[jboss-dev-forums] [Design of JBossCache] - Re: Partial state transfer -when target root integration is

[vblagojevic@jboss.com]

We need delim because in JGroups once channel1 requests partial state with channel1.getState(String state_id) it eventually receives setState callback with the *same state_id*. This is a problem for partial state transfer that has to be integrated in a different subroot that source subroot.

I am not sure I understand your question regarding BR. I've seen BR code and it transfers state in a map through RPC call. Maybe we have to convert this somehow to make use of partial state transfer.

I am providing code, still local on my laptop, that explains how this encoding is done. I think code will be more clear than my English :) 

TreeCache.MessageListenerAdaptor.getState
public byte[] getState(String state_id)
  |       {
  |          String sourceRoot = state_id;
  |          boolean hasDifferentSourceAndIntegrationRoots = state_id.indexOf(StateTransferManager.PARTIAL_STATE_DELIMETER)>0;                        
  |          if(hasDifferentSourceAndIntegrationRoots)
  |          {
  |             sourceRoot = state_id.split(StateTransferManager.PARTIAL_STATE_DELIMETER)[0];
  |          }                 
  |          try
  |          {
  |             return _getState(Fqn.fromString(sourceRoot), timeout, true, true);
  |          }
  |          catch (Throwable t)
  |          {           
  |             my_log.error("Caught " + t.getClass().getName() +
  |                          " while responding to partial state transfer request;" +
  |                          " returning null", t);
  |             return null;
  |          }
  |       }


TreeCache.MessageListenerAdaptor.setState
public void setState(String state_id, byte[] state)
  |       {
  |          String targetRoot = state_id;
  |          boolean hasDifferentSourceAndIntegrationRoots = state_id.indexOf(StateTransferManager.PARTIAL_STATE_DELIMETER)>0;               
  |          if(hasDifferentSourceAndIntegrationRoots)
  |          {
  |             targetRoot = state_id.split(StateTransferManager.PARTIAL_STATE_DELIMETER)[1];
  |          }              
  |          try
  |          {
  | 
  |             if (state != null)            
  |             {
  |                my_log.debug("Setting received partial state for subroot " +state_id);
  |                Fqn subroot = Fqn.fromString(targetRoot);
  |                Region region = regionManager.getRegion(subroot,false);                              
  |                ClassLoader cl = null;
  |                if(region!= null)
  |                {
  |                // If a classloader is registered for the node's region, use it
  |                   cl = region.getClassLoader();
  |                }
  |                getStateTransferManager().setState(state, subroot, cl);
  |                isStateSet = true;
  |             }                                    
  |          }
  | ....
  | ...
  | }

TreeCache.fetchPartialState()
 
  | public void fetchPartialState(Object sources [], Fqn sourceTarget, Fqn integrationTarget) throws Exception
  |    { 
  |       String encodedStateId = sourceTarget + StateTransferManager.PARTIAL_STATE_DELIMETER + integrationTarget;
  |       fetchPartialState(sources,encodedStateId);      
  |    }
  | 

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