// compute the probabilities of the links in the routing table,
// using the utilizations of the links on the ring. 

*operation* void compute_probabilities(RoutingTable* rtable, Ring* ring)
*traverse*
  *from* ProbAlg
  *to* {Priority}
*wrapper* Priority
  (@
     rtable->compute_priority_probabilities(ring);
   @)


// this is the standard priority algorithm used for the computation
// of the probabilities. 

*operation* void compute_priority_probabilities(Ring* ring)
*traverse*
  *from* RoutingTable
  *through* -> *, dag, *,
            -> *, neighbors, *
  *to* DagNeighbor
*carry* *in* VNode* source_vnode = (@ get_source() @),
        *inout* double all_product = (@ 1.0 @),
        *inout* double part_product = (@ 1.0 @),
        *inout* double all_sum = (@ 0.0 @),
	*in* VNode* next_default_vnode
*along*
  *from* DagAdjacency
  *through* -> *, neighbors, *
  *to* DagNeighbor
*wrapper* DagAdjacency
  (@
     VirtualAdjacency* adj = ring->find(get_source());
     next_default_vnode = ring->get_nextdefault(adj)->get_source();
     compute_all_product_sum(ring, all_product, all_sum);
   @)
*wrapper* DagNeighbor
  (@
     double util = ring->get_utilization(source_vnode, get_neighbor());
     double prob;
     if (all_sum)
       prob = (1.0 - util) * part_product + all_product * ((1.0 - util) / all_sum);
     else if (get_neighbor() == next_default_vnode)
       prob = 1.0;    // always follow the default link
     else
       prob = 0.0;
     this->get_prob()->set_val(prob);
     part_product *= util;
   @)
     

// find the product of the utilizations of all the neighbors of the
// DAG adjacency and also compute the sum of (1-util) for all neighbors.

*operation* void compute_all_product_sum(Ring* ring, double& product, double& sum)
*traverse*
  *from* DagAdjacency
  *through* -> *, neighbors, *
  *to-stop* VNode
*carry* *in* VNode* source_vnode = (@ get_source() @)
*along*
  *from* DagAdjacency
  *through* -> *, neighbors, *
  *to-stop* VNode
*wrapper* VNode
  (@
     double util = ring->get_utilization(source_vnode, this);
     product *= util;
     sum += (1.0 - util);
   @)