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/* | |

* Elastic Binary Trees - macros for Indirect Multi-Byte data nodes. | |

* Version 6.0.5 | |

* (C) 2002-2011 - 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 | |

*/ | |

#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)) | |

return 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) | |

return NULL; | |

else | |

return 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) | |

return NULL; | |

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); | |

return node; | |

} | |

/* 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++)) | |

return 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) | |

return NULL; | |

side &= 1; | |

troot = node->node.branches.b[side]; | |

} | |

} | |

/* 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 = root; | |

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); | |

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; | |

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; | |

} |