text: /*
   * Copyright (c) 2017-2019 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/session.h>
  #include <vnet/session/application.h>
  #include <vnet/session/application_interface.h>
  #include <vnet/session/application_local.h>
  #include <vnet/session/session_debug.h>
  #include <svm/queue.h>
  #include <sys/timerfd.h>
  
  #define app_check_thread_and_barrier(_fn, _arg)				\
    if (!vlib_thread_is_main_w_barrier ())				\
      {									\
       vlib_rpc_call_main_thread (_fn, (u8 *) _arg, sizeof(*_arg));	\
        return;								\
     }
  
  static void
  session_wrk_timerfd_update (session_worker_t *wrk, u64 time_ns)
  {
    struct itimerspec its;
  
    its.it_value.tv_sec = 0;
    its.it_value.tv_nsec = time_ns;
    its.it_interval.tv_sec = 0;
    its.it_interval.tv_nsec = its.it_value.tv_nsec;
  
    if (timerfd_settime (wrk->timerfd, 0, &its, NULL) == -1)
      clib_warning ("timerfd_settime");
  }
  
  always_inline u64
  session_wrk_tfd_timeout (session_wrk_state_t state, u32 thread_index)
  {
    if (state == SESSION_WRK_INTERRUPT)
      return thread_index ? 1e6 : vlib_num_workers () ? 5e8 : 1e6;
    else if (state == SESSION_WRK_IDLE)
      return thread_index ? 1e8 : vlib_num_workers () ? 5e8 : 1e8;
    else
      return 0;
  }
  
  static inline void
  session_wrk_set_state (session_worker_t *wrk, session_wrk_state_t state)
  {
    u64 time_ns;
  
    wrk->state = state;
    if (wrk->timerfd == -1)
      return;
    time_ns = session_wrk_tfd_timeout (state, wrk->vm->thread_index);
    session_wrk_timerfd_update (wrk, time_ns);
  }
  
  static transport_endpt_ext_cfg_t *
  session_mq_get_ext_config (application_t *app, uword offset)
  {
    svm_fifo_chunk_t *c;
    fifo_segment_t *fs;
  
    fs = application_get_rx_mqs_segment (app);
    c = fs_chunk_ptr (fs->h, offset);
    return (transport_endpt_ext_cfg_t *) c->data;
  }
  
  static void
  session_mq_free_ext_config (application_t *app, uword offset)
  {
    svm_fifo_chunk_t *c;
    fifo_segment_t *fs;
  
    fs = application_get_rx_mqs_segment (app);
    c = fs_chunk_ptr (fs->h, offset);
    fifo_segment_collect_chunk (fs, 0 /* only one slice */, c);
  }
  
  static void
  session_mq_listen_handler (void *data)
  {
    session_listen_msg_t *mp = (session_listen_msg_t *) data;
    vnet_listen_args_t _a, *a = &_a;
    app_worker_t *app_wrk;
    application_t *app;
    int rv;
  
    app_check_thread_and_barrier (session_mq_listen_handler, mp);
  
    app = application_lookup (mp->client_index);
    if (!app)
      return;
  
    clib_memset (a, 0, sizeof (*a));
    a->sep.is_ip4 = mp->is_ip4;
    ip_copy (&a->sep.ip, &mp->ip, mp->is_ip4);
    a->sep.port = mp->port;
    a->sep.fib_index = mp->vrf;
    a->sep.sw_if_index = ENDPOINT_INVALID_INDEX;
    a->sep.transport_proto = mp->proto;
    a->app_index = app->app_index;
    a->wrk_map_index = mp->wrk_index;
    a->sep_ext.transport_flags = mp->flags;
  
    if (mp->ext_config)
      a->sep_ext.ext_cfg = session_mq_get_ext_config (app, mp->ext_config);
  
    if ((rv = vnet_listen (a)))
      clib_warning ("listen returned: %U", format_session_error, rv);
  
    app_wrk = application_get_worker (app, mp->wrk_index);
    mq_send_session_bound_cb (app_wrk->wrk_index, mp->context, a->handle, rv);
  
    if (mp->ext_config)
      session_mq_free_ext_config (app, mp->ext_config);
  }
  
  static void
  session_mq_listen_uri_handler (void *data)
  {
    session_listen_uri_msg_t *mp = (session_listen_uri_msg_t *) data;
    vnet_listen_args_t _a, *a = &_a;
    app_worker_t *app_wrk;
    application_t *app;
    int rv;
  
    app_check_thread_and_barrier (session_mq_listen_uri_handler, mp);
  
    app = application_lookup (mp->client_index);
    if (!app)
      return;
  
    clib_memset (a, 0, sizeof (*a));
    a->uri = (char *) mp->uri;
    a->app_index = app->app_index;
    rv = vnet_bind_uri (a);
  
    app_wrk = application_get_worker (app, 0);
    mq_send_session_bound_cb (app_wrk->wrk_index, mp->context, a->handle, rv);
  }
  
  static void
  session_mq_connect_one (session_connect_msg_t *mp)
  {
    vnet_connect_args_t _a, *a = &_a;
    app_worker_t *app_wrk;
    application_t *app;
    int rv;
  
    app = application_lookup (mp->client_index);
    if (!app)
      return;
  
    clib_memset (a, 0, sizeof (*a));
    a->sep.is_ip4 = mp->is_ip4;
    clib_memcpy_fast (&a->sep.ip, &mp->ip, sizeof (mp->ip));
    a->sep.port = mp->port;
    a->sep.transport_proto = mp->proto;
    a->sep.peer.fib_index = mp->vrf;
    a->sep.dscp = mp->dscp;
    clib_memcpy_fast (&a->sep.peer.ip, &mp->lcl_ip, sizeof (mp->lcl_ip));
    if (mp->is_ip4)
      {
        ip46_address_mask_ip4 (&a->sep.ip);
        ip46_address_mask_ip4 (&a->sep.peer.ip);
      }
    a->sep.peer.port = mp->lcl_port;
    a->sep.peer.sw_if_index = ENDPOINT_INVALID_INDEX;
    a->sep_ext.parent_handle = mp->parent_handle;
    a->sep_ext.transport_flags = mp->flags;
    a->api_context = mp->context;
    a->app_index = app->app_index;
    a->wrk_map_index = mp->wrk_index;
  
    if (mp->ext_config)
      a->sep_ext.ext_cfg = session_mq_get_ext_config (app, mp->ext_config);
  
    if ((rv = vnet_connect (a)))
      {
        clib_warning ("connect returned: %U", format_session_error, rv);
        app_wrk = application_get_worker (app, mp->wrk_index);
        mq_send_session_connected_cb (app_wrk->wrk_index, mp->context, 0, rv);
      }
  
    if (mp->ext_config)
      session_mq_free_ext_config (app, mp->ext_config);
  }
  
  static void
  session_mq_handle_connects_rpc (void *arg)
  {
    u32 max_connects = 32, n_connects = 0;
    vlib_main_t *vm = vlib_get_main ();
    session_evt_elt_t *he, *elt, *next;
    session_worker_t *fwrk, *wrk;
  
    ASSERT (vlib_get_thread_index () == 0);
  
    /* Pending connects on linked list pertaining to first worker */
    fwrk = session_main_get_worker (1);
    if (!fwrk->n_pending_connects)
      goto update_state;
  
    vlib_worker_thread_barrier_sync (vm);
  
    he = clib_llist_elt (fwrk->event_elts, fwrk->pending_connects);
    elt = clib_llist_next (fwrk->event_elts, evt_list, he);
  
    /* Avoid holding the barrier for too long */
    while (n_connects < max_connects && elt != he)
      {
        next = clib_llist_next (fwrk->event_elts, evt_list, elt);
        clib_llist_remove (fwrk->event_elts, evt_list, elt);
        session_mq_connect_one (session_evt_ctrl_data (fwrk, elt));
        session_evt_ctrl_data_free (fwrk, elt);
        clib_llist_put (fwrk->event_elts, elt);
        elt = next;
        n_connects += 1;
      }
  
    /* Decrement with worker barrier */
    fwrk->n_pending_connects -= n_connects;
  
    vlib_worker_thread_barrier_release (vm);
  
  update_state:
  
    /* Switch worker to poll mode if it was in interrupt mode and had work or
     * back to interrupt if threshold of loops without a connect is passed.
     * While in poll mode, reprogram connects rpc */
    wrk = session_main_get_worker (0);
    if (wrk->state != SESSION_WRK_POLLING)
      {
        if (n_connects)
  	{
  	  session_wrk_set_state (wrk, SESSION_WRK_POLLING);
  	  vlib_node_set_state (vm, session_queue_node.index,
  			       VLIB_NODE_STATE_POLLING);
  	  wrk->no_connect_loops = 0;
  	}
      }
    else
      {
        if (!n_connects)
  	{
  	  if (++wrk->no_connect_loops > 1e5)
  	    {
  	      session_wrk_set_state (wrk, SESSION_WRK_INTERRUPT);
  	      vlib_node_set_state (vm, session_queue_node.index,
  				   VLIB_NODE_STATE_INTERRUPT);
  	    }
  	}
        else
  	wrk->no_connect_loops = 0;
      }
  
    if (wrk->state == SESSION_WRK_POLLING)
      {
        elt = session_evt_alloc_ctrl (wrk);
        elt->evt.event_type = SESSION_CTRL_EVT_RPC;
        elt->evt.rpc_args.fp = session_mq_handle_connects_rpc;
      }
  }
  
  static void
  session_mq_connect_handler (session_worker_t *wrk, session_evt_elt_t *elt)
  {
    u32 thread_index = wrk - session_main.wrk;
    session_evt_elt_t *he;
  
