adding getFlowRulesByGroupId to the flowservice

Change-Id: Idfcc86277b28af99e201f3bdfdf139217d77244c

@@ -84,6 +84,15 @@ public interface FlowRuleService {
     Iterable<FlowRule> getFlowRulesById(ApplicationId id);
 
     /**
+     * Returns a list of rules filterd by application and group id.
+     *
+     * @param appId the application id to lookup
+     * @param groupId the groupid to lookup
+     * @return collection of flow rules
+     */
+    Iterable<FlowRule> getFlowRulesByGroupId(ApplicationId appId, short groupId);
+
+    /**
      * Applies a batch operation of FlowRules.
      *
      * @param batch batch operation to apply

@@ -166,6 +166,20 @@ public class FlowRuleManager
     }
 
     @Override
+    public Iterable<FlowRule> getFlowRulesByGroupId(ApplicationId appId, short groupId) {
+        Set<FlowRule> matches = Sets.newHashSet();
+        long toLookUp = ((long) appId.id() << 16) | groupId;
+        for (Device d : deviceService.getDevices()) {
+            for (FlowEntry flowEntry : store.getFlowEntries(d.id())) {
+                if ((flowEntry.id().value() >>> 32) == toLookUp) {
+                    matches.add(flowEntry);
+                }
+            }
+        }
+        return matches;
+    }
+
+    @Override
     public Future<CompletedBatchOperation> applyBatch(
             FlowRuleBatchOperation batch) {
         Multimap<DeviceId, FlowRuleBatchEntry> perDeviceBatches =