Added a WallClockTimestamp and associated interface/implementation for generating it. This will be used by the initial implementation of distributed host store
diff --git a/core/store/dist/src/main/java/org/onlab/onos/store/host/impl/HostClockManager.java b/core/store/dist/src/main/java/org/onlab/onos/store/host/impl/HostClockManager.java
new file mode 100644
index 0000000..49eeb06
--- /dev/null
+++ b/core/store/dist/src/main/java/org/onlab/onos/store/host/impl/HostClockManager.java
@@ -0,0 +1,38 @@
+package org.onlab.onos.store.host.impl;
+
+import static org.slf4j.LoggerFactory.getLogger;
+
+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.net.host.HostClockService;
+import org.onlab.onos.store.Timestamp;
+import org.onlab.onos.store.impl.WallClockTimestamp;
+import org.onlab.packet.MacAddress;
+import org.slf4j.Logger;
+
+/**
+ * HostClockService to issue Timestamps based on local wallclock time.
+ */
+@Component(immediate = true)
+@Service
+public class HostClockManager implements HostClockService {
+
+ private final Logger log = getLogger(getClass());
+
+ @Activate
+ public void activate() {
+ log.info("Started");
+ }
+
+ @Deactivate
+ public void deactivate() {
+ log.info("Stopped");
+ }
+
+ @Override
+ public Timestamp getTimestamp(MacAddress hostMac) {
+ return new WallClockTimestamp();
+ }
+}
diff --git a/core/store/dist/src/main/java/org/onlab/onos/store/impl/MastershipBasedTimestamp.java b/core/store/dist/src/main/java/org/onlab/onos/store/impl/MastershipBasedTimestamp.java
index e6317bb..9721024a 100644
--- a/core/store/dist/src/main/java/org/onlab/onos/store/impl/MastershipBasedTimestamp.java
+++ b/core/store/dist/src/main/java/org/onlab/onos/store/impl/MastershipBasedTimestamp.java
@@ -10,8 +10,12 @@
import com.google.common.collect.ComparisonChain;
/**
- * Default implementation of Timestamp.
- * TODO: Better documentation.
+ * A logical timestamp that derives its value from two things:
+ * <ul>
+ * <li> The current mastership term of the device.</li>
+ * <li> The value of the counter used for tracking topology events observed from
+ * the device during that current time of a device. </li>
+ * </ul>
*/
public final class MastershipBasedTimestamp implements Timestamp {
diff --git a/core/store/dist/src/main/java/org/onlab/onos/store/impl/WallClockTimestamp.java b/core/store/dist/src/main/java/org/onlab/onos/store/impl/WallClockTimestamp.java
new file mode 100644
index 0000000..38d23c1
--- /dev/null
+++ b/core/store/dist/src/main/java/org/onlab/onos/store/impl/WallClockTimestamp.java
@@ -0,0 +1,66 @@
+package org.onlab.onos.store.impl;
+
+import static com.google.common.base.Preconditions.checkArgument;
+
+import java.util.Objects;
+
+import org.onlab.onos.store.Timestamp;
+
+import com.google.common.base.MoreObjects;
+import com.google.common.collect.ComparisonChain;
+
+/**
+ * A Timestamp that derives its value from the prevailing
+ * wallclock time on the controller where it is generated.
+ */
+public class WallClockTimestamp implements Timestamp {
+
+ private final long unixTimestamp;
+
+ public WallClockTimestamp() {
+ unixTimestamp = System.currentTimeMillis();
+ }
+
+ @Override
+ public int compareTo(Timestamp o) {
+ checkArgument(o instanceof WallClockTimestamp,
+ "Must be WallClockTimestamp", o);
+ WallClockTimestamp that = (WallClockTimestamp) o;
+
+ return ComparisonChain.start()
+ .compare(this.unixTimestamp, that.unixTimestamp)
+ .result();
+ }
+ @Override
+ public int hashCode() {
+ return Objects.hash(unixTimestamp);
+ }
+
+ @Override
+ public boolean equals(Object obj) {
+ if (this == obj) {
+ return true;
+ }
+ if (!(obj instanceof WallClockTimestamp)) {
+ return false;
+ }
+ WallClockTimestamp that = (WallClockTimestamp) obj;
+ return Objects.equals(this.unixTimestamp, that.unixTimestamp);
+ }
+
+ @Override
+ public String toString() {
+ return MoreObjects.toStringHelper(getClass())
+ .add("unixTimestamp", unixTimestamp)
+ .toString();
+ }
+
+ /**
+ * Returns the unixTimestamp.
+ *
+ * @return unix timestamp
+ */
+ public long unixTimestamp() {
+ return unixTimestamp;
+ }
+}