ONOS-4422 Implemented device discovery in Bmv2 device provider and other

improvements

- Added listener for hello messages received from Bmv2 devices
- Added a periodic poller task to check device reachability and port
information updates
- Avoids periodically re-connecting the device if it is already
available in the core
- Fixed minor bug in Bmv2ThriftClient

Change-Id: I416d1880773e11b2ac6fa062d8be2b8f280786fb

@@ -80,9 +80,9 @@ public final class Bmv2ThriftClient implements Bmv2Client {
     // Seconds after a client is expired (and connection closed) in the cache.
     private static final int CLIENT_CACHE_TIMEOUT = 60;
     // Number of connection retries after a network error.
-    private static final int NUM_CONNECTION_RETRIES = 10;
+    private static final int NUM_CONNECTION_RETRIES = 3;
     // Time between retries in milliseconds.
-    private static final int TIME_BETWEEN_RETRIES = 200;
+    private static final int TIME_BETWEEN_RETRIES = 300;
 
     // Static client cache where clients are removed after a predefined timeout.
     private static final LoadingCache<DeviceId, Bmv2ThriftClient>
@@ -125,6 +125,15 @@ public final class Bmv2ThriftClient implements Bmv2Client {
     }
 
     /**
+     * Force a close of the transport session (if one is open) with the given device.
+     *
+     * @param deviceId device id
+     */
+    public static void forceDisconnectOf(DeviceId deviceId) {
+        CLIENT_CACHE.invalidate(deviceId);
+    }
+
+    /**
      * Pings the device. Returns true if the device is reachable,
      * false otherwise.
      *
@@ -392,7 +401,7 @@ public final class Bmv2ThriftClient implements Bmv2Client {
             LOG.debug("Packet transmission requested! > portNumber={}, packet={}", portNumber, packet);
         } catch (TException e) {
             LOG.debug("Exception while requesting packet transmission: {} > portNumber={}, packet={}",
-                      portNumber, packet);
+                      e, portNumber, packet);
             throw new Bmv2RuntimeException(e.getMessage(), e);
         }
     }

@@ -173,7 +173,12 @@ public final class SafeThriftClient {
         private static void reconnectOrThrowException(TTransport transport, int maxRetries, long timeBetweenRetries)
                 throws TTransportException {
             int errors = 0;
+            try {
                 transport.close();
+            } catch (Exception e) {
+                // Thrift seems to have a bug where if the transport is already closed a SocketException is thrown.
+                // However, such an exception is not advertised by .close(), hence the general-purpose catch.
+            }
 
             while (errors < maxRetries) {
                 try {
@@ -182,7 +187,7 @@ public final class SafeThriftClient {
                     LOG.debug("Reconnection successful");
                     break;
                 } catch (TTransportException e) {
-                    LOG.error("Error while reconnecting:", e);
+                    LOG.debug("Error while reconnecting:", e);
                     errors++;
 
                     if (errors < maxRetries) {