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From "Smuts, Aaron" <Aaron.Sm...@travelocity.com>
Subject RE: RE: Possible bug in JCS with IdleTime element attribute
Date Thu, 18 Jan 2007 18:24:59 GMT
I thought idle time at the element level was long gone.  Hmmn.  There is
max idle time at the region, which is for the memory shrinker.  I'll
have to look into it.

http://jakarta.apache.org/jcs/RegionProperties.html



> -----Original Message-----
> From: Allen Wyatt [mailto:amw@rocketmail.com]
> Sent: Thursday, January 18, 2007 12:15 PM
> To: jcs-users@jakarta.apache.org
> Subject: RE: RE: Possible bug in JCS with IdleTime element attribute
> 
> Ard Schrijvers suggested changing use of "jcs" below to "cache"
because he
> thought "jcs" just had default configuration.  This is wrong.  I
stepped
> through the code and saw that when the elements were being put in the
> cache they were put in with an idle time of 5 seconds as I setup in
the
> setupProperties() method, not with a default value of idle time.
Anyway,
> the "cache" object doesn't have get() and put() methods so it can't be
> used directly for storing information in JCS.  I access the "cache"
object
> directly only to be able to retrieve the element attributes associated
> with the cache (getElementAttributes) and the count of expired items
> (getMissCountExpired).
> 
> It looks to me like there is a bug in JCS as I originally thought.
> Stepping in the code, when it tries to get the item from the cache (in
> LRUMemoryCache.get()) it sets the last access time to now which messes
up
> the later checking of how long the item has been idle.  I think the
code
> that is getting the item from the cache should call
> LRUMemoryCache.getQuiet() instead of LRUMemoryCache.get().  That code
is
> in CompositeCache.get().  I'm not sure what other effects calling
> LRUMemoryCache.getQuiet() instead of LRUMemoryCache.get() will have
> though.
> 
> 
> 
> 
> 
> 
> -----Original Message-----
> 
> From: Ard Schrijvers [mailto:a.schrijvers@hippo.nl]
> To: jcs-users@jakarta.apache.org
> 
> Subject: RE: Possible bug in JCS with IdleTime element attribute
> 
> 
> 
> 
> 
> 
> 
> 
> >
> 
> 
> > 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.
> 
> 
> 
> 
> 
> I thin you have a bug in your test...
> 
> 
> 
> 
> 
> >
> 
> 
> > 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" );
> 
> 
> 
> 
> 
> now, cache is the cache you get from your configured
> CompositeCacheManager. I think, your jcs has just default
configuration,
> because I do not see where it is configured..?
> 
> 
> 
> 
> 
> If you replace jcs below, with cache, you probably will
> see, everything works just fine,
> 
> 
> 
> 
> 
> Regards Ard
> 
> 
> 
> 
> 
> >
> 
> 
> >     // 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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> 
> 
> >
> 
> 
> >
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> 
> >
> 
> 
> 
> 
> 
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