[infinispan-dev] InternalCacheValue, Marshalling and Cache Stores

[Manik Surtani]

As pointed out by genman, the use of InternalCacheEntries (ICEs) in  
certain cache stores can lead to unnecessary marshalling of a key  
twice, impacting both time to marshall and space consumed by the  
resulting byte stream.

Cache stores specifically affected are the JdbcStringBasedCacheStore,  
BdbjeCacheStore, JdbmCacheStore and ClusteredCacheLoader.

The ClusteredGetCommand - used by both the ClusteredCacheLoader as  
well as the DistributionInterceptor for remote lookups - is also  
affected.  There is no point in a remote host marshalling the key in  
ICE as a part of the response stream, the caller already has the key  
as it was a part of the request.

All the same, we cannot remove the key portion of ICE or exclude it  
from marshalling as it is needed for other purposes such as state  
transfer.  Bucket-based cache stores too require the key to be stored  
with the entry.

So to work around this, I have provided an additional interface:  
InternalCacheValue (ICV).  This is a representation of a value (+ any  
information pertaining to expiry).  So essentially all the stuff in an  
ICE minus the key.

An ICV is obtained by invoking ICE.toInternalCacheValue().  The cache  
stores mentioned above - and ClusteredGetCommand - should make sure  
they marshall ICVs rather than ICEs.

When loading entries, an ICE can be created by using  
ICV.toInternalCacheEntry(Object key).

Could the respective authors of the stores above please modify their  
code accordingly - I've just checked in the ICV changes in trunk.

Cheers
--
Manik Surtani
manik at jboss.org
Lead, Infinispan
Lead, JBoss Cache
http://www.infinispan.org
http://www.jbosscache.org