    /* No workers, so just deal with the connect now */
    if (PREDICT_FALSE (!thread_index))
      {
        session_mq_connect_one (session_evt_ctrl_data (wrk, elt));
        return;
      }
  
    if (PREDICT_FALSE (thread_index != 1))
      {
        clib_warning ("Connect on wrong thread. Dropping");
        return;
      }
  
    /* Add to pending list to be handled by main thread */
    he = clib_llist_elt (wrk->event_elts, wrk->pending_connects);
    clib_llist_add_tail (wrk->event_elts, evt_list, elt, he);
  
    /* Decremented with worker barrier */
    wrk->n_pending_connects += 1;
    if (wrk->n_pending_connects == 1)
      {
        vlib_node_set_interrupt_pending (vlib_get_main_by_index (0),
  				       session_queue_node.index);
        session_send_rpc_evt_to_thread (0, session_mq_handle_connects_rpc, 0);
      }
  }
  
  static void
  session_mq_connect_uri_handler (void *data)
  {
    session_connect_uri_msg_t *mp = (session_connect_uri_msg_t *) data;
    vnet_connect_args_t _a, *a = &_a;
    app_worker_t *app_wrk;
    application_t *app;
    int rv;
  
    app_check_thread_and_barrier (session_mq_connect_uri_handler, mp);
  
    app = application_lookup (mp->client_index);
    if (!app)
      return;
  
    clib_memset (a, 0, sizeof (*a));
    a->uri = (char *) mp->uri;
    a->api_context = mp->context;
    a->app_index = app->app_index;
    if ((rv = vnet_connect_uri (a)))
      {
        clib_warning ("connect_uri returned: %d", rv);
        app_wrk = application_get_worker (app, 0 /* default wrk only */ );
        mq_send_session_connected_cb (app_wrk->wrk_index, mp->context, 0, rv);
      }
  }
  
  static void
  session_mq_shutdown_handler (void *data)
  {
    session_shutdown_msg_t *mp = (session_shutdown_msg_t *) data;
    vnet_shutdown_args_t _a, *a = &_a;
    application_t *app;
  
    app = application_lookup (mp->client_index);
    if (!app)
      return;
  
    a->app_index = app->app_index;
    a->handle = mp->handle;
    vnet_shutdown_session (a);
  }
  
  static void
  session_mq_disconnect_handler (void *data)
  {
    session_disconnect_msg_t *mp = (session_disconnect_msg_t *) data;
    vnet_disconnect_args_t _a, *a = &_a;
    application_t *app;
  
    app = application_lookup (mp->client_index);
    if (!app)
      return;
  
    a->app_index = app->app_index;
    a->handle = mp->handle;
    vnet_disconnect_session (a);
  }
  
  static void
  app_mq_detach_handler (void *data)
  {
    session_app_detach_msg_t *mp = (session_app_detach_msg_t *) data;
    vnet_app_detach_args_t _a, *a = &_a;
    application_t *app;
  
    app_check_thread_and_barrier (app_mq_detach_handler, mp);
  
    app = application_lookup (mp->client_index);
    if (!app)
      return;
  
    a->app_index = app->app_index;
    a->api_client_index = mp->client_index;
    vnet_application_detach (a);
  }
  
  static void
  session_mq_unlisten_rpc (session_unlisten_msg_t *mp)
  {
    vlib_main_t *vm = vlib_get_main ();
    vnet_unlisten_args_t _a, *a = &_a;
    app_worker_t *app_wrk;
    session_handle_t sh;
    application_t *app;
    u32 context;
    int rv;
  
    sh = mp->handle;
    context = mp->context;
  
    app = application_lookup (mp->client_index);
    if (!app)
      return;
  
    clib_memset (a, 0, sizeof (*a));
    a->app_index = app->app_index;
    a->handle = sh;
    a->wrk_map_index = mp->wrk_index;
  
    vlib_worker_thread_barrier_sync (vm);
  
    if ((rv = vnet_unlisten (a)))
      clib_warning ("unlisten returned: %d", rv);
  
    vlib_worker_thread_barrier_release (vm);
  
    app_wrk = application_get_worker (app, a->wrk_map_index);
    if (!app_wrk)
      return;
  
    mq_send_unlisten_reply (app_wrk, sh, context, rv);
    clib_mem_free (mp);
  }
  
  static void
  session_mq_unlisten_handler (session_worker_t *wrk, session_evt_elt_t *elt)
  {
    u32 thread_index = wrk - session_main.wrk;
    session_unlisten_msg_t *mp, *arg;
  
    mp = session_evt_ctrl_data (wrk, elt);
    arg = clib_mem_alloc (sizeof (session_unlisten_msg_t));
    clib_memcpy_fast (arg, mp, sizeof (*arg));
  
    if (PREDICT_FALSE (!thread_index))
      {
        session_mq_unlisten_rpc (arg);
        return;
      }
  
    session_send_rpc_evt_to_thread_force (0, session_mq_unlisten_rpc, arg);
  }
  
  static void
  session_mq_accepted_reply_handler (void *data)
  {
    session_accepted_reply_msg_t *mp = (session_accepted_reply_msg_t *) data;
    vnet_disconnect_args_t _a = { 0 }, *a = &_a;
    session_state_t old_state;
    app_worker_t *app_wrk;
    session_t *s;
  
    /* Mail this back from the main thread. We're not polling in main
     * thread so we're using other workers for notifications. */
    if (session_thread_from_handle (mp->handle) == 0 && vlib_num_workers () &&
        vlib_get_thread_index () != 0)
      {
        vlib_rpc_call_main_thread (session_mq_accepted_reply_handler,
  				 (u8 *) mp, sizeof (*mp));
        return;
      }
  
    s = session_get_from_handle_if_valid (mp->handle);
    if (!s)
      return;
  
    app_wrk = app_worker_get (s->app_wrk_index);
    if (app_wrk->app_index != mp->context)
      {
        clib_warning ("app doesn't own session");
        return;
      }
  
    /* Server isn't interested, disconnect the session */
    if (mp->retval)
      {
        a->app_index = mp->context;
        a->handle = mp->handle;
        vnet_disconnect_session (a);
        return;
      }
  
    /* Special handling for cut-through sessions */
    if (!session_has_transport (s))
      {
        s->session_state = SESSION_STATE_READY;
        ct_session_connect_notify (s, SESSION_E_NONE);
        return;
      }
  
    old_state = s->session_state;
    s->session_state = SESSION_STATE_READY;
  
    if (!svm_fifo_is_empty_prod (s->rx_fifo))
      app_worker_lock_and_send_event (app_wrk, s, SESSION_IO_EVT_RX);
  
    /* Closed while waiting for app to reply. Resend disconnect */
    if (old_state >= SESSION_STATE_TRANSPORT_CLOSING)
      {
        app_worker_close_notify (app_wrk, s);
        s->session_state = old_state;
        return;
      }
  }
  
  static void
  session_mq_reset_reply_handler (void *data)
  {
    vnet_disconnect_args_t _a = { 0 }, *a = &_a;
    session_reset_reply_msg_t *mp;
    app_worker_t *app_wrk;
    session_t *s;
    application_t *app;
    u32 index, thread_index;
  
    mp = (session_reset_reply_msg_t *) data;
    app = application_lookup (mp->context);
    if (!app)
      return;
  
    session_parse_handle (mp->handle, &index, &thread_index);
    s = session_get_if_valid (index, thread_index);
  
    /* No session or not the right session */
    if (!s || s->session_state < SESSION_STATE_TRANSPORT_CLOSING)
      return;
  
    app_wrk = app_worker_get (s->app_wrk_index);
    if (!app_wrk || app_wrk->app_index != app->app_index)
      {
        clib_warning ("App %u does not own handle 0x%lx!", app->app_index,
  		    mp->handle);
        return;
      }
  
    /* Client objected to resetting the session, log and continue */
    if (mp->retval)
      {
        clib_warning ("client retval %d", mp->retval);
        return;
      }
  
