Netty epoll support. Now with updated pom.xml and features.xml to bring in the dependencies

@@ -15,6 +15,7 @@
         <bundle>mvn:io.netty/netty-transport/4.0.23.Final</bundle>
         <bundle>mvn:io.netty/netty-handler/4.0.23.Final</bundle>
         <bundle>mvn:io.netty/netty-codec/4.0.23.Final</bundle>
+        <bundle>io.netty/netty-transport-native-epoll/4.0.23.Final</bundle>
         <bundle>mvn:commons-pool/commons-pool/1.6</bundle>
 
         <bundle>mvn:com.hazelcast/hazelcast/3.3</bundle>

@@ -312,6 +312,11 @@
               <artifactId>netty-codec</artifactId>
               <version>${netty4.version}</version>
             </dependency>
+            <dependency>
+              <groupId>io.netty</groupId>
+              <artifactId>netty-transport-native-epoll</artifactId>
+              <version>${netty4.version}</version>
+            </dependency>
         </dependencies>
     </dependencyManagement>
 

@@ -55,6 +55,10 @@
           <groupId>io.netty</groupId>
           <artifactId>netty-codec</artifactId>
         </dependency>
+        <dependency>
+          <groupId>io.netty</groupId>
+          <artifactId>netty-transport-native-epoll</artifactId>
+        </dependency>
     </dependencies>
 
 </project>

@@ -16,7 +16,12 @@ import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.ChannelInitializer;
 import io.netty.channel.ChannelOption;
 import io.netty.channel.EventLoopGroup;
+import io.netty.channel.ServerChannel;
 import io.netty.channel.SimpleChannelInboundHandler;
+import io.netty.channel.epoll.Epoll;
+import io.netty.channel.epoll.EpollEventLoopGroup;
+import io.netty.channel.epoll.EpollServerSocketChannel;
+import io.netty.channel.epoll.EpollSocketChannel;
 import io.netty.channel.nio.NioEventLoopGroup;
 import io.netty.channel.socket.SocketChannel;
 import io.netty.channel.socket.nio.NioServerSocketChannel;
@@ -40,9 +45,6 @@ public class NettyMessagingService implements MessagingService {
 
     private final int port;
     private final Endpoint localEp;
-    private final EventLoopGroup bossGroup = new NioEventLoopGroup();
-    private EventLoopGroup workerGroup;
-    private Class<? extends Channel> channelClass;
     private final ConcurrentMap<String, MessageHandler> handlers = new ConcurrentHashMap<>();
     private final Cache<Long, AsyncResponse> responseFutures = CacheBuilder.newBuilder()
             .maximumSize(100000)
@@ -53,10 +55,32 @@ public class NettyMessagingService implements MessagingService {
     private final GenericKeyedObjectPool<Endpoint, Channel> channels
             = new GenericKeyedObjectPool<Endpoint, Channel>(new OnosCommunicationChannelFactory());
 
-    // TODO: make this configurable.
+    private EventLoopGroup serverGroup;
+    private EventLoopGroup clientGroup;
+    private Class<? extends ServerChannel> serverChannelClass;
+    private Class<? extends Channel> clientChannelClass;
+
     private void initEventLoopGroup() {
-        workerGroup = new NioEventLoopGroup();
-        channelClass = NioSocketChannel.class;
+        // try Epoll first and if that does work, use nio.
+        // TODO: make this configurable.
+        try {
+            if (Epoll.isAvailable()) {
+                clientGroup = new EpollEventLoopGroup();
+                serverGroup = new EpollEventLoopGroup();
+                serverChannelClass = EpollServerSocketChannel.class;
+                clientChannelClass = EpollSocketChannel.class;
+                return;
+            } else {
+                log.info("Netty epoll support is not available. Proceeding with nio.");
+            }
+
+        } catch (Throwable t) {
+            log.warn("Failed to initialize epoll sockets. Proceeding with nio.", t);
+        }
+        clientGroup = new NioEventLoopGroup();
+        serverGroup = new NioEventLoopGroup();
+        serverChannelClass = NioServerSocketChannel.class;
+        clientChannelClass = NioSocketChannel.class;
     }
 
     public NettyMessagingService() {
@@ -84,8 +108,8 @@ public class NettyMessagingService implements MessagingService {
 
     public void deactivate() throws Exception {
         channels.close();
-        bossGroup.shutdownGracefully();
-        workerGroup.shutdownGracefully();
+        serverGroup.shutdownGracefully();
+        clientGroup.shutdownGracefully();
     }
 
     @Override
@@ -149,8 +173,8 @@ public class NettyMessagingService implements MessagingService {
         b.option(ChannelOption.WRITE_BUFFER_LOW_WATER_MARK, 8 * 1024);
         // TODO: Need JVM options to configure PooledByteBufAllocator.
         b.option(ChannelOption.ALLOCATOR, PooledByteBufAllocator.DEFAULT);
-        b.group(bossGroup, workerGroup)
-            .channel(NioServerSocketChannel.class)
+        b.group(serverGroup, clientGroup)
+            .channel(serverChannelClass)
             .childHandler(new OnosCommunicationChannelInitializer())
             .option(ChannelOption.SO_BACKLOG, 128)
             .childOption(ChannelOption.SO_KEEPALIVE, true);
@@ -178,10 +202,10 @@ public class NettyMessagingService implements MessagingService {
             bootstrap.option(ChannelOption.ALLOCATOR, PooledByteBufAllocator.DEFAULT);
             bootstrap.option(ChannelOption.WRITE_BUFFER_HIGH_WATER_MARK, 32 * 1024);
             bootstrap.option(ChannelOption.WRITE_BUFFER_LOW_WATER_MARK, 8 * 1024);
-            bootstrap.group(workerGroup);
+            bootstrap.group(clientGroup);
             // TODO: Make this faster:
             // http://normanmaurer.me/presentations/2014-facebook-eng-netty/slides.html#37.0
-            bootstrap.channel(channelClass);
+            bootstrap.channel(clientChannelClass);
             bootstrap.option(ChannelOption.SO_KEEPALIVE, true);
             bootstrap.handler(new OnosCommunicationChannelInitializer());
             // Start the client.