src/vnet/session/session_node.c - fdio/vpp - Gitiles

 /*
  * Copyright (c) 2017 Cisco and/or its affiliates.
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at:
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #include <math.h>
 #include <vlib/vlib.h>
 #include <vnet/vnet.h>
 #include <vppinfra/elog.h>
 #include <vnet/session/transport.h>
 #include <vnet/session/application.h>
 #include <vnet/session/session_debug.h>
 #include <svm/queue.h>

 vlib_node_registration_t session_queue_node;

 typedef struct
 {
   u32 session_index;
   u32 server_thread_index;
 } session_queue_trace_t;

 /* packet trace format function */
 static u8 *
 format_session_queue_trace (u8 * s, va_list * args)
 {
   CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
   CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
   session_queue_trace_t *t = va_arg (*args, session_queue_trace_t *);

   s = format (s, "SESSION_QUEUE: session index %d, server thread index %d",
 	      t->session_index, t->server_thread_index);
   return s;
 }

 vlib_node_registration_t session_queue_node;

 #define foreach_session_queue_error		\
 _(TX, "Packets transmitted")                  	\
 _(TIMER, "Timer events")			\
 _(NO_BUFFER, "Out of buffers")

 typedef enum
 {
 #define _(sym,str) SESSION_QUEUE_ERROR_##sym,
   foreach_session_queue_error
 #undef _
     SESSION_QUEUE_N_ERROR,
 } session_queue_error_t;

 static char *session_queue_error_strings[] = {
 #define _(sym,string) string,
   foreach_session_queue_error
 #undef _
 };

 always_inline void
 session_tx_fifo_chain_tail (session_manager_main_t * smm, vlib_main_t * vm,
 			    u8 thread_index, svm_fifo_t * fifo,
 			    vlib_buffer_t * b0, u32 bi0, u8 n_bufs_per_seg,
 			    u32 left_from_seg, u32 * left_to_snd0,
 			    u16 * n_bufs, u32 * tx_offset, u16 deq_per_buf,
 			    u8 peek_data)
 {
   vlib_buffer_t *chain_b0, *prev_b0;
   u32 chain_bi0, to_deq;
   u16 len_to_deq0, n_bytes_read;
   u8 *data0, j;

   b0->flags |= VLIB_BUFFER_TOTAL_LENGTH_VALID;
   b0->total_length_not_including_first_buffer = 0;

   chain_bi0 = bi0;
   chain_b0 = b0;
   to_deq = left_from_seg;
   for (j = 1; j < n_bufs_per_seg; j++)
     {
       prev_b0 = chain_b0;
       len_to_deq0 = clib_min (to_deq, deq_per_buf);

       *n_bufs -= 1;
       chain_bi0 = smm->tx_buffers[thread_index][*n_bufs];
       _vec_len (smm->tx_buffers[thread_index]) = *n_bufs;

       chain_b0 = vlib_get_buffer (vm, chain_bi0);
       chain_b0->current_data = 0;
       data0 = vlib_buffer_get_current (chain_b0);
       if (peek_data)
 	{
 	  n_bytes_read = svm_fifo_peek (fifo, *tx_offset, len_to_deq0, data0);
 	  *tx_offset += n_bytes_read;
 	}
       else
 	{
 	  n_bytes_read = svm_fifo_dequeue_nowait (fifo, len_to_deq0, data0);
 	}
       ASSERT (n_bytes_read == len_to_deq0);
       chain_b0->current_length = n_bytes_read;
       b0->total_length_not_including_first_buffer += chain_b0->current_length;

       /* update previous buffer */
       prev_b0->next_buffer = chain_bi0;
       prev_b0->flags |= VLIB_BUFFER_NEXT_PRESENT;

       /* update current buffer */
       chain_b0->next_buffer = 0;

       to_deq -= n_bytes_read;
       if (to_deq == 0)
 	break;
     }
   ASSERT (to_deq == 0
 	  && b0->total_length_not_including_first_buffer == left_from_seg);
   *left_to_snd0 -= left_from_seg;
 }

 always_inline int
 session_tx_fifo_read_and_snd_i (vlib_main_t * vm, vlib_node_runtime_t * node,
 				session_manager_main_t * smm,
 				session_fifo_event_t * e0,
 				stream_session_t * s0, u32 thread_index,
 				int *n_tx_packets, u8 peek_data)
 {
   u32 n_trace = vlib_get_trace_count (vm, node);
   u32 left_to_snd0, max_len_to_snd0, len_to_deq0, snd_space0;
   u32 n_bufs_per_evt, n_frames_per_evt, n_bufs_per_frame;
   transport_connection_t *tc0;
   transport_proto_vft_t *transport_vft;
   transport_proto_t tp;
   u32 next_index, next0, *to_next, n_left_to_next, bi0;
   vlib_buffer_t *b0;
   u32 tx_offset = 0, max_dequeue0, n_bytes_per_seg, left_for_seg;
   u16 snd_mss0, n_bufs_per_seg, n_bufs;
   u8 *data0;
   int i, n_bytes_read;
   u32 n_bytes_per_buf, deq_per_buf, deq_per_first_buf;
   u32 bufs_alloc, bufs_now;

   next_index = next0 = smm->session_type_to_next[s0->session_type];

   tp = session_get_transport_proto (s0);
   transport_vft = transport_protocol_get_vft (tp);
   tc0 = transport_vft->get_connection (s0->connection_index, thread_index);

   /* Make sure we have space to send and there's something to dequeue */
   snd_mss0 = transport_vft->send_mss (tc0);
   snd_space0 = transport_vft->send_space (tc0);

   /* Can't make any progress */
   if (snd_space0 == 0 || snd_mss0 == 0)
     {
       vec_add1 (smm->pending_event_vector[thread_index], *e0);
       return 0;
     }

   /* Allow enqueuing of a new event */
   svm_fifo_unset_event (s0->server_tx_fifo);

   /* Check how much we can pull. */
   max_dequeue0 = svm_fifo_max_dequeue (s0->server_tx_fifo);

   if (peek_data)
     {
       /* Offset in rx fifo from where to peek data */
       tx_offset = transport_vft->tx_fifo_offset (tc0);
       if (PREDICT_FALSE (tx_offset >= max_dequeue0))
 	max_dequeue0 = 0;
       else
 	max_dequeue0 -= tx_offset;
     }

   /* Nothing to read return */
   if (max_dequeue0 == 0)
     return 0;