    /* This comes as a response to a reset, transport only waiting for
     * confirmation to remove connection state, no need to disconnect */
    a->handle = mp->handle;
    a->app_index = app->app_index;
    vnet_disconnect_session (a);
  }
  
  static void
  session_mq_disconnected_handler (void *data)
  {
    session_disconnected_reply_msg_t *rmp;
    vnet_disconnect_args_t _a, *a = &_a;
    svm_msg_q_msg_t _msg, *msg = &_msg;
    session_disconnected_msg_t *mp;
    app_worker_t *app_wrk;
    session_event_t *evt;
    session_t *s;
    application_t *app;
    int rv = 0;
  
    mp = (session_disconnected_msg_t *) data;
    if (!(s = session_get_from_handle_if_valid (mp->handle)))
      {
        clib_warning ("could not disconnect handle %llu", mp->handle);
        return;
      }
    app_wrk = app_worker_get (s->app_wrk_index);
    app = application_lookup (mp->client_index);
    if (!(app_wrk && app && app->app_index == app_wrk->app_index))
      {
        clib_warning ("could not disconnect session: %llu app: %u",
  		    mp->handle, mp->client_index);
        return;
      }
  
    a->handle = mp->handle;
    a->app_index = app_wrk->wrk_index;
    rv = vnet_disconnect_session (a);
  
    svm_msg_q_lock_and_alloc_msg_w_ring (app_wrk->event_queue,
  				       SESSION_MQ_CTRL_EVT_RING,
  				       SVM_Q_WAIT, msg);
    evt = svm_msg_q_msg_data (app_wrk->event_queue, msg);
    clib_memset (evt, 0, sizeof (*evt));
    evt->event_type = SESSION_CTRL_EVT_DISCONNECTED_REPLY;
    rmp = (session_disconnected_reply_msg_t *) evt->data;
    rmp->handle = mp->handle;
    rmp->context = mp->context;
    rmp->retval = rv;
    svm_msg_q_add_and_unlock (app_wrk->event_queue, msg);
  }
  
  static void
  session_mq_disconnected_reply_handler (void *data)
  {
    session_disconnected_reply_msg_t *mp;
    vnet_disconnect_args_t _a, *a = &_a;
    application_t *app;
  
    mp = (session_disconnected_reply_msg_t *) data;
  
    /* Client objected to disconnecting the session, log and continue */
    if (mp->retval)
      {
        clib_warning ("client retval %d", mp->retval);
        return;
      }
  
    /* Disconnect has been confirmed. Confirm close to transport */
    app = application_lookup (mp->context);
    if (app)
      {
        a->handle = mp->handle;
        a->app_index = app->app_index;
        vnet_disconnect_session (a);
      }
  }
  
  static void
  session_mq_worker_update_handler (void *data)
  {
    session_worker_update_msg_t *mp = (session_worker_update_msg_t *) data;
    session_worker_update_reply_msg_t *rmp;
    svm_msg_q_msg_t _msg, *msg = &_msg;
    app_worker_t *app_wrk;
    u32 owner_app_wrk_map;
    session_event_t *evt;
    session_t *s;
    application_t *app;
  
    app = application_lookup (mp->client_index);
    if (!app)
      return;
    if (!(s = session_get_from_handle_if_valid (mp->handle)))
      {
        clib_warning ("invalid handle %llu", mp->handle);
        return;
      }
    app_wrk = app_worker_get (s->app_wrk_index);
    if (app_wrk->app_index != app->app_index)
      {
        clib_warning ("app %u does not own session %llu", app->app_index,
  		    mp->handle);
        return;
      }
    owner_app_wrk_map = app_wrk->wrk_map_index;
    app_wrk = application_get_worker (app, mp->wrk_index);
  
    /* This needs to come from the new owner */
    if (mp->req_wrk_index == owner_app_wrk_map)
      {
        session_req_worker_update_msg_t *wump;
  
        svm_msg_q_lock_and_alloc_msg_w_ring (app_wrk->event_queue,
  					   SESSION_MQ_CTRL_EVT_RING,
  					   SVM_Q_WAIT, msg);
        evt = svm_msg_q_msg_data (app_wrk->event_queue, msg);
        clib_memset (evt, 0, sizeof (*evt));
        evt->event_type = SESSION_CTRL_EVT_REQ_WORKER_UPDATE;
        wump = (session_req_worker_update_msg_t *) evt->data;
        wump->session_handle = mp->handle;
        svm_msg_q_add_and_unlock (app_wrk->event_queue, msg);
        return;
      }
  
    app_worker_own_session (app_wrk, s);
  
    /*
     * Send reply
     */
    svm_msg_q_lock_and_alloc_msg_w_ring (app_wrk->event_queue,
  				       SESSION_MQ_CTRL_EVT_RING,
  				       SVM_Q_WAIT, msg);
    evt = svm_msg_q_msg_data (app_wrk->event_queue, msg);
    clib_memset (evt, 0, sizeof (*evt));
    evt->event_type = SESSION_CTRL_EVT_WORKER_UPDATE_REPLY;
    rmp = (session_worker_update_reply_msg_t *) evt->data;
    rmp->handle = mp->handle;
    if (s->rx_fifo)
      rmp->rx_fifo = fifo_segment_fifo_offset (s->rx_fifo);
    if (s->tx_fifo)
      rmp->tx_fifo = fifo_segment_fifo_offset (s->tx_fifo);
    rmp->segment_handle = session_segment_handle (s);
    svm_msg_q_add_and_unlock (app_wrk->event_queue, msg);
  
    /*
     * Retransmit messages that may have been lost
     */
    if (s->tx_fifo && !svm_fifo_is_empty (s->tx_fifo))
      session_send_io_evt_to_thread (s->tx_fifo, SESSION_IO_EVT_TX);
  
    if (s->rx_fifo && !svm_fifo_is_empty (s->rx_fifo))
      app_worker_lock_and_send_event (app_wrk, s, SESSION_IO_EVT_RX);
  
    if (s->session_state >= SESSION_STATE_TRANSPORT_CLOSING)
      app_worker_close_notify (app_wrk, s);
  }
  
  static void
  session_mq_app_wrk_rpc_handler (void *data)
  {
    session_app_wrk_rpc_msg_t *mp = (session_app_wrk_rpc_msg_t *) data;
    svm_msg_q_msg_t _msg, *msg = &_msg;
    session_app_wrk_rpc_msg_t *rmp;
    app_worker_t *app_wrk;
    session_event_t *evt;
    application_t *app;
  
    app = application_lookup (mp->client_index);
    if (!app)
      return;
  
    app_wrk = application_get_worker (app, mp->wrk_index);
  
    svm_msg_q_lock_and_alloc_msg_w_ring (app_wrk->event_queue,
  				       SESSION_MQ_CTRL_EVT_RING, SVM_Q_WAIT,
  				       msg);
    evt = svm_msg_q_msg_data (app_wrk->event_queue, msg);
    clib_memset (evt, 0, sizeof (*evt));
    evt->event_type = SESSION_CTRL_EVT_APP_WRK_RPC;
    rmp = (session_app_wrk_rpc_msg_t *) evt->data;
    clib_memcpy (rmp->data, mp->data, sizeof (mp->data));
    svm_msg_q_add_and_unlock (app_wrk->event_queue, msg);
  }
  
  static void
  session_mq_transport_attr_handler (void *data)
  {
    session_transport_attr_msg_t *mp = (session_transport_attr_msg_t *) data;
    session_transport_attr_reply_msg_t *rmp;
    svm_msg_q_msg_t _msg, *msg = &_msg;
    app_worker_t *app_wrk;
    session_event_t *evt;
    application_t *app;
    session_t *s;
    int rv;
  
    app = application_lookup (mp->client_index);
    if (!app)
      return;
  
    if (!(s = session_get_from_handle_if_valid (mp->handle)))
      {
        clib_warning ("invalid handle %llu", mp->handle);
        return;
      }
    app_wrk = app_worker_get (s->app_wrk_index);
    if (app_wrk->app_index != app->app_index)
      {
        clib_warning ("app %u does not own session %llu", app->app_index,
  		    mp->handle);
        return;
      }
  
    rv = session_transport_attribute (s, mp->is_get, &mp->attr);
  
    svm_msg_q_lock_and_alloc_msg_w_ring (
      app_wrk->event_queue, SESSION_MQ_CTRL_EVT_RING, SVM_Q_WAIT, msg);
    evt = svm_msg_q_msg_data (app_wrk->event_queue, msg);
    clib_memset (evt, 0, sizeof (*evt));
    evt->event_type = SESSION_CTRL_EVT_TRANSPORT_ATTR_REPLY;
    rmp = (session_transport_attr_reply_msg_t *) evt->data;
    rmp->handle = mp->handle;
    rmp->retval = rv;
    rmp->is_get = mp->is_get;
    if (!rv && mp->is_get)
      rmp->attr = mp->attr;
    svm_msg_q_add_and_unlock (app_wrk->event_queue, msg);
  }
  
  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 index %d thread index %d",
  	      t->session_index, t->server_thread_index);
    return s;
  }
  
  #define foreach_session_queue_error                                           \
    _ (TX, tx, INFO, "Packets transmitted")                                     \
    _ (TIMER, timer, INFO, "Timer events")                                      \
    _ (NO_BUFFER, no_buffer, ERROR, "Out of buffers")
  
  typedef enum
  {
  #define _(f, n, s, d) SESSION_QUEUE_ERROR_##f,
    foreach_session_queue_error
  #undef _
      SESSION_QUEUE_N_ERROR,
  } session_queue_error_t;
  
  static vlib_error_desc_t session_error_counters[] = {
  #define _(f, n, s, d) { #n, d, VL_COUNTER_SEVERITY_##s },
    foreach_session_queue_error
  #undef _
  };
  
  enum
  {
    SESSION_TX_NO_BUFFERS = -2,
    SESSION_TX_NO_DATA,
    SESSION_TX_OK
  };
  
  static void
  session_tx_trace_frame (vlib_main_t * vm, vlib_node_runtime_t * node,
  			u32 next_index, u32 * to_next, u16 n_segs,
  			session_t * s, u32 n_trace)
  {
    while (n_trace && n_segs)
      {
        vlib_buffer_t *b = vlib_get_buffer (vm, to_next[0]);
        if (PREDICT_TRUE
  	  (vlib_trace_buffer
  	   (vm, node, next_index, b, 1 /* follow_chain */ )))
  	{
  	  session_queue_trace_t *t =
  	    vlib_add_trace (vm, node, b, sizeof (*t));
  	  t->session_index = s->session_index;
  	  t->server_thread_index = s->thread_index;
  	  n_trace--;
  	}
        to_next++;
        n_segs--;
      }
    vlib_set_trace_count (vm, node, n_trace);
  }
  
  always_inline void
  session_tx_fifo_chain_tail (vlib_main_t * vm, session_tx_context_t * ctx,
  			    vlib_buffer_t * b, u16 * n_bufs, u8 peek_data)
  {
    vlib_buffer_t *chain_b, *prev_b;
    u32 chain_bi0, to_deq, left_from_seg;
    u16 len_to_deq, n_bytes_read;
    u8 *data, j;
  
    b->flags |= VLIB_BUFFER_TOTAL_LENGTH_VALID;
    b->total_length_not_including_first_buffer = 0;
  
    chain_b = b;
    left_from_seg = clib_min (ctx->sp.snd_mss - b->current_length,
  			    ctx->left_to_snd);
    to_deq = left_from_seg;
    for (j = 1; j < ctx->n_bufs_per_seg; j++)
      {
        prev_b = chain_b;
        len_to_deq = clib_min (to_deq, ctx->deq_per_buf);
  
