+ u32 n_written, max_dequeue, max_enqueue, max_transfer;
+ int actual_transfer;
+ svm_fifo_t *tx_fifo, *rx_fifo;
+ builtin_server_main_t *bsm = &builtin_server_main;
+ session_fifo_event_t evt;
+ static int serial_number = 0;
+
+ max_dequeue = svm_fifo_max_dequeue (s->server_rx_fifo);
+ max_enqueue = svm_fifo_max_enqueue (s->server_tx_fifo);
+
+ if (PREDICT_FALSE (max_dequeue == 0))
+ {
+ return 0;
+ }
+
+ tx_fifo = s->server_tx_fifo;
+ rx_fifo = s->server_rx_fifo;
+
+ /* Number of bytes we're going to copy */
+ max_transfer = (max_dequeue < max_enqueue) ? max_dequeue : max_enqueue;
+
+ /* No space in tx fifo */
+ if (PREDICT_FALSE (max_transfer == 0))
+ {
+ /* XXX timeout for session that are stuck */
+
+ /* Program self-tap to retry */
+ if (svm_fifo_set_event (rx_fifo))
+ {
+ evt.fifo = rx_fifo;
+ evt.event_type = FIFO_EVENT_BUILTIN_RX;
+ evt.event_id = 0;
+ unix_shared_memory_queue_add (bsm->vpp_queue[s->thread_index],
+ (u8 *) & evt,
+ 0 /* do wait for mutex */ );
+ }
+
+ return 0;
+ }
+
+ svm_fifo_unset_event (rx_fifo);
+
+ vec_validate (bsm->rx_buf, max_transfer - 1);
+ _vec_len (bsm->rx_buf) = max_transfer;
+
+ actual_transfer = svm_fifo_dequeue_nowait (rx_fifo, 0, max_transfer,
+ bsm->rx_buf);
+ ASSERT (actual_transfer == max_transfer);
+
+// test_bytes (bsm, actual_transfer);
+
+ /*
+ * Echo back
+ */
+
+ n_written =
+ svm_fifo_enqueue_nowait (tx_fifo, 0, actual_transfer, bsm->rx_buf);
+ ASSERT (n_written == max_transfer);
+
+ if (svm_fifo_set_event (tx_fifo))
+ {
+ /* Fabricate TX event, send to vpp */
+ evt.fifo = tx_fifo;
+ evt.event_type = FIFO_EVENT_SERVER_TX;
+ evt.event_id = serial_number++;
+
+ unix_shared_memory_queue_add (bsm->vpp_queue[s->thread_index],
+ (u8 *) & evt, 0 /* do wait for mutex */ );
+ }
+