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Diffstat (limited to 'include/import/ebmbtree.h')
| -rw-r--r-- | include/import/ebmbtree.h | 850 |
1 files changed, 850 insertions, 0 deletions
diff --git a/include/import/ebmbtree.h b/include/import/ebmbtree.h new file mode 100644 index 0000000..365042e --- /dev/null +++ b/include/import/ebmbtree.h @@ -0,0 +1,850 @@ +/* + * Elastic Binary Trees - macros and structures for 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 _EBMBTREE_H +#define _EBMBTREE_H + +#include <string.h> +#include "ebtree.h" + +/* Return the structure of type <type> whose member <member> points to <ptr> */ +#define ebmb_entry(ptr, type, member) container_of(ptr, type, member) + +/* + * 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 forceinline struct ebmb_node *ebmb_first(struct eb_root *root) +{ + return ebmb_entry(eb_first(root), struct ebmb_node, node); +} + +/* Return rightmost node in the tree, or NULL if none */ +static forceinline struct ebmb_node *ebmb_last(struct eb_root *root) +{ + return ebmb_entry(eb_last(root), struct ebmb_node, node); +} + +/* Return next node in the tree, or NULL if none */ +static forceinline struct ebmb_node *ebmb_next(struct ebmb_node *ebmb) +{ + return ebmb_entry(eb_next(&ebmb->node), struct ebmb_node, node); +} + +/* Return previous node in the tree, or NULL if none */ +static forceinline struct ebmb_node *ebmb_prev(struct ebmb_node *ebmb) +{ + return ebmb_entry(eb_prev(&ebmb->node), struct ebmb_node, node); +} + +/* Return next leaf node within a duplicate sub-tree, or NULL if none. */ +static inline struct ebmb_node *ebmb_next_dup(struct ebmb_node *ebmb) +{ + return ebmb_entry(eb_next_dup(&ebmb->node), struct ebmb_node, node); +} + +/* Return previous leaf node within a duplicate sub-tree, or NULL if none. */ +static inline struct ebmb_node *ebmb_prev_dup(struct ebmb_node *ebmb) +{ + return ebmb_entry(eb_prev_dup(&ebmb->node), struct ebmb_node, node); +} + +/* Return next node in the tree, skipping duplicates, or NULL if none */ +static forceinline struct ebmb_node *ebmb_next_unique(struct ebmb_node *ebmb) +{ + return ebmb_entry(eb_next_unique(&ebmb->node), struct ebmb_node, node); +} + +/* Return previous node in the tree, skipping duplicates, or NULL if none */ +static forceinline struct ebmb_node *ebmb_prev_unique(struct ebmb_node *ebmb) +{ + return ebmb_entry(eb_prev_unique(&ebmb->node), struct ebmb_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 forceinline void ebmb_delete(struct ebmb_node *ebmb) +{ + eb_delete(&ebmb->node); +} + +/* The following functions are not inlined by default. They are declared + * in ebmbtree.c, which simply relies on their inline version. + */ +struct ebmb_node *ebmb_lookup(struct eb_root *root, const void *x, unsigned int len); +struct ebmb_node *ebmb_insert(struct eb_root *root, struct ebmb_node *new, unsigned int len); +struct ebmb_node *ebmb_lookup_longest(struct eb_root *root, const void *x); +struct ebmb_node *ebmb_lookup_prefix(struct eb_root *root, const void *x, unsigned int pfx); +struct ebmb_node *ebmb_insert_prefix(struct eb_root *root, struct ebmb_node *new, unsigned int len); + +/* start from a valid leaf and find the next matching prefix that's either a + * duplicate, or immediately shorter than the node's current one and still + * matches it. The purpose is to permit a caller that is not satisfied with a + * result provided by ebmb_lookup_longest() to evaluate the next matching + * entry. Given that shorter keys are necessarily attached to nodes located + * above the current one, it's sufficient to restart from the current leaf and + * go up until we find a shorter prefix, or a non-matching one. + */ +static inline struct ebmb_node *ebmb_lookup_shorter(struct ebmb_node *start) +{ + eb_troot_t *t = start->node.leaf_p; + struct ebmb_node *node; + + /* first, check for duplicates */ + node = ebmb_next_dup(start); + if (node) + return node; + + while (1) { + if (eb_gettag(t) == EB_LEFT) { + /* Walking up from left branch. We must ensure that we never + * walk beyond root. + */ + if (unlikely(eb_clrtag((eb_untag(t, EB_LEFT))->b[EB_RGHT]) == NULL)) + return NULL; + node = container_of(eb_root_to_node(eb_untag(t, EB_LEFT)), struct ebmb_node, node); + } else { + /* Walking up from right branch, so we cannot be below + * root. However, if we end up on a node with an even + * and positive bit, this is a cover node, which mandates + * that the left branch only contains cover values, so we + * must descend it. + */ + node = container_of(eb_root_to_node(eb_untag(t, EB_RGHT)), struct ebmb_node, node); + if (node->node.bit > 0 && !