   /* Ensure we're not writing more than transport window allows */
   if (max_dequeue0 < snd_space0)
     {
       /* Constrained by tx queue. Try to send only fully formed segments */
       max_len_to_snd0 = (max_dequeue0 > snd_mss0) ?
 	max_dequeue0 - max_dequeue0 % snd_mss0 : max_dequeue0;
       /* TODO Nagle ? */
     }
   else
     {
       /* Expectation is that snd_space0 is already a multiple of snd_mss */
       max_len_to_snd0 = snd_space0;
     }

   n_bytes_per_buf = vlib_buffer_free_list_buffer_size
     (vm, VLIB_BUFFER_DEFAULT_FREE_LIST_INDEX);
   ASSERT (n_bytes_per_buf > MAX_HDRS_LEN);
   n_bytes_per_seg = MAX_HDRS_LEN + snd_mss0;
   n_bufs_per_seg = ceil ((double) n_bytes_per_seg / n_bytes_per_buf);
   n_bufs_per_evt = ceil ((double) max_len_to_snd0 / n_bytes_per_seg);
   n_frames_per_evt = ceil ((double) n_bufs_per_evt / VLIB_FRAME_SIZE);
   n_bufs_per_frame = n_bufs_per_seg * VLIB_FRAME_SIZE;

   deq_per_buf = clib_min (snd_mss0, n_bytes_per_buf);
   deq_per_first_buf = clib_min (snd_mss0, n_bytes_per_buf - MAX_HDRS_LEN);

   n_bufs = vec_len (smm->tx_buffers[thread_index]);
   left_to_snd0 = max_len_to_snd0;
   for (i = 0; i < n_frames_per_evt; i++)
     {
       /* Make sure we have at least one full frame of buffers ready */
       if (PREDICT_FALSE (n_bufs < n_bufs_per_frame))
 	{
 	  vec_validate (smm->tx_buffers[thread_index],
 			n_bufs + n_bufs_per_frame - 1);
 	  bufs_alloc = 0;
 	  do
 	    {
 	      bufs_now =
 		vlib_buffer_alloc (vm,
 				   &smm->tx_buffers[thread_index][n_bufs +
 								  bufs_alloc],
 				   n_bufs_per_frame - bufs_alloc);
 	      bufs_alloc += bufs_now;
 	    }
 	  while (bufs_now > 0 && ((bufs_alloc + n_bufs < n_bufs_per_frame)));

 	  n_bufs += bufs_alloc;
 	  _vec_len (smm->tx_buffers[thread_index]) = n_bufs;

 	  if (PREDICT_FALSE (n_bufs < n_bufs_per_frame))
 	    {
 	      vec_add1 (smm->pending_event_vector[thread_index], *e0);
 	      return -1;
 	    }
 	  ASSERT (n_bufs >= n_bufs_per_frame);
 	}

       vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
       while (left_to_snd0 && n_left_to_next)
 	{
 	  /*
 	   * Handle first buffer in chain separately
 	   */

 	  len_to_deq0 = clib_min (left_to_snd0, deq_per_first_buf);
 	  if (left_to_snd0 > len_to_deq0 && n_left_to_next > 1)
 	    {
 	      vlib_buffer_t *pb;
 	      u32 pbi = smm->tx_buffers[thread_index][n_bufs - 2];
 	      pb = vlib_get_buffer (vm, pbi);
 	      vlib_prefetch_buffer_header (pb, LOAD);
 	    }

 	  /* Get free buffer */
 	  ASSERT (n_bufs >= 1);
 	  bi0 = smm->tx_buffers[thread_index][--n_bufs];
 	  _vec_len (smm->tx_buffers[thread_index]) = n_bufs;

 	  /* usual speculation, or the enqueue_x1 macro will barf */
 	  to_next[0] = bi0;
 	  to_next += 1;
 	  n_left_to_next -= 1;

 	  b0 = vlib_get_buffer (vm, bi0);
 	  b0->error = 0;
 	  b0->flags = VNET_BUFFER_F_LOCALLY_ORIGINATED;
 	  b0->current_data = 0;
 	  b0->total_length_not_including_first_buffer = 0;

 	  data0 = vlib_buffer_make_headroom (b0, MAX_HDRS_LEN);
 	  if (peek_data)
 	    {
 	      n_bytes_read = svm_fifo_peek (s0->server_tx_fifo, tx_offset,
 					    len_to_deq0, data0);
 	      if (n_bytes_read <= 0)
 		goto dequeue_fail;
 	      /* Keep track of progress locally, transport is also supposed to
 	       * increment it independently when pushing the header */
 	      tx_offset += n_bytes_read;
 	    }
 	  else
 	    {
 	      n_bytes_read = svm_fifo_dequeue_nowait (s0->server_tx_fifo,
 						      len_to_deq0, data0);
 	      if (n_bytes_read <= 0)
 		goto dequeue_fail;
 	    }

 	  b0->current_length = n_bytes_read;

 	  left_to_snd0 -= n_bytes_read;
 	  *n_tx_packets = *n_tx_packets + 1;

 	  /*
 	   * Fill in the remaining buffers in the chain, if any
 	   */
 	  if (PREDICT_FALSE (n_bufs_per_seg > 1 && left_to_snd0))
 	    {
 	      left_for_seg = clib_min (snd_mss0 - n_bytes_read, left_to_snd0);
 	      session_tx_fifo_chain_tail (smm, vm, thread_index,
 					  s0->server_tx_fifo, b0, bi0,
 					  n_bufs_per_seg, left_for_seg,
 					  &left_to_snd0, &n_bufs, &tx_offset,
 					  deq_per_buf, peek_data);
 	    }

 	  /* Ask transport to push header after current_length and
 	   * total_length_not_including_first_buffer are updated */
 	  transport_vft->push_header (tc0, b0);

 	  /* *INDENT-OFF* */
 	  SESSION_EVT_DBG(SESSION_EVT_DEQ, s0, ({
 	      ed->data[0] = e0->event_type;
 	      ed->data[1] = max_dequeue0;
 	      ed->data[2] = len_to_deq0;
 	      ed->data[3] = left_to_snd0;
 	  }));
 	  /* *INDENT-ON* */

 	  VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b0);

 	  if (PREDICT_FALSE (n_trace > 0))
 	    {
 	      session_queue_trace_t *t0;
 	      vlib_trace_buffer (vm, node, next_index, b0,
 				 1 /* follow_chain */ );
 	      vlib_set_trace_count (vm, node, --n_trace);
 	      t0 = vlib_add_trace (vm, node, b0, sizeof (*t0));
 	      t0->session_index = s0->session_index;
 	      t0->server_thread_index = s0->thread_index;
 	    }

