auto-reconnect mechinism

Author: ningning-chen

src/main/java/com/cisco/trex/stateless/TRexTransport.java

@@ -13,6 +13,7 @@
 import org.zeromq.SocketType;
 import org.zeromq.ZMQ;
 import org.zeromq.ZMQException;
+import zmq.ZError;
 
 /** TRex Transport class to create zmq socket for connection to trex server */
 public class TRexTransport {
@@ -133,17 +134,47 @@ public synchronized String sendJson(String json) {
     try {
       zmqSocket.send(compressed);
     } catch (ZMQException e) {
-      throw new IllegalStateException(
-          "Did not get any response from server "
-              + getHost()
-              + " within timeout "
-              + zmqSocket.getReceiveTimeOut(),
-          e);
+      throwTimeoutException(e);
     }
     byte[] msg = zmqSocket.recv();
+    // add this if-block to deal with the connect lost error  which is caused
+    // after a long time the client-server don't interactive
+    if (msg == null && zmqSocket.errno() == ZError.ENOTCONN) {
+      zmqSocket.connect(this.connectionString);
+      try {
+        zmqSocket.send(compressed);
+      } catch (ZMQException e) {
+        throwTimeoutException(e);
+      }
+      msg = zmqSocket.recv();
+    }
+
+    if (msg == null) {
+      zmqSocket.connect(this.connectionString);
+      try {
+        zmqSocket.send(compressed);
+      } catch (ZMQException e) {
+        throw new IllegalStateException(
+            "Did not get any response from server "
+                + getHost()
+                + " within timeout "
+                + zmqSocket.getReceiveTimeOut(),
+            e);
+      }
+      msg = zmqSocket.recv();
+    }
 
     String response = this.dataCompressor.decompressBytesToString(msg);
     LOGGER.debug("JSON Resp: {}", response);
     return response;
   }
+
+  private void throwTimeoutException(Exception e) {
+    throw new IllegalStateException(
+        "Did not get any response from server "
+            + getHost()
+            + " within timeout "
+            + zmqSocket.getReceiveTimeOut(),
+        e);
+  }
 }