vcl: always fill buffer or drain rx fifo

Type: improvement

Signed-off-by: Florin Coras <fcoras@cisco.com>
Change-Id: Ibbe438aa6f2fe6d9f55c56ca6d3aec1a29b32cad
(cherry picked from commit 4a2c794c431c72364e241fa14327f03e35b886b7)

diff --git a/src/vcl/vppcom.c b/src/vcl/vppcom.c
index 9174e5d..dd8ffb4 100644 (file)
--- a/src/vcl/vppcom.c
+++ b/src/vcl/vppcom.c
@@ -1892,7 +1892,7 @@ vppcom_session_read_internal (uint32_t session_handle, void *buf, int n,
                              u8 peek)
 {
   vcl_worker_t *wrk = vcl_worker_get_current ();
-  int n_read = 0, is_nonblocking;
+  int rv, n_read = 0, is_nonblocking;
   vcl_session_t *s = 0;
   svm_fifo_t *rx_fifo;
   svm_msg_q_msg_t msg;
@@ -1949,10 +1949,15 @@ vppcom_session_read_internal (uint32_t session_handle, void *buf, int n,
        }
     }
 
+read_again:
+
   if (s->is_dgram)
-    n_read = app_recv_dgram_raw (rx_fifo, buf, n, &s->transport, 0, peek);
+    rv = app_recv_dgram_raw (rx_fifo, buf, n, &s->transport, 0, peek);
   else
-    n_read = app_recv_stream_raw (rx_fifo, buf, n, 0, peek);
+    rv = app_recv_stream_raw (rx_fifo, buf, n, 0, peek);
+
+  ASSERT (rv >= 0);
+  n_read += rv;
 
   if (svm_fifo_is_empty_cons (rx_fifo))
     {
@@ -1960,12 +1965,19 @@ vppcom_session_read_internal (uint32_t session_handle, void *buf, int n,
       if (!svm_fifo_is_empty_cons (rx_fifo)
          && svm_fifo_set_event (s->rx_fifo) && is_nonblocking)
        {
-         session_event_t *e;
          vec_add2 (wrk->unhandled_evts_vector, e, 1);
          e->event_type = SESSION_IO_EVT_RX;
          e->session_index = s->session_index;
        }
     }
+  else if (PREDICT_FALSE (rv < n))
+    {
+      /* More data enqueued while reading. Try to drain it
+       * or fill the buffer */
+      buf += rv;
+      n -= rv;
+      goto read_again;
+    }
 
   if (PREDICT_FALSE (svm_fifo_needs_deq_ntf (rx_fifo, n_read)))
     {