vcl: keep track of unexpected events

If sessions are marked as blocking, events for other sessions received
while waiting for the blocking sessions, are added to a pending list and
processed later.

Change-Id: Ia6c71006b1c2bcb78af708390da0cd436af397cc
Signed-off-by: Florin Coras <fcoras@cisco.com>

1 files changed, 293 insertions, 251 deletions

diff --git a/src/vcl/vppcom.c b/src/vcl/vppcom.c
index df8f4cae964..cf3a770f045 100644
--- a/src/vcl/vppcom.c
+++ b/src/vcl/vppcom.c
@@ -478,8 +478,8 @@ vcl_session_bound_handler (vcl_worker_t * wrk, session_bound_msg_t * mp)
   return sid;
 }
 
-int
-vcl_handle_mq_ctrl_event (vcl_worker_t * wrk, session_event_t * e)
+static int
+vcl_handle_mq_event (vcl_worker_t * wrk, session_event_t * e)
 {
   session_accepted_msg_t *accepted_msg;
   session_disconnected_msg_t *disconnected_msg;
@@ -491,9 +491,10 @@ vcl_handle_mq_ctrl_event (vcl_worker_t * wrk, session_event_t * e)
   switch (e->event_type)
     {
     case FIFO_EVENT_APP_RX:
-      clib_warning ("unhandled rx: sid %u (0x%x)",
-		    e->fifo->client_session_index,
-		    e->fifo->client_session_index);
+    case FIFO_EVENT_APP_TX:
+    case SESSION_IO_EVT_CT_RX:
+    case SESSION_IO_EVT_CT_TX:
+      vec_add1 (wrk->unhandled_evts_vector, *e);
       break;
     case SESSION_CTRL_EVT_ACCEPTED:
       accepted_msg = (session_accepted_msg_t *) e->data;
@@ -524,7 +525,7 @@ vcl_handle_mq_ctrl_event (vcl_worker_t * wrk, session_event_t * e)
 	  break;
 	}
       session->session_state = STATE_DISCONNECT;
-      VDBG (0, "disconnected handle 0xllx, sid %u", disconnected_msg->handle,
+      VDBG (0, "disconnected handle 0x%llx, sid %u", disconnected_msg->handle,
 	    sid);
       break;
     case SESSION_CTRL_EVT_RESET:
@@ -569,7 +570,7 @@ vppcom_wait_for_session_state_change (u32 session_index,
       if (svm_msg_q_sub (wrk->app_event_queue, &msg, SVM_Q_NOWAIT, 0))
 	continue;
       e = svm_msg_q_msg_data (wrk->app_event_queue, &msg);
-      vcl_handle_mq_ctrl_event (wrk, e);
+      vcl_handle_mq_event (wrk, e);
       svm_msg_q_free_msg (wrk->app_event_queue, &msg);
     }
   while (clib_time_now (&wrk->clib_time) < timeout);
@@ -1313,7 +1314,7 @@ vppcom_session_read_internal (uint32_t session_handle, void *buf, int n,
 	  svm_msg_q_unlock (mq);
 	  if (!vcl_is_rx_evt_for_session (e, s->session_index, is_ct))
 	    {
-	      vcl_handle_mq_ctrl_event (wrk, e);
+	      vcl_handle_mq_event (wrk, e);
 	      svm_msg_q_free_msg (mq, &msg);
 	      continue;
 	    }
@@ -1406,7 +1407,7 @@ vppcom_session_read_segments (uint32_t session_handle,
 	  svm_msg_q_unlock (mq);
 	  if (!vcl_is_rx_evt_for_session (e, s->session_index, is_ct))
 	    {
-	      vcl_handle_mq_ctrl_event (wrk, e);
+	      vcl_handle_mq_event (wrk, e);
 	      svm_msg_q_free_msg (mq, &msg);
 	      continue;
 	    }
@@ -1559,7 +1560,7 @@ vppcom_session_write (uint32_t session_handle, void *buf, size_t n)
 
 	  if (!vcl_is_tx_evt_for_session (e, s->session_index,
 					  s->our_evt_q != 0))
-	    vcl_handle_mq_ctrl_event (wrk, e);
+	    vcl_handle_mq_event (wrk, e);
 	  svm_msg_q_free_msg (mq, &msg);
 	}
     }
@@ -1680,21 +1681,124 @@ if (PREDICT_FALSE (svm_fifo_is_empty (_fifo)))			\
       break;							\
   }								\
 
