Added GossipLinkStore with basic replication for link state.

+package org.onlab.onos.store.link.impl;
+
+import org.onlab.onos.store.cluster.messaging.MessageSubject;
+
+/**
+ * MessageSubjects used by GossipLinkStore peer-peer communication.
+ */
+public final class GossipLinkStoreMessageSubjects {
+
+    private GossipLinkStoreMessageSubjects() {}
+
+    public static final MessageSubject LINK_UPDATE = new MessageSubject("peer-link-update");
+    public static final MessageSubject LINK_REMOVED = new MessageSubject("peer-link-removed");
+}

+package org.onlab.onos.store.link.impl;
+
+import com.google.common.base.MoreObjects;
+
+import org.onlab.onos.net.link.LinkDescription;
+import org.onlab.onos.net.provider.ProviderId;
+import org.onlab.onos.store.common.impl.Timestamped;
+
+/**
+ * Information published by GossipDeviceStore to notify peers of a device
+ * change event.
+ */
+public class InternalLinkEvent {
+
+    private final ProviderId providerId;
+    private final Timestamped<LinkDescription> linkDescription;
+
+    protected InternalLinkEvent(
+            ProviderId providerId,
+            Timestamped<LinkDescription> linkDescription) {
+        this.providerId = providerId;
+        this.linkDescription = linkDescription;
+    }
+
+    public ProviderId providerId() {
+        return providerId;
+    }
+
+    public Timestamped<LinkDescription> linkDescription() {
+        return linkDescription;
+    }
+
+    @Override
+    public String toString() {
+        return MoreObjects.toStringHelper(getClass())
+                .add("providerId", providerId)
+                .add("linkDescription", linkDescription)
+                .toString();
+    }
+
+    // for serializer
+    protected InternalLinkEvent() {
+        this.providerId = null;
+        this.linkDescription = null;
+    }
+}

+package org.onlab.onos.store.link.impl;
+
+import org.onlab.onos.net.LinkKey;
+import org.onlab.onos.store.Timestamp;
+
+import com.google.common.base.MoreObjects;
+
+/**
+ * Information published by GossipLinkStore to notify peers of a link
+ * being removed.
+ */
+public class InternalLinkRemovedEvent {
+
+    private final LinkKey linkKey;
+    private final Timestamp timestamp;
+
+    /**
+     * Creates a InternalLinkRemovedEvent.
+     * @param linkKey identifier of the removed link.
+     * @param timestamp timestamp of when the link was removed.
+     */
+    public InternalLinkRemovedEvent(LinkKey linkKey, Timestamp timestamp) {
+        this.linkKey = linkKey;
+        this.timestamp = timestamp;
+    }
+
+    public LinkKey linkKey() {
+        return linkKey;
+    }
+
+    public Timestamp timestamp() {
+        return timestamp;
+    }
+
+    @Override
+    public String toString() {
+        return MoreObjects.toStringHelper(getClass())
+                .add("linkKey", linkKey)
+                .add("timestamp", timestamp)
+                .toString();
+    }
+
+    // for serializer
+    @SuppressWarnings("unused")
+    private InternalLinkRemovedEvent() {
+        linkKey = null;
+        timestamp = null;
+    }
+}
\ No newline at end of file