(node->node.bit & 1)) + return ebmb_entry(eb_walk_down(t, EB_LEFT), struct ebmb_node, node); + } + + /* Note that <t> cannot be NULL at this stage */ + t = node->node.node_p; + + /* this is a node attached to a deeper (and possibly different) + * leaf, not interesting for us. + */ + if (node->node.pfx >= start->node.pfx) + continue; + + if (check_bits(start->key, node->key, 0, node->node.pfx) == 0) + break; + } + return node; +} + +/* 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 __ebmb_delete(struct ebmb_node *ebmb) +{ + __eb_delete(&ebmb->node); +} + +/* 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 ebmb_node *__ebmb_lookup(struct eb_root *root, const void *x, unsigned int len) +{ + struct ebmb_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 ebmb_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 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 (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 (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 (((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 ebmb_node, node.branches); + ret_node: + return node; + ret_null: + return NULL; +} + +/* Insert ebmb_node <new> into subtree starting at node root <root>. + * Only new->key needs be set with the key. The ebmb_node is returned. + * If root->b[EB_RGHT]==1, the tree may only contain unique keys. The + * len is specified in bytes. It is absolutely mandatory that this length + * is the same for all keys in the tree. This function cannot be used to + * insert strings. + */ +static forceinline struct ebmb_node * +__ebmb_insert(struct eb_root *root, struct ebmb_node *new, unsigned int len) +{ + struct ebmb_node *old; + unsigned int side; + eb_troot_t *troot, **up_ptr; + eb_troot_t *root_right; + int diff; + int bit; + eb_troot_t *new_left, *new_rght; + eb_troot_t *new_leaf; + 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)) { + /* insert above a leaf */ + old = container_of(eb_untag(troot, EB_LEAF), + struct ebmb_node, node.branches); + new->node.node_p = old->node.leaf_p; + up_ptr = &old->node.leaf_p; + goto check_bit_and_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; + + if (unlikely(old->node.bit < 0)) { + /* We're above a duplicate tree, so we must compare the whole value */ + new->node.node_p = old->node.node_p; + up_ptr = &old->node.node_p; + check_bit_and_break: + bit = equal_bits(new->key, old->key, bit, len << 3); + break; + } + + /* 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. + */ + + bit = equal_bits(new->key, old->key, bit, old_node_bit); + if (unlikely(bit < old_node_bit)) { + /* 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[]. + */ + new->node.node_p = old->node.node_p; + up_ptr = &old->node.node_p; + break; + } + /* we don't want to skip bits for further comparisons, so we must limit <bit>. + * However, since we're going down around <old_node_bit>, we know it will be + * properly matched, so we can skip this bit. + */ + bit = old_node_bit + 1; + + /* walk down */ + root = &old->node.branches; + side = old_node_bit & 7; + side ^= 7; + side = (new->key[old_node_bit >> 3] >> side) & 1; + troot = root->b[side]; + } + + 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); + + new->node.bit = bit; + + /* 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.bit = -1; /* mark as new dup tree, just in case */ + + if (likely(eb_gettag(root_right))) { + /* we refuse to duplicate this key if the tree is + * tagged as containing only unique keys. + */ + return old; + } + + if (eb_gettag(troot) != EB_LEAF) { + /* there was already a dup tree below */ + struct eb_node *ret; + ret = eb_insert_dup(&old->node, &new->node); + return container_of(ret, struct