Added initial implementation of Topology-related event and
event metrics collector. It can be loaded by one of the following two (new)
features: onos-app-metrics, onos-app-metrics-topology
After loading the module, it subscribes for topology-related events
and keeps the following state:
(a) The last 10 events
(b) The timestamp of the last event (ms after epoch) as observed by this
module
(c) The rate of the topology events: count, median rate, average rate
over the last 1, 5 or 15 minutes
The following CLI commands are added:
* onos:topology-events
Shows the last 10 topology events
* onos:topology-events-metrics
Shows the timestamp of the last event, and the rate of the topology
events: see (b) and (c) above
diff --git a/apps/metrics/topology/src/main/java/org/onlab/onos/metrics/topology/TopologyMetricsService.java b/apps/metrics/topology/src/main/java/org/onlab/onos/metrics/topology/TopologyMetricsService.java
new file mode 100644
index 0000000..cc370fa
--- /dev/null
+++ b/apps/metrics/topology/src/main/java/org/onlab/onos/metrics/topology/TopologyMetricsService.java
@@ -0,0 +1,35 @@
+package org.onlab.onos.metrics.topology;
+
+import java.util.List;
+
+import com.codahale.metrics.Gauge;
+import com.codahale.metrics.Meter;
+import org.onlab.onos.net.topology.TopologyEvent;
+
+/**
+ * Service interface exported by TopologyMetrics.
+ */
+public interface TopologyMetricsService {
+ /**
+ * Gets the last saved topology events.
+ *
+ * @return the last saved topology events.
+ */
+ public List<TopologyEvent> getEvents();
+
+ /**
+ * Gets the Metrics' Gauge for the last topology event timestamp
+ * (ms from the epoch).
+ *
+ * @return the Metrics' Gauge for the last topology event timestamp
+ * (ms from the epoch)
+ */
+ public Gauge<Long> lastEventTimestampEpochMsGauge();
+
+ /**
+ * Gets the Metrics' Meter for the topology events rate.
+ *
+ * @return the Metrics' Meter for the topology events rate
+ */
+ public Meter eventRateMeter();
+}