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

• Type: Bug
• Status: Closed
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: jcs-1.2.7.9.2
• Component/s: Indexed Disk Cache
• Assignee: Aaron Smuts
• Reporter: Kevin Preece
• Created: 07/Dec/06 12:55
• Updated: 25/Dec/16 18:39
• Resolved: 19/Mar/07 13:18

Description

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:

1. 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

1. 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

1. 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