VCL: close-on-empty state transition refactoring.

- Refactor session disconnect/close state
  transitions. Only remove session state
  when app calls close().  Add HUP/reset
  feedback by returning ECONNRESET.
- Update debug messages.
- Use VCL_LOCK_AND_GET_SESSION macro more
  extensively

Change-Id: I23d372834b901a6726e6d6c1061df73ad967882f
Signed-off-by: Dave Wallace <dwallacelf@gmail.com>

3 files changed, 764 insertions, 661 deletions

diff --git a/src/vcl/vppcom.c b/src/vcl/vppcom.c
index 2e867c7f036..2ccb2b86705 100644
--- a/src/vcl/vppcom.c
+++ b/src/vcl/vppcom.c
@@ -66,14 +66,18 @@ typedef enum
 
 typedef enum
 {
-  STATE_START,
-  STATE_CONNECT,
-  STATE_LISTEN,
-  STATE_ACCEPT,
-  STATE_DISCONNECT,
-  STATE_FAILED
+  STATE_START = 0x01,
+  STATE_CONNECT = 0x02,
+  STATE_LISTEN = 0x04,
+  STATE_ACCEPT = 0x08,
+  STATE_CLOSE_ON_EMPTY = 0x10,
+  STATE_DISCONNECT = 0x20,
+  STATE_FAILED = 0x40
 } session_state_t;
 
+#define SERVER_STATE_OPEN  (STATE_ACCEPT|STATE_CLOSE_ON_EMPTY)
+#define CLIENT_STATE_OPEN  (STATE_CONNECT|STATE_CLOSE_ON_EMPTY)
+
 typedef struct epoll_event vppcom_epoll_event_t;
 
 typedef struct
@@ -152,7 +156,6 @@ typedef struct vppcom_main_t_
   u8 init;
   u32 debug;
   u32 *client_session_index_fifo;
-  volatile u32 bind_session_index;
   int main_cpu;
 
   /* vpe input queue */
@@ -209,11 +212,8 @@ do {                                                    \
   if (PREDICT_FALSE (rv))                               \
     {                                                   \
       clib_spinlock_unlock (&vcm->sessions_lockp);      \
-                                                        \
-      if (VPPCOM_DEBUG > 0)                             \
-        clib_warning ("[%s] ERROR: Invalid ##I (%u)!",  \
-                      getpid (), I);                  \
-                                                        \
+      clib_warning ("[%s] ERROR: Invalid ##I (%u)!",    \
+                    getpid (), I);                      \
       goto done;                                        \
     }                                                   \
 } while (0)
@@ -272,6 +272,10 @@ vppcom_session_state_str (session_state_t state)
       st = "STATE_ACCEPT";
       break;
 
+    case STATE_CLOSE_ON_EMPTY:
+      st = "STATE_CLOSE_ON_EMPTY";
+      break;
+
     case STATE_DISCONNECT:
       st = "STATE_DISCONNECT";
       break;
@@ -321,6 +325,8 @@ vppcom_session_table_lookup_listener (u64 listener_handle)
 {
   uword *p;
   u64 handle = listener_handle | (1ULL << 63);
+  session_t *session;
+
   p = hash_get (vcm->session_index_by_vpp_handles, handle);
   if (!p)
     {
@@ -336,7 +342,9 @@ vppcom_session_table_lookup_listener (u64 listener_handle)
       return 0;
     }
 
-  return pool_elt_at_index (vcm->sessions, p[0]);
+  session = pool_elt_at_index (vcm->sessions, p[0]);
+  ASSERT (session->is_listen);
+  return session;
 }
 
 static inline void
@@ -434,13 +442,19 @@ vppcom_wait_for_session_state_change (u32 session_index,
 	  clib_spinlock_unlock (&vcm->sessions_lockp);
 	  return VPPCOM_OK;
 	}
+      if (session->state == STATE_FAILED)
+	{
+	  clib_spinlock_unlock (&vcm->sessions_lockp);
+	  return VPPCOM_ECONNREFUSED;
+	}
+
       clib_spinlock_unlock (&vcm->sessions_lockp);
     }
   while (clib_time_now (&vcm->clib_time) < timeout);
 
   if (VPPCOM_DEBUG > 0)
-    clib_warning ("[%d] timeout waiting for state %s (%d)", getpid (),
-		  vppcom_session_state_str (state), state);
+    clib_warning ("[%d] timeout waiting for state 0x%x (%s)", getpid (),
+		  state, vppcom_session_state_str (state));
   return VPPCOM_ETIMEDOUT;
 }
 