-static int
-vcl_select_handle_mq (vcl_worker_t * wrk, svm_msg_q_t * mq,
-		      unsigned long n_bits, unsigned long *read_map,
-		      unsigned long *write_map, unsigned long *except_map,
-		      double time_to_wait, u32 * bits_set)
+static void
+vcl_select_handle_mq_event (vcl_worker_t * wrk, session_event_t * e,
+			    unsigned long n_bits, unsigned long *read_map,
+			    unsigned long *write_map,
+			    unsigned long *except_map, u32 * bits_set)
 {
   session_disconnected_msg_t *disconnected_msg;
   session_connected_msg_t *connected_msg;
   session_accepted_msg_t *accepted_msg;
   vcl_session_msg_t *vcl_msg;
   vcl_session_t *session;
+  u64 handle;
+  u32 sid;
+
+  switch (e->event_type)
+    {
+    case FIFO_EVENT_APP_RX:
+      vcl_fifo_rx_evt_valid_or_break (e->fifo);
+      sid = e->fifo->client_session_index;
+      session = vcl_session_get (wrk, sid);
+      if (!session)
+	break;
+      if (sid < n_bits && read_map)
+	{
+	  clib_bitmap_set_no_check (read_map, sid, 1);
+	  *bits_set += 1;
+	}
+      break;
+    case FIFO_EVENT_APP_TX:
+      sid = e->fifo->client_session_index;
+      session = vcl_session_get (wrk, sid);
+      if (!session)
+	break;
+      if (sid < n_bits && write_map)
+	{
+	  clib_bitmap_set_no_check (write_map, sid, 1);
+	  *bits_set += 1;
+	}
+      break;
+    case SESSION_IO_EVT_CT_TX:
+      vcl_fifo_rx_evt_valid_or_break (e->fifo);
+      session = vcl_ct_session_get_from_fifo (wrk, e->fifo, 0);
+      if (!session)
+	break;
+      sid = session->session_index;
+      if (sid < n_bits && read_map)
+	{
+	  clib_bitmap_set_no_check (read_map, sid, 1);
+	  *bits_set += 1;
+	}
+      break;
+    case SESSION_IO_EVT_CT_RX:
+      session = vcl_ct_session_get_from_fifo (wrk, e->fifo, 1);
+      if (!session)
+	break;
+      sid = session->session_index;
+      if (sid < n_bits && write_map)
+	{
+	  clib_bitmap_set_no_check (write_map, sid, 1);
+	  *bits_set += 1;
+	}
+      break;
+    case SESSION_CTRL_EVT_ACCEPTED:
+      accepted_msg = (session_accepted_msg_t *) e->data;
+      handle = accepted_msg->listener_handle;
+      session = vcl_session_table_lookup_listener (wrk, handle);
+      if (!session)
+	{
+	  clib_warning ("VCL<%d>: ERROR: couldn't find listen session:"
+			"listener handle %llx", getpid (), handle);
+	  break;
+	}
+
+      clib_fifo_add2 (session->accept_evts_fifo, vcl_msg);
+      vcl_msg->accepted_msg = *accepted_msg;
+      sid = session->session_index;
+      if (sid < n_bits && read_map)
+	{
+	  clib_bitmap_set_no_check (read_map, sid, 1);
+	  *bits_set += 1;
+	}
+      break;
+    case SESSION_CTRL_EVT_CONNECTED:
+      connected_msg = (session_connected_msg_t *) e->data;
+      vcl_session_connected_handler (wrk, connected_msg);
+      break;
+    case SESSION_CTRL_EVT_DISCONNECTED:
+      disconnected_msg = (session_disconnected_msg_t *) e->data;
+      sid = vcl_session_index_from_vpp_handle (wrk, disconnected_msg->handle);
+      if (sid < n_bits && except_map)
+	{
+	  clib_bitmap_set_no_check (except_map, sid, 1);
+	  *bits_set += 1;
+	}
+      break;
+    case SESSION_CTRL_EVT_RESET:
+      sid = vcl_session_reset_handler (wrk, (session_reset_msg_t *) e->data);
+      if (sid < n_bits && except_map)
+	{
+	  clib_bitmap_set_no_check (except_map, sid, 1);
+	  *bits_set += 1;
+	}
+      break;
+    default:
+      clib_warning ("unhandled: %u", e->event_type);
+      break;
+    }
+}
+
+static int
+vcl_select_handle_mq (vcl_worker_t * wrk, svm_msg_q_t * mq,
+		      unsigned long n_bits, unsigned long *read_map,
+		      unsigned long *write_map, unsigned long *except_map,
+		      double time_to_wait, u32 * bits_set)
+{
   svm_msg_q_msg_t *msg;
   session_event_t *e;
-  u32 i, sid;
-  u64 handle;
+  u32 i;
 
