Preliminary checkin for implementing version aware topology state.

@@ -16,6 +16,7 @@ import org.onlab.onos.cluster.ClusterService;
 import org.onlab.onos.cluster.MastershipEvent;
 import org.onlab.onos.cluster.MastershipListener;
 import org.onlab.onos.cluster.MastershipService;
+import org.onlab.onos.cluster.MastershipTerm;
 import org.onlab.onos.event.AbstractListenerRegistry;
 import org.onlab.onos.event.EventDeliveryService;
 import org.onlab.onos.net.Device;
@@ -36,6 +37,7 @@ import org.onlab.onos.net.device.DeviceStoreDelegate;
 import org.onlab.onos.net.device.PortDescription;
 import org.onlab.onos.net.provider.AbstractProviderRegistry;
 import org.onlab.onos.net.provider.AbstractProviderService;
+import org.onlab.onos.store.common.ClockService;
 import org.slf4j.Logger;
 
 /**
@@ -74,6 +76,9 @@ implements DeviceService, DeviceAdminService, DeviceProviderRegistry {
     @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
     protected MastershipService mastershipService;
 
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected ClockService clockService;
+
     @Activate
     public void activate() {
         store.setDelegate(delegate);
@@ -250,6 +255,8 @@ implements DeviceService, DeviceAdminService, DeviceProviderRegistry {
         @Override
         public void event(MastershipEvent event) {
             if (event.master().equals(clusterService.getLocalNode().id())) {
+                MastershipTerm term = mastershipService.requestTermService().getMastershipTerm(event.subject());
+                clockService.setMastershipTerm(event.subject(), term);
                 applyRole(event.subject(), MastershipRole.MASTER);
             } else {
                 applyRole(event.subject(), MastershipRole.STANDBY);

+package org.onlab.onos.store.common;
+
+import org.onlab.onos.cluster.MastershipTerm;
+import org.onlab.onos.net.DeviceId;
+import org.onlab.onos.store.Timestamp;
+
+/**
+ * Interface for a logical clock service that vends per device timestamps.
+ */
+public interface ClockService {
+    
+    /**
+     * Returns a new timestamp for the specified deviceId.
+     * @param deviceId device identifier.
+     * @return timestamp.
+     */
+    public Timestamp getTimestamp(DeviceId deviceId);
+    
+    /**
+     * Updates the mastership term for the specified deviceId.
+     * @param deviceId device identifier.
+     * @param term mastership term.
+     */
+    public void setMastershipTerm(DeviceId deviceId, MastershipTerm term);
+}

+package org.onlab.onos.store.device.impl;
+
+import static org.slf4j.LoggerFactory.getLogger;
+
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+import java.util.concurrent.atomic.AtomicInteger;
+
+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.Service;
+import org.onlab.onos.cluster.MastershipTerm;
+import org.onlab.onos.net.DeviceId;
+import org.onlab.onos.store.Timestamp;
+import org.onlab.onos.store.common.ClockService;
+import org.onlab.onos.store.impl.OnosTimestamp;
+import org.slf4j.Logger;
+
+@Component(immediate = true)
+@Service
+public class OnosClockService implements ClockService {
+    
+    private final Logger log = getLogger(getClass());
+
+    // TODO: Implement per device ticker that is reset to 0 at the beginning of a new term.
+    private final AtomicInteger ticker = new AtomicInteger(0);
+    private ConcurrentMap<DeviceId, MastershipTerm> deviceMastershipTerms = new ConcurrentHashMap<>();
+    
+    @Activate
+    public void activate() {
+        log.info("Started");
+    }
+
+    @Deactivate
+    public void deactivate() {
+        log.info("Stopped");
+    }
+    
+    @Override
+    public Timestamp getTimestamp(DeviceId deviceId) {
+        MastershipTerm term = deviceMastershipTerms.get(deviceId);
+        if (term == null) {
+            throw new IllegalStateException("Requesting timestamp for a deviceId without mastership");
+        }
+        return new OnosTimestamp(term.termNumber(), ticker.incrementAndGet());
+    }
+
+    @Override
+    public void setMastershipTerm(DeviceId deviceId, MastershipTerm term) {
+        deviceMastershipTerms.put(deviceId, term);
+    }
+}