 	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
 					   to_next, n_left_to_next,
 					   bi0, next0);
 	}
       vlib_put_next_frame (vm, node, next_index, n_left_to_next);
     }

   /* If we couldn't dequeue all bytes mark as partially read */
   if (max_len_to_snd0 < max_dequeue0)
     {
       /* If we don't already have new event */
       if (svm_fifo_set_event (s0->server_tx_fifo))
 	{
 	  vec_add1 (smm->pending_event_vector[thread_index], *e0);
 	}
     }
   return 0;

 dequeue_fail:
   /*
    * Can't read from fifo. If we don't already have an event, save as partially
    * read, return buff to free list and return
    */
   clib_warning ("dequeue fail");

   if (svm_fifo_set_event (s0->server_tx_fifo))
     {
       vec_add1 (smm->pending_event_vector[thread_index], *e0);
     }
   vlib_put_next_frame (vm, node, next_index, n_left_to_next + 1);
   _vec_len (smm->tx_buffers[thread_index]) += 1;

   return 0;
 }

 int
 session_tx_fifo_peek_and_snd (vlib_main_t * vm, vlib_node_runtime_t * node,
 			      session_manager_main_t * smm,
 			      session_fifo_event_t * e0,
 			      stream_session_t * s0, u32 thread_index,
 			      int *n_tx_pkts)
 {
   return session_tx_fifo_read_and_snd_i (vm, node, smm, e0, s0, thread_index,
 					 n_tx_pkts, 1);
 }

 int
 session_tx_fifo_dequeue_and_snd (vlib_main_t * vm, vlib_node_runtime_t * node,
 				 session_manager_main_t * smm,
 				 session_fifo_event_t * e0,
 				 stream_session_t * s0, u32 thread_index,
 				 int *n_tx_pkts)
 {
   return session_tx_fifo_read_and_snd_i (vm, node, smm, e0, s0, thread_index,
 					 n_tx_pkts, 0);
 }

 int
 session_tx_fifo_dequeue_internal (vlib_main_t * vm,
 				  vlib_node_runtime_t * node,
 				  session_manager_main_t * smm,
 				  session_fifo_event_t * e0,
 				  stream_session_t * s0, u32 thread_index,
 				  int *n_tx_pkts)
 {
   application_t *app;
   app = application_get (s0->opaque);
   svm_fifo_unset_event (s0->server_tx_fifo);
   return app->cb_fns.builtin_app_tx_callback (s0);
 }

 always_inline stream_session_t *
 session_event_get_session (session_fifo_event_t * e, u8 thread_index)
 {
   return session_get_if_valid (e->fifo->master_session_index, thread_index);
 }

 void
 dump_thread_0_event_queue (void)
 {
   session_manager_main_t *smm = vnet_get_session_manager_main ();
   vlib_main_t *vm = &vlib_global_main;
   u32 my_thread_index = vm->thread_index;
   session_fifo_event_t _e, *e = &_e;
   stream_session_t *s0;
   int i, index;
   i8 *headp;

   svm_queue_t *q;
   q = smm->vpp_event_queues[my_thread_index];

   index = q->head;

   for (i = 0; i < q->cursize; i++)
     {
       headp = (i8 *) (&q->data[0] + q->elsize * index);
       clib_memcpy (e, headp, q->elsize);

       switch (e->event_type)
 	{
 	case FIFO_EVENT_APP_TX:
 	  s0 = session_event_get_session (e, my_thread_index);
 	  fformat (stdout, "[%04d] TX session %d\n", i, s0->session_index);
 	  break;

 	case FIFO_EVENT_DISCONNECT:
 	  s0 = session_get_from_handle (e->session_handle);
 	  fformat (stdout, "[%04d] disconnect session %d\n", i,
 		   s0->session_index);
 	  break;

 	case FIFO_EVENT_BUILTIN_RX:
 	  s0 = session_event_get_session (e, my_thread_index);
 	  fformat (stdout, "[%04d] builtin_rx %d\n", i, s0->session_index);
 	  break;

 	case FIFO_EVENT_RPC:
 	  fformat (stdout, "[%04d] RPC call %llx with %llx\n",
 		   i, (u64) (e->rpc_args.fp), (u64) (e->rpc_args.arg));
 	  break;

 	default:
 	  fformat (stdout, "[%04d] unhandled event type %d\n",
 		   i, e->event_type);
 	  break;
 	}

       index++;

       if (index == q->maxsize)
 	index = 0;
     }
 }

 static u8
 session_node_cmp_event (session_fifo_event_t * e, svm_fifo_t * f)
 {
   stream_session_t *s;
   switch (e->event_type)
     {
     case FIFO_EVENT_APP_RX:
     case FIFO_EVENT_APP_TX:
     case FIFO_EVENT_BUILTIN_RX:
       if (e->fifo == f)
 	return 1;
       break;
     case FIFO_EVENT_DISCONNECT:
       break;
     case FIFO_EVENT_RPC:
       s = session_get_from_handle (e->session_handle);
       if (!s)
 	{
 	  clib_warning ("session has event but doesn't exist!");
 	  break;
 	}
       if (s->server_rx_fifo == f || s->server_tx_fifo == f)
 	return 1;
       break;
     default:
       break;
     }
   return 0;
 }

 u8
 session_node_lookup_fifo_event (svm_fifo_t * f, session_fifo_event_t * e)
 {
   session_manager_main_t *smm = vnet_get_session_manager_main ();
   svm_queue_t *q;
   session_fifo_event_t *pending_event_vector, *evt;
   int i, index, found = 0;
   i8 *headp;
   u8 thread_index;

