[CORD-197] Properly handles a flow with empty instruction

Change-Id: Ia465fdc8df1dca7a46249cd4cd8d41faf8461c3a

@@ -234,6 +234,7 @@ public final class DefaultTrafficTreatment implements TrafficTreatment {
 
             switch (instruction.type()) {
                 case DROP:
+                case NOACTION:
                 case OUTPUT:
                 case GROUP:
                 case L0MODIFICATION:
@@ -259,9 +260,23 @@ public final class DefaultTrafficTreatment implements TrafficTreatment {
             return this;
         }
 
+        /**
+         * Add a NOACTION when DROP instruction is explicitly specified.
+         *
+         * @return the traffic treatment builder
+         */
         @Override
         public Builder drop() {
-            return add(Instructions.createDrop());
+            return add(Instructions.createNoAction());
+        }
+
+        /**
+         * Add a NOACTION when no instruction is specified.
+         *
+         * @return the traffic treatment builder
+         */
+        private Builder noAction() {
+            return add(Instructions.createNoAction());
         }
 
         @Override
@@ -459,14 +474,10 @@ public final class DefaultTrafficTreatment implements TrafficTreatment {
 
         @Override
         public TrafficTreatment build() {
-            //Don't add DROP instruction by default when instruction
-            //set is empty. This will be handled in DefaultSingleTablePipeline
-            //driver.
-
-            //if (deferred.size() == 0 && immediate.size() == 0
-            //        && table == null && !clear) {
-            //    drop();
-            //}
+            if (deferred.size() == 0 && immediate.size() == 0
+                    && table == null && !clear) {
+                noAction();
+            }
             return new DefaultTrafficTreatment(deferred, immediate, table, clear, meta, meter);
         }
 

@@ -27,9 +27,18 @@ public interface Instruction {
         /**
          * Signifies that the traffic should be dropped.
          */
+        @Deprecated
         DROP,
 
         /**
+         * Signifies that the traffic requires no action.
+         *
+         * In OF10, the behavior of NOACTION is DROP.
+         * In OF13, the behavior depends on current Action Set.
+         */
+        NOACTION,
+
+        /**
          * Signifies that the traffic should be output to a port.
          */
         OUTPUT,

@@ -68,11 +68,21 @@ public final class Instructions {
      *
      * @return drop instruction
      */
+    @Deprecated
     public static DropInstruction createDrop() {
         return new DropInstruction();
     }
 
     /**
+     * Creates a no action instruction.
+     *
+     * @return no action instruction
+     */
+    public static NoActionInstruction createNoAction() {
+        return new NoActionInstruction();
+    }
+
+    /**
      * Creates a group instruction.
      *
      * @param groupId Group Id
@@ -450,6 +460,7 @@ public final class Instructions {
     /**
      *  Drop instruction.
      */
+    @Deprecated
     public static final class DropInstruction implements Instruction {
 
         private DropInstruction() {}
@@ -482,6 +493,40 @@ public final class Instructions {
     }
 
     /**
+     *  No Action instruction.
+     */
+    public static final class NoActionInstruction implements Instruction {
+
+        private NoActionInstruction() {}
+
+        @Override
+        public Type type() {
+            return Type.NOACTION;
+        }
+
+        @Override
+        public String toString() {
+            return toStringHelper(type().toString()).toString();
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(type().ordinal());
+        }
+
+        @Override
+        public boolean equals(Object obj) {
+            if (this == obj) {
+                return true;
+            }
+            if (obj instanceof NoActionInstruction) {
+                return true;
+            }
+            return false;
+        }
+    }
+
+    /**
      *  Output Instruction.
      */
     public static final class OutputInstruction implements Instruction {

@@ -339,6 +339,7 @@ public final class KryoNamespaces {
                     Criterion.Type.class,
                     DefaultTrafficTreatment.class,
                     Instructions.DropInstruction.class,
+                    Instructions.NoActionInstruction.class,
                     Instructions.OutputInstruction.class,
                     Instructions.GroupInstruction.class,
                     Instructions.TableTypeTransition.class,

@@ -221,11 +221,6 @@ public class FlowEntryBuilder {
 
     private TrafficTreatment buildTreatment() {
         TrafficTreatment.Builder builder = DefaultTrafficTreatment.builder();
-        // If this is a drop rule
-        if (instructions.size() == 0) {
-            builder.drop();
-            return builder.build();
-        }
         for (OFInstruction in : instructions) {
             switch (in.getType()) {
                 case GOTO_TABLE:

@@ -142,7 +142,7 @@ public class FlowModBuilderVer10 extends FlowModBuilder {
         for (Instruction i : treatment.immediate()) {
             switch (i.type()) {
             case DROP:
-                log.warn("Saw drop action; assigning drop action");
+            case NOACTION:
                 return Collections.emptyList();
             case L2MODIFICATION:
                 act = buildL2Modification(i);

@@ -215,6 +215,7 @@ public class FlowModBuilderVer13 extends FlowModBuilder {
         for (Instruction i : treatments) {
             switch (i.type()) {
                 case DROP:
+                case NOACTION:
                     return Collections.emptyList();
                 case L0MODIFICATION:
                     actions.add(buildL0Modification(i));