   svm_msg_q_lock (mq);
   if (svm_msg_q_is_empty (mq))
@@ -1730,104 +1834,10 @@ vcl_select_handle_mq (vcl_worker_t * wrk, svm_msg_q_t * mq,
     {
       msg = vec_elt_at_index (wrk->mq_msg_vector, i);
       e = svm_msg_q_msg_data (mq, msg);
-      switch (e->event_type)
-	{
-	case FIFO_EVENT_APP_RX:
-	  vcl_fifo_rx_evt_valid_or_break (e->fifo);
-	  sid = e->fifo->client_session_index;
-	  session = vcl_session_get (wrk, sid);
-	  if (!session)
-	    break;
-	  if (sid < n_bits && read_map)
-	    {
-	      clib_bitmap_set_no_check (read_map, sid, 1);
-	      *bits_set += 1;
-	    }
-	  break;
-	case FIFO_EVENT_APP_TX:
-	  sid = e->fifo->client_session_index;
-	  session = vcl_session_get (wrk, sid);
-	  if (!session)
-	    break;
-	  if (sid < n_bits && write_map)
-	    {
-	      clib_bitmap_set_no_check (write_map, sid, 1);
-	      *bits_set += 1;
-	    }
-	  break;
-	case SESSION_IO_EVT_CT_TX:
-	  vcl_fifo_rx_evt_valid_or_break (e->fifo);
-	  session = vcl_ct_session_get_from_fifo (wrk, e->fifo, 0);
-	  if (!session)
-	    break;
-	  sid = session->session_index;
-	  if (sid < n_bits && read_map)
-	    {
-	      clib_bitmap_set_no_check (read_map, sid, 1);
-	      *bits_set += 1;
-	    }
-	  break;
-	case SESSION_IO_EVT_CT_RX:
-	  session = vcl_ct_session_get_from_fifo (wrk, e->fifo, 1);
-	  if (!session)
-	    break;
-	  sid = session->session_index;
-	  if (sid < n_bits && write_map)
-	    {
-	      clib_bitmap_set_no_check (write_map, sid, 1);
-	      *bits_set += 1;
-	    }
-	  break;
-	case SESSION_CTRL_EVT_ACCEPTED:
-	  accepted_msg = (session_accepted_msg_t *) e->data;
-	  handle = accepted_msg->listener_handle;
-	  session = vcl_session_table_lookup_listener (wrk, handle);
-	  if (!session)
-	    {
-	      clib_warning ("VCL<%d>: ERROR: couldn't find listen session:"
-			    "listener handle %llx", getpid (), handle);
-	      break;
-	    }
-
-	  clib_fifo_add2 (session->accept_evts_fifo, vcl_msg);
-	  vcl_msg->accepted_msg = *accepted_msg;
-	  sid = session->session_index;
-	  if (sid < n_bits && read_map)
-	    {
-	      clib_bitmap_set_no_check (read_map, sid, 1);
-	      *bits_set += 1;
-	    }
-	  break;
-	case SESSION_CTRL_EVT_CONNECTED:
-	  connected_msg = (session_connected_msg_t *) e->data;
-	  vcl_session_connected_handler (wrk, connected_msg);
-	  break;
-	case SESSION_CTRL_EVT_DISCONNECTED:
-	  disconnected_msg = (session_disconnected_msg_t *) e->data;
-	  sid = vcl_session_index_from_vpp_handle (wrk,
-						   disconnected_msg->handle);
-	  if (sid < n_bits && except_map)
-	    {
-	      clib_bitmap_set_no_check (except_map, sid, 1);
-	      *bits_set += 1;
-	    }
-	  break;
-	case SESSION_CTRL_EVT_RESET:
-	  sid = vcl_session_reset_handler (wrk,
-					   (session_reset_msg_t *) e->data);
-	  if (sid < n_bits && except_map)
-	    {
-	      clib_bitmap_set_no_check (except_map, sid, 1);
-	      *bits_set += 1;
-	    }
-	  break;
-	default:
-	  clib_warning ("unhandled: %u", e->event_type);
-	  break;
-	}
+      vcl_select_handle_mq_event (wrk, e, n_bits, read_map, write_map,
+				  except_map, bits_set);
       svm_msg_q_free_msg (mq, msg);
     }
-
   vec_reset_length (wrk->mq_msg_vector);
   return *bits_set;
 }
@@ -1898,7 +1908,7 @@ vppcom_select (unsigned long n_bits, unsigned long *read_map,
   u32 sid, minbits = clib_max (n_bits, BITS (uword)), bits_set = 0;
   vcl_worker_t *wrk = vcl_worker_get_current ();
   vcl_session_t *session = 0;
-  int rv;
+  int rv, i;
 