@@ -638,46 +652,10 @@ static void
 vl_api_disconnect_session_reply_t_handler (vl_api_disconnect_session_reply_t *
 					   mp)
 {
-  uword *p;
-  u32 session_index = ~0;
-
-  p = hash_get (vcm->session_index_by_vpp_handles, mp->handle);
-  if (p)
-    {
-      session_t *session = 0;
-      int rv;
-
-      session_index = p[0];
-      hash_unset (vcm->session_index_by_vpp_handles, mp->handle);
-      clib_spinlock_lock (&vcm->sessions_lockp);
-      rv = vppcom_session_at_index (session_index, &session);
-      if (PREDICT_FALSE (rv))
-	{
-	  if (VPPCOM_DEBUG > 1)
-	    clib_warning ("[%d] invalid session, sid %u has been closed!",
-			  getpid (), session_index);
-	}
-      else
-	{
-	  if (VPPCOM_DEBUG > 1)
-	    clib_warning ("[%d] vpp handle 0x%llx, sid %u disconnected!",
-			  getpid (), mp->handle, session_index);
-
-	  session->state = STATE_DISCONNECT;
-	}
-      clib_spinlock_unlock (&vcm->sessions_lockp);
-    }
-  else
-    {
-      if (VPPCOM_DEBUG > 1)
-	clib_warning ("[%d] couldn't find session: unknown vpp handle 0x%llx",
-		      getpid (), mp->handle);
-    }
-
   if (mp->retval)
-    clib_warning ("[%d] disconnect_session vpp handle 0x%llx, sid %u "
-		  "failed: %U", getpid (), mp->handle, session_index,
-		  format_api_error, ntohl (mp->retval));
+    clib_warning ("[%d] vpp handle 0x%llx: disconnect session failed: %U",
+		  getpid (), mp->handle, format_api_error,
+		  ntohl (mp->retval));
 }
 
 static void
@@ -707,57 +685,35 @@ vl_api_map_another_segment_t_handler (vl_api_map_another_segment_t * mp)
 static void
 vl_api_disconnect_session_t_handler (vl_api_disconnect_session_t * mp)
 {
-  session_t *session = 0;
-  vl_api_disconnect_session_reply_t *rmp;
   uword *p;
-  int rv = 0, rval;
 
   p = hash_get (vcm->session_index_by_vpp_handles, mp->handle);
-  if (VPPCOM_DEBUG > 0)
+  if (p)
     {
-      if (!p)
-	{
-	  clib_warning ("[%d] request to disconnect invalid handle (%u)!",
-			getpid (), mp->handle);
-	  rv = -11;
-	  goto done;
-	}
-      clib_warning ("[%d] disconnecting handle %u sid (%u)!", getpid (),
-		    mp->handle, p[0]);
-    }
+      int rv;
+      session_t *session = 0;
+      u32 session_index = p[0];
 
-  goto done;
+      VCL_LOCK_AND_GET_SESSION (session_index, &session);
+      session->state = STATE_CLOSE_ON_EMPTY;
 
-  if (p)
-    {
-      clib_spinlock_lock (&vcm->sessions_lockp);
-      rval = vppcom_session_at_index (p[0], &session);
-      if (PREDICT_FALSE (rval))
-	{
-	  if (VPPCOM_DEBUG > 1)
-	    clib_warning ("[%d] invalid session, sid (%u) has been closed!",
-			  getpid (), p[0]);
-	}
-      else
-	pool_put (vcm->sessions, session);
+      if (VPPCOM_DEBUG > 1)
+	clib_warning ("[%d] vpp handle 0x%llx, sid %u: "
+		      "setting state to %d (%s)",
+		      getpid (), mp->handle, session_index, session->state,
+		      vppcom_session_state_str (session->state));
       clib_spinlock_unlock (&vcm->sessions_lockp);
-      hash_unset (vcm->session_index_by_vpp_handles, mp->handle);
+      return;
+
+    done:
+      if (VPPCOM_DEBUG > 1)
+	clib_warning ("[%d] vpp handle 0x%llx, sid %u: "
+		      "session lookup failed!",
+		      getpid (), mp->handle, session_index);
     }
   else
-    {
-      clib_warning ("[%d] couldn't find session: unknown vpp handle 0x%llx",
-		    getpid (), mp->handle);
-      rv = -11;
-    }
-
-done:
-  rmp = vl_msg_api_alloc (sizeof (*rmp));
-  memset (rmp, 0, sizeof (*rmp));
-
-  rmp->_vl_msg_id = ntohs (VL_API_DISCONNECT_SESSION_REPLY);
-  rmp->retval = htonl (rv);
-  rmp->handle = mp->handle;
-  vl_msg_api_send_shmem (vcm->vl_input_queue, (u8 *) & rmp);
+    clib_warning ("[%d] vpp handle 0x%llx: session lookup by "
+		  "handle failed!", getpid (), mp->handle);
 }
 
