BVS-447 Flow Path Visualization

Implemented backend for the REST API to retrieve the flow path between a pair of hosts

src/main/java/net/floodlightcontroller/linkdiscovery/ILinkDiscoveryService.java

@@ -40,6 +40,13 @@ public interface ILinkDiscoveryService extends IFloodlightService {
      */
     public Map<Link, LinkInfo> getLinks();
 
+    /**
+     * Retrieves the link info for a given link
+     * @param link link for which the link info should be returned
+     * @return the link info for the given link
+     */
+    public LinkInfo getLinkInfo(Link link);
+
     /**
      * Returns link type of a given link
      * @param info

src/main/java/net/floodlightcontroller/linkdiscovery/LinkInfo.java

@@ -40,6 +40,12 @@ public class LinkInfo {
         this.lastBddpReceivedTime = null;
     }
 
+    public LinkInfo(LinkInfo fromLinkInfo) {
+        this.firstSeenTime = fromLinkInfo.getFirstSeenTime();
+        this.lastLldpReceivedTime = fromLinkInfo.getUnicastValidTime();
+        this.lastBddpReceivedTime = fromLinkInfo.getMulticastValidTime();
+    }
+
     protected Long firstSeenTime;
     protected Long lastLldpReceivedTime; /* Standard LLLDP received time */
     protected Long lastBddpReceivedTime; /* Modified LLDP received time  */

src/main/java/net/floodlightcontroller/linkdiscovery/internal/LinkDiscoveryManager.java

-/**
+floodlight/src/main/java/net/floodlightcontroller/linkdiscovery/LinkInfo.java/**
  *    Copyright 2011, Big Switch Networks, Inc.
  *    Originally created by David Erickson, Stanford University
  *
@@ -508,6 +508,18 @@ public class LinkDiscoveryManager implements IOFMessageListener,
         return result;
     }
 
+    @Override
+    public LinkInfo getLinkInfo(Link link) {
+        lock.readLock().lock();
+        LinkInfo linkInfo = links.get(link);
+        LinkInfo retLinkInfo = null;
+        if (linkInfo != null) {
+            retLinkInfo  = new LinkInfo(linkInfo);
+        }
+        lock.readLock().unlock();
+        return retLinkInfo;
+    }
+
     @Override
     public String getName() {
         return MODULE_NAME;