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Diffstat (limited to 'include/import/ebimtree.h')
| -rw-r--r-- | include/import/ebimtree.h | 324 |
1 files changed, 324 insertions, 0 deletions
diff --git a/include/import/ebimtree.h b/include/import/ebimtree.h new file mode 100644 index 0000000..0afbdd1 --- /dev/null +++ b/include/import/ebimtree.h @@ -0,0 +1,324 @@ +/* + * 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. + */ +struct ebpt_node *ebim_lookup(struct eb_root *root, const void *x, unsigned int len); +struct ebpt_node *ebim_insert(struct eb_root *root, struct ebpt_node *new, unsigned int len); + +/* Find the first occurrence 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 (eb_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 (eb_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 surprising 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 */ |