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/*
* Elastic Binary Trees - macros and structures for operations on pointer nodes.
* Version 4.0
* (C) 2002-2008 - Willy Tarreau <w@1wt.eu>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef _COMMON_EBPTTREE_H
#define _COMMON_EBPTTREE_H
#include "ebtree.h"
/* Return the structure of type <type> whose member <member> points to <ptr> */
#define ebpt_entry(ptr, type, member) container_of(ptr, type, member)
#define EBPT_ROOT EB_ROOT
#define EBPT_TREE_HEAD EB_TREE_HEAD
/* on *almost* all platforms, a pointer can be cast into a size_t which is unsigned */
#ifndef PTR_INT_TYPE
#define PTR_INT_TYPE size_t
#endif
typedef PTR_INT_TYPE ptr_t;
/* This structure carries a node, a leaf, and a key. It must start with the
* eb_node so that it can be cast into an eb_node. We could also have put some
* sort of transparent union here to reduce the indirection level, but the fact
* is, the end user is not meant to manipulate internals, so this is pointless.
*/
struct ebpt_node {
struct eb_node node; /* the tree node, must be at the beginning */
void *key;
};
/*
* Exported functions and macros.
* Many of them are always inlined because they are extremely small, and
* are generally called at most once or twice in a program.
*/
/* Return leftmost node in the tree, or NULL if none */
static inline struct ebpt_node *ebpt_first(struct eb_root *root)
{
return ebpt_entry(eb_first(root), struct ebpt_node, node);
}
/* Return rightmost node in the tree, or NULL if none */
static inline struct ebpt_node *ebpt_last(struct eb_root *root)
{
return ebpt_entry(eb_last(root), struct ebpt_node, node);
}
/* Return next node in the tree, or NULL if none */
static inline struct ebpt_node *ebpt_next(struct ebpt_node *ebpt)
{
return ebpt_entry(eb_next(&ebpt->node), struct ebpt_node, node);
}
/* Return previous node in the tree, or NULL if none */
static inline struct ebpt_node *ebpt_prev(struct ebpt_node *ebpt)
{
return ebpt_entry(eb_prev(&ebpt->node), struct ebpt_node, node);
}
/* Return next node in the tree, skipping duplicates, or NULL if none */
static inline struct ebpt_node *ebpt_next_unique(struct ebpt_node *ebpt)
{
return ebpt_entry(eb_next_unique(&ebpt->node), struct ebpt_node, node);
}
/* Return previous node in the tree, skipping duplicates, or NULL if none */
static inline struct ebpt_node *ebpt_prev_unique(struct ebpt_node *ebpt)
{
return ebpt_entry(eb_prev_unique(&ebpt->node), struct ebpt_node, node);
}
/* Delete node from the tree if it was linked in. Mark the node unused. Note
* that this function relies on a non-inlined generic function: eb_delete.
*/
static inline void ebpt_delete(struct ebpt_node *ebpt)
{
eb_delete(&ebpt->node);
}
/*
* The following functions are not inlined by default. They are declared
* in ebpttree.c, which simply relies on their inline version.
*/
REGPRM2 struct ebpt_node *ebpt_lookup(struct eb_root *root, void *x);
REGPRM2 struct ebpt_node *ebpt_insert(struct eb_root *root, struct ebpt_node *new);
/*
* The following functions are less likely to be used directly, because their
* code is larger. The non-inlined version is preferred.
*/
/* Delete node from the tree if it was linked in. Mark the node unused. */
static forceinline void __ebpt_delete(struct ebpt_node *ebpt)
{
__eb_delete(&ebpt->node);
}
/*
* Find the first occurence of a key in the tree <root>. If none can be
* found, return NULL.
*/
static forceinline struct ebpt_node *__ebpt_lookup(struct eb_root *root, void *x)
{
struct ebpt_node *node;
eb_troot_t *troot;
ptr_t y;
troot = root->b[EB_LEFT];
if (unlikely(troot == NULL))
return NULL;
while (1) {
if ((eb_gettag(troot) == EB_LEAF)) {
node = container_of(eb_untag(troot, EB_LEAF),
struct ebpt_node, node.branches);
if (node->key == x)
return node;
else
return NULL;
}
node = container_of(eb_untag(troot, EB_NODE),
struct ebpt_node, node.branches);
y = (ptr_t)node->key ^ (ptr_t)x;
if (!y) {
/* Either we found the node which holds the key, or
* we have a dup tree. In the later case, we have to
* walk it down left to get the first entry.
*/
if (node->node.bit < 0) {
troot = node->node.branches.b[EB_LEFT];
while (eb_gettag(troot) != EB_LEAF)
troot = (eb_untag(troot, EB_NODE))->b[EB_LEFT];
node = container_of(eb_untag(troot, EB_LEAF),
struct ebpt_node, node.branches);
}
return node;
}
if ((y >> node->node.bit) >= EB_NODE_BRANCHES)
return NULL; /* no more common bits */
troot = node->node.branches.b[((ptr_t)x >> node->node.bit) & EB_NODE_BRANCH_MASK];
}
}
/* Insert ebpt_node <new> into subtree starting at node root <root>.
* Only new->key needs be set with the key. The ebpt_node is returned.
* If root->b[EB_RGHT]==1, the tree may only contain unique keys.