   ASSERT (e);
   thread_index = f->master_thread_index;
   /*
    * Search evt queue
    */
   q = smm->vpp_event_queues[thread_index];
   index = q->head;
   for (i = 0; i < q->cursize; i++)
     {
       headp = (i8 *) (&q->data[0] + q->elsize * index);
       clib_memcpy (e, headp, q->elsize);
       found = session_node_cmp_event (e, f);
       if (found)
 	return 1;
       if (++index == q->maxsize)
 	index = 0;
     }
   /*
    * Search pending events vector
    */
   pending_event_vector = smm->pending_event_vector[thread_index];
   vec_foreach (evt, pending_event_vector)
   {
     found = session_node_cmp_event (evt, f);
     if (found)
       {
 	clib_memcpy (e, evt, sizeof (*evt));
 	break;
       }
   }
   return found;
 }

 static uword
 session_queue_node_fn (vlib_main_t * vm, vlib_node_runtime_t * node,
 		       vlib_frame_t * frame)
 {
   session_manager_main_t *smm = vnet_get_session_manager_main ();
   session_fifo_event_t *my_pending_event_vector, *pending_disconnects, *e;
   session_fifo_event_t *my_fifo_events;
   u32 n_to_dequeue, n_events;
   svm_queue_t *q;
   application_t *app;
   int n_tx_packets = 0;
   u32 my_thread_index = vm->thread_index;
   int i, rv;
   f64 now = vlib_time_now (vm);
   void (*fp) (void *);

   SESSION_EVT_DBG (SESSION_EVT_POLL_GAP_TRACK, smm, my_thread_index);

   /*
    *  Update transport time
    */
   transport_update_time (now, my_thread_index);

   /*
    * Get vpp queue events
    */
   q = smm->vpp_event_queues[my_thread_index];
   if (PREDICT_FALSE (q == 0))
     return 0;

   my_fifo_events = smm->free_event_vector[my_thread_index];

   /* min number of events we can dequeue without blocking */
   n_to_dequeue = q->cursize;
   my_pending_event_vector = smm->pending_event_vector[my_thread_index];
   pending_disconnects = smm->pending_disconnects[my_thread_index];

   if (!n_to_dequeue && !vec_len (my_pending_event_vector)
       && !vec_len (pending_disconnects))
     return 0;

   SESSION_EVT_DBG (SESSION_EVT_DEQ_NODE, 0);

   /*
    * If we didn't manage to process previous events try going
    * over them again without dequeuing new ones.
    */
   /* XXX: Block senders to sessions that can't keep up */
   if (0 && vec_len (my_pending_event_vector) >= 100)
     {
       clib_warning ("too many fifo events unsolved");
       goto skip_dequeue;
     }

   /* See you in the next life, don't be late */
   if (pthread_mutex_trylock (&q->mutex))
     return 0;

   for (i = 0; i < n_to_dequeue; i++)
     {
       vec_add2 (my_fifo_events, e, 1);
       svm_queue_sub_raw (q, (u8 *) e);
     }

   /* The other side of the connection is not polling */
   if (q->cursize < (q->maxsize / 8))
     (void) pthread_cond_broadcast (&q->condvar);
   pthread_mutex_unlock (&q->mutex);

   vec_append (my_fifo_events, my_pending_event_vector);
   vec_append (my_fifo_events, smm->pending_disconnects[my_thread_index]);

   _vec_len (my_pending_event_vector) = 0;
   smm->pending_event_vector[my_thread_index] = my_pending_event_vector;
   _vec_len (smm->pending_disconnects[my_thread_index]) = 0;

 skip_dequeue:
   n_events = vec_len (my_fifo_events);
   for (i = 0; i < n_events; i++)
     {
       stream_session_t *s0;	/* $$$ prefetch 1 ahead maybe */
       session_fifo_event_t *e0;

       e0 = &my_fifo_events[i];

       switch (e0->event_type)
 	{
 	case FIFO_EVENT_APP_TX:
 	  s0 = session_event_get_session (e0, my_thread_index);

 	  if (PREDICT_FALSE (!s0))
 	    {
 	      clib_warning ("It's dead, Jim!");
 	      continue;
 	    }
 	  /* Can retransmit for closed sessions but can't do anything if
 	   * session is not ready or closed */
 	  if (PREDICT_FALSE (s0->session_state < SESSION_STATE_READY))
 	    {
 	      vec_add1 (smm->pending_event_vector[my_thread_index], *e0);
 	      continue;
 	    }
 	  /* Spray packets in per session type frames, since they go to
 	   * different nodes */
 	  rv = (smm->session_tx_fns[s0->session_type]) (vm, node, smm, e0, s0,
 							my_thread_index,
 							&n_tx_packets);
 	  /* Out of buffers */
 	  if (PREDICT_FALSE (rv < 0))
 	    {
 	      vlib_node_increment_counter (vm, node->node_index,
 					   SESSION_QUEUE_ERROR_NO_BUFFER, 1);
 	      continue;
 	    }
 	  break;
 	case FIFO_EVENT_DISCONNECT:
 	  /* Make sure disconnects run after the pending list is drained */
 	  if (!e0->postponed)
 	    {
 	      e0->postponed = 1;
 	      vec_add1 (smm->pending_disconnects[my_thread_index], *e0);
 	      continue;
 	    }
 	  s0 = session_get_from_handle (e0->session_handle);
 	  stream_session_disconnect_transport (s0);
 	  break;
 	case FIFO_EVENT_BUILTIN_RX:
 	  s0 = session_event_get_session (e0, my_thread_index);
 	  if (PREDICT_FALSE (!s0))
 	    continue;
 	  svm_fifo_unset_event (s0->server_rx_fifo);
 	  app = application_get (s0->app_index);
 	  app->cb_fns.builtin_app_rx_callback (s0);
 	  break;
 	case FIFO_EVENT_RPC:
 	  fp = e0->rpc_args.fp;
 	  (*fp) (e0->rpc_args.arg);
 	  break;

 	default:
 	  clib_warning ("unhandled event type %d", e0->event_type);
 	}
     }

   _vec_len (my_fifo_events) = 0;
   smm->free_event_vector[my_thread_index] = my_fifo_events;

   vlib_node_increment_counter (vm, session_queue_node.index,
 			       SESSION_QUEUE_ERROR_TX, n_tx_packets);

   SESSION_EVT_DBG (SESSION_EVT_DEQ_NODE, 1);

   return n_tx_packets;
 }

 /* *INDENT-OFF* */
 VLIB_REGISTER_NODE (session_queue_node) =
 {
   .function = session_queue_node_fn,
   .name = "session-queue",
   .format_trace = format_session_queue_trace,
   .type = VLIB_NODE_TYPE_INPUT,
   .n_errors = ARRAY_LEN (session_queue_error_strings),
   .error_strings = session_queue_error_strings,
   .state = VLIB_NODE_STATE_DISABLED,
 };
 /* *INDENT-ON* */

 static clib_error_t *
 session_queue_exit (vlib_main_t * vm)
 {
   if (vec_len (vlib_mains) < 2)
     return 0;