   ASSERT (sizeof (clib_bitmap_t) == sizeof (long int));
 
@@ -1972,6 +1982,13 @@ check_rd:
 
 check_mq:
 
+  for (i = 0; i < vec_len (wrk->unhandled_evts_vector); i++)
+    {
+      vcl_select_handle_mq_event (wrk, &wrk->unhandled_evts_vector[i], n_bits,
+				  read_map, write_map, except_map, &bits_set);
+    }
+  vec_reset_length (wrk->unhandled_evts_vector);
+
   if (vcm->cfg.use_mq_eventfd)
     vppcom_select_eventfd (wrk, n_bits, read_map, write_map, except_map,
 			   time_to_wait, &bits_set);
@@ -2275,10 +2292,9 @@ done:
   return rv;
 }
 
-static int
-vcl_epoll_wait_handle_mq (vcl_worker_t * wrk, svm_msg_q_t * mq,
-			  struct epoll_event *events, u32 maxevents,
-			  double wait_for_time, u32 * num_ev)
+static inline void
+vcl_epoll_wait_handle_mq_event (vcl_worker_t * wrk, session_event_t * e,
+				struct epoll_event *events, u32 * num_ev)
 {
   session_disconnected_msg_t *disconnected_msg;
   session_connected_msg_t *connected_msg;
@@ -2287,9 +2303,131 @@ vcl_epoll_wait_handle_mq (vcl_worker_t * wrk, svm_msg_q_t * mq,
   u32 sid = ~0, session_events;
   vcl_session_msg_t *vcl_msg;
   vcl_session_t *session;
+  u8 add_event = 0;
+
+  switch (e->event_type)
+    {
+    case FIFO_EVENT_APP_RX:
+      ASSERT (e->fifo->client_thread_index == vcl_get_worker_index ());
+      vcl_fifo_rx_evt_valid_or_break (e->fifo);
+      sid = e->fifo->client_session_index;
+      session = vcl_session_get (wrk, sid);
+      session_events = session->vep.ev.events;
+      if (!(EPOLLIN & session->vep.ev.events))
+	break;
+      add_event = 1;
+      events[*num_ev].events |= EPOLLIN;
+      session_evt_data = session->vep.ev.data.u64;
+      break;
+    case FIFO_EVENT_APP_TX:
+      sid = e->fifo->client_session_index;
+      session = vcl_session_get (wrk, sid);
+      session_events = session->vep.ev.events;
+      if (!(EPOLLOUT & session_events))
+	break;
+      add_event = 1;
+      events[*num_ev].events |= EPOLLOUT;
+      session_evt_data = session->vep.ev.data.u64;
+      break;
+    case SESSION_IO_EVT_CT_TX:
+      vcl_fifo_rx_evt_valid_or_break (e->fifo);
+      session = vcl_ct_session_get_from_fifo (wrk, e->fifo, 0);
+      sid = session->session_index;
+      session_events = session->vep.ev.events;
+      if (!(EPOLLIN & session->vep.ev.events))
+	break;
+      add_event = 1;
+      events[*num_ev].events |= EPOLLIN;
+      session_evt_data = session->vep.ev.data.u64;
+      break;
+    case SESSION_IO_EVT_CT_RX:
+      session = vcl_ct_session_get_from_fifo (wrk, e->fifo, 1);
+      sid = session->session_index;
+      session_events = session->vep.ev.events;
+      if (!(EPOLLOUT & session_events))
+	break;
+      add_event = 1;
+      events[*num_ev].events |= EPOLLOUT;