        *n_bufs -= 1;
        chain_bi0 = ctx->tx_buffers[*n_bufs];
        chain_b = vlib_get_buffer (vm, chain_bi0);
        chain_b->current_data = 0;
        data = vlib_buffer_get_current (chain_b);
        if (peek_data)
  	{
  	  n_bytes_read = svm_fifo_peek (ctx->s->tx_fifo,
  					ctx->sp.tx_offset, len_to_deq, data);
  	  ctx->sp.tx_offset += n_bytes_read;
  	}
        else
  	{
  	  if (ctx->transport_vft->transport_options.tx_type ==
  	      TRANSPORT_TX_DGRAM)
  	    {
  	      svm_fifo_t *f = ctx->s->tx_fifo;
  	      session_dgram_hdr_t *hdr = &ctx->hdr;
  	      u16 deq_now;
  	      u32 offset;
  
  	      deq_now = clib_min (hdr->data_length - hdr->data_offset,
  				  len_to_deq);
  	      offset = hdr->data_offset + SESSION_CONN_HDR_LEN;
  	      n_bytes_read = svm_fifo_peek (f, offset, deq_now, data);
  	      ASSERT (n_bytes_read > 0);
  
  	      hdr->data_offset += n_bytes_read;
  	      if (hdr->data_offset == hdr->data_length)
  		{
  		  offset = hdr->data_length + SESSION_CONN_HDR_LEN;
  		  svm_fifo_dequeue_drop (f, offset);
  		  if (ctx->left_to_snd > n_bytes_read)
  		    svm_fifo_peek (ctx->s->tx_fifo, 0, sizeof (ctx->hdr),
  				   (u8 *) & ctx->hdr);
  		}
  	      else if (ctx->left_to_snd == n_bytes_read)
  		svm_fifo_overwrite_head (ctx->s->tx_fifo, (u8 *) & ctx->hdr,
  					 sizeof (session_dgram_pre_hdr_t));
  	    }
  	  else
  	    n_bytes_read = svm_fifo_dequeue (ctx->s->tx_fifo,
  					     len_to_deq, data);
  	}
        ASSERT (n_bytes_read == len_to_deq);
        chain_b->current_length = n_bytes_read;
        b->total_length_not_including_first_buffer += chain_b->current_length;
  
        /* update previous buffer */
        prev_b->next_buffer = chain_bi0;
        prev_b->flags |= VLIB_BUFFER_NEXT_PRESENT;
  
        /* update current buffer */
        chain_b->next_buffer = 0;
  
        to_deq -= n_bytes_read;
        if (to_deq == 0)
  	break;
      }
    ASSERT (to_deq == 0
  	  && b->total_length_not_including_first_buffer == left_from_seg);
    ctx->left_to_snd -= left_from_seg;
  }
  
  always_inline void
  session_tx_fill_buffer (vlib_main_t * vm, session_tx_context_t * ctx,
  			vlib_buffer_t * b, u16 * n_bufs, u8 peek_data)
  {
    u32 len_to_deq;
    u8 *data0;
    int n_bytes_read;
  
    /*
     * Start with the first buffer in chain
     */
    b->error = 0;
    b->flags = VNET_BUFFER_F_LOCALLY_ORIGINATED;
    b->current_data = 0;
  
    data0 = vlib_buffer_make_headroom (b, TRANSPORT_MAX_HDRS_LEN);
    len_to_deq = clib_min (ctx->left_to_snd, ctx->deq_per_first_buf);
  
    if (peek_data)
      {
        n_bytes_read = svm_fifo_peek (ctx->s->tx_fifo, ctx->sp.tx_offset,
  				    len_to_deq, data0);
        ASSERT (n_bytes_read > 0);
        /* Keep track of progress locally, transport is also supposed to
         * increment it independently when pushing the header */
        ctx->sp.tx_offset += n_bytes_read;
      }
    else
      {
        if (ctx->transport_vft->transport_options.tx_type == TRANSPORT_TX_DGRAM)
  	{
  	  session_dgram_hdr_t *hdr = &ctx->hdr;
  	  svm_fifo_t *f = ctx->s->tx_fifo;
  	  u16 deq_now;
  	  u32 offset;
  
  	  ASSERT (hdr->data_length > hdr->data_offset);
  	  deq_now = clib_min (hdr->data_length - hdr->data_offset,
  			      len_to_deq);
  	  offset = hdr->data_offset + SESSION_CONN_HDR_LEN;
  	  n_bytes_read = svm_fifo_peek (f, offset, deq_now, data0);
  	  ASSERT (n_bytes_read > 0);
  
  	  if (transport_connection_is_cless (ctx->tc))
  	    {
  	      ip_copy (&ctx->tc->rmt_ip, &hdr->rmt_ip, ctx->tc->is_ip4);
  	      ctx->tc->rmt_port = hdr->rmt_port;
  	    }
  	  hdr->data_offset += n_bytes_read;
  	  if (hdr->data_offset == hdr->data_length)
  	    {
  	      offset = hdr->data_length + SESSION_CONN_HDR_LEN;
  	      svm_fifo_dequeue_drop (f, offset);
  	      if (ctx->left_to_snd > n_bytes_read)
  		svm_fifo_peek (ctx->s->tx_fifo, 0, sizeof (ctx->hdr),
  			       (u8 *) & ctx->hdr);
  	    }
  	  else if (ctx->left_to_snd == n_bytes_read)
  	    svm_fifo_overwrite_head (ctx->s->tx_fifo, (u8 *) & ctx->hdr,
  				     sizeof (session_dgram_pre_hdr_t));
  	}
        else
  	{
  	  n_bytes_read = svm_fifo_dequeue (ctx->s->tx_fifo,
  					   len_to_deq, data0);
  	  ASSERT (n_bytes_read > 0);
  	}
      }
    b->current_length = n_bytes_read;
    ctx->left_to_snd -= n_bytes_read;
  
    /*
     * Fill in the remaining buffers in the chain, if any
     */
    if (PREDICT_FALSE (ctx->n_bufs_per_seg > 1 && ctx->left_to_snd))
      session_tx_fifo_chain_tail (vm, ctx, b, n_bufs, peek_data);
  }
  
  always_inline u8
  session_tx_not_ready (session_t * s, u8 peek_data)
  {
    if (peek_data)
      {
        if (PREDICT_TRUE (s->session_state == SESSION_STATE_READY))
  	return 0;
        /* Can retransmit for closed sessions but can't send new data if
         * session is not ready or closed */
        else if (s->session_state < SESSION_STATE_READY)
  	{
  	  /* Allow accepting session to send custom packets.
  	   * For instance, tcp want to send acks in established, but
  	   * the app has not called accept() yet */
  	  if (s->session_state == SESSION_STATE_ACCEPTING &&
  	      (s->flags & SESSION_F_CUSTOM_TX))
  	    return 0;
  	  return 1;
  	}
        else if (s->session_state >= SESSION_STATE_TRANSPORT_CLOSED)
  	{
  	  /* Allow closed transports to still send custom packets.
  	   * For instance, tcp may want to send acks in time-wait. */
  	  if (s->session_state != SESSION_STATE_TRANSPORT_DELETED
  	      && (s->flags & SESSION_F_CUSTOM_TX))
  	    return 0;
  	  return 2;
  	}
      }
    return 0;
  }
  
  always_inline transport_connection_t *
  session_tx_get_transport (session_tx_context_t * ctx, u8 peek_data)
  {
    if (peek_data)
      {
        return ctx->transport_vft->get_connection (ctx->s->connection_index,
  						 ctx->s->thread_index);
      }
    else
      {
        if (ctx->s->session_state == SESSION_STATE_LISTENING)
  	return ctx->transport_vft->get_listener (ctx->s->connection_index);
        else
  	{
  	  return ctx->transport_vft->get_connection (ctx->s->connection_index,
  						     ctx->s->thread_index);
  	}
      }
  }
  
  always_inline void
  session_tx_set_dequeue_params (vlib_main_t * vm, session_tx_context_t * ctx,
  			       u32 max_segs, u8 peek_data)
  {
    u32 n_bytes_per_buf, n_bytes_per_seg;
  
    n_bytes_per_buf = vlib_buffer_get_default_data_size (vm);
    ctx->max_dequeue = svm_fifo_max_dequeue_cons (ctx->s->tx_fifo);
  
    if (peek_data)
      {
        /* Offset in rx fifo from where to peek data */
        if (PREDICT_FALSE (ctx->sp.tx_offset >= ctx->max_dequeue))
  	{
  	  ctx->max_len_to_snd = 0;
  	  return;
  	}
        ctx->max_dequeue -= ctx->sp.tx_offset;
      }
    else
      {
        if (ctx->transport_vft->transport_options.tx_type == TRANSPORT_TX_DGRAM)
  	{
  	  u32 len, chain_limit;
  
  	  if (ctx->max_dequeue <= sizeof (ctx->hdr))
  	    {
  	      ctx->max_len_to_snd = 0;
  	      return;
  	    }
  
  	  svm_fifo_peek (ctx->s->tx_fifo, 0, sizeof (ctx->hdr),
  			 (u8 *) & ctx->hdr);
  	  ASSERT (ctx->hdr.data_length > ctx->hdr.data_offset);
  	  len = ctx->hdr.data_length - ctx->hdr.data_offset;
  
