Use the Executor interface when specifying where to handle incoming messages
This is done so that one can simply specify a direct executor.
Change-Id: I1c3ea977dd7c2d604588d587fd67f7012355eedf
diff --git a/utils/netty/src/main/java/org/onlab/netty/MessagingService.java b/utils/netty/src/main/java/org/onlab/netty/MessagingService.java
index d7823d4..77246cb 100644
--- a/utils/netty/src/main/java/org/onlab/netty/MessagingService.java
+++ b/utils/netty/src/main/java/org/onlab/netty/MessagingService.java
@@ -17,7 +17,7 @@
 
 import java.io.IOException;
 import java.util.concurrent.CompletableFuture;
-import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executor;
 
 /**
  * Interface for low level messaging primitives.
@@ -48,7 +48,7 @@
      * @param handler message handler
      * @param executor executor to use for running message handler logic.
      */
-    public void registerHandler(String type, MessageHandler handler, ExecutorService executor);
+    public void registerHandler(String type, MessageHandler handler, Executor executor);
 
     /**
      * Registers a new message handler for message type.
diff --git a/utils/netty/src/main/java/org/onlab/netty/NettyMessagingService.java b/utils/netty/src/main/java/org/onlab/netty/NettyMessagingService.java
index f96bb0b..3bdf0ac 100644
--- a/utils/netty/src/main/java/org/onlab/netty/NettyMessagingService.java
+++ b/utils/netty/src/main/java/org/onlab/netty/NettyMessagingService.java
@@ -42,7 +42,7 @@
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentMap;
-import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executor;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
 import java.util.concurrent.atomic.AtomicLong;
@@ -202,11 +202,11 @@
     }
 
     @Override
-    public void registerHandler(String type, MessageHandler handler, ExecutorService executor) {
+    public void registerHandler(String type, MessageHandler handler, Executor executor) {
         handlers.put(type, new MessageHandler() {
             @Override
             public void handle(Message message) throws IOException {
-                executor.submit(() -> {
+                executor.execute(() -> {
                     try {
                         handler.handle(message);
                     } catch (Exception e) {