void Dijkstra::calcPath(Workload& request, Graph& network, Stats& stats) {
bool pathFound=false;
bool exitLoop=false;
Element current; // current Element
Visited visited; // Visited list
Priority items; // priority queue
double previousCost=-1;
// 1. Get initial Start node
current.id=request.origin;
current.cost=0;
current.parent=request.origin; // TODO - possible problem...
items.push(current);
// 2. Loop until we have found a valid path
//while (!exitLoop && !items.empty()){
while (!items.empty()){
// Pop from the priority queue
current=items.top();
//std::cout<<"Current: "<<current.id<<" | Parent: "<<current.parent<< " | Goal:"<<request.destination<<std::endl;
items.pop(); // remove the element from the list
if (pathFound){
if(current.cost>previousCost){
exitLoop=true; // we want to exit the main loop
break;
}
}
previousCost=current.cost;
if (visited.find(current.id)==visited.end()) { //visited.find(current.id)==visited.end()
// Check if desired node
if (current.id==request.destination){ // Found the node!
pathFound=true;
//std::cout<<std::endl<<request.origin<<request.destination<<std::endl;
exitLoop=true; // TODO - remove me in future but currently bug when this is not here ????? map appears to be losing the parent of N for some weird reason..
}
else { // push the valid children which have bandwidth and are not allready visited onto the priority queue
network.begin(current.id,request.time);
while (!network.end()) {
pushChild(network.nextChild(),current,visited,items,network,request.time);
}
}
// Append the current node to the visited list
visited.insert(std::pair<char,Element>(current.id,current)); // be careful that the node is not allready in the visited list..possibly
}
}
// 3. Choose one valid path at random and backtrack -> calculate and append statistics...
if (pathFound){ // we have a valid path... -> backtrack to allocate resources
backTrack(request.origin,request.destination,request.time ,request.timeDuration ,visited,network,stats);
}
else {
//Path was impossible -> add blocked circuit
stats.addCircuit(false);
}
}
/*
* Function: allocates resources in the Graph moving along the path from start to finish in the visited map
*/
void Dijkstra::backTrack(char start, char finish, double startTime,double duration, Visited& visited,Graph &network, Stats &stats) {
bool atEnd=false;
char parentNode;
bool blocked=false;
char currentNode;
int hops=0;
double propDelay=0;
//int access=0;
std::vector<std::pair<char,char> > links; // stores the links we have visited..
std::vector <char> visit;
// 1. While we have not reached the finish node, allocate resources
currentNode=finish;
srand(time(NULL));
std::vector<char >::iterator it2;
//std::cout<<finish;
while (!atEnd){
// 1. Get the current Node
// access=rand()%(visited.at(currentNode).parents.size());
// it2=std::find(visit.begin(),visit.end(),visited.at(currentNode).parents.at(access));
// int count=0;
// while (it2!=visit.end()){
// access=rand()%(visited.at(currentNode).parents.size());
// it2=std::find(visit.begin(),visit.end(),visited.at(currentNode).parents.at(access));
// if (count > 50){
// break;
// }
// count++;
// }
//parentNode=visited.at(currentNode).parents.front(); // TODO - modify this to be random access
//parentNode=visited.at(currentNode).parents.at(access); // Completely random access
parentNode=visited.at(currentNode).parent; // TODO - modify this to be random access from the vector as shown above...
//std::cout<<parentNode;
if (parentNode == start){ // we have reached the last link -> add last connection and exit loop
atEnd=true;
}
if (network.getUsage(currentNode,parentNode,startTime) == 1.0){ // we have a blocked node
//std::cout<<std::endl<<"Blocked Path! | Current: "<<currentNode<<" Parent: "<<parentNode<< std::endl;
blocked=true;
}
links.push_back(std::pair<char,char>(currentNode,parentNode));
visit.push_back(currentNode);
//3. Increment number hops and propagation delay of link
hops++; // increment number of hops
propDelay += network.getDelay(currentNode,parentNode);
currentNode=parentNode;// make our current Node now the chosen parentNode
}
//std::cout<<std::endl;
if (blocked){ // Assign usage to respective units and update states
stats.addCircuit(false);
}
else {
for (__gnu_cxx::__normal_iterator<std::pair<char, char>*, std::vector<std::pair<char, char>, std::allocator<std::pair<char, char> > > > it=links.begin();it!=links.end();++it){
network.setUsage(it->first,it->second,startTime,duration);
}
stats.addCircuit(true);
stats.updateHopAverage(hops);
stats.updatePropAverage(propDelay);
}
}