  	  /* Process multiple dgrams if smaller than min (buf_space, mss).
  	   * This avoids handling multiple dgrams if they require buffer
  	   * chains */
  	  chain_limit = clib_min (n_bytes_per_buf - TRANSPORT_MAX_HDRS_LEN,
  				  ctx->sp.snd_mss);
  	  if (ctx->hdr.data_length <= chain_limit)
  	    {
  	      u32 first_dgram_len, dgram_len, offset, max_offset;
  	      session_dgram_hdr_t hdr;
  
  	      ctx->sp.snd_mss = clib_min (ctx->sp.snd_mss, len);
  	      offset = ctx->hdr.data_length + sizeof (session_dgram_hdr_t);
  	      first_dgram_len = len;
  	      max_offset = clib_min (ctx->max_dequeue, 16 << 10);
  
  	      while (offset < max_offset)
  		{
  		  svm_fifo_peek (ctx->s->tx_fifo, offset, sizeof (ctx->hdr),
  				 (u8 *) & hdr);
  		  ASSERT (hdr.data_length > hdr.data_offset);
  		  dgram_len = hdr.data_length - hdr.data_offset;
  		  if (len + dgram_len > ctx->max_dequeue
  		      || first_dgram_len != dgram_len)
  		    break;
  		  len += dgram_len;
  		  offset += sizeof (hdr) + hdr.data_length;
  		}
  	    }
  
  	  ctx->max_dequeue = len;
  	}
      }
    ASSERT (ctx->max_dequeue > 0);
  
    /* Ensure we're not writing more than transport window allows */
    if (ctx->max_dequeue < ctx->sp.snd_space)
      {
        /* Constrained by tx queue. Try to send only fully formed segments */
        ctx->max_len_to_snd = (ctx->max_dequeue > ctx->sp.snd_mss) ?
  	(ctx->max_dequeue - (ctx->max_dequeue % ctx->sp.snd_mss)) :
  	ctx->max_dequeue;
        /* TODO Nagle ? */
      }
    else
      {
        /* Expectation is that snd_space0 is already a multiple of snd_mss */
        ctx->max_len_to_snd = ctx->sp.snd_space;
      }
  
    /* Check if we're tx constrained by the node */
    ctx->n_segs_per_evt = ceil ((f64) ctx->max_len_to_snd / ctx->sp.snd_mss);
    if (ctx->n_segs_per_evt > max_segs)
      {
        ctx->n_segs_per_evt = max_segs;
        ctx->max_len_to_snd = max_segs * ctx->sp.snd_mss;
      }
  
    ASSERT (n_bytes_per_buf > TRANSPORT_MAX_HDRS_LEN);
    if (ctx->n_segs_per_evt > 1)
      {
        u32 n_bytes_last_seg, n_bufs_last_seg;
  
        n_bytes_per_seg = TRANSPORT_MAX_HDRS_LEN + ctx->sp.snd_mss;
        n_bytes_last_seg = TRANSPORT_MAX_HDRS_LEN + ctx->max_len_to_snd
  	- ((ctx->n_segs_per_evt - 1) * ctx->sp.snd_mss);
        ctx->n_bufs_per_seg = ceil ((f64) n_bytes_per_seg / n_bytes_per_buf);
        n_bufs_last_seg = ceil ((f64) n_bytes_last_seg / n_bytes_per_buf);
        ctx->n_bufs_needed = ((ctx->n_segs_per_evt - 1) * ctx->n_bufs_per_seg)
  	+ n_bufs_last_seg;
      }
    else
      {
        n_bytes_per_seg = TRANSPORT_MAX_HDRS_LEN + ctx->max_len_to_snd;
        ctx->n_bufs_per_seg = ceil ((f64) n_bytes_per_seg / n_bytes_per_buf);
        ctx->n_bufs_needed = ctx->n_bufs_per_seg;
      }
  
    ctx->deq_per_buf = clib_min (ctx->sp.snd_mss, n_bytes_per_buf);
    ctx->deq_per_first_buf = clib_min (ctx->sp.snd_mss,
  				     n_bytes_per_buf -
  				     TRANSPORT_MAX_HDRS_LEN);
  }
  
  always_inline void
  session_tx_maybe_reschedule (session_worker_t * wrk,
  			     session_tx_context_t * ctx,
  			     session_evt_elt_t * elt)
  {
    session_t *s = ctx->s;
  
    svm_fifo_unset_event (s->tx_fifo);
    if (svm_fifo_max_dequeue_cons (s->tx_fifo) > ctx->sp.tx_offset)
      {
        if (svm_fifo_set_event (s->tx_fifo))
  	session_evt_add_head_old (wrk, elt);
      }
    else
      {
        transport_connection_deschedule (ctx->tc);
      }
  }
  
  always_inline int
  session_tx_fifo_read_and_snd_i (session_worker_t * wrk,
  				vlib_node_runtime_t * node,
  				session_evt_elt_t * elt,
  				int *n_tx_packets, u8 peek_data)
  {
    u32 n_trace, n_left, pbi, next_index, max_burst;
    session_tx_context_t *ctx = &wrk->ctx;
    session_main_t *smm = &session_main;
    session_event_t *e = &elt->evt;
    vlib_main_t *vm = wrk->vm;
    transport_proto_t tp;
    vlib_buffer_t *pb;
    u16 n_bufs, rv;
  
    if (PREDICT_FALSE ((rv = session_tx_not_ready (ctx->s, peek_data))))
      {
        if (rv < 2)
  	session_evt_add_old (wrk, elt);
        return SESSION_TX_NO_DATA;
      }
  
    next_index = smm->session_type_to_next[ctx->s->session_type];
    max_burst = SESSION_NODE_FRAME_SIZE - *n_tx_packets;
  
    tp = session_get_transport_proto (ctx->s);
    ctx->transport_vft = transport_protocol_get_vft (tp);
    ctx->tc = session_tx_get_transport (ctx, peek_data);
  
    if (PREDICT_FALSE (e->event_type == SESSION_IO_EVT_TX_FLUSH))
      {
        if (ctx->transport_vft->flush_data)
  	ctx->transport_vft->flush_data (ctx->tc);
        e->event_type = SESSION_IO_EVT_TX;
      }
  
    if (ctx->s->flags & SESSION_F_CUSTOM_TX)
      {
        u32 n_custom_tx;
        ctx->s->flags &= ~SESSION_F_CUSTOM_TX;
        ctx->sp.max_burst_size = max_burst;
        n_custom_tx = ctx->transport_vft->custom_tx (ctx->tc, &ctx->sp);
        *n_tx_packets += n_custom_tx;
        if (PREDICT_FALSE
  	  (ctx->s->session_state >= SESSION_STATE_TRANSPORT_CLOSED))
  	return SESSION_TX_OK;
        max_burst -= n_custom_tx;
        if (!max_burst || (ctx->s->flags & SESSION_F_CUSTOM_TX))
  	{
  	  session_evt_add_old (wrk, elt);
  	  return SESSION_TX_OK;
  	}
      }
  
    /* Connection previously descheduled because it had no data to send.
     * Clear descheduled flag and reset pacer if in use */
    if (transport_connection_is_descheduled (ctx->tc))
      transport_connection_clear_descheduled (ctx->tc);
  
    transport_connection_snd_params (ctx->tc, &ctx->sp);
  
    if (!ctx->sp.snd_space)
      {
        /* If the deschedule flag was set, remove session from scheduler.
         * Transport is responsible for rescheduling this session. */
        if (ctx->sp.flags & TRANSPORT_SND_F_DESCHED)
  	transport_connection_deschedule (ctx->tc);
        /* Request to postpone the session, e.g., zero-wnd and transport
         * is not currently probing */
        else if (ctx->sp.flags & TRANSPORT_SND_F_POSTPONE)
  	session_evt_add_old (wrk, elt);
        /* This flow queue is "empty" so it should be re-evaluated before
         * the ones that have data to send. */
        else
  	session_evt_add_head_old (wrk, elt);
  
        return SESSION_TX_NO_DATA;
      }
  
    if (transport_connection_is_tx_paced (ctx->tc))
      {
        u32 snd_space = transport_connection_tx_pacer_burst (ctx->tc);
        if (snd_space < TRANSPORT_PACER_MIN_BURST)
  	{
  	  session_evt_add_head_old (wrk, elt);
  	  return SESSION_TX_NO_DATA;
  	}
        snd_space = clib_min (ctx->sp.snd_space, snd_space);
        ctx->sp.snd_space = snd_space >= ctx->sp.snd_mss ?
  	snd_space - snd_space % ctx->sp.snd_mss : snd_space;
      }
  