+      session_evt_data = session->vep.ev.data.u64;
+      break;
+    case SESSION_CTRL_EVT_ACCEPTED:
+      accepted_msg = (session_accepted_msg_t *) e->data;
+      handle = accepted_msg->listener_handle;
+      session = vcl_session_table_lookup_listener (wrk, handle);
+      if (!session)
+	{
+	  clib_warning ("VCL<%d>: ERROR: couldn't find listen session:"
+			"listener handle %llx", getpid (), handle);
+	  break;
+	}
+
+      clib_fifo_add2 (session->accept_evts_fifo, vcl_msg);
+      vcl_msg->accepted_msg = *accepted_msg;
+      session_events = session->vep.ev.events;
+      if (!(EPOLLIN & session_events))
+	break;
+
+      add_event = 1;
+      events[*num_ev].events |= EPOLLIN;
+      session_evt_data = session->vep.ev.data.u64;
+      break;
+    case SESSION_CTRL_EVT_CONNECTED:
+      connected_msg = (session_connected_msg_t *) e->data;
+      vcl_session_connected_handler (wrk, connected_msg);
+      /* Generate EPOLLOUT because there's no connected event */
+      sid = vcl_session_index_from_vpp_handle (wrk, connected_msg->handle);
+      session = vcl_session_get (wrk, sid);
+      session_events = session->vep.ev.events;
+      if (EPOLLOUT & session_events)
+	{
+	  add_event = 1;
+	  events[*num_ev].events |= EPOLLOUT;
+	  session_evt_data = session->vep.ev.data.u64;
+	}
+      break;
+    case SESSION_CTRL_EVT_DISCONNECTED:
+      disconnected_msg = (session_disconnected_msg_t *) e->data;
+      sid = vcl_session_index_from_vpp_handle (wrk, disconnected_msg->handle);
+      if (!(session = vcl_session_get (wrk, sid)))
+	break;
+      add_event = 1;
+      events[*num_ev].events |= EPOLLHUP | EPOLLRDHUP;
+      session_evt_data = session->vep.ev.data.u64;
+      session_events = session->vep.ev.events;
+      break;
+    case SESSION_CTRL_EVT_RESET:
+      sid = vcl_session_reset_handler (wrk, (session_reset_msg_t *) e->data);
+      if (!(session = vcl_session_get (wrk, sid)))
+	break;
+      add_event = 1;
+      events[*num_ev].events |= EPOLLHUP | EPOLLRDHUP;
+      session_evt_data = session->vep.ev.data.u64;
+      session_events = session->vep.ev.events;
+      break;
+    default:
+      VDBG (0, "unhandled: %u", e->event_type);
+      break;
+    }
+
+  if (add_event)
+    {
+      events[*num_ev].data.u64 = session_evt_data;
+      if (EPOLLONESHOT & session_events)
+	{
+	  session = vcl_session_get (wrk, sid);
+	  session->vep.ev.events = 0;
+	}
+      *num_ev += 1;
+    }
+}
+
+static int
+vcl_epoll_wait_handle_mq (vcl_worker_t * wrk, svm_msg_q_t * mq,
+			  struct epoll_event *events, u32 maxevents,
+			  double wait_for_time, u32 * num_ev)
+{
   svm_msg_q_msg_t *msg;
   session_event_t *e;
-  u8 add_event;
   int i;
 
