[jira] Commented: (JCS-15) Removing entries using a name group does not remove them from the disk cache.

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https://issues.apache.org/jira/browse/JCS-15?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12482011
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Aaron Smuts commented on JCS-15:
--------------------------------

I understand the problem.  When using the internal lru for key storage the disk 
cache cannot do partial removes properly.  It's remving from an interator that 
is a copy of the underlying LRU.  Hence, it has no effect.

I will either change the iterator, or change the remove call for partial keys.

> Removing entries using a name group does not remove them from the disk cache.
> -----------------------------------------------------------------------------
>
>                 Key: JCS-15
>                 URL: https://issues.apache.org/jira/browse/JCS-15
>             Project: JCS
>          Issue Type: Bug
>          Components: Indexed Disk Cache
>    Affects Versions: jcs-1.2.7.9.2
>            Reporter: Kevin Preece
>         Assigned To: Aaron Smuts
>            Priority: Critical
>
> The scenario is that I add entries to the cache using name groups, e.g. using 
> keys "0:key0", "0:key1", "1:key0", etc. then issue a remove using a name 
> group, e.g. "0:".
> If all the entries are in memory the remove succeeds.  However if some or all 
> have been spooled out to disk those that have been spooled out do not get 
> removed from the cache.  The code fragment and cache.ccf at the end of this 
> post show the problem.  I'm looking at the source checked out of trunk this 
> morning and IndexedDiskCache.java last changed on 2006-09-22 with revision id 
> 449025 (I originally spotted this issue in release 1.2.7.9.2).  Two problems 
> that are immediately obvious are:
> 1.  The lookup on line 660 always returns null unless I have an item in the 
> cache with key exactly equal to "0:" (which I don't).  I think it should be 
> "keyHash.get( k )"
> 2.  The iter.remove() on line 662 appears to be operating on a copy of the 
> keys.
> I've not tested it, but it looks like the else-if block for GroupId keys 
> suffers the same problems.  Also if optimization is enabled for the disk file 
> I suspect data corruption will occur eventually, but again I've not tested 
> this.
> Unfortunately this has stopped us using JCS because we rely on this 
> functionality working since our cache is too big to fit entirely in memory.
> try
> {
>    JCS cache = JCS.getInstance( "GeneralCache" );
>    
>    for ( int ii = 0; ii < 100; ++ii )
>    {
>       for ( int jj = 0; jj < 10; ++jj )
>       {
>          final String k = jj + ":key" + ii;
>          final String d = "Some data for key " + k;
>          
>          cache.put( k, d );
>       }
>    }
>    System.out.println( cache.get( "0:key0" ) );
>    cache.remove( "0:" );
>    // Next line should print "null"
>    System.out.println( cache.get( "0:key0" ) );
> }
> catch ( CacheException e )
> {
>    e.printStackTrace();
> }
> try
> {
>    JCS cache = JCS.getInstance( "GeneralCache2" );
>    
>    for ( int ii = 0; ii < 100; ++ii )
>    {
>       for ( int jj = 0; jj < 10; ++jj )
>       {
>          final String k = jj + ":key" + ii;
>          final String d = "Some data for key " + k;
>          
>          cache.put( k, d );
>       }
>    }
>    System.out.println( cache.get( "0:key0" ) );
>    cache.remove( "0:" );
>    // Next line should print "null"
>    System.out.println( cache.get( "0:key0" ) );
> }
> catch ( CacheException e )
> {
>    e.printStackTrace();
> }
> The contents of cache.ccf are:
> # DEFAULT CACHE REGION   
> jcs.default=DC
> jcs.default.cacheattributes=org.apache.jcs.engine.CompositeCacheAttributes
> jcs.default.cacheattributes.MaxObjects=1
> jcs.default.cacheattributes.MemoryCacheName=org.apache.jcs.engine.memory.lru.LRUMemoryCache
> # PRE-DEFINED CACHE REGIONS   
> jcs.region.GeneralCache=DC
> jcs.region.GeneralCache.cacheattributes=org.apache.jcs.engine.CompositeCacheAttributes
> jcs.region.GeneralCache.cacheattributes.MaxObjects=1
> jcs.region.GeneralCache.cacheattributes.MemoryCacheName=org.apache.jcs.engine.memory.lru.LRUMemoryCache
> jcs.region.GeneralCache.cacheattributes.UseMemoryShrinker=true
> jcs.region.GeneralCache.cacheattributes.MaxMemoryIdleTimeSeconds=3600
> jcs.region.GeneralCache.cacheattributes.ShrinkerIntervalSeconds=60
> jcs.region.GeneralCache.cacheattributes.MaxSpoolPerRun=500
> jcs.region.GeneralCache.elementattributes=org.apache.jcs.engine.ElementAttributes
> jcs.region.GeneralCache.elementattributes.IsEternal=false
> jcs.region.GeneralCache2=
> jcs.region.GeneralCache2.cacheattributes=org.apache.jcs.engine.CompositeCacheAttributes
> jcs.region.GeneralCache2.cacheattributes.MaxObjects=2000
> jcs.region.GeneralCache2.cacheattributes.MemoryCacheName=org.apache.jcs.engine.memory.lru.LRUMemoryCache
> jcs.region.GeneralCache2.cacheattributes.UseMemoryShrinker=true
> jcs.region.GeneralCache2.cacheattributes.MaxMemoryIdleTimeSeconds=3600
> jcs.region.GeneralCache2.cacheattributes.ShrinkerIntervalSeconds=60
> jcs.region.GeneralCache2.cacheattributes.MaxSpoolPerRun=500
> jcs.region.GeneralCache2.elementattributes=org.apache.jcs.engine.ElementAttributes
> jcs.region.GeneralCache2.elementattributes.IsEternal=false
> # AVAILABLE AUXILIARY CACHES   
> jcs.auxiliary.DC=org.apache.jcs.auxiliary.disk.indexed.IndexedDiskCacheFactory
> jcs.auxiliary.DC.attributes=org.apache.jcs.auxiliary.disk.indexed.IndexedDiskCacheAttributes
> jcs.auxiliary.DC.attributes.DiskPath=cache-files
> jcs.auxiliary.DC.attributes.maxKeySize=100000

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