    /* Check how much we can pull. */
    session_tx_set_dequeue_params (vm, ctx, max_burst, peek_data);
  
    if (PREDICT_FALSE (!ctx->max_len_to_snd))
      {
        transport_connection_tx_pacer_reset_bucket (ctx->tc, 0);
        session_tx_maybe_reschedule (wrk, ctx, elt);
        return SESSION_TX_NO_DATA;
      }
  
    vec_validate_aligned (ctx->tx_buffers, ctx->n_bufs_needed - 1,
  			CLIB_CACHE_LINE_BYTES);
    n_bufs = vlib_buffer_alloc (vm, ctx->tx_buffers, ctx->n_bufs_needed);
    if (PREDICT_FALSE (n_bufs < ctx->n_bufs_needed))
      {
        if (n_bufs)
  	vlib_buffer_free (vm, ctx->tx_buffers, n_bufs);
        session_evt_add_head_old (wrk, elt);
        vlib_node_increment_counter (wrk->vm, node->node_index,
  				   SESSION_QUEUE_ERROR_NO_BUFFER, 1);
        return SESSION_TX_NO_BUFFERS;
      }
  
    if (transport_connection_is_tx_paced (ctx->tc))
      transport_connection_tx_pacer_update_bytes (ctx->tc, ctx->max_len_to_snd);
  
    ctx->left_to_snd = ctx->max_len_to_snd;
    n_left = ctx->n_segs_per_evt;
  
    vec_validate (ctx->transport_pending_bufs, n_left);
  
    while (n_left >= 4)
      {
        vlib_buffer_t *b0, *b1;
        u32 bi0, bi1;
  
        pbi = ctx->tx_buffers[n_bufs - 3];
        pb = vlib_get_buffer (vm, pbi);
        vlib_prefetch_buffer_header (pb, STORE);
        pbi = ctx->tx_buffers[n_bufs - 4];
        pb = vlib_get_buffer (vm, pbi);
        vlib_prefetch_buffer_header (pb, STORE);
  
        bi0 = ctx->tx_buffers[--n_bufs];
        bi1 = ctx->tx_buffers[--n_bufs];
  
        b0 = vlib_get_buffer (vm, bi0);
        b1 = vlib_get_buffer (vm, bi1);
  
        session_tx_fill_buffer (vm, ctx, b0, &n_bufs, peek_data);
        session_tx_fill_buffer (vm, ctx, b1, &n_bufs, peek_data);
  
        ctx->transport_pending_bufs[ctx->n_segs_per_evt - n_left] = b0;
        ctx->transport_pending_bufs[ctx->n_segs_per_evt - n_left + 1] = b1;
        n_left -= 2;
  
        vec_add1 (wrk->pending_tx_buffers, bi0);
        vec_add1 (wrk->pending_tx_buffers, bi1);
        vec_add1 (wrk->pending_tx_nexts, next_index);
        vec_add1 (wrk->pending_tx_nexts, next_index);
      }
    while (n_left)
      {
        vlib_buffer_t *b0;
        u32 bi0;
  
        if (n_left > 1)
  	{
  	  pbi = ctx->tx_buffers[n_bufs - 2];
  	  pb = vlib_get_buffer (vm, pbi);
  	  vlib_prefetch_buffer_header (pb, STORE);
  	}
  
        bi0 = ctx->tx_buffers[--n_bufs];
        b0 = vlib_get_buffer (vm, bi0);
        session_tx_fill_buffer (vm, ctx, b0, &n_bufs, peek_data);
  
        ctx->transport_pending_bufs[ctx->n_segs_per_evt - n_left] = b0;
        n_left -= 1;
  
        vec_add1 (wrk->pending_tx_buffers, bi0);
        vec_add1 (wrk->pending_tx_nexts, next_index);
      }
  
    /* Ask transport to push headers */
    ctx->transport_vft->push_header (ctx->tc, ctx->transport_pending_bufs,
  				   ctx->n_segs_per_evt);
  
    if (PREDICT_FALSE ((n_trace = vlib_get_trace_count (vm, node)) > 0))
      session_tx_trace_frame (vm, node, next_index, wrk->pending_tx_buffers,
  			    ctx->n_segs_per_evt, ctx->s, n_trace);
  
    if (PREDICT_FALSE (n_bufs))
      vlib_buffer_free (vm, ctx->tx_buffers, n_bufs);
  
    *n_tx_packets += ctx->n_segs_per_evt;
  
    SESSION_EVT (SESSION_EVT_DEQ, ctx->s, ctx->max_len_to_snd, ctx->max_dequeue,
  	       ctx->s->tx_fifo->has_event, wrk->last_vlib_time);
  
    ASSERT (ctx->left_to_snd == 0);
  
    /* If we couldn't dequeue all bytes reschedule as old flow. Otherwise,
     * check if application enqueued more data and reschedule accordingly */
    if (ctx->max_len_to_snd < ctx->max_dequeue)
      session_evt_add_old (wrk, elt);
    else
      session_tx_maybe_reschedule (wrk, ctx, elt);
  
    if (!peek_data)
      {
        u32 n_dequeued = ctx->max_len_to_snd;
        if (ctx->transport_vft->transport_options.tx_type == TRANSPORT_TX_DGRAM)
  	n_dequeued += ctx->n_segs_per_evt * SESSION_CONN_HDR_LEN;
        if (svm_fifo_needs_deq_ntf (ctx->s->tx_fifo, n_dequeued))
  	session_dequeue_notify (ctx->s);
      }
    return SESSION_TX_OK;
  }
  
  int
  session_tx_fifo_peek_and_snd (session_worker_t * wrk,
  			      vlib_node_runtime_t * node,
  			      session_evt_elt_t * e, int *n_tx_packets)
  {
    return session_tx_fifo_read_and_snd_i (wrk, node, e, n_tx_packets, 1);
  }
  
  int
  session_tx_fifo_dequeue_and_snd (session_worker_t * wrk,
  				 vlib_node_runtime_t * node,
  				 session_evt_elt_t * e, int *n_tx_packets)
  {
    return session_tx_fifo_read_and_snd_i (wrk, node, e, n_tx_packets, 0);
  }
  
  int
  session_tx_fifo_dequeue_internal (session_worker_t * wrk,
  				  vlib_node_runtime_t * node,
  				  session_evt_elt_t * elt, int *n_tx_packets)
  {
    transport_send_params_t *sp = &wrk->ctx.sp;
    session_t *s = wrk->ctx.s;
    u32 n_packets;
  
    if (PREDICT_FALSE (s->session_state >= SESSION_STATE_TRANSPORT_CLOSED))
      return 0;
  
    /* Clear custom-tx flag used to request reschedule for tx */
    s->flags &= ~SESSION_F_CUSTOM_TX;
  
    sp->flags = 0;
    sp->bytes_dequeued = 0;
    sp->max_burst_size = clib_min (SESSION_NODE_FRAME_SIZE - *n_tx_packets,
  				 TRANSPORT_PACER_MAX_BURST_PKTS);
  
    n_packets = transport_custom_tx (session_get_transport_proto (s), s, sp);
    *n_tx_packets += n_packets;
  
    if (s->flags & SESSION_F_CUSTOM_TX)
      {
        session_evt_add_old (wrk, elt);
      }
    else if (!(sp->flags & TRANSPORT_SND_F_DESCHED))
      {
        svm_fifo_unset_event (s->tx_fifo);
        if (svm_fifo_max_dequeue_cons (s->tx_fifo))
  	if (svm_fifo_set_event (s->tx_fifo))
  	  session_evt_add_head_old (wrk, elt);
      }
  
    if (sp->bytes_dequeued &&
        svm_fifo_needs_deq_ntf (s->tx_fifo, sp->bytes_dequeued))
      session_dequeue_notify (s);
  
    return n_packets;
  }
  
  always_inline session_t *
  session_event_get_session (session_worker_t * wrk, session_event_t * e)
  {
    if (PREDICT_FALSE (pool_is_free_index (wrk->sessions, e->session_index)))
      return 0;
  