+package org.onlab.onos.store.device.impl;
+
+import org.onlab.onos.store.Timestamp;
+
+/**
+ * Wrapper class for a entity that is versioned 
+ * and can either be up or down.
+ *
+ * @param <T> type of the value.
+ */
+public class VersionedValue<T> {
+    private final T entity;
+    private final Timestamp timestamp;
+    private final boolean isUp;
+    
+    public VersionedValue(T entity, boolean isUp, Timestamp timestamp) {
+        this.entity = entity;
+        this.isUp = isUp;
+        this.timestamp = timestamp;
+    }
+    
+    /**
+     * Returns the value.
+     * @return value.
+     */
+    public T entity() {
+        return entity;
+    }
+    
+    /**
+     * Tells whether the entity is up or down.
+     * @return true if up, false otherwise.
+     */
+    public boolean isUp() {
+        return isUp;
+    }
+    
+    /**
+     * Returns the timestamp (version) associated with this entity.
+     * @return timestamp.
+     */
+    public Timestamp timestamp() {
+        return timestamp;
+    }
+}

 package org.onlab.onos.store.impl;
 
-import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Preconditions.checkArgument;
 
 import java.util.Objects;
 
-import org.onlab.onos.net.ElementId;
 import org.onlab.onos.store.Timestamp;
 
 import com.google.common.base.MoreObjects;
@@ -14,22 +12,20 @@ import com.google.common.collect.ComparisonChain;
 // If it is store specific, implement serializable interfaces?
 /**
  * Default implementation of Timestamp.
+ * TODO: Better documentation.
  */
 public final class OnosTimestamp implements Timestamp {
 
-    private final ElementId id;
     private final int termNumber;
     private final int sequenceNumber;
 
     /**
      * Default version tuple.
      *
-     * @param id identifier of the element
      * @param termNumber the mastership termNumber
      * @param sequenceNumber  the sequenceNumber number within the termNumber
      */
-    public OnosTimestamp(ElementId id, int termNumber, int sequenceNumber) {
-        this.id = checkNotNull(id);
+    public OnosTimestamp(int termNumber, int sequenceNumber) {
         this.termNumber = termNumber;
         this.sequenceNumber = sequenceNumber;
     }
@@ -38,9 +34,6 @@ public final class OnosTimestamp implements Timestamp {
     public int compareTo(Timestamp o) {
         checkArgument(o instanceof OnosTimestamp, "Must be OnosTimestamp", o);
         OnosTimestamp that = (OnosTimestamp) o;
-        checkArgument(this.id.equals(that.id),
-                "Cannot compare version for different element this:%s, that:%s",
-                    this, that);
 
         return ComparisonChain.start()
                 .compare(this.termNumber, that.termNumber)
@@ -50,7 +43,7 @@ public final class OnosTimestamp implements Timestamp {
 
     @Override
     public int hashCode() {
-        return Objects.hash(id, termNumber, sequenceNumber);
+        return Objects.hash(termNumber, sequenceNumber);
     }
 
     @Override
@@ -62,30 +55,19 @@ public final class OnosTimestamp implements Timestamp {
             return false;
         }
         OnosTimestamp that = (OnosTimestamp) obj;
-        return Objects.equals(this.id, that.id) &&
-                Objects.equals(this.termNumber, that.termNumber) &&
+        return Objects.equals(this.termNumber, that.termNumber) &&
                 Objects.equals(this.sequenceNumber, that.sequenceNumber);
     }
 
     @Override
     public String toString() {
         return MoreObjects.toStringHelper(getClass())
-                    .add("id", id)
                     .add("termNumber", termNumber)
                     .add("sequenceNumber", sequenceNumber)
                     .toString();
     }
 
     /**
-     * Returns the element.
-     *
-     * @return element identifier
-     */
-    public ElementId id() {
-        return id;
-    }
-
-    /**
      * Returns the termNumber.
      *
      * @return termNumber

 package org.onlab.onos.store.serializers;
 
-import org.onlab.onos.net.ElementId;
 import org.onlab.onos.store.impl.OnosTimestamp;
 
 import com.esotericsoftware.kryo.Kryo;
@@ -20,18 +19,17 @@ public class OnosTimestampSerializer extends Serializer<OnosTimestamp> {
         // non-null, immutable
         super(false, true);
     }
+
     @Override
     public void write(Kryo kryo, Output output, OnosTimestamp object) {
-        kryo.writeClassAndObject(output, object.id());
         output.writeInt(object.termNumber());
         output.writeInt(object.sequenceNumber());
     }
 
     @Override
     public OnosTimestamp read(Kryo kryo, Input input, Class<OnosTimestamp> type) {
-        ElementId id = (ElementId) kryo.readClassAndObject(input);
         final int term = input.readInt();
         final int sequence = input.readInt();
-        return new OnosTimestamp(id, term, sequence);
+        return new OnosTimestamp(term, sequence);
     }
 }