*/
static forceinline struct ebpt_node *
__ebpt_insert(struct eb_root *root, struct ebpt_node *new) {
struct ebpt_node *old;
unsigned int side;
eb_troot_t *troot;
void *newkey; /* caching the key saves approximately one cycle */
eb_troot_t *root_right = root;
side = EB_LEFT;
troot = root->b[EB_LEFT];
root_right = root->b[EB_RGHT];
if (unlikely(troot == NULL)) {
/* Tree is empty, insert the leaf part below the left branch */
root->b[EB_LEFT] = eb_dotag(&new->node.branches, EB_LEAF);
new->node.leaf_p = eb_dotag(root, EB_LEFT);
new->node.node_p = NULL; /* node part unused */
return new;
}
/* The tree descent is fairly easy :
* - first, check if we have reached a leaf node
* - second, check if we have gone too far
* - third, reiterate
* Everywhere, we use <new> for the node node we are inserting, <root>
* for the node we attach it to, and <old> for the node we are
* displacing below <new>. <troot> will always point to the future node
* (tagged with its type). <side> carries the side the node <new> is
* attached to below its parent, which is also where previous node
* was attached. <newkey> carries the key being inserted.
*/
newkey = new->key;
while (1) {
if (unlikely(eb_gettag(troot) == EB_LEAF)) {
eb_troot_t *new_left, *new_rght;
eb_troot_t *new_leaf, *old_leaf;
old = container_of(eb_untag(troot, EB_LEAF),
struct ebpt_node, node.branches);
new_left = eb_dotag(&new->node.branches, EB_LEFT);
new_rght = eb_dotag(&new->node.branches, EB_RGHT);
new_leaf = eb_dotag(&new->node.branches, EB_LEAF);
old_leaf = eb_dotag(&old->node.branches, EB_LEAF);
new->node.node_p = old->node.leaf_p;
/* Right here, we have 3 possibilities :
- the tree does not contain the key, and we have
new->key < old->key. We insert new above old, on
the left ;
- the tree does not contain the key, and we have
new->key > old->key. We insert new above old, on
the right ;
- the tree does contain the key, which implies it
is alone. We add the new key next to it as a
first duplicate.
The last two cases can easily be partially merged.
*/
if (new->key < old->key) {
new->node.leaf_p = new_left;
old->node.leaf_p = new_rght;
new->node.branches.b[EB_LEFT] = new_leaf;
new->node.branches.b[EB_RGHT] = old_leaf;
} else {
/* we may refuse to duplicate this key if the tree is
* tagged as containing only unique keys.
*/
if ((new->key == old->key) && eb_gettag(root_right))
return old;
/* new->key >= old->key, new goes the right */
old->node.leaf_p = new_left;
new->node.leaf_p = new_rght;
new->node.branches.b[EB_LEFT] = old_leaf;
new->node.branches.b[EB_RGHT] = new_leaf;
if (new->key == old->key) {
new->node.bit = -1;
root->b[side] = eb_dotag(&new->node.branches, EB_NODE);
return new;
}
}
break;
}
/* OK we're walking down this link */
old = container_of(eb_untag(troot, EB_NODE),
struct ebpt_node, node.branches);
/* Stop going down when we don't have common bits anymore. We
* also stop in front of a duplicates tree because it means we
* have to insert above.
*/
if ((old->node.bit < 0) || /* we're above a duplicate tree, stop here */
((((ptr_t)new->key ^ (ptr_t)old->key) >> old->node.bit) >= EB_NODE_BRANCHES)) {
/* The tree did not contain the key, so we insert <new> before the node
* <old>, and set ->bit to designate the lowest bit position in <new>
* which applies to ->branches.b[].
*/
eb_troot_t *new_left, *new_rght;
eb_troot_t *new_leaf, *old_node;
new_left = eb_dotag(&new->node.branches, EB_LEFT);
new_rght = eb_dotag(&new->node.branches, EB_RGHT);
new_leaf = eb_dotag(&new->node.branches, EB_LEAF);
old_node = eb_dotag(&old->node.branches, EB_NODE);
new->node.node_p = old->node.node_p;
if (new->key < old->key) {
new->node.leaf_p = new_left;
old->node.node_p = new_rght;
new->node.branches.b[EB_LEFT] = new_leaf;
new->node.branches.b[EB_RGHT] = old_node;
}
else if (new->key > old->key) {
old->node.node_p = new_left;
new->node.leaf_p = new_rght;
new->node.branches.b[EB_LEFT] = old_node;
new->node.branches.b[EB_RGHT] = new_leaf;
}
else {
struct eb_node *ret;
ret = eb_insert_dup(&old->node, &new->node);
return container_of(ret, struct ebpt_node, node);
}
break;
}
/* walk down */
root = &old->node.branches;
side = ((ptr_t)newkey >> old->node.bit) & EB_NODE_BRANCH_MASK;
troot = root->b[side];
}
/* Ok, now we are inserting <new> between <root> and <old>. <old>'s
* parent is already set to <new>, and the <root>'s branch is still in
* <side>. Update the root's leaf till we have it. Note that we can also
* find the side by checking the side of new->node.node_p.
*/
/* We need the common higher bits between new->key and old->key.
* What differences are there between new->key and the node here ?
* NOTE that bit(new) is always < bit(root) because highest
* bit of new->key and old->key are identical here (otherwise they
* would sit on different branches).
*/
// note that if EB_NODE_BITS > 1, we should check that it's still >= 0
/* let the compiler choose the best branch based on the pointer size */
if (sizeof(ptr_t) == 4)
new->node.bit = flsnz((ptr_t)new->key ^ (ptr_t)old->key) - EB_NODE_BITS;
else
new->node.bit = fls64((ptr_t)new->key ^ (ptr_t)old->key) - EB_NODE_BITS;
root->b[side] = eb_dotag(&new->node.branches, EB_NODE);
return new;
}
#endif /* _COMMON_EBPTTREE_H */