session vcl: refactor builtin tx event for main tx

Rename unused SESSION_IO_EVT_BUILTIN_TX to SESSION_IO_EVT_TX_MAIN and
leverage it for non-connected udp tx.

Non-connected udp sessions are listeners and are therefore allocated on
main thread. Consequently, whenever session queue node is not polling
main, tx events generated by external applications might be missed or
processed with some delay. To solve this, request that apps use
SESSION_IO_EVT_TX_MAIN tx events as opposed to SESSION_IO_EVT_TX and
send that to first worker as opposed to main.

Type: fix

Signed-off-by: Florin Coras <fcoras@cisco.com>
Change-Id: I5df5ac3dc80c0f192b2eefb1d465e9deefe8786b

1 files changed, 5 insertions, 3 deletions

diff --git a/src/vnet/session/session_node.c b/src/vnet/session/session_node.c
index f1a006722fe..c61e89bf398 100644
--- a/src/vnet/session/session_node.c
+++ b/src/vnet/session/session_node.c
@@ -1776,11 +1776,13 @@ session_event_dispatch_io (session_worker_t * wrk, vlib_node_runtime_t * node,
       app_wrk = app_worker_get (s->app_wrk_index);
       app_worker_builtin_rx (app_wrk, s);
       break;
-    case SESSION_IO_EVT_BUILTIN_TX:
-      s = session_get_from_handle_if_valid (e->session_handle);
+    case SESSION_IO_EVT_TX_MAIN:
+      s = session_get_if_valid (e->session_index, 0 /* main thread */);
+      if (PREDICT_FALSE (!s))
+	break;
       wrk->ctx.s = s;
       if (PREDICT_TRUE (s != 0))
-	session_tx_fifo_dequeue_internal (wrk, node, elt, n_tx_packets);
+	(smm->session_tx_fns[s->session_type]) (wrk, node, elt, n_tx_packets);
       break;
     default:
       clib_warning ("unhandled event type %d", e->event_type);