   svm_msg_q_lock (mq);
@@ -2320,141 +2458,26 @@ vcl_epoll_wait_handle_mq (vcl_worker_t * wrk, svm_msg_q_t * mq,
     {
       msg = vec_elt_at_index (wrk->mq_msg_vector, i);
       e = svm_msg_q_msg_data (mq, msg);
-      add_event = 0;
-      switch (e->event_type)
-	{
-	case FIFO_EVENT_APP_RX:
-	  ASSERT (e->fifo->client_thread_index == vcl_get_worker_index ());
-	  vcl_fifo_rx_evt_valid_or_break (e->fifo);
-	  sid = e->fifo->client_session_index;
-	  session = vcl_session_get (wrk, sid);
-	  session_events = session->vep.ev.events;
-	  if (!(EPOLLIN & session->vep.ev.events))
-	    break;
-	  add_event = 1;
-	  events[*num_ev].events |= EPOLLIN;
-	  session_evt_data = session->vep.ev.data.u64;
-	  break;
-	case FIFO_EVENT_APP_TX:
-	  sid = e->fifo->client_session_index;
-	  session = vcl_session_get (wrk, sid);
-	  session_events = session->vep.ev.events;
-	  if (!(EPOLLOUT & session_events))
-	    break;
-	  add_event = 1;
-	  events[*num_ev].events |= EPOLLOUT;
-	  session_evt_data = session->vep.ev.data.u64;
-	  break;
-	case SESSION_IO_EVT_CT_TX:
-	  vcl_fifo_rx_evt_valid_or_break (e->fifo);
-	  session = vcl_ct_session_get_from_fifo (wrk, e->fifo, 0);
-	  sid = session->session_index;
-	  session_events = session->vep.ev.events;
-	  if (!(EPOLLIN & session->vep.ev.events))
-	    break;
-	  add_event = 1;
-	  events[*num_ev].events |= EPOLLIN;
-	  session_evt_data = session->vep.ev.data.u64;
-	  break;
-	case SESSION_IO_EVT_CT_RX:
-	  session = vcl_ct_session_get_from_fifo (wrk, e->fifo, 1);
-	  sid = session->session_index;
-	  session_events = session->vep.ev.events;
-	  if (!(EPOLLOUT & session_events))
-	    break;
-	  add_event = 1;
-	  events[*num_ev].events |= EPOLLOUT;
-	  session_evt_data = session->vep.ev.data.u64;
-	  break;
-	case SESSION_CTRL_EVT_ACCEPTED:
-	  accepted_msg = (session_accepted_msg_t *) e->data;
-	  handle = accepted_msg->listener_handle;
-	  session = vcl_session_table_lookup_listener (wrk, handle);
-	  if (!session)
-	    {
-	      clib_warning ("VCL<%d>: ERROR: couldn't find listen session:"
-			    "listener handle %llx", getpid (), handle);
-	      break;
-	    }
-
-	  clib_fifo_add2 (session->accept_evts_fifo, vcl_msg);
-	  vcl_msg->accepted_msg = *accepted_msg;
-	  session_events = session->vep.ev.events;
-	  if (!(EPOLLIN & session_events))
-	    break;
-
-	  add_event = 1;
-	  events[*num_ev].events |= EPOLLIN;
-	  session_evt_data = session->vep.ev.data.u64;
-	  break;
-	case SESSION_CTRL_EVT_CONNECTED:
-	  connected_msg = (session_connected_msg_t *) e->data;
-	  vcl_session_connected_handler (wrk, connected_msg);
-	  /* Generate EPOLLOUT because there's no connected event */
-	  sid = vcl_session_index_from_vpp_handle (wrk,
-						   connected_msg->handle);
-	  session = vcl_session_get (wrk, sid);
-	  session_events = session->vep.ev.events;
-	  if (EPOLLOUT & session_events)
-	    {
-	      add_event = 1;
-	      events[*num_ev].events |= EPOLLOUT;
-	      session_evt_data = session->vep.ev.data.u64;
-	    }
-	  break;
-	case SESSION_CTRL_EVT_DISCONNECTED:
-	  disconnected_msg = (session_disconnected_msg_t *) e->data;
-	  sid = vcl_session_index_from_vpp_handle (wrk,
-						   disconnected_msg->handle);
-	  if (!(session = vcl_session_get (wrk, sid)))
-	    break;
-	  add_event = 1;
-	  events[*num_ev].events |= EPOLLHUP | EPOLLRDHUP;
-	  session_evt_data = session->vep.ev.data.u64;
-	  session_events = session->vep.ev.events;
-	  break;
-	case SESSION_CTRL_EVT_RESET:
-	  sid = vcl_session_reset_handler (wrk,
-					   (session_reset_msg_t *) e->data);
-	  if (!(session = vcl_session_get (wrk, sid)))
-	    break;
-	  add_event = 1;
-	  events[*num_ev].events |= EPOLLHUP | EPOLLRDHUP;
-	  session_evt_data = session->vep.ev.data.u64;
-	  session_events = session->vep.ev.events;
-	  break;
-	default:
-	  VDBG (0, "unhandled: %u", e->event_type);
-	  svm_msg_q_free_msg (mq, msg);
-	  continue;
-	}
+      vcl_epoll_wait_handle_mq_event (wrk, e, events, num_ev);
       svm_msg_q_free_msg (mq, msg);
-
-      if (add_event)
+      if (*num_ev == maxevents)
 	{
-	  events[*num_ev].data.u64 = session_evt_data;
-	  if (EPOLLONESHOT & session_events)
-	    {
-	      session = vcl_session_get (wrk, sid);
-	      session->vep.ev.events = 0;
-	    }
-	  *num_ev += 1;
-	  if (*num_ev == maxevents)
-	    break;
+	  i += 1;
+	  break;
 	}
     }
 
