/*
* Elastic Binary Trees - macros for Indirect Multi-Byte data nodes.
* Version 6.0.6
* (C) 2002-2011 - Willy Tarreau <w@1wt.eu>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation, version 2.1
* exclusively.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef _EBIMTREE_H
#define _EBIMTREE_H
#include <string.h>
#include "ebtree.h"
#include "ebpttree.h"
/* These functions and macros rely on Pointer nodes and use the <key> entry as
* a pointer to an indirect key. Most operations are performed using ebpt_*.
*/
/* The following functions are not inlined by default. They are declared
* in ebimtree.c, which simply relies on their inline version.
*/
REGPRM3 struct ebpt_node *ebim_lookup(struct eb_root *root, const void *x, unsigned int len);
REGPRM3 struct ebpt_node *ebim_insert(struct eb_root *root, struct ebpt_node *new, unsigned int len);
/* Find the first occurence of a key of a least <len> bytes matching <x> in the
* tree <root>. The caller is responsible for ensuring that <len> will not exceed
* the common parts between the tree's keys and <x>. In case of multiple matches,
* the leftmost node is returned. This means that this function can be used to
* lookup string keys by prefix if all keys in the tree are zero-terminated. If
* no match is found, NULL is returned. Returns first node if <len> is zero.
*/
static forceinline struct ebpt_node *
__ebim_lookup(struct eb_root *root, const void *x, unsigned int len)
{
struct ebpt_node *node;
eb_troot_t *troot;
int pos, side;
int node_bit;
troot = root->b[EB_LEFT];
if (unlikely(troot == NULL))
goto ret_null;
if (unlikely(len == 0))
goto walk_down;
pos = 0;
while (1) {
if (eb_gettag(troot) == EB_LEAF) {
node = container_of(eb_untag(troot, EB_LEAF),
struct ebpt_node, node.branches);
if (memcmp(node->key + pos, x, len) != 0)
goto ret_null;
else
goto ret_node;
}
node = container_of(eb_untag(troot, EB_NODE),
struct ebpt_node, node.branches);
node_bit = node->node.bit;
if (node_bit < 0) {
/* We have a dup tree now. Either it's for the same
* value, and we walk down left, or it's a different
* one and we don't have our key.
*/
if (memcmp(node->key + pos, x, len) != 0)
goto ret_null;
else
goto walk_left;
}
/* OK, normal data node, let's walk down. We check if all full
* bytes are equal, and we start from the last one we did not
* completely check. We stop as soon as we reach the last byte,
* because we must decide to go left/right or abort.
*/
node_bit = ~node_bit + (pos << 3) + 8; // = (pos<<3) + (7 - node_bit)
if (node_bit < 0) {
/* This surprizing construction gives better performance
* because gcc does not try to reorder the loop. Tested to
* be fine with 2.95 to 4.2.
*/
while (1) {
if (*(unsigned char*)(node->key + pos++) ^ *(unsigned char*)(x++))
goto ret_null; /* more than one full byte is different */
if (--len == 0)
goto walk_left; /* return first node if all bytes matched */
node_bit += 8;
if (node_bit >= 0)
break;
}
}
/* here we know that only the last byte differs, so node_bit < 8.
* We have 2 possibilities :
* - more than the last bit differs => return NULL
* - walk down on side = (x[pos] >> node_bit) & 1
*/
side = *(unsigned char *)x >> node_bit;
if (((*(unsigned char*)(node->key + pos) >> node_bit) ^ side) > 1)
goto ret_null;
side &= 1;
troot = node->node.branches.b[side];
}
walk_left:
troot = node->node.branches.b[EB_LEFT];
walk_down:
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);
ret_node:
return node;
ret_null:
return NULL;
}
/* 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. The
* len is specified in bytes.
*/
static forceinline struct ebpt_node *
__ebim_insert(struct eb_root *root, struct ebpt_node *new, unsigned int len)
{
struct ebpt_node *old;
unsigned int side;
eb_troot_t *troot;
eb_troot_t *root_right;
int diff;
int bit;
int old_node_bit;
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;
}
len <<= 3;
/* 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.
*/
bit = 0;
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.
*/
bit = equal_bits(new->key, old->key, bit, len);
/* Note: we can compare more bits than the current node's because as
* long as they are identical, we know we descend along the correct
* side. However we don't want to start to compare past the end.
*/
diff = 0;
if (((unsigned)bit >> 3) < len)
diff = cmp_bits(new->key, old->key, bit);
if (diff < 0) {
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 (diff == 0 && 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 (diff == 0) {
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);
old_node_bit = old->node.bit;
/* 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. Note: we can compare more bits than
* the current node's because as long as they are identical, we
* know we descend along the correct side.
*/
if (old_node_bit < 0) {
/* we're above a duplicate tree, we must compare till the end */
bit = equal_bits(new->key, old->key, bit, len);
goto dup_tree;
}
else if (bit < old_node_bit) {
bit = equal_bits(new->key, old->key, bit, old_node_bit);
}
if (bit < old_node_bit) { /* we don't have all bits in common */
/* 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;
dup_tree:
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;
/* Note: we can compare more bits than the current node's because as
* long as they are identical, we know we descend along the correct
* side. However we don't want to start to compare past the end.
*/
diff = 0;
if (((unsigned)bit >> 3) < len)
diff = cmp_bits(new->key, old->key, bit);
if (diff < 0) {
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 (diff > 0) {
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 = (((unsigned char *)new->key)[old_node_bit >> 3] >> (~old_node_bit & 7)) & 1;
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.
* This number of bits is already in <bit>.
*/
new->node.bit = bit;
root->b[side] = eb_dotag(&new->node.branches, EB_NODE);
return new;
}
#endif /* _EBIMTREE_H */