session/tcp: support tx flush mark

For tcp this means that the last enqueued data goes out with a psh bit
set.

Change-Id: I29d357ecae6f02e748b59a7b799150ec73d14ba2
Signed-off-by: Florin Coras <fcoras@cisco.com>

7 files changed, 47 insertions, 4 deletions

diff --git a/src/vnet/session/session.h b/src/vnet/session/session.h
index d5f040edc59..be2490fbe95 100644
--- a/src/vnet/session/session.h
+++ b/src/vnet/session/session.h
@@ -36,6 +36,7 @@ typedef enum
   SESSION_IO_EVT_CT_RX,
   FIFO_EVENT_APP_TX,
   SESSION_IO_EVT_CT_TX,
+  SESSION_IO_EVT_TX_FLUSH,
   FIFO_EVENT_DISCONNECT,
   FIFO_EVENT_BUILTIN_RX,
   FIFO_EVENT_BUILTIN_TX,
@@ -519,6 +520,13 @@ transport_max_rx_enqueue (transport_connection_t * tc)
 }
 
 always_inline u32
+transport_max_tx_dequeue (transport_connection_t * tc)
+{
+  stream_session_t *s = session_get (tc->s_index, tc->thread_index);
+  return svm_fifo_max_dequeue (s->server_tx_fifo);
+}
+
+always_inline u32
 transport_rx_fifo_size (transport_connection_t * tc)
 {
   stream_session_t *s = session_get (tc->s_index, tc->thread_index);
diff --git a/src/vnet/session/session_node.c b/src/vnet/session/session_node.c
index 14576685a76..f4e0eaa993e 100644
--- a/src/vnet/session/session_node.c
+++ b/src/vnet/session/session_node.c
@@ -572,9 +572,17 @@ session_tx_fifo_read_and_snd_i (vlib_main_t * vm, vlib_node_runtime_t * node,
   ctx->transport_vft = transport_protocol_get_vft (tp);
   ctx->tc = session_tx_get_transport (ctx, peek_data);
   ctx->snd_mss = ctx->transport_vft->send_mss (ctx->tc);
-  ctx->snd_space =
-    transport_connection_snd_space (ctx->tc, vm->clib_time.last_cpu_time,
-				    ctx->snd_mss);
+
+  if (PREDICT_FALSE (e->event_type == SESSION_IO_EVT_TX_FLUSH))
+    {
+      if (ctx->transport_vft->flush_data)
+	ctx->transport_vft->flush_data (ctx->tc);
+    }
+
+  ctx->snd_space = transport_connection_snd_space (ctx->tc,
+						   vm->
+						   clib_time.last_cpu_time,
+						   ctx->snd_mss);
   if (ctx->snd_space == 0 || ctx->snd_mss == 0)
     {
       vec_add1 (wrk->pending_event_vector, *e);
@@ -828,6 +836,7 @@ session_queue_node_fn (vlib_main_t * vm, vlib_node_runtime_t * node,
       e = &fifo_events[i];
       switch (e->event_type)
 	{
+	case SESSION_IO_EVT_TX_FLUSH:
 	case FIFO_EVENT_APP_TX:
 	  /* Don't try to send more that one frame per dispatch cycle */
 	  if (n_tx_packets == VLIB_FRAME_SIZE)
diff --git a/src/vnet/session/transport_interface.h b/src/vnet/session/transport_interface.h
index 3bfed415874..10579c45c64 100644
--- a/src/vnet/session/transport_interface.h
+++ b/src/vnet/session/transport_interface.h
@@ -61,6 +61,7 @@ typedef struct _transport_proto_vft
   u32 (*send_space) (transport_connection_t * tc);
   u32 (*tx_fifo_offset) (transport_connection_t * tc);
   void (*update_time) (f64 time_now, u8 thread_index);
+  void (*flush_data) (transport_connection_t *tconn);
 
   /*
    * Connection retrieval
diff --git a/src/vnet/tcp/tcp.c b/src/vnet/tcp/tcp.c
index f703d634b54..6d6a880eda8 100644
--- a/src/vnet/tcp/tcp.c
+++ b/src/vnet/tcp/tcp.c
@@ -1123,6 +1123,16 @@ tcp_session_push_header (transport_connection_t * tconn, vlib_buffer_t * b)
   return tcp_push_header (tc, b);
 }
 