   /*
    * Shut off (especially) worker-thread session nodes.
    * Otherwise, vpp can crash as the main thread unmaps the
    * API segment.
    */
   vlib_worker_thread_barrier_sync (vm);
   session_node_enable_disable (0 /* is_enable */ );
   vlib_worker_thread_barrier_release (vm);
   return 0;
 }

 VLIB_MAIN_LOOP_EXIT_FUNCTION (session_queue_exit);

 /*
  * fd.io coding-style-patch-verification: ON
  *
  * Local Variables:
  * eval: (c-set-style "gnu")
  * End:
  */
	/*
	* Copyright (c) 2017 Cisco and/or its affiliates.
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at:
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#include <math.h>
	#include <vlib/vlib.h>
	#include <vnet/vnet.h>
	#include <vppinfra/elog.h>
	#include <vnet/session/transport.h>
	#include <vnet/session/application.h>
	#include <vnet/session/session_debug.h>
	#include <svm/queue.h>

	vlib_node_registration_t session_queue_node;

	typedef struct
	{
	u32 session_index;
	u32 server_thread_index;
	} session_queue_trace_t;

	/* packet trace format function */
	static u8 *
	format_session_queue_trace (u8 * s, va_list * args)
	{
	CLIB_UNUSED (vlib_main_t * vm) = va_arg (args, vlib_main_t );
	CLIB_UNUSED (vlib_node_t * node) = va_arg (args, vlib_node_t );
	session_queue_trace_t t = va_arg (args, session_queue_trace_t *);

	s = format (s, "SESSION_QUEUE: session index %d, server thread index %d",
	t->session_index, t->server_thread_index);
	return s;
	}

	vlib_node_registration_t session_queue_node;

	#define foreach_session_queue_error \
	_(TX, "Packets transmitted") \
	_(TIMER, "Timer events") \
	_(NO_BUFFER, "Out of buffers")

	typedef enum
	{
	#define _(sym,str) SESSION_QUEUE_ERROR_##sym,
	foreach_session_queue_error
	#undef _
	SESSION_QUEUE_N_ERROR,
	} session_queue_error_t;

	static char *session_queue_error_strings[] = {
	#define _(sym,string) string,
	foreach_session_queue_error
	#undef _
	};

	always_inline void
	session_tx_fifo_chain_tail (session_manager_main_t * smm, vlib_main_t * vm,
	u8 thread_index, svm_fifo_t * fifo,
	vlib_buffer_t * b0, u32 bi0, u8 n_bufs_per_seg,
	u32 left_from_seg, u32 * left_to_snd0,
	u16 * n_bufs, u32 * tx_offset, u16 deq_per_buf,
	u8 peek_data)
	{
	vlib_buffer_t chain_b0, prev_b0;
	u32 chain_bi0, to_deq;
	u16 len_to_deq0, n_bytes_read;
	u8 *data0, j;

	b0->flags \|= VLIB_BUFFER_TOTAL_LENGTH_VALID;
	b0->total_length_not_including_first_buffer = 0;

	chain_bi0 = bi0;
	chain_b0 = b0;
	to_deq = left_from_seg;
	for (j = 1; j < n_bufs_per_seg; j++)
	{
	prev_b0 = chain_b0;
	len_to_deq0 = clib_min (to_deq, deq_per_buf);

	*n_bufs -= 1;
	chain_bi0 = smm->tx_buffers[thread_index][*n_bufs];
	_vec_len (smm->tx_buffers[thread_index]) = *n_bufs;

	chain_b0 = vlib_get_buffer (vm, chain_bi0);
	chain_b0->current_data = 0;
	data0 = vlib_buffer_get_current (chain_b0);
	if (peek_data)
	{
	n_bytes_read = svm_fifo_peek (fifo, *tx_offset, len_to_deq0, data0);
	*tx_offset += n_bytes_read;
	}
	else
	{
	n_bytes_read = svm_fifo_dequeue_nowait (fifo, len_to_deq0, data0);
	}
	ASSERT (n_bytes_read == len_to_deq0);
	chain_b0->current_length = n_bytes_read;
	b0->total_length_not_including_first_buffer += chain_b0->current_length;

	/* update previous buffer */
	prev_b0->next_buffer = chain_bi0;
	prev_b0->flags \|= VLIB_BUFFER_NEXT_PRESENT;

	/* update current buffer */
	chain_b0->next_buffer = 0;

	to_deq -= n_bytes_read;
	if (to_deq == 0)
	break;
	}
	ASSERT (to_deq == 0
	&& b0->total_length_not_including_first_buffer == left_from_seg);
	*left_to_snd0 -= left_from_seg;
	}

	always_inline int
	session_tx_fifo_read_and_snd_i (vlib_main_t * vm, vlib_node_runtime_t * node,
	session_manager_main_t * smm,
	session_fifo_event_t * e0,
	stream_session_t * s0, u32 thread_index,
	int *n_tx_packets, u8 peek_data)
	{
	u32 n_trace = vlib_get_trace_count (vm, node);
	u32 left_to_snd0, max_len_to_snd0, len_to_deq0, snd_space0;
	u32 n_bufs_per_evt, n_frames_per_evt, n_bufs_per_frame;
	transport_connection_t *tc0;
	transport_proto_vft_t *transport_vft;
	transport_proto_t tp;
	u32 next_index, next0, *to_next, n_left_to_next, bi0;
	vlib_buffer_t *b0;
	u32 tx_offset = 0, max_dequeue0, n_bytes_per_seg, left_for_seg;
	u16 snd_mss0, n_bufs_per_seg, n_bufs;
	u8 *data0;
	int i, n_bytes_read;
	u32 n_bytes_per_buf, deq_per_buf, deq_per_first_buf;
	u32 bufs_alloc, bufs_now;

	next_index = next0 = smm->session_type_to_next[s0->session_type];

	tp = session_get_transport_proto (s0);
	transport_vft = transport_protocol_get_vft (tp);
	tc0 = transport_vft->get_connection (s0->connection_index, thread_index);

	/* Make sure we have space to send and there's something to dequeue */
	snd_mss0 = transport_vft->send_mss (tc0);
	snd_space0 = transport_vft->send_space (tc0);

	/* Can't make any progress */
	if (snd_space0 == 0 \|\| snd_mss0 == 0)
	{
	vec_add1 (smm->pending_event_vector[thread_index], *e0);
	return 0;
	}

	/* Allow enqueuing of a new event */
	svm_fifo_unset_event (s0->server_tx_fifo);