    ASSERT (session_is_valid (e->session_index, wrk->vm->thread_index));
    return pool_elt_at_index (wrk->sessions, e->session_index);
  }
  
  always_inline void
  session_event_dispatch_ctrl (session_worker_t * wrk, session_evt_elt_t * elt)
  {
    clib_llist_index_t ei;
    void (*fp) (void *);
    session_event_t *e;
    session_t *s;
  
    ei = clib_llist_entry_index (wrk->event_elts, elt);
    e = &elt->evt;
  
    switch (e->event_type)
      {
      case SESSION_CTRL_EVT_RPC:
        fp = e->rpc_args.fp;
        (*fp) (e->rpc_args.arg);
        break;
      case SESSION_CTRL_EVT_HALF_CLOSE:
        s = session_get_from_handle_if_valid (e->session_handle);
        if (PREDICT_FALSE (!s))
  	break;
        session_transport_half_close (s);
        break;
      case SESSION_CTRL_EVT_CLOSE:
        s = session_get_from_handle_if_valid (e->session_handle);
        if (PREDICT_FALSE (!s))
  	break;
        session_transport_close (s);
        break;
      case SESSION_CTRL_EVT_RESET:
        s = session_get_from_handle_if_valid (e->session_handle);
        if (PREDICT_FALSE (!s))
  	break;
        session_transport_reset (s);
        break;
      case SESSION_CTRL_EVT_LISTEN:
        session_mq_listen_handler (session_evt_ctrl_data (wrk, elt));
        break;
      case SESSION_CTRL_EVT_LISTEN_URI:
        session_mq_listen_uri_handler (session_evt_ctrl_data (wrk, elt));
        break;
      case SESSION_CTRL_EVT_UNLISTEN:
        session_mq_unlisten_handler (wrk, elt);
        break;
      case SESSION_CTRL_EVT_CONNECT:
        session_mq_connect_handler (wrk, elt);
        break;
      case SESSION_CTRL_EVT_CONNECT_URI:
        session_mq_connect_uri_handler (session_evt_ctrl_data (wrk, elt));
        break;
      case SESSION_CTRL_EVT_SHUTDOWN:
        session_mq_shutdown_handler (session_evt_ctrl_data (wrk, elt));
        break;
      case SESSION_CTRL_EVT_DISCONNECT:
        session_mq_disconnect_handler (session_evt_ctrl_data (wrk, elt));
        break;
      case SESSION_CTRL_EVT_DISCONNECTED:
        session_mq_disconnected_handler (session_evt_ctrl_data (wrk, elt));
        break;
      case SESSION_CTRL_EVT_ACCEPTED_REPLY:
        session_mq_accepted_reply_handler (session_evt_ctrl_data (wrk, elt));
        break;
      case SESSION_CTRL_EVT_DISCONNECTED_REPLY:
        session_mq_disconnected_reply_handler (session_evt_ctrl_data (wrk,
  								    elt));
        break;
      case SESSION_CTRL_EVT_RESET_REPLY:
        session_mq_reset_reply_handler (session_evt_ctrl_data (wrk, elt));
        break;
      case SESSION_CTRL_EVT_WORKER_UPDATE:
        session_mq_worker_update_handler (session_evt_ctrl_data (wrk, elt));
        break;
      case SESSION_CTRL_EVT_APP_DETACH:
        app_mq_detach_handler (session_evt_ctrl_data (wrk, elt));
        break;
      case SESSION_CTRL_EVT_APP_WRK_RPC:
        session_mq_app_wrk_rpc_handler (session_evt_ctrl_data (wrk, elt));
        break;
      case SESSION_CTRL_EVT_TRANSPORT_ATTR:
        session_mq_transport_attr_handler (session_evt_ctrl_data (wrk, elt));
        break;
      default:
        clib_warning ("unhandled event type %d", e->event_type);
      }
  
    /* Regrab elements in case pool moved */
    elt = clib_llist_elt (wrk->event_elts, ei);
    if (!clib_llist_elt_is_linked (elt, evt_list))
      {
        e = &elt->evt;
        if (e->event_type >= SESSION_CTRL_EVT_BOUND)
  	session_evt_ctrl_data_free (wrk, elt);
        clib_llist_put (wrk->event_elts, elt);
      }
    SESSION_EVT (SESSION_EVT_COUNTS, CNT_CTRL_EVTS, 1, wrk);
  }
  
  always_inline void
  session_event_dispatch_io (session_worker_t * wrk, vlib_node_runtime_t * node,
  			   session_evt_elt_t * elt, int *n_tx_packets)
  {
    session_main_t *smm = &session_main;
    app_worker_t *app_wrk;
    clib_llist_index_t ei;
    session_event_t *e;
    session_t *s;
  
    ei = clib_llist_entry_index (wrk->event_elts, elt);
    e = &elt->evt;
  
    switch (e->event_type)
      {
      case SESSION_IO_EVT_TX_FLUSH:
      case SESSION_IO_EVT_TX:
        s = session_event_get_session (wrk, e);
        if (PREDICT_FALSE (!s))
  	break;
        CLIB_PREFETCH (s->tx_fifo, sizeof (*(s->tx_fifo)), LOAD);
        wrk->ctx.s = s;
        /* Spray packets in per session type frames, since they go to
         * different nodes */
        (smm->session_tx_fns[s->session_type]) (wrk, node, elt, n_tx_packets);
        break;
      case SESSION_IO_EVT_RX:
        s = session_event_get_session (wrk, e);
        if (!s)
  	break;
        transport_app_rx_evt (session_get_transport_proto (s),
  			    s->connection_index, s->thread_index);
        break;
      case SESSION_IO_EVT_BUILTIN_RX:
        s = session_event_get_session (wrk, e);
        if (PREDICT_FALSE (!s || s->session_state >= SESSION_STATE_CLOSING))
  	break;
        svm_fifo_unset_event (s->rx_fifo);
        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);
        wrk->ctx.s = s;
        if (PREDICT_TRUE (s != 0))
  	session_tx_fifo_dequeue_internal (wrk, node, elt, n_tx_packets);
        break;
      default:
        clib_warning ("unhandled event type %d", e->event_type);
      }
  
    SESSION_EVT (SESSION_IO_EVT_COUNTS, e->event_type, 1, wrk);
  
    /* Regrab elements in case pool moved */
    elt = clib_llist_elt (wrk->event_elts, ei);
    if (!clib_llist_elt_is_linked (elt, evt_list))
      clib_llist_put (wrk->event_elts, elt);
  }
  
  /* *INDENT-OFF* */
  static const u32 session_evt_msg_sizes[] = {
  #define _(symc, sym) 							\
    [SESSION_CTRL_EVT_ ## symc] = sizeof (session_ ## sym ##_msg_t),
    foreach_session_ctrl_evt
  #undef _
  };
  /* *INDENT-ON* */
  
  always_inline void
  session_update_time_subscribers (session_main_t *smm, clib_time_type_t now,
  				 u32 thread_index)
  {
    session_update_time_fn *fn;
  
    vec_foreach (fn, smm->update_time_fns)
      (*fn) (now, thread_index);
  }
  
  always_inline void
  session_evt_add_to_list (session_worker_t * wrk, session_event_t * evt)
  {
    session_evt_elt_t *elt;
  
    if (evt->event_type >= SESSION_CTRL_EVT_RPC)
      {
        elt = session_evt_alloc_ctrl (wrk);
        if (evt->event_type >= SESSION_CTRL_EVT_BOUND)
  	{
  	  elt->evt.ctrl_data_index = session_evt_ctrl_data_alloc (wrk);
  	  elt->evt.event_type = evt->event_type;
  	  clib_memcpy_fast (session_evt_ctrl_data (wrk, elt), evt->data,
  			    session_evt_msg_sizes[evt->event_type]);
  	}
        else
  	{
  	  /* Internal control events fit into io events footprint */
  	  clib_memcpy_fast (&elt->evt, evt, sizeof (elt->evt));
  	}
      }
    else
      {
        elt = session_evt_alloc_new (wrk);
        clib_memcpy_fast (&elt->evt, evt, sizeof (elt->evt));
      }
  }
  
  static void
  session_flush_pending_tx_buffers (session_worker_t * wrk,
  				  vlib_node_runtime_t * node)
  {
    vlib_buffer_enqueue_to_next_vec (wrk->vm, node, &wrk->pending_tx_buffers,
  				   &wrk->pending_tx_nexts,
  				   vec_len (wrk->pending_tx_nexts));
    vec_reset_length (wrk->pending_tx_buffers);
    vec_reset_length (wrk->pending_tx_nexts);
  }
  
  int
  session_wrk_handle_mq (session_worker_t *wrk, svm_msg_q_t *mq)
  {
    svm_msg_q_msg_t _msg, *msg = &_msg;
    u32 i, n_to_dequeue = 0;
    session_event_t *evt;
  
    n_to_dequeue = svm_msg_q_size (mq);
    for (i = 0; i < n_to_dequeue; i++)
      {
        svm_msg_q_sub_raw (mq, msg);
        evt = svm_msg_q_msg_data (mq, msg);
        session_evt_add_to_list (wrk, evt);
        svm_msg_q_free_msg (mq, msg);
      }
  
    return n_to_dequeue;
  }
  
  static void
  session_wrk_update_state (session_worker_t *wrk)
  {
    vlib_main_t *vm = wrk->vm;
  
    if (wrk->state == SESSION_WRK_POLLING)
      {
        if (clib_llist_elts (wrk->event_elts) == 4 &&
  	  vlib_last_vectors_per_main_loop (vm) < 1)
  	{
  	  session_wrk_set_state (wrk, SESSION_WRK_INTERRUPT);
  	  vlib_node_set_state (vm, session_queue_node.index,
  			       VLIB_NODE_STATE_INTERRUPT);
  	}
      }
    else if (wrk->state == SESSION_WRK_INTERRUPT)
      {
        if (clib_llist_elts (wrk->event_elts) > 4 ||
  	  vlib_last_vectors_per_main_loop (vm) > 1)
  	{
  	  session_wrk_set_state (wrk, SESSION_WRK_POLLING);
  	  vlib_node_set_state (vm, session_queue_node.index,
  			       VLIB_NODE_STATE_POLLING);
  	}
        else if (PREDICT_FALSE (!pool_elts (wrk->sessions)))
  	{
  	  session_wrk_set_state (wrk, SESSION_WRK_IDLE);
  	}
      }
    else
      {
        if (clib_llist_elts (wrk->event_elts))
  	{
  	  session_wrk_set_state (wrk, SESSION_WRK_INTERRUPT);
  	}
      }
  }
  
  static uword
  session_queue_node_fn (vlib_main_t * vm, vlib_node_runtime_t * node,
  		       vlib_frame_t * frame)
  {
    u32 thread_index = vm->thread_index, __clib_unused n_evts;
    session_evt_elt_t *elt, *ctrl_he, *new_he, *old_he;
    session_main_t *smm = vnet_get_session_main ();
    session_worker_t *wrk = &smm->wrk[thread_index];
    clib_llist_index_t ei, next_ei, old_ti;
    int n_tx_packets;
  