-  vec_reset_length (wrk->mq_msg_vector);
+  vec_delete (wrk->mq_msg_vector, i, 0);
+
   return *num_ev;
 }
 
 static int
 vppcom_epoll_wait_condvar (vcl_worker_t * wrk, struct epoll_event *events,
-			   int maxevents, double wait_for_time)
+			   int maxevents, u32 n_evts, double wait_for_time)
 {
   vcl_cut_through_registration_t *cr;
   double total_wait = 0, wait_slice;
-  u32 num_ev = 0;
   int rv;
 
   wait_for_time = (wait_for_time == -1) ? (double) 10e9 : wait_for_time;
@@ -2465,31 +2488,30 @@ vppcom_epoll_wait_condvar (vcl_worker_t * wrk, struct epoll_event *events,
       vcl_ct_registration_lock (wrk);
       /* *INDENT-OFF* */
       pool_foreach (cr, wrk->cut_through_registrations, ({
-        vcl_epoll_wait_handle_mq (wrk, cr->mq, events, maxevents, 0, &num_ev);
+        vcl_epoll_wait_handle_mq (wrk, cr->mq, events, maxevents, 0, &n_evts);
       }));
       /* *INDENT-ON* */
       vcl_ct_registration_unlock (wrk);
 
       rv = vcl_epoll_wait_handle_mq (wrk, wrk->app_event_queue, events,
-				     maxevents, num_ev ? 0 : wait_slice,
-				     &num_ev);
+				     maxevents, n_evts ? 0 : wait_slice,
+				     &n_evts);
       if (rv)
 	total_wait += wait_slice;
-      if (num_ev)
-	return num_ev;
+      if (n_evts)
+	return n_evts;
     }
   while (total_wait < wait_for_time);
-  return (int) num_ev;
+  return n_evts;
 }
 
 static int
 vppcom_epoll_wait_eventfd (vcl_worker_t * wrk, struct epoll_event *events,
-			   int maxevents, double wait_for_time)
+			   int maxevents, u32 n_evts, double wait_for_time)
 {
   vcl_mq_evt_conn_t *mqc;
   int __clib_unused n_read;
   int n_mq_evts, i;
-  u32 n_evts = 0;
   u64 buf;
 
   vec_validate (wrk->mq_events, pool_elts (wrk->mq_evt_conns));
@@ -2511,6 +2533,8 @@ vppcom_epoll_wait (uint32_t vep_handle, struct epoll_event *events,
 {
   vcl_worker_t *wrk = vcl_worker_get_current ();
   vcl_session_t *vep_session;
+  u32 n_evts = 0;
+  int i;
 
   if (PREDICT_FALSE (maxevents <= 0))
     {
@@ -2532,10 +2556,28 @@ vppcom_epoll_wait (uint32_t vep_handle, struct epoll_event *events,
 
   memset (events, 0, sizeof (*events) * maxevents);
 
+  if (vec_len (wrk->unhandled_evts_vector))
+    {
+      for (i = 0; i < vec_len (wrk->unhandled_evts_vector); i++)
+	{
+	  vcl_epoll_wait_handle_mq_event (wrk, &wrk->unhandled_evts_vector[i],
+					  events, &n_evts);
+	  if (n_evts == maxevents)
+	    {
+	      i += 1;
+	      break;
+	    }
+	}
+
+      vec_delete (wrk->unhandled_evts_vector, i, 0);
+    }
+
   if (vcm->cfg.use_mq_eventfd)
-    return vppcom_epoll_wait_eventfd (wrk, events, maxevents, wait_for_time);
+    return vppcom_epoll_wait_eventfd (wrk, events, maxevents, n_evts,
+				      wait_for_time);
 
-  return vppcom_epoll_wait_condvar (wrk, events, maxevents, wait_for_time);
+  return vppcom_epoll_wait_condvar (wrk, events, maxevents, n_evts,
+				    wait_for_time);
 }
 
 int