[ONOS-6607] Get active flow entries count in FlowRuleService

Change-Id: I68b4d916f92427c06a82d3622fcc05738f64541c
diff --git a/core/api/src/main/java/org/onosproject/net/flow/FlowRuleStore.java b/core/api/src/main/java/org/onosproject/net/flow/FlowRuleStore.java
index f1cb90c..0281009 100644
--- a/core/api/src/main/java/org/onosproject/net/flow/FlowRuleStore.java
+++ b/core/api/src/main/java/org/onosproject/net/flow/FlowRuleStore.java
@@ -136,4 +136,12 @@
      * @return the flow table statistics
      */
     Iterable<TableStatisticsEntry> getTableStatistics(DeviceId deviceId);
+
+    /**
+     * Returns number of flow rules in ADDED state for specified device.
+     *
+     * @param deviceId the device ID
+     * @return number of flow rules in ADDED state
+     */
+    long getActiveFlowRuleCount(DeviceId deviceId);
 }