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/* | |

* Elastic Binary Trees - macros to manipulate String 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 | |

*/ | |

/* These functions and macros rely on Multi-Byte nodes */ | |

#ifndef _EBSTTREE_H | |

#define _EBSTTREE_H | |

#include "ebtree.h" | |

#include "ebmbtree.h" | |

/* The following functions are not inlined by default. They are declared | |

* in ebsttree.c, which simply relies on their inline version. | |

*/ | |

REGPRM2 struct ebmb_node *ebst_lookup(struct eb_root *root, const char *x); | |

REGPRM2 struct ebmb_node *ebst_insert(struct eb_root *root, struct ebmb_node *new); | |

/* Find the first occurence of a length <len> string <x> in the tree <root>. | |

* It's the caller's reponsibility to use this function only on trees which | |

* only contain zero-terminated strings, and that no null character is present | |

* in string <x> in the first <len> chars. If none can be found, return NULL. | |

*/ | |

static forceinline struct ebmb_node * | |

ebst_lookup_len(struct eb_root *root, const char *x, unsigned int len) | |

{ | |

struct ebmb_node *node; | |

node = ebmb_lookup(root, x, len); | |

if (!node || node->key[len] != 0) | |

return NULL; | |

return node; | |

} | |

/* Find the first occurence of a zero-terminated string <x> in the tree <root>. | |

* It's the caller's reponsibility to use this function only on trees which | |

* only contain zero-terminated strings. If none can be found, return NULL. | |

*/ | |

static forceinline struct ebmb_node *__ebst_lookup(struct eb_root *root, const void *x) | |

{ | |

struct ebmb_node *node; | |

eb_troot_t *troot; | |

int bit; | |

int node_bit; | |

troot = root->b[EB_LEFT]; | |

if (unlikely(troot == NULL)) | |

return NULL; | |

bit = 0; | |

while (1) { | |

if ((eb_gettag(troot) == EB_LEAF)) { | |

node = container_of(eb_untag(troot, EB_LEAF), | |

struct ebmb_node, node.branches); | |

if (strcmp((char *)node->key, x) == 0) | |

return node; | |

else | |

return NULL; | |

} | |

node = container_of(eb_untag(troot, EB_NODE), | |

struct ebmb_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 (strcmp((char *)node->key, x) != 0) | |

return NULL; | |

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 ebmb_node, node.branches); | |

return node; | |

} | |

/* OK, normal data node, let's walk down but don't compare data | |

* if we already reached the end of the key. | |

*/ | |

if (likely(bit >= 0)) { | |

bit = string_equal_bits(x, node->key, bit); | |

if (likely(bit < node_bit)) { | |

if (bit >= 0) | |

return NULL; /* no more common bits */ | |

/* bit < 0 : we reached the end of the key. If we | |

* are in a tree with unique keys, we can return | |

* this node. Otherwise we have to walk it down | |

* and stop comparing bits. | |

*/ | |

if (eb_gettag(root->b[EB_RGHT])) | |

return node; | |

} | |

/* if the bit is larger than the node's, we must bound it | |

* because we might have compared too many bytes with an | |

* inappropriate leaf. For a test, build a tree from "0", | |

* "WW", "W", "S" inserted in this exact sequence and lookup | |

* "W" => "S" is returned without this assignment. | |

*/ | |

else | |

bit = node_bit; | |

} | |

troot = node->node.branches.b[(((unsigned char*)x)[node_bit >> 3] >> | |

(~node_bit & 7)) & 1]; | |

} | |

} | |

/* Insert ebmb_node <new> into subtree starting at node root <root>. Only | |

* new->key needs be set with the zero-terminated string key. The ebmb_node is | |

* returned. If root->b[EB_RGHT]==1, the tree may only contain unique keys. The | |

* caller is responsible for properly terminating the key with a zero. | |

*/ | |

static forceinline struct ebmb_node * | |

__ebst_insert(struct eb_root *root, struct ebmb_node *new) | |

{ | |

struct ebmb_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; | |

} | |

/* 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 ebmb_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 (bit >= 0) | |

bit = string_equal_bits(new->key, old->key, bit); | |

if (bit < 0) { | |

/* key was already there */ | |

/* we may refuse to duplicate this key if the tree is | |

* tagged as containing only unique keys. | |

*/ | |

if (eb_gettag(root_right)) | |

return old; | |

/* new arbitrarily goes to the right and tops the dup tree */ | |

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; | |

new->node.bit = -1; | |

root->b[side] = eb_dotag(&new->node.branches, EB_NODE); | |

return new; | |

} | |

diff = cmp_bits(new->key, old->key, bit); | |

if (diff < 0) { | |

/* new->key < old->key, new takes the left */ | |

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 { | |

/* new->key > old->key, new takes 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; | |

} | |

break; | |

} | |

/* OK we're walking down this link */ | |

old = container_of(eb_untag(troot, EB_NODE), | |

struct ebmb_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 (bit >= 0 && (bit < old_node_bit || old_node_bit < 0)) | |

bit = string_equal_bits(new->key, old->key, bit); | |

if (unlikely(bit < 0)) { | |

/* Perfect match, we must only stop on head of dup tree | |

* or walk down to a leaf. | |

*/ | |

if (old_node_bit < 0) { | |

/* We know here that string_equal_bits matched all | |

* bits and that we're on top of a dup tree, then | |

* we can perform the dup insertion and return. | |

*/ | |

struct eb_node *ret; | |

ret = eb_insert_dup(&old->node, &new->node); | |

return container_of(ret, struct ebmb_node, node); | |

} | |

/* OK so let's walk down */ | |

} | |

else if (bit < old_node_bit || old_node_bit < 0) { | |

/* The tree did not contain the key, or we stopped on top of a dup | |

* tree, possibly containing the key. In the former case, we insert | |

* <new> before the node <old>, and set ->bit to designate the lowest | |

* bit position in <new> which applies to ->branches.b[]. In the later | |

* case, we add the key to the existing dup tree. Note that we cannot | |

* enter here if we match an intermediate node's key that is not the | |

* head of a dup tree. | |

*/ | |

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; | |

/* we can never match all bits here */ | |

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 { | |

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; | |

} | |

break; | |

} | |

/* walk down */ | |

root = &old->node.branches; | |

side = (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>. | |

* NOTE: we can't get here whit bit < 0 since we found a dup ! | |

*/ | |

new->node.bit = bit; | |

root->b[side] = eb_dotag(&new->node.branches, EB_NODE); | |

return new; | |

} | |

#endif /* _EBSTTREE_H */ | |