Re: [infinispan-dev] [ISPN-125] Reading part of dynamic externalizer mappings

Hi, Re: https://jira.jboss.org/jira/browse/ISPN-125 I've been thinking more about this and I don't have the reading part very clear. At runtime, it's very easy to check the externalizer map to see if there's externalizer for class A and if there isn't any, inspect the class for @Marshallable annotation, instantiate the A's Externalizer class and add it to the map. However, the reading part is a fairly difficult problem to crack cos all you'd get would be an Id which you'd need to map back to an Externalizer that will be used for reading. However, how does the reader know what's the mapping Id to Externalizer mapping? One option, rather brutal, would be to look up the entire classpath for a class containing a @Marshallable with the index you're after. Another option would be that the 1st time someone writes an instance of that class A, it adds a String form of the fully qualified class name to the wire. So, the reader can check the externalizer map and if the id not present, read the class name and resolve it and add the mapping. However, this breaks the moment you have two different nodes sending a class for the 1st time. They would both add the class name but only the 1st one to arrive would resolve the class name correctly, the 2nd time it arrives on the node, cos the mapping would already be there, it would read the object directly, failing cos there's also the class name on the wire. Anyone has any other ideas? It's worth bearing in mind that adding this dynamic behaviour adds complexity the code and it forces previously non-concurrent collections to be concurrent, hence performance will degrade compared to the current solution. It's worth keeping in mind that users will always be able to implement their j.i.Externalizable, which will be less performant than our internal solution but might be reasonable enough. One thing is for sure here, the indexes need to be tied down and I'm already working on it. -- Galder Zamarreño Sr. Software Engineer Infinispan, JBoss Cache _______________________________________________ infinispan-dev mailing list infinispan-dev(a)lists.jboss.org http://lists.jboss.org/mailman/listinfo/infinispan-dev