//private static ThreadLocal<Region> instances = new ThreadLocal<Region>(() => new Region());
//public static Region Instance
//{
// get { return instances.Value; }
//}
/// <summary>
/// This method only add regional nodes to the first region.
/// Subsequent node additions to latter regions are done inside of
/// <see cref="PredictiveForest.Update(System.Device.Location.GeoCoordinate, double)" />.
/// </summary>
/// <param name="nodes"></param>
public void Update(IEnumerable <Node> nodes)
{
var newRegion = new ConcurrentDictionary <int, RegionalNode>();
foreach (var node in nodes)
{
var regionalNode = new RegionalNode(node, null);
newRegion.TryAdd(node.NodeID, regionalNode);
}
Regions.TryAdd(RegionCount, newRegion);
}
public void Update(Coordinate center, double radius)
{
if (CurrentStep == 0)
{
MRegion.Update(GetRoadNetwork().GetNodesWithinRange(center, radius));
MRegion.Regions.TryGetValue(CurrentStep, out var region);
ExpandPredictiveTrees(region);
CurrentStep += 1;
return;
}
// retrieve all nodes from previous region
MRegion.Regions.TryGetValue(CurrentStep - 1, out var pastNodes);
// gathering child nodes from previous region
var children = new HashSet <int>();
foreach (var kv in pastNodes)
{
children.UnionWith(kv.Value.Children);
}
// gathering new nodes within latest region
var currentNodes = new HashSet <int>();
foreach (var n in GetRoadNetwork().GetNodesWithinRange(center, radius))
{
currentNodes.Add(n.NodeID);
}
// only keep the nodes from newest region which intersects the previous region's children
currentNodes.IntersectWith(children);
// pruning children from the nodes of previous region
// for each node in previous region, intersect its set of children with current nodes
// if the resulting set is empty, the previous node is obsolete
var obsoleteParents = new HashSet <int>();
var validParents = new HashSet <int>();
foreach (var kv in pastNodes)
{
var pastNode = kv.Value;
pastNode.Children.IntersectWith(currentNodes);
if (pastNode.Children.Count == 0)
{
obsoleteParents.Add(pastNode.NodeID);
continue;
}
validParents.Add(pastNode.NodeID);
}
// adding all valid nodes to the latest region
// Note: the first region is initialized in <see cref="Region.Update(IEnumerable{Node})"/>
//
var newRegion = new ConcurrentDictionary <int, RegionalNode>();
foreach (var nodeID in currentNodes) // note that current node has been cleared of all dead-end nodes
{
GetRoadNetwork().Nodes.TryGetValue(nodeID, out var node);
var currentNode = new RegionalNode(node, validParents);
newRegion.TryAdd(nodeID, currentNode);
}
// add newest region to the Region buffer
// make sure the new region is added to buffer before pruning obsolete parents
// because the pruning function needs reference to this new region
MRegion.Regions.TryAdd(CurrentStep, newRegion);
PruneRegions(CurrentStep - 1, obsoleteParents);
ExpandPredictiveTrees(newRegion); // Populate and expand predictive trees for new region
CurrentStep += 1; // increment how many steps we've received updates from
}