 static void
@@ -776,20 +732,32 @@ vl_api_reset_session_t_handler (vl_api_reset_session_t * mp)
       rval = vppcom_session_at_index (p[0], &session);
       if (PREDICT_FALSE (rval))
 	{
-	  if (VPPCOM_DEBUG > 1)
-	    clib_warning ("[%d] invalid session, sid (%u) has been closed!",
-			  getpid (), p[0]);
+	  rv = VNET_API_ERROR_INVALID_VALUE_2;
+	  clib_warning ("[%d] ERROR: sid %u: session lookup failed! "
+			"returning %d %U",
+			getpid (), p[0], rv, format_api_error, rv);
 	}
       else
-	pool_put (vcm->sessions, session);
+	{
+	  /* TBD: should this disconnect immediately and
+	   * flush the fifos?
+	   */
+	  session->state = STATE_CLOSE_ON_EMPTY;
+
+	  if (VPPCOM_DEBUG > 1)
+	    clib_warning ("[%d] vpp handle 0x%llx, sid %u: "
+			  "state set to %d (%s)!", getpid (),
+			  mp->handle, p[0], session->state,
+			  vppcom_session_state_str (session->state));
+	}
       clib_spinlock_unlock (&vcm->sessions_lockp);
-      hash_unset (vcm->session_index_by_vpp_handles, mp->handle);
     }
   else
     {
-      clib_warning ("[%d] couldn't find session: unknown vpp handle 0x%llx",
-		    getpid (), mp->handle);
-      rv = -11;
+      rv = VNET_API_ERROR_INVALID_VALUE;
+      clib_warning ("[%d] ERROR: vpp handle 0x%llx: session lookup "
+		    "failed! returning %d %U",
+		    getpid (), mp->handle, rv, format_api_error, rv);
     }
 
   rmp = vl_msg_api_alloc (sizeof (*rmp));
@@ -809,24 +777,25 @@ vl_api_connect_session_reply_t_handler (vl_api_connect_session_reply_t * mp)
   u8 is_cut_thru = 0;
   int rv;
 
+  session_index = mp->context;
   if (mp->retval)
     {
-      clib_warning ("[%d] connect failed: %U", getpid (), format_api_error,
+      clib_warning ("[%d] ERROR: sid %u: connect failed! %U",
+		    getpid (), session_index, format_api_error,
 		    ntohl (mp->retval));
       return;
     }
 
-  session_index = mp->context;
   if (VPPCOM_DEBUG > 1)
-    clib_warning ("[%d] session_index = %d 0x%08x", getpid (),
-		  session_index, session_index);
+    clib_warning ("[%d] sid %u: got a connect reply!",
+		  getpid (), session_index);
 
   clib_spinlock_lock (&vcm->sessions_lockp);
   if (pool_is_free_index (vcm->sessions, session_index))
     {
       clib_spinlock_unlock (&vcm->sessions_lockp);
       if (VPPCOM_DEBUG > 1)
-	clib_warning ("[%d] invalid session, sid %d is closed!",
+	clib_warning ("[%d] sid %d: session lookup failed!",
 		      getpid (), session_index);
       return;
     }
@@ -905,10 +874,6 @@ vppcom_send_connect_sock (session_t * session, u32 session_index)
   cmp->client_index = vcm->my_client_index;
   cmp->context = session_index;
 
-  if (VPPCOM_DEBUG > 1)
-    clib_warning ("[%d] session_index = %d 0x%08x",
-		  getpid (), session_index, session_index);
-
   cmp->vrf = session->vrf;
   cmp->is_ip4 = session->peer_addr.is_ip4;
   clib_memcpy (cmp->ip, &session->peer_addr.ip46, sizeof (cmp->ip));
@@ -919,16 +884,38 @@ vppcom_send_connect_sock (session_t * session, u32 session_index)
 }
 
 static inline void
-vppcom_send_disconnect (session_t * session)
+vppcom_send_disconnect_session_reply (u64 vpp_handle, u32 session_index,
+				      int rv)
+{
+  vl_api_disconnect_session_reply_t *rmp;
+
+  if (VPPCOM_DEBUG > 1)
+    clib_warning ("[%d] vpp handle 0x%llx, sid %u: sending disconnect msg",
+		  getpid (), vpp_handle, session_index);
+
+  rmp = vl_msg_api_alloc (sizeof (*rmp));
+  memset (rmp, 0, sizeof (*rmp));
+
+  rmp->_vl_msg_id = ntohs (VL_API_DISCONNECT_SESSION_REPLY);
+  rmp->retval = htonl (rv);
+  rmp->handle = vpp_handle;
+  vl_msg_api_send_shmem (vcm->vl_input_queue, (u8 *) & rmp);
+}
+
+static inline void
+vppcom_send_disconnect_session (u64 vpp_handle, u32 session_index)
 {
   vl_api_disconnect_session_t *dmp;
 
-  /* Assumes caller as acquired the spinlock: vcm->sessions_lockp */
+  if (VPPCOM_DEBUG > 1)
+    clib_warning ("[%d] vpp handle 0x%llx, sid %u: sending disconnect msg",
+		  getpid (), vpp_handle, session_index);
+
   dmp = vl_msg_api_alloc (sizeof (*dmp));
   memset (dmp, 0, sizeof (*dmp));
   dmp->_vl_msg_id =