer;
}
}
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