FIB: store the node type not the function pointer.

Saves memory at no appreciable performance cost.
before:
  DBGvpp# sh fib mem
  FIB memory
               Name               Size  in-use /allocated   totals
               Entry               80      7   /   150      560/12000

after:
  DBGvpp# sh fib mem
  FIB memory
               Name               Size  in-use /allocated   totals
               Entry               72      7   /    7       504/504

Change-Id: Ic5d3920ceb57b54260dc9af2078c26484335fef1
Signed-off-by: Neale Ranns <nranns@cisco.com>

5 files changed, 11 insertions, 15 deletions

diff --git a/src/vnet/fib/fib_entry.c b/src/vnet/fib/fib_entry.c
index 74c6a4a587b..35716cacc29 100644
--- a/src/vnet/fib/fib_entry.c
+++ b/src/vnet/fib/fib_entry.c
@@ -191,9 +191,7 @@ format_fib_entry (u8 * s, va_list * args)
 static fib_entry_t*
 fib_entry_from_fib_node (fib_node_t *node)
 {
-#if CLIB_DEBUG > 0
     ASSERT(FIB_NODE_TYPE_ENTRY == node->fn_type);
-#endif
     return ((fib_entry_t*)node);
 }
 
diff --git a/src/vnet/fib/fib_node.c b/src/vnet/fib/fib_node.c
index db3e22bb3b8..54c300aec1e 100644
--- a/src/vnet/fib/fib_node.c
+++ b/src/vnet/fib/fib_node.c
@@ -183,14 +183,11 @@ void
 fib_node_init (fib_node_t *node,
 	       fib_node_type_t type)
 {
-#if CLIB_DEBUG > 0
     /**
-     * The node's type. make sure we are dynamic/down casting correctly
+     * The node's type. used to retrieve the VFT.
      */
     node->fn_type = type;
-#endif
     node->fn_locks = 0;
-    node->fn_vft = &fn_vfts[type];
     node->fn_children = FIB_NODE_INDEX_INVALID;
 }
 
@@ -213,7 +210,7 @@ fib_node_unlock (fib_node_t *node)
 
     if (0 == node->fn_locks)
     {
-	node->fn_vft->fnv_last_lock(node);
+	fn_vfts[node->fn_type].fnv_last_lock(node);
     }
 }
 
diff --git a/src/vnet/fib/fib_node.h b/src/vnet/fib/fib_node.h
index d4c96c90b77..532efd54dee 100644
--- a/src/vnet/fib/fib_node.h
+++ b/src/vnet/fib/fib_node.h
@@ -52,7 +52,7 @@ typedef enum fib_node_type_t_ {
      */
     FIB_NODE_TYPE_TEST,
     FIB_NODE_TYPE_LAST = FIB_NODE_TYPE_TEST,
-} fib_node_type_t;
+} __attribute__ ((packed)) fib_node_type_t;
 
 #define FIB_NODE_TYPE_MAX (FIB_NODE_TYPE_LAST + 1)
 
@@ -284,18 +284,21 @@ typedef struct fib_node_vft_t_ {
  * Objects in the FIB form a graph.
  */
 typedef struct fib_node_t_ {
-#if CLIB_DEBUG > 0
     /**
      * The node's type. make sure we are dynamic/down casting correctly
      */
     fib_node_type_t fn_type;
-#endif
+
+    /**
+     * Some pad space the concrete/derived type is free to use
+     */
+    u16 fn_pad;
     /**
      * The node's VFT.
      * we could store the type here instead, and lookup the VFT using that. But
      * I like this better,
      */
-    const fib_node_vft_t *fn_vft;
+//    const fib_node_vft_t *fn_vft;
 
     /**
      * Vector of nodes that depend upon/use/share this node
@@ -309,6 +312,8 @@ typedef struct fib_node_t_ {
     u32 fn_locks;
 } fib_node_t;
 
+STATIC_ASSERT(sizeof(fib_node_t) == 12, "FIB node type is growing");
+
 /**
  * @brief
  *  Register the function table for a given type
diff --git a/src/vnet/fib/fib_path.c b/src/vnet/fib/fib_path.c
index 79291ca8c9a..c6677fb12f2 100644
--- a/src/vnet/fib/fib_path.c
+++ b/src/vnet/fib/fib_path.c
@@ -439,9 +439,7 @@ fib_path_get_node (fib_node_index_t index)
 static fib_path_t*
 fib_path_from_fib_node (fib_node_t *node)
 {
-#if CLIB_DEBUG > 0
     ASSERT(FIB_NODE_TYPE_PATH == node->fn_type);
-#endif
     return ((fib_path_t*)node);
 }
 
diff --git a/src/vnet/fib/fib_path_list.c b/src/vnet/fib/fib_path_list.c
index f9477406ed3..597a700a448 100644
--- a/src/vnet/fib/fib_path_list.c
+++ b/src/vnet/fib/fib_path_list.c
@@ -116,9 +116,7 @@ fib_path_list_get_node (fib_node_index_t index)
 static fib_path_list_t*
 fib_path_list_from_fib_node (fib_node_t *node)
 {
-#if CLIB_DEBUG > 0
     ASSERT(FIB_NODE_TYPE_PATH_LIST == node->fn_type);
-#endif
     return ((fib_path_list_t*)node);
 }