+static void
+tcp_session_flush_data (transport_connection_t * tconn)
+{
+  tcp_connection_t *tc = (tcp_connection_t *) tconn;
+  if (tc->flags & TCP_CONN_PSH_PENDING)
+    return;
+  tc->flags |= TCP_CONN_PSH_PENDING;
+  tc->psh_seq = tc->snd_una_max + transport_max_tx_dequeue (tconn) - 1;
+}
+
 /* *INDENT-OFF* */
 const static transport_proto_vft_t tcp_proto = {
   .enable = vnet_tcp_enable_disable,
@@ -1139,6 +1149,7 @@ const static transport_proto_vft_t tcp_proto = {
   .send_space = tcp_session_send_space,
   .update_time = tcp_update_time,
   .tx_fifo_offset = tcp_session_tx_fifo_offset,
+  .flush_data = tcp_session_flush_data,
   .format_connection = format_tcp_session,
   .format_listener = format_tcp_listener_session,
   .format_half_open = format_tcp_half_open_session,
diff --git a/src/vnet/tcp/tcp.h b/src/vnet/tcp/tcp.h
index 5b235b65d74..46b03ac14b4 100644
--- a/src/vnet/tcp/tcp.h
+++ b/src/vnet/tcp/tcp.h
@@ -124,6 +124,7 @@ extern timer_expiration_handler tcp_timer_retransmit_syn_handler;
   _(FRXT_PENDING, "Fast-retransmit pending")	\
   _(FRXT_FIRST, "Fast-retransmit first again")	\
   _(DEQ_PENDING, "Pending dequeue acked")	\
+  _(PSH_PENDING, "Pending psh packet")		\
 
 typedef enum _tcp_connection_flag_bits
 {
@@ -334,6 +335,8 @@ typedef struct _tcp_connection
   u32 last_fib_check;	/**< Last time we checked fib route for peer */
   u32 sw_if_index;	/**< Interface for the connection */
   u32 tx_fifo_size;	/**< Tx fifo size. Used to constrain cwnd */
+
+  u32 psh_seq;		/**< Add psh header for seg that includes this */
 } tcp_connection_t;
 
 /* *INDENT-OFF* */
diff --git a/src/vnet/tcp/tcp_input.c b/src/vnet/tcp/tcp_input.c
index dff18029155..f04fa5d8901 100644
--- a/src/vnet/tcp/tcp_input.c
+++ b/src/vnet/tcp/tcp_input.c
@@ -543,6 +543,12 @@ tcp_handle_postponed_dequeues (tcp_worker_ctx_t * wrk)
       tc->burst_acked = 0;
       tcp_validate_txf_size (tc, tc->snd_una_max - tc->snd_una);
 
+      if (PREDICT_FALSE (tc->flags & TCP_CONN_PSH_PENDING))
+	{
+	  if (seq_leq (tc->psh_seq, tc->snd_una))
+	    tc->flags &= ~TCP_CONN_PSH_PENDING;
+	}
+
       /* If everything has been acked, stop retransmit timer
        * otherwise update. */
       tcp_retransmit_timer_update (tc);
diff --git a/src/vnet/tcp/tcp_output.c b/src/vnet/tcp/tcp_output.c
index 74fc15fe6cc..7cee34995e3 100644
--- a/src/vnet/tcp/tcp_output.c
+++ b/src/vnet/tcp/tcp_output.c
@@ -1169,7 +1169,12 @@ tcp_push_hdr_i (tcp_connection_t * tc, vlib_buffer_t * b,
     advertise_wnd = tcp_window_to_advertise (tc, next_state);
 
   flags = tcp_make_state_flags (tc, next_state);
-
+  if (PREDICT_FALSE (tc->flags & TCP_CONN_PSH_PENDING))
+    {
+      if (seq_geq (tc->psh_seq, tc->snd_nxt)
+	  && seq_lt (tc->psh_seq, tc->snd_nxt + data_len))
+	flags |= TCP_FLAG_PSH;
+    }
   th = vlib_buffer_push_tcp (b, tc->c_lcl_port, tc->c_rmt_port, tc->snd_nxt,
 			     tc->rcv_nxt, tcp_hdr_opts_len, flags,
 			     advertise_wnd);