-package org.onlab.onos.store.link.impl;
-
-import static org.onlab.onos.net.Link.Type.DIRECT;
-import static org.onlab.onos.net.Link.Type.INDIRECT;
-import static org.onlab.onos.net.link.LinkEvent.Type.LINK_ADDED;
-import static org.onlab.onos.net.link.LinkEvent.Type.LINK_REMOVED;
-import static org.onlab.onos.net.link.LinkEvent.Type.LINK_UPDATED;
-import static org.slf4j.LoggerFactory.getLogger;
-
-import java.util.HashSet;
-import java.util.Set;
-import java.util.concurrent.ConcurrentHashMap;
-import java.util.concurrent.ConcurrentMap;
-
-import org.apache.felix.scr.annotations.Activate;
-import org.apache.felix.scr.annotations.Component;
-import org.apache.felix.scr.annotations.Deactivate;
-import org.apache.felix.scr.annotations.Reference;
-import org.apache.felix.scr.annotations.ReferenceCardinality;
-import org.apache.felix.scr.annotations.Service;
-import org.onlab.onos.net.ConnectPoint;
-import org.onlab.onos.net.DefaultLink;
-import org.onlab.onos.net.DeviceId;
-import org.onlab.onos.net.Link;
-import org.onlab.onos.net.LinkKey;
-import org.onlab.onos.net.link.LinkDescription;
-import org.onlab.onos.net.link.LinkEvent;
-import org.onlab.onos.net.link.LinkStore;
-import org.onlab.onos.net.link.LinkStoreDelegate;
-import org.onlab.onos.net.provider.ProviderId;
-import org.onlab.onos.store.AbstractStore;
-import org.onlab.onos.store.ClockService;
-import org.onlab.onos.store.Timestamp;
-import org.slf4j.Logger;
-
-import com.google.common.collect.HashMultimap;
-import com.google.common.collect.ImmutableSet;
-import com.google.common.collect.Multimap;
-import com.google.common.collect.ImmutableSet.Builder;
-
-import static com.google.common.base.Preconditions.checkArgument;
-import static com.google.common.base.Preconditions.checkState;
-
-//TODO: Add support for multiple provider and annotations
-/**
- * Manages inventory of infrastructure links using a protocol that takes into consideration
- * the order in which events occur.
- */
-// FIXME: This does not yet implement the full protocol.
-// The full protocol requires the sender of LLDP message to include the
-// version information of src device/port and the receiver to
-// take that into account when figuring out if a more recent src
-// device/port down event renders the link discovery obsolete.
-@Component(immediate = true)
-@Service
-public class OnosDistributedLinkStore
-    extends AbstractStore<LinkEvent, LinkStoreDelegate>
-    implements LinkStore {
-
-    private final Logger log = getLogger(getClass());
-
-    // Link inventory
-    private ConcurrentMap<LinkKey, VersionedValue<Link>> links;
-
-    public static final String LINK_NOT_FOUND = "Link between %s and %s not found";
-
-    // TODO synchronize?
-    // Egress and ingress link sets
-    private final Multimap<DeviceId, VersionedValue<Link>> srcLinks = HashMultimap.create();
-    private final Multimap<DeviceId, VersionedValue<Link>> dstLinks = HashMultimap.create();
-
-    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
-    protected ClockService clockService;
-
-    @Activate
-    public void activate() {
-
-        links = new ConcurrentHashMap<>();
-
-        log.info("Started");
-    }
-
-    @Deactivate
-    public void deactivate() {
-        log.info("Stopped");
-    }
-
-    @Override
-    public int getLinkCount() {
-        return links.size();
-    }
-
-    @Override
-    public Iterable<Link> getLinks() {
-        Builder<Link> builder = ImmutableSet.builder();
-        synchronized (this) {
-            for (VersionedValue<Link> link : links.values()) {
-                builder.add(link.entity());
-            }
-            return builder.build();
-        }
-    }
-
-    @Override
-    public Set<Link> getDeviceEgressLinks(DeviceId deviceId) {
-        Set<VersionedValue<Link>> egressLinks = ImmutableSet.copyOf(srcLinks.get(deviceId));
-        Set<Link> rawEgressLinks = new HashSet<>();
-        for (VersionedValue<Link> link : egressLinks) {
-            rawEgressLinks.add(link.entity());
-        }
-        return rawEgressLinks;
-    }
-
-    @Override
-    public Set<Link> getDeviceIngressLinks(DeviceId deviceId) {
-        Set<VersionedValue<Link>> ingressLinks = ImmutableSet.copyOf(dstLinks.get(deviceId));
-        Set<Link> rawIngressLinks = new HashSet<>();
-        for (VersionedValue<Link> link : ingressLinks) {
-            rawIngressLinks.add(link.entity());
-        }
-        return rawIngressLinks;
-    }
-
-    @Override
-    public Link getLink(ConnectPoint src, ConnectPoint dst) {
-        VersionedValue<Link> link = links.get(new LinkKey(src, dst));
-        checkArgument(link != null, "LINK_NOT_FOUND", src, dst);
-        return link.entity();
-    }
-
-    @Override
-    public Set<Link> getEgressLinks(ConnectPoint src) {
-        Set<Link> egressLinks = new HashSet<>();
-        for (VersionedValue<Link> link : srcLinks.get(src.deviceId())) {
-            if (link.entity().src().equals(src)) {
-                egressLinks.add(link.entity());
-            }
-        }
-        return egressLinks;
-    }
-
-    @Override
-    public Set<Link> getIngressLinks(ConnectPoint dst) {
-        Set<Link> ingressLinks = new HashSet<>();
-        for (VersionedValue<Link> link : dstLinks.get(dst.deviceId())) {
-            if (link.entity().dst().equals(dst)) {
-                ingressLinks.add(link.entity());
-            }
-        }
-        return ingressLinks;
-    }
-
-    @Override
-    public LinkEvent createOrUpdateLink(ProviderId providerId,
-                                        LinkDescription linkDescription) {
-
-        final DeviceId destinationDeviceId = linkDescription.dst().deviceId();
-        final Timestamp newTimestamp = clockService.getTimestamp(destinationDeviceId);
-
-        LinkKey key = new LinkKey(linkDescription.src(), linkDescription.dst());
-        VersionedValue<Link> link = links.get(key);
-        if (link == null) {
-            return createLink(providerId, key, linkDescription, newTimestamp);
-        }
-
-        checkState(newTimestamp.compareTo(link.timestamp()) > 0,
-                "Existing Link has a timestamp in the future!");
-
-        return updateLink(providerId, link, key, linkDescription, newTimestamp);
-    }
-
-    // Creates and stores the link and returns the appropriate event.
-    private LinkEvent createLink(ProviderId providerId, LinkKey key,
-            LinkDescription linkDescription, Timestamp timestamp) {
-        VersionedValue<Link> link = new VersionedValue<Link>(new DefaultLink(providerId, key.src(), key.dst(),
-                linkDescription.type()), true, timestamp);
-        synchronized (this) {
-            links.put(key, link);
-            addNewLink(link, timestamp);
-        }
-        // FIXME: notify peers.
-        return new LinkEvent(LINK_ADDED, link.entity());
-    }
-
-    // update Egress and ingress link sets
-    private void addNewLink(VersionedValue<Link> link, Timestamp timestamp) {
-        Link rawLink = link.entity();
-        synchronized (this) {
-            srcLinks.put(rawLink.src().deviceId(), link);
-            dstLinks.put(rawLink.dst().deviceId(), link);
-        }
-    }
-
-    // Updates, if necessary the specified link and returns the appropriate event.
-    private LinkEvent updateLink(ProviderId providerId, VersionedValue<Link> existingLink,
-                                 LinkKey key, LinkDescription linkDescription, Timestamp timestamp) {
-        // FIXME confirm Link update condition is OK
-        if (existingLink.entity().type() == INDIRECT && linkDescription.type() == DIRECT) {
-            synchronized (this) {
-
-                VersionedValue<Link> updatedLink = new VersionedValue<Link>(
-                        new DefaultLink(providerId, existingLink.entity().src(), existingLink.entity().dst(),
-                                        linkDescription.type()), true, timestamp);
-                links.replace(key, existingLink, updatedLink);
-
-                replaceLink(existingLink, updatedLink);
-                // FIXME: notify peers.
-                return new LinkEvent(LINK_UPDATED, updatedLink.entity());
-            }
-        }
-        return null;
-    }
-
-    // update Egress and ingress link sets
-    private void replaceLink(VersionedValue<Link> current, VersionedValue<Link> updated) {
-        synchronized (this) {
-            srcLinks.remove(current.entity().src().deviceId(), current);
-            dstLinks.remove(current.entity().dst().deviceId(), current);
-
-            srcLinks.put(current.entity().src().deviceId(), updated);
-            dstLinks.put(current.entity().dst().deviceId(), updated);
-        }
-    }
-
-    @Override
-    public LinkEvent removeLink(ConnectPoint src, ConnectPoint dst) {
-        synchronized (this) {
-            LinkKey key = new LinkKey(src, dst);
-            VersionedValue<Link> link = links.remove(key);
-            if (link != null) {
-                removeLink(link);
-                // notify peers
-                return new LinkEvent(LINK_REMOVED, link.entity());
-            }
-            return null;
-        }
-    }
-
-    // update Egress and ingress link sets
-    private void removeLink(VersionedValue<Link> link) {
-        synchronized (this) {
-            srcLinks.remove(link.entity().src().deviceId(), link);
-            dstLinks.remove(link.entity().dst().deviceId(), link);
-        }
-    }
-}