	/* Check how much we can pull. */
	max_dequeue0 = svm_fifo_max_dequeue (s0->server_tx_fifo);

	if (peek_data)
	{
	/* Offset in rx fifo from where to peek data */
	tx_offset = transport_vft->tx_fifo_offset (tc0);
	if (PREDICT_FALSE (tx_offset >= max_dequeue0))
	max_dequeue0 = 0;
	else
	max_dequeue0 -= tx_offset;
	}

	/* Nothing to read return */
	if (max_dequeue0 == 0)
	return 0;

	/* Ensure we're not writing more than transport window allows */
	if (max_dequeue0 < snd_space0)
	{
	/* Constrained by tx queue. Try to send only fully formed segments */
	max_len_to_snd0 = (max_dequeue0 > snd_mss0) ?
	max_dequeue0 - max_dequeue0 % snd_mss0 : max_dequeue0;
	/* TODO Nagle ? */
	}
	else
	{
	/* Expectation is that snd_space0 is already a multiple of snd_mss */
	max_len_to_snd0 = snd_space0;
	}

	n_bytes_per_buf = vlib_buffer_free_list_buffer_size
	(vm, VLIB_BUFFER_DEFAULT_FREE_LIST_INDEX);
	ASSERT (n_bytes_per_buf > MAX_HDRS_LEN);
	n_bytes_per_seg = MAX_HDRS_LEN + snd_mss0;
	n_bufs_per_seg = ceil ((double) n_bytes_per_seg / n_bytes_per_buf);
	n_bufs_per_evt = ceil ((double) max_len_to_snd0 / n_bytes_per_seg);
	n_frames_per_evt = ceil ((double) n_bufs_per_evt / VLIB_FRAME_SIZE);
	n_bufs_per_frame = n_bufs_per_seg * VLIB_FRAME_SIZE;

	deq_per_buf = clib_min (snd_mss0, n_bytes_per_buf);
	deq_per_first_buf = clib_min (snd_mss0, n_bytes_per_buf - MAX_HDRS_LEN);

	n_bufs = vec_len (smm->tx_buffers[thread_index]);
	left_to_snd0 = max_len_to_snd0;
	for (i = 0; i < n_frames_per_evt; i++)
	{
	/* Make sure we have at least one full frame of buffers ready */
	if (PREDICT_FALSE (n_bufs < n_bufs_per_frame))
	{
	vec_validate (smm->tx_buffers[thread_index],
	n_bufs + n_bufs_per_frame - 1);
	bufs_alloc = 0;
	do
	{
	bufs_now =
	vlib_buffer_alloc (vm,
	&smm->tx_buffers[thread_index][n_bufs +
	bufs_alloc],
	n_bufs_per_frame - bufs_alloc);
	bufs_alloc += bufs_now;
	}
	while (bufs_now > 0 && ((bufs_alloc + n_bufs < n_bufs_per_frame)));

	n_bufs += bufs_alloc;
	_vec_len (smm->tx_buffers[thread_index]) = n_bufs;

	if (PREDICT_FALSE (n_bufs < n_bufs_per_frame))
	{
	vec_add1 (smm->pending_event_vector[thread_index], *e0);
	return -1;
	}
	ASSERT (n_bufs >= n_bufs_per_frame);
	}

	vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
	while (left_to_snd0 && n_left_to_next)
	{
	/*
	* Handle first buffer in chain separately
	*/

	len_to_deq0 = clib_min (left_to_snd0, deq_per_first_buf);
	if (left_to_snd0 > len_to_deq0 && n_left_to_next > 1)
	{
	vlib_buffer_t *pb;
	u32 pbi = smm->tx_buffers[thread_index][n_bufs - 2];
	pb = vlib_get_buffer (vm, pbi);
	vlib_prefetch_buffer_header (pb, LOAD);
	}

	/* Get free buffer */
	ASSERT (n_bufs >= 1);
	bi0 = smm->tx_buffers[thread_index][--n_bufs];
	_vec_len (smm->tx_buffers[thread_index]) = n_bufs;

	/* usual speculation, or the enqueue_x1 macro will barf */
	to_next[0] = bi0;
	to_next += 1;
	n_left_to_next -= 1;

	b0 = vlib_get_buffer (vm, bi0);
	b0->error = 0;
	b0->flags = VNET_BUFFER_F_LOCALLY_ORIGINATED;
	b0->current_data = 0;
	b0->total_length_not_including_first_buffer = 0;

	data0 = vlib_buffer_make_headroom (b0, MAX_HDRS_LEN);
	if (peek_data)
	{
	n_bytes_read = svm_fifo_peek (s0->server_tx_fifo, tx_offset,
	len_to_deq0, data0);
	if (n_bytes_read <= 0)
	goto dequeue_fail;
	/* Keep track of progress locally, transport is also supposed to
	* increment it independently when pushing the header */
	tx_offset += n_bytes_read;
	}
	else
	{
	n_bytes_read = svm_fifo_dequeue_nowait (s0->server_tx_fifo,
	len_to_deq0, data0);
	if (n_bytes_read <= 0)
	goto dequeue_fail;
	}

	b0->current_length = n_bytes_read;

	left_to_snd0 -= n_bytes_read;
	n_tx_packets = n_tx_packets + 1;

	/*
	* Fill in the remaining buffers in the chain, if any
	*/
	if (PREDICT_FALSE (n_bufs_per_seg > 1 && left_to_snd0))
	{
	left_for_seg = clib_min (snd_mss0 - n_bytes_read, left_to_snd0);
	session_tx_fifo_chain_tail (smm, vm, thread_index,
	s0->server_tx_fifo, b0, bi0,
	n_bufs_per_seg, left_for_seg,
	&left_to_snd0, &n_bufs, &tx_offset,
	deq_per_buf, peek_data);
	}

	/* Ask transport to push header after current_length and
	* total_length_not_including_first_buffer are updated */
	transport_vft->push_header (tc0, b0);

	/* INDENT-OFF */
	SESSION_EVT_DBG(SESSION_EVT_DEQ, s0, ({
	ed->data[0] = e0->event_type;
	ed->data[1] = max_dequeue0;
	ed->data[2] = len_to_deq0;
	ed->data[3] = left_to_snd0;
	}));
	/* INDENT-ON */

	VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b0);

	if (PREDICT_FALSE (n_trace > 0))
	{
	session_queue_trace_t *t0;
	vlib_trace_buffer (vm, node, next_index, b0,
	1 /* follow_chain */ );
	vlib_set_trace_count (vm, node, --n_trace);
	t0 = vlib_add_trace (vm, node, b0, sizeof (*t0));
	t0->session_index = s0->session_index;
	t0->server_thread_index = s0->thread_index;
	}

	vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
	to_next, n_left_to_next,
	bi0, next0);
	}
	vlib_put_next_frame (vm, node, next_index, n_left_to_next);
	}

	/* If we couldn't dequeue all bytes mark as partially read */
	if (max_len_to_snd0 < max_dequeue0)
	{
	/* If we don't already have new event */
	if (svm_fifo_set_event (s0->server_tx_fifo))
	{
	vec_add1 (smm->pending_event_vector[thread_index], *e0);
	}
	}
	return 0;

	dequeue_fail:
	/*
	* Can't read from fifo. If we don't already have an event, save as partially
	* read, return buff to free list and return
	*/
	clib_warning ("dequeue fail");

	if (svm_fifo_set_event (s0->server_tx_fifo))
	{
	vec_add1 (smm->pending_event_vector[thread_index], *e0);
	}
	vlib_put_next_frame (vm, node, next_index, n_left_to_next + 1);
	_vec_len (smm->tx_buffers[thread_index]) += 1;

	return 0;
	}

	int
	session_tx_fifo_peek_and_snd (vlib_main_t * vm, vlib_node_runtime_t * node,
	session_manager_main_t * smm,
	session_fifo_event_t * e0,
	stream_session_t * s0, u32 thread_index,
	int *n_tx_pkts)
	{
	return session_tx_fifo_read_and_snd_i (vm, node, smm, e0, s0, thread_index,
	n_tx_pkts, 1);
	}

	int
	session_tx_fifo_dequeue_and_snd (vlib_main_t * vm, vlib_node_runtime_t * node,
	session_manager_main_t * smm,
	session_fifo_event_t * e0,
	stream_session_t * s0, u32 thread_index,
	int *n_tx_pkts)
	{
	return session_tx_fifo_read_and_snd_i (vm, node, smm, e0, s0, thread_index,
	n_tx_pkts, 0);
	}

	int
	session_tx_fifo_dequeue_internal (vlib_main_t * vm,
	vlib_node_runtime_t * node,
	session_manager_main_t * smm,
	session_fifo_event_t * e0,
	stream_session_t * s0, u32 thread_index,
	int *n_tx_pkts)
	{
	application_t *app;
	app = application_get (s0->opaque);
	svm_fifo_unset_event (s0->server_tx_fifo);
	return app->cb_fns.builtin_app_tx_callback (s0);
	}

	always_inline stream_session_t *
	session_event_get_session (session_fifo_event_t * e, u8 thread_index)
	{
	return session_get_if_valid (e->fifo->master_session_index, thread_index);
	}

	void
	dump_thread_0_event_queue (void)
	{
	session_manager_main_t *smm = vnet_get_session_manager_main ();
	vlib_main_t *vm = &vlib_global_main;
	u32 my_thread_index = vm->thread_index;
	session_fifo_event_t _e, *e = &_e;
	stream_session_t *s0;
	int i, index;
	i8 *headp;

	svm_queue_t *q;
	q = smm->vpp_event_queues[my_thread_index];

	index = q->head;

	for (i = 0; i < q->cursize; i++)
	{
	headp = (i8 ) (&q->data[0] + q->elsize index);
	clib_memcpy (e, headp, q->elsize);

	switch (e->event_type)
	{
	case FIFO_EVENT_APP_TX:
	s0 = session_event_get_session (e, my_thread_index);
	fformat (stdout, "[%04d] TX session %d\n", i, s0->session_index);
	break;

	case FIFO_EVENT_DISCONNECT:
	s0 = session_get_from_handle (e->session_handle);
	fformat (stdout, "[%04d] disconnect session %d\n", i,
	s0->session_index);
	break;

	case FIFO_EVENT_BUILTIN_RX:
	s0 = session_event_get_session (e, my_thread_index);
	fformat (stdout, "[%04d] builtin_rx %d\n", i, s0->session_index);
	break;

	case FIFO_EVENT_RPC:
	fformat (stdout, "[%04d] RPC call %llx with %llx\n",
	i, (u64) (e->rpc_args.fp), (u64) (e->rpc_args.arg));
	break;

	default:
	fformat (stdout, "[%04d] unhandled event type %d\n",
	i, e->event_type);
	break;
	}

	index++;

	if (index == q->maxsize)
	index = 0;
	}
	}

	static u8
	session_node_cmp_event (session_fifo_event_t * e, svm_fifo_t * f)
	{
	stream_session_t *s;
	switch (e->event_type)
	{
	case FIFO_EVENT_APP_RX:
	case FIFO_EVENT_APP_TX:
	case FIFO_EVENT_BUILTIN_RX:
	if (e->fifo == f)
	return 1;
	break;
	case FIFO_EVENT_DISCONNECT:
	break;
	case FIFO_EVENT_RPC:
	s = session_get_from_handle (e->session_handle);
	if (!s)
	{
	clib_warning ("session has event but doesn't exist!");
	break;
	}
	if (s->server_rx_fifo == f \|\| s->server_tx_fifo == f)
	return 1;
	break;
	default:
	break;
	}
	return 0;
	}

	u8
	session_node_lookup_fifo_event (svm_fifo_t * f, session_fifo_event_t * e)
	{
	session_manager_main_t *smm = vnet_get_session_manager_main ();
	svm_queue_t *q;
	session_fifo_event_t pending_event_vector, evt;
	int i, index, found = 0;
	i8 *headp;
	u8 thread_index;

	ASSERT (e);
	thread_index = f->master_thread_index;
	/*
	* Search evt queue
	*/
	q = smm->vpp_event_queues[thread_index];
	index = q->head;
	for (i = 0; i < q->cursize; i++)
	{
	headp = (i8 ) (&q->data[0] + q->elsize index);
	clib_memcpy (e, headp, q->elsize);
	found = session_node_cmp_event (e, f);
	if (found)
	return 1;
	if (++index == q->maxsize)
	index = 0;
	}
	/*
	* Search pending events vector
	*/
	pending_event_vector = smm->pending_event_vector[thread_index];
	vec_foreach (evt, pending_event_vector)
	{
	found = session_node_cmp_event (evt, f);
	if (found)
	{
	clib_memcpy (e, evt, sizeof (*evt));
	break;
	}
	}
	return found;
	}

	static uword
	session_queue_node_fn (vlib_main_t * vm, vlib_node_runtime_t * node,
	vlib_frame_t * frame)
	{
	session_manager_main_t *smm = vnet_get_session_manager_main ();
	session_fifo_event_t my_pending_event_vector, pending_disconnects, *e;
	session_fifo_event_t *my_fifo_events;
	u32 n_to_dequeue, n_events;
	svm_queue_t *q;
	application_t *app;
	int n_tx_packets = 0;
	u32 my_thread_index = vm->thread_index;
	int i, rv;
	f64 now = vlib_time_now (vm);
	void (fp) (void );

