vcl: add api to retrieve num bytes for tx

Type: improvement
Signed-off-by: Florin Coras <fcoras@cisco.com>
Change-Id: Iaa1b026e2baea1c03f8c75e7d6879d0ff6d379d6
diff --git a/src/vcl/vppcom.c b/src/vcl/vppcom.c
index a0a0336..a0bbae1 100644
--- a/src/vcl/vppcom.c
+++ b/src/vcl/vppcom.c
@@ -3585,7 +3585,19 @@
       VDBG (2, "VPPCOM_ATTR_GET_NWRITE: sh %u, nwrite = %d", session_handle,
 	    rv);
       break;
-
+    case VPPCOM_ATTR_GET_NWRITEQ:
+      if (PREDICT_FALSE (!buffer || !buflen || *buflen != sizeof (int)))
+	{
+	  rv = VPPCOM_EINVAL;
+	  break;
+	}
+      if (!session->tx_fifo || session->session_state == VCL_STATE_DETACHED)
+	{
+	  rv = VPPCOM_EINVAL;
+	  break;
+	}
+      *(int *) buffer = svm_fifo_max_dequeue (session->tx_fifo);
+      break;
     case VPPCOM_ATTR_GET_FLAGS:
       if (PREDICT_TRUE (buffer && buflen && (*buflen >= sizeof (*flags))))
 	{