@@ -24,6 +24,7 @@ import org.onlab.onos.net.Port;
 import org.onlab.onos.net.PortNumber;
 import org.onlab.onos.net.PortNumber;
 import org.onlab.onos.net.device.DefaultDeviceDescription;
 import org.onlab.onos.net.device.DefaultDeviceDescription;
 import org.onlab.onos.net.device.DefaultPortDescription;
 import org.onlab.onos.net.device.DefaultPortDescription;
+import org.onlab.onos.net.link.DefaultLinkDescription;
 import org.onlab.onos.net.provider.ProviderId;
 import org.onlab.onos.net.provider.ProviderId;
 import org.onlab.onos.store.Timestamp;
 import org.onlab.onos.store.Timestamp;
 import org.onlab.packet.IpAddress;
 import org.onlab.packet.IpAddress;
@@ -58,6 +59,7 @@ public final class KryoPoolUtil {
                     DefaultControllerNode.class,
                     DefaultControllerNode.class,
                     DefaultDevice.class,
                     DefaultDevice.class,
                     DefaultDeviceDescription.class,
                     DefaultDeviceDescription.class,
+                    DefaultLinkDescription.class,
                     MastershipRole.class,
                     MastershipRole.class,
                     Port.class,
                     Port.class,
                     DefaultPortDescription.class,
                     DefaultPortDescription.class,