	SESSION_EVT_DBG (SESSION_EVT_POLL_GAP_TRACK, smm, my_thread_index);

	/*
	* Update transport time
	*/
	transport_update_time (now, my_thread_index);

	/*
	* Get vpp queue events
	*/
	q = smm->vpp_event_queues[my_thread_index];
	if (PREDICT_FALSE (q == 0))
	return 0;

	my_fifo_events = smm->free_event_vector[my_thread_index];

	/* min number of events we can dequeue without blocking */
	n_to_dequeue = q->cursize;
	my_pending_event_vector = smm->pending_event_vector[my_thread_index];
	pending_disconnects = smm->pending_disconnects[my_thread_index];

	if (!n_to_dequeue && !vec_len (my_pending_event_vector)
	&& !vec_len (pending_disconnects))
	return 0;

	SESSION_EVT_DBG (SESSION_EVT_DEQ_NODE, 0);

	/*
	* If we didn't manage to process previous events try going
	* over them again without dequeuing new ones.
	*/
	/* XXX: Block senders to sessions that can't keep up */
	if (0 && vec_len (my_pending_event_vector) >= 100)
	{
	clib_warning ("too many fifo events unsolved");
	goto skip_dequeue;
	}

	/* See you in the next life, don't be late */
	if (pthread_mutex_trylock (&q->mutex))
	return 0;

	for (i = 0; i < n_to_dequeue; i++)
	{
	vec_add2 (my_fifo_events, e, 1);
	svm_queue_sub_raw (q, (u8 *) e);
	}

	/* The other side of the connection is not polling */
	if (q->cursize < (q->maxsize / 8))
	(void) pthread_cond_broadcast (&q->condvar);
	pthread_mutex_unlock (&q->mutex);

	vec_append (my_fifo_events, my_pending_event_vector);
	vec_append (my_fifo_events, smm->pending_disconnects[my_thread_index]);

	_vec_len (my_pending_event_vector) = 0;
	smm->pending_event_vector[my_thread_index] = my_pending_event_vector;
	_vec_len (smm->pending_disconnects[my_thread_index]) = 0;

	skip_dequeue:
	n_events = vec_len (my_fifo_events);
	for (i = 0; i < n_events; i++)
	{
	stream_session_t s0; / $$$ prefetch 1 ahead maybe */
	session_fifo_event_t *e0;

	e0 = &my_fifo_events[i];

	switch (e0->event_type)
	{
	case FIFO_EVENT_APP_TX:
	s0 = session_event_get_session (e0, my_thread_index);

	if (PREDICT_FALSE (!s0))
	{
	clib_warning ("It's dead, Jim!");
	continue;
	}
	/* Can retransmit for closed sessions but can't do anything if
	* session is not ready or closed */
	if (PREDICT_FALSE (s0->session_state < SESSION_STATE_READY))
	{
	vec_add1 (smm->pending_event_vector[my_thread_index], *e0);
	continue;
	}
	/* Spray packets in per session type frames, since they go to
	* different nodes */
	rv = (smm->session_tx_fns[s0->session_type]) (vm, node, smm, e0, s0,
	my_thread_index,
	&n_tx_packets);
	/* Out of buffers */
	if (PREDICT_FALSE (rv < 0))
	{
	vlib_node_increment_counter (vm, node->node_index,
	SESSION_QUEUE_ERROR_NO_BUFFER, 1);
	continue;
	}
	break;
	case FIFO_EVENT_DISCONNECT:
	/* Make sure disconnects run after the pending list is drained */
	if (!e0->postponed)
	{
	e0->postponed = 1;
	vec_add1 (smm->pending_disconnects[my_thread_index], *e0);
	continue;
	}
	s0 = session_get_from_handle (e0->session_handle);
	stream_session_disconnect_transport (s0);
	break;
	case FIFO_EVENT_BUILTIN_RX:
	s0 = session_event_get_session (e0, my_thread_index);
	if (PREDICT_FALSE (!s0))
	continue;
	svm_fifo_unset_event (s0->server_rx_fifo);
	app = application_get (s0->app_index);
	app->cb_fns.builtin_app_rx_callback (s0);
	break;
	case FIFO_EVENT_RPC:
	fp = e0->rpc_args.fp;
	(*fp) (e0->rpc_args.arg);
	break;

	default:
	clib_warning ("unhandled event type %d", e0->event_type);
	}
	}

	_vec_len (my_fifo_events) = 0;
	smm->free_event_vector[my_thread_index] = my_fifo_events;

	vlib_node_increment_counter (vm, session_queue_node.index,
	SESSION_QUEUE_ERROR_TX, n_tx_packets);

	SESSION_EVT_DBG (SESSION_EVT_DEQ_NODE, 1);

	return n_tx_packets;
	}

	/* INDENT-OFF */
	VLIB_REGISTER_NODE (session_queue_node) =
	{
	.function = session_queue_node_fn,
	.name = "session-queue",
	.format_trace = format_session_queue_trace,
	.type = VLIB_NODE_TYPE_INPUT,
	.n_errors = ARRAY_LEN (session_queue_error_strings),
	.error_strings = session_queue_error_strings,
	.state = VLIB_NODE_STATE_DISABLED,
	};
	/* INDENT-ON */

	static clib_error_t *
	session_queue_exit (vlib_main_t * vm)
	{
	if (vec_len (vlib_mains) < 2)
	return 0;

	/*
	* Shut off (especially) worker-thread session nodes.
	* Otherwise, vpp can crash as the main thread unmaps the
	* API segment.
	*/
	vlib_worker_thread_barrier_sync (vm);
	session_node_enable_disable (0 /* is_enable */ );
	vlib_worker_thread_barrier_release (vm);
	return 0;
	}

	VLIB_MAIN_LOOP_EXIT_FUNCTION (session_queue_exit);

	/*
	* fd.io coding-style-patch-verification: ON
	*
	* Local Variables:
	* eval: (c-set-style "gnu")
	* End:
	*/