Splay tree: use struct member

[splitice]

Perhaps a refactoring of the splay tree ( splay_node_t) node would be a good idea.

Basically if you put the splay_node_t struct minus the data pointer as a member in the struct being inserted you would:

• Reduce pointer indirection (minor)
• Be able to local the splay_node_t without performing a search from the subnet cache (good for /32 removal)

It would be best if splay_* functions become macros referencing the named struct to enforce this (safe) usage splay_insert_node(subnet_tree, subnet, splay_global). Getting the data pointer from splay_node_t can be done with offsetof and contained within a helper macro.

There may be other improvements outside of the subnet system as well as splay_node_t is used in many places.

For an example of what I mean using the subnet_t usage of the splay tree:

typedef struct subnet_t {
struct splay_node_t splay_global;
struct splay_node_t splay_node;
// ... existing members
}

Where splay_node_t is:

typedef struct splay_node_t {
	/* Linked list part */

	struct splay_node_t *next;
	struct splay_node_t *prev;

	/* Tree part */

	struct splay_node_t *parent;
	struct splay_node_t *left;
	struct splay_node_t *right;
}