    SESSION_EVT (SESSION_EVT_DISPATCH_START, wrk);
  
    session_wrk_update_time (wrk, vlib_time_now (vm));
  
    /*
     *  Update transport time
     */
    session_update_time_subscribers (smm, wrk->last_vlib_time, thread_index);
    n_tx_packets = vec_len (wrk->pending_tx_buffers);
    SESSION_EVT (SESSION_EVT_DSP_CNTRS, UPDATE_TIME, wrk);
  
    /*
     *  Dequeue new internal mq events
     */
  
    n_evts = session_wrk_handle_mq (wrk, wrk->vpp_event_queue);
    SESSION_EVT (SESSION_EVT_DSP_CNTRS, MQ_DEQ, wrk, n_evts);
  
    /*
     * Handle control events
     */
  
    ei = wrk->ctrl_head;
    ctrl_he = clib_llist_elt (wrk->event_elts, ei);
    next_ei = clib_llist_next_index (ctrl_he, evt_list);
    old_ti = clib_llist_prev_index (ctrl_he, evt_list);
    while (ei != old_ti)
      {
        ei = next_ei;
        elt = clib_llist_elt (wrk->event_elts, next_ei);
        next_ei = clib_llist_next_index (elt, evt_list);
        clib_llist_remove (wrk->event_elts, evt_list, elt);
        session_event_dispatch_ctrl (wrk, elt);
      }
  
    SESSION_EVT (SESSION_EVT_DSP_CNTRS, CTRL_EVTS, wrk);
  
    /*
     * Handle the new io events.
     */
  
    new_he = clib_llist_elt (wrk->event_elts, wrk->new_head);
    old_he = clib_llist_elt (wrk->event_elts, wrk->old_head);
    old_ti = clib_llist_prev_index (old_he, evt_list);
  
    ei = clib_llist_next_index (new_he, evt_list);
    while (ei != wrk->new_head && n_tx_packets < SESSION_NODE_FRAME_SIZE)
      {
        elt = clib_llist_elt (wrk->event_elts, ei);
        ei = clib_llist_next_index (elt, evt_list);
        clib_llist_remove (wrk->event_elts, evt_list, elt);
        session_event_dispatch_io (wrk, node, elt, &n_tx_packets);
      }
  
    SESSION_EVT (SESSION_EVT_DSP_CNTRS, NEW_IO_EVTS, wrk);
  
    /*
     * Handle the old io events, if we had any prior to processing the new ones
     */
  
    if (old_ti != wrk->old_head)
      {
        old_he = clib_llist_elt (wrk->event_elts, wrk->old_head);
        ei = clib_llist_next_index (old_he, evt_list);
  
        while (n_tx_packets < SESSION_NODE_FRAME_SIZE)
  	{
  	  elt = clib_llist_elt (wrk->event_elts, ei);
  	  next_ei = clib_llist_next_index (elt, evt_list);
  	  clib_llist_remove (wrk->event_elts, evt_list, elt);
  
  	  session_event_dispatch_io (wrk, node, elt, &n_tx_packets);
  
  	  if (ei == old_ti)
  	    break;
  
  	  ei = next_ei;
  	};
      }
  
    SESSION_EVT (SESSION_EVT_DSP_CNTRS, OLD_IO_EVTS, wrk);
  
    if (vec_len (wrk->pending_tx_buffers))
      session_flush_pending_tx_buffers (wrk, node);
  
    vlib_node_increment_counter (vm, session_queue_node.index,
  			       SESSION_QUEUE_ERROR_TX, n_tx_packets);
  
    SESSION_EVT (SESSION_EVT_DISPATCH_END, wrk, n_tx_packets);
  
    if (wrk->flags & SESSION_WRK_F_ADAPTIVE)
      session_wrk_update_state (wrk);
  
    return n_tx_packets;
  }
  
  /* *INDENT-OFF* */
  VLIB_REGISTER_NODE (session_queue_node) = {
    .function = session_queue_node_fn,
    .flags = VLIB_NODE_FLAG_TRACE_SUPPORTED,
    .name = "session-queue",
    .format_trace = format_session_queue_trace,
    .type = VLIB_NODE_TYPE_INPUT,
    .n_errors = SESSION_QUEUE_N_ERROR,
    .error_counters = session_error_counters,
    .state = VLIB_NODE_STATE_DISABLED,
  };
  /* *INDENT-ON* */
  
  static clib_error_t *
  session_wrk_tfd_read_ready (clib_file_t *cf)
  {
    session_worker_t *wrk = session_main_get_worker (cf->private_data);
    u64 buf;
    int rv;
  
    vlib_node_set_interrupt_pending (wrk->vm, session_queue_node.index);
    rv = read (wrk->timerfd, &buf, sizeof (buf));
    if (rv < 0 && errno != EAGAIN)
      clib_unix_warning ("failed");
    return 0;
  }
  
  static clib_error_t *
  session_wrk_tfd_write_ready (clib_file_t *cf)
  {
    return 0;
  }
  
  void
  session_wrk_enable_adaptive_mode (session_worker_t *wrk)
  {
    u32 thread_index = wrk->vm->thread_index;
    clib_file_t template = { 0 };
  
    if ((wrk->timerfd = timerfd_create (CLOCK_MONOTONIC, TFD_NONBLOCK)) < 0)
      clib_warning ("timerfd_create");
  
    template.read_function = session_wrk_tfd_read_ready;
    template.write_function = session_wrk_tfd_write_ready;
    template.file_descriptor = wrk->timerfd;
    template.private_data = thread_index;
    template.polling_thread_index = thread_index;
    template.description = format (0, "session-wrk-tfd-%u", thread_index);
  
    wrk->timerfd_file = clib_file_add (&file_main, &template);
    wrk->flags |= SESSION_WRK_F_ADAPTIVE;
  }
  
  static clib_error_t *
  session_queue_exit (vlib_main_t * vm)
  {
    if (vlib_get_n_threads () < 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);
  
  static uword
  session_queue_run_on_main (vlib_main_t * vm)
  {
    vlib_node_runtime_t *node;
  
    node = vlib_node_get_runtime (vm, session_queue_node.index);
    return session_queue_node_fn (vm, node, 0);
  }
  
  static uword
  session_queue_process (vlib_main_t * vm, vlib_node_runtime_t * rt,
  		       vlib_frame_t * f)
  {
    uword *event_data = 0;
    f64 timeout = 1.0;
    uword event_type;
  
    while (1)
      {
        vlib_process_wait_for_event_or_clock (vm, timeout);
        event_type = vlib_process_get_events (vm, (uword **) & event_data);
  
        switch (event_type)
  	{
  	case SESSION_Q_PROCESS_RUN_ON_MAIN:
  	  /* Run session queue node on main thread */
  	  session_queue_run_on_main (vm);
  	  break;
  	case SESSION_Q_PROCESS_STOP:
  	  vlib_node_set_state (vm, session_queue_process_node.index,
  			       VLIB_NODE_STATE_DISABLED);
  	  timeout = 100000.0;
  	  break;
  	case ~0:
  	  /* Timed out. Run on main to ensure all events are handled */
  	  session_queue_run_on_main (vm);
  	  break;
  	}
        vec_reset_length (event_data);
      }
    return 0;
  }
  
  /* *INDENT-OFF* */
  VLIB_REGISTER_NODE (session_queue_process_node) =
  {
    .function = session_queue_process,
    .type = VLIB_NODE_TYPE_PROCESS,
    .name = "session-queue-process",
    .state = VLIB_NODE_STATE_DISABLED,
  };
  /* *INDENT-ON* */
  
  static_always_inline uword
  session_queue_pre_input_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
  				vlib_frame_t * frame)
  {
    session_main_t *sm = &session_main;
    if (!sm->wrk[0].vpp_event_queue)
      return 0;
    node = vlib_node_get_runtime (vm, session_queue_node.index);
    return session_queue_node_fn (vm, node, frame);
  }
  
  /* *INDENT-OFF* */
  VLIB_REGISTER_NODE (session_queue_pre_input_node) =
  {
    .function = session_queue_pre_input_inline,
    .type = VLIB_NODE_TYPE_PRE_INPUT,
    .name = "session-queue-main",
    .state = VLIB_NODE_STATE_DISABLED,
  };
  /* *INDENT-ON* */
  
  /*
   * fd.io coding-style-patch-verification: ON
   *
   * Local Variables:
   * eval: (c-set-style "gnu")
   * End:
   */
  