| package net.onrc.onos.apps.segmentrouting; |
| |
| import java.util.HashMap; |
| import java.util.HashSet; |
| import java.util.LinkedList; |
| |
| import net.onrc.onos.core.topology.Link; |
| import net.onrc.onos.core.topology.LinkData; |
| import net.onrc.onos.core.topology.Switch; |
| import net.onrc.onos.core.util.Dpid; |
| import net.onrc.onos.core.intent.Path; |
| |
| /** |
| * This class creates bandwidth constrained breadth first tree and returns paths |
| * from root switch to leaf switches which satisfies the bandwidth condition. If |
| * bandwidth parameter is not specified, the normal breadth first tree will be |
| * calculated. The paths are snapshot paths at the point of the class |
| * instantiation. |
| */ |
| public class ECMPShortestPathGraph { |
| LinkedList<Switch> switchQueue = new LinkedList<>(); |
| HashSet<Dpid> switchSearched = new HashSet<>(); |
| HashMap<Dpid, LinkData> upstreamLinks = new HashMap<>(); |
| HashMap<Dpid, Path> paths = new HashMap<>(); |
| Switch rootSwitch; |
| |
| /** |
| * Constructor. |
| * |
| * @param rootSwitch root of the BFS tree |
| */ |
| public ECMPShortestPathGraph(Switch rootSwitch) { |
| this.rootSwitch = rootSwitch; |
| calcECMPShortestPathGraph(); |
| } |
| |
| /** |
| * Calculates the BFS tree using any provided constraints and Intents. |
| */ |
| private void calcECMPShortestPathGraph() { |
| switchQueue.add(rootSwitch); |
| switchSearched.add(rootSwitch.getDpid()); |
| while (!switchQueue.isEmpty()) { |
| Switch sw = switchQueue.poll(); |
| for (Link link : sw.getOutgoingLinks()) { |
| Switch reachedSwitch = link.getDstPort().getSwitch(); |
| if (switchSearched.contains(reachedSwitch.getDpid())) { |
| continue; |
| } |
| switchQueue.add(reachedSwitch); |
| switchSearched.add(reachedSwitch.getDpid()); |
| upstreamLinks.put(reachedSwitch.getDpid(), new LinkData(link)); |
| } |
| } |
| } |
| |
| /** |
| * Return the computed path from the root switch to the leaf switch. |
| * |
| * @param leafSwitch the leaf switch |
| * @return the Path from the root switch to the leaf switch |
| */ |
| public Path getPath(Switch leafSwitch) { |
| Path path = paths.get(leafSwitch.getDpid()); |
| Dpid rootSwitchDpid = rootSwitch.getDpid(); |
| if (path == null && switchSearched.contains(leafSwitch.getDpid())) { |
| path = new Path(); |
| Dpid sw = leafSwitch.getDpid(); |
| while (!sw.equals(rootSwitchDpid)) { |
| LinkData upstreamLink = upstreamLinks.get(sw); |
| path.add(0, upstreamLink); |
| sw = upstreamLink.getSrc().getDpid(); |
| } |
| paths.put(leafSwitch.getDpid(), path); |
| } |
| return path; |
| } |
| } |