Merge pull request #1 from hechaoli/listen_async

Make startListeningOnPort() asynchronous

README.md

@@ -75,8 +75,7 @@ System.out.println(Arrays.toString(dbs));
 From above example we can see the steps of getting an `OvsdbClient` object.
 
 (1) Construct a `OvsdbPassiveConnectionListener`. The `OvsdbPassiveConnectionListenerImpl`
-takes a `ScheduledExecutorService` for asynchronous operations. The thread pool has to contain at 
-least 2 idle threads because 1 thread will be used to listen on the port.  
+takes a `ScheduledExecutorService` for asynchronous operations.
 (2) Implement the `ConnectionCallback` interface and construct a callback object.  
 (3) Start listening on the port.  
 (4) Get the `OvsdbClient` object from the callback and use it for operations on the OVSDB server.

ovsdb-client/src/main/java/com/vmware/ovsdb/service/impl/OvsdbPassiveConnectionListenerImpl.java

@@ -59,15 +59,15 @@ public void startListening(
       int port, ConnectionCallback connectionCallback
   ) {
     isListeningCheckWithThrow(port);
-    executorService.submit(() -> startListeningOnPort(port, null, connectionCallback));
+    startListeningOnPort(port, null, connectionCallback);
   }
 
   @Override
   public void startListeningWithSsl(
       int port, SslContext sslContext, ConnectionCallback connectionCallback
   ) {
     isListeningCheckWithThrow(port);
-    executorService.submit(() -> startListeningOnPort(port, sslContext, connectionCallback));
+    startListeningOnPort(port, sslContext, connectionCallback);
   }
 
   @Override
@@ -104,15 +104,17 @@ private void startListeningOnPort(
       ChannelFuture channelFuture = serverBootstrap.bind(port).sync();
       serverChannelMap.put(port,  channelFuture.channel());
 
-      // Wait until the server socket is closed.
-      channelFuture.channel().closeFuture().sync();
+      channelFuture.channel().closeFuture().addListener(future -> {
+        // Shut down all event loops to terminate all threads.
+        bossGroup.shutdownGracefully();
+        workerGroup.shutdownGracefully();
+        LOGGER.info("Ovsdb listener at port {} stopped.", port);
+      });
     } catch (InterruptedException ex) {
       LOGGER.error("Netty server is interrupted while starting listener at port " + port, ex);
-    } finally {
       // Shut down all event loops to terminate all threads.
       bossGroup.shutdownGracefully();
       workerGroup.shutdownGracefully();
-      LOGGER.info("Ovsdb listener at port {} stopped.", port);
     }
   }