protected int LowestDelay(GraphNode src, GraphNode dst)
{
ConnectionList cl = src.ConnectionTable.GetConnections(ConnectionType.Structured);
Connection fastest_con = cl[0];
int lowest_delay = Int32.MaxValue;
int second_half = Int32.MaxValue;
foreach(Connection con in cl) {
GraphEdge edge = con.Edge as GraphEdge;
int delay = edge.Delay;
if(delay == 0) {
continue;
}
GraphNode mid = _addr_to_node[fastest_con.Address as AHAddress];
int delay2 = CalculateDelay(mid, dst);
if(second_half == 0) {
continue;
}
if(delay < lowest_delay) {
fastest_con = con;
lowest_delay = delay;
second_half = delay2;
}
}
return lowest_delay + second_half;
}
///</summary>Creates a new Graph for simulate routing algorithms.</summary>
///<param name="count">The network size not including the clusters.</param>
///<param name="near">The amount of connections on the left or right of a
///node.</param>
///<param name="shortcuts">The amount of far connections had per node.</param>
///<param name="latency">(optional)count x count matrix containing the
///latency between ///two points.</param>
///<param name="cluster_count">A cluster is a 100 node network operating on
///a single point in the network. A cluster cannot communicate directly
///with another cluster.</param>
///<param name="dataset">A square dataset consisting of pairwise latencies.</param>
public Graph(int count, int near, int shortcuts, int random_seed, List<List<int>> dataset)
{
_latency_map = dataset;
_rand = new Random(random_seed);
GraphNode.SetSeed(_rand.Next());
_addr_to_node = new Dictionary<AHAddress, GraphNode>(count);
_addrs = new List<AHAddress>(count);
_addr_to_index = new Dictionary<AHAddress, int>(count);
// first we create our regular network
while(_addrs.Count < count) {
AHAddress addr = GenerateAddress();
GraphNode node = new GraphNode(addr);
_addr_to_node[addr] = node;
_addrs.Add(addr);
}
FixLists();
for(int i = 0; i < count; i++) {
GraphNode cnode = _addr_to_node[_addrs[i]];
ConnectionList cons = cnode.ConnectionTable.GetConnections(ConnectionType.Structured);
// We select our left and right neighbors up to near out (so we get 2*near connections)
// Then we check to make sure we don't already have this connection, since the other guy
// may have added it, if we don't we create one and add it.
for(int j = 1; j <= near; j++) {
int left = i - j;
if(left < 0) {
left += count;
}
GraphNode lnode = _addr_to_node[_addrs[left]];
if(!cons.Contains(lnode.Address)) {
int delay = CalculateDelay(cnode, lnode);
AddConnection(cnode, lnode, delay);
AddConnection(lnode, cnode, delay);
}
int right = i+j;
if(right >= count) {
right -= count;
}
GraphNode rnode = _addr_to_node[_addrs[right]];
// No one has this connection, let's add it to both sides.
if(!cons.Contains(rnode.Address)) {
int delay = CalculateDelay(cnode, rnode);
AddConnection(cnode, rnode, delay);
AddConnection(rnode, cnode, delay);
}
}
// Let's add shortcuts so that we have at least the minimum number of shortcuts
while(cnode.Shortcuts < shortcuts) {
cons = cnode.ConnectionTable.GetConnections(ConnectionType.Structured);
AHAddress addr = ComputeShortcutTarget(cnode.Address);
addr = FindNodeNearestToAddress(addr);
if(cons.Contains(addr) || addr.Equals(cnode.Address)) {
continue;
}
GraphNode snode = _addr_to_node[addr];
cons = snode.ConnectionTable.GetConnections(ConnectionType.Structured);
int delay = CalculateDelay(cnode, snode);
if(delay == -1) {
continue;
}
AddConnection(cnode, snode, delay);
AddConnection(snode, cnode, delay);
cnode.Shortcuts++;
snode.Shortcuts++;
}
}
foreach(GraphNode gn in _addr_to_node.Values) {
gn.UpdateSystem();
}
}
///<summary>Calculates the delay between two nodes.</summary>
protected virtual int CalculateDelay(GraphNode node1, GraphNode node2)
{
if(_latency_map != null) {
int mod = _latency_map.Count;
int x = node1.UniqueID % mod;
int y = node2.UniqueID % mod;
return (int) (_latency_map[x][y] / 1000.0);
}
return _rand.Next(10, 240);
}
///<summary>Creates an edge and a connection from node2 to node1 including
///the edge. Note: this is unidirectional, this must be called twice,
///swapping node1 with node2 for a connection to be complete.</summary>
protected void AddConnection(GraphNode node1, GraphNode node2, int delay)
{
Edge edge = new GraphEdge(delay);
Connection con = new Connection(edge, node2.Address, ConnectionType.Structured.ToString(), null, null);
node1.ConnectionTable.Add(con);
}
///<summary>Calculates the delay between two nodes.</summary>
protected virtual int CalculateDelay(GraphNode node1, GraphNode node2)
{
if(node1 == node2) {
return 0;
}
if(_latency_map != null) {
int mod = _latency_map.Count;
int x = node1.UniqueID % mod;
int y = node2.UniqueID % mod;
if(x == y) {
return 0;
} else if(_latency_map[x][y] <= 0) {
_latency_map[x][y] = 1000 * 1000;
}
return (int) (_latency_map[x][y] / 1000.0);
}
return _rand.Next(10, 240);
}