ebmb_node, node); + } + /* otherwise fall through */ + } + + if (diff >= 0) { + new->node.branches.b[EB_LEFT] = troot; + new->node.branches.b[EB_RGHT] = new_leaf; + new->node.leaf_p = new_rght; + *up_ptr = new_left; + } + else { + new->node.branches.b[EB_LEFT] = new_leaf; + new->node.branches.b[EB_RGHT] = troot; + new->node.leaf_p = new_left; + *up_ptr = new_rght; + } + + /* 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. + */ + + root->b[side] = eb_dotag(&new->node.branches, EB_NODE); + return new; +} + + +/* Find the first occurrence of the longest prefix matching a key <x> in the + * tree <root>. It's the caller's responsibility to ensure that key <x> is at + * least as long as the keys in the tree. Note that this can be ensured by + * having a byte at the end of <x> which cannot be part of any prefix, typically + * the trailing zero for a string. If none can be found, return NULL. + */ +static forceinline struct ebmb_node *__ebmb_lookup_longest(struct eb_root *root, const void *x) +{ + struct ebmb_node *node; + eb_troot_t *troot, *cover; + int pos, side; + int node_bit; + + troot = root->b[EB_LEFT]; + if (unlikely(troot == NULL)) + return NULL; + + cover = NULL; + pos = 0; + while (1) { + if ((eb_gettag(troot) == EB_LEAF)) { + node = container_of(eb_untag(troot, EB_LEAF), + struct ebmb_node, node.branches); + if (check_bits(x - pos, node->key, pos, node->node.pfx)) + goto not_found; + + return node; + } + 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 (check_bits(x - pos, node->key, pos, node->node.pfx)) + goto not_found; + + 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; + } + + node_bit >>= 1; /* strip cover bit */ + node_bit = ~node_bit + (pos << 3) + 8; // = (pos<<3) + (7 - node_bit) + if (node_bit < 0) { + /* This uncommon 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) { + x++; pos++; + if (node->key[pos-1] ^ *(unsigned char*)(x-1)) + goto not_found; /* more than one full byte is different */ + node_bit += 8; + if (node_bit >= 0) + break; + } + } + + /* here we know that only the last byte differs, so 0 <= node_bit <= 7. + * We have 2 possibilities : + * - more than the last bit differs => data does not match + * - walk down on side = (x[pos] >> node_bit) & 1 + */ + side = *(unsigned char *)x >> node_bit; + if (((node->key[pos] >> node_bit) ^ side) > 1) + goto not_found; + + if (!(node->node.bit & 1)) { + /* This is a cover node, let's keep a reference to it + * for later. The covering subtree is on the left, and + * the covered subtree is on the right, so we have to + * walk down right. + */ + cover = node->node.branches.b[EB_LEFT]; + troot = node->node.branches.b[EB_RGHT]; + continue; + } + side &= 1; + troot = node->node.branches.b[side]; + } + + not_found: + /* Walk down last cover tree if it exists. It does not matter if cover is NULL */ + return ebmb_entry(eb_walk_down(cover, EB_LEFT), struct ebmb_node, node); +} + + +/* Find the first occurrence of a prefix matching a key <x> of <pfx> BITS in the + * tree <root>. It's the caller's responsibility to ensure that key <x> is at + * least as long as the keys in the tree. Note that this can be ensured by + * having a byte at the end of <x> which cannot be part of any prefix, typically + * the trailing zero for a string. If none can be found, return NULL. + */ +static forceinline struct ebmb_node *__ebmb_lookup_prefix(struct eb_root *root, const void *x, unsigned int pfx) +{ + struct ebmb_node *node; + eb_troot_t *troot; + int pos, side; + int node_bit; + + troot = root->b[EB_LEFT]; + if (unlikely(troot == NULL)) + return NULL; + + pos = 0; + while (1) { + if ((eb_gettag(troot) == EB_LEAF)) { + node = container_of(eb_untag(troot, EB_LEAF), + struct ebmb_node, node.branches); + if (node->node.pfx != pfx) + return NULL; + if (check_bits(x - pos, node->key, pos, node->node.pfx)) + return NULL; + return node; + } + 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 (node->node.pfx != pfx) + return NULL; + if (check_bits(x - pos, node->key, pos, node->node.pfx)) + 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; + } + + node_bit >>= 1; /* strip cover bit */ + node_bit = ~node_bit + (pos << 3) + 8; // = (pos<<3) + (7 - node_bit) + if (node_bit < 0) { + /* This uncommon 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) { + x++; pos++; + if (node->key[pos-1] ^ *(unsigned char*)(x-1)) + return NULL; /* more than one full byte is different */ + node_bit += 8; + if (node_bit >= 0) + break; + } + } + + /* here we know that only the last byte differs, so 0 <= node_bit <= 7. + * We have 2 possibilities : + * - more than the last bit differs => data does not match + * - walk down on side = (x[pos] >> node_bit) & 1 + */ + side = *(unsigned char *)x >> node_bit; + if (((node->key[pos] >> node_bit) ^ side) > 1) + return NULL; + + if (!(node->node.bit & 1)) { + /* This is a cover node, it may be the entry we're + * looking for. We already know that it matches all the + * bits, let's compare prefixes and descend the cover + * subtree if they match. + */ + if ((unsigned short)node->node.bit >> 1 == pfx) + troot = node->node.branches.b[EB_LEFT]; + else + troot = node->node.branches.b[EB_RGHT]; + continue; + } + side &= 1; + troot = node->node.branches.b[side]; + } +} + + +/* Insert ebmb_node <new> into a prefix subtree starting at node root <root>. + * Only new->key and new->pfx need be set with the key and its prefix length. + * Note that bits between <pfx> and <len> are theoretically ignored and should be + * zero, as it is not certain yet that they will always be ignored everywhere + * (eg in bit compare functions). + * The ebmb_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 ebmb_node * +__ebmb_insert_prefix(struct eb_root *root, struct ebmb_node *new, unsigned int len) +{ + struct ebmb_node *old; + unsigned int side; + eb_troot_t *troot, **up_ptr; + eb_troot_t *root_right; + int diff; + int bit; + eb_troot_t *new_left, *new_rght; + eb_troot_t *new_leaf; + int old_node_bit; + unsigned int npfx = new->node.pfx; + unsigned int npfx1 = npfx << 1; + const unsigned char *nkey = new->key; + + 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; + if (len > npfx) + len = npfx; + + /* 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)) { + /* Insert above a leaf. Note that this leaf could very + * well be part of a cover node. + */ + old = container_of(eb_untag(troot, EB_LEAF), + struct ebmb_node, node.branches); + new->node.node_p = old->node.leaf_p; + up_ptr = &old->node.leaf_p; + goto check_bit_and_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; + /* Note that old_node_bit can be : + * < 0 : dup tree + * = 2N : cover node for N bits + * = 2N+1 : normal node at N bits + */ + + if (unlikely(old_node_bit < 0)) { + /* We're above a duplicate tree, so we must compare the whole value */ + new->node.node_p = old->node.node_p; + up_ptr = &old->node.node_p; + check_bit_and_break: + /* No need to compare everything if the leaves are shorter than the new one. */ + if (len > old->node.pfx) + len = old->node.pfx; + bit = equal_bits(nkey, old->key, bit, len); + break; + } + + /* WARNING: for the two blocks below, <bit> is counted in half-bits */ + + bit = equal_bits(nkey, old->key, bit, old_node_bit >> 1); + bit = (bit << 1) + 1; // assume comparisons with normal nodes + + /* we must always check that our prefix is larger than the nodes + * we visit, otherwise we have to stop going down. The following + * test is able to stop before both normal and cover nodes. + */ + if (bit >= npfx1 && npfx1 < old_node_bit) { + /* insert cover node here on the left */ + new->node.node_p = old->node.node_p; + up_ptr = &old->node.node_p; + new->node.bit = npfx1; + diff = -1; + goto insert_above; + } + + if (unlikely(bit < old_node_bit)) { + /* 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[]. We know that the bit is not + * greater than the prefix length thanks to the test above. + */ + new->node.node_p = old->node.node_p; + up_ptr = &old->node.node_p; + new->node.bit = bit; + diff = cmp_bits(nkey, old->key, bit >> 1); + goto insert_above; + } + + if (!(old_node_bit & 1)) { + /* if we encounter a cover node with our exact prefix length, it's + * necessarily the same value, so we insert there as a duplicate on + * the left. For that, we go down on the left and the leaf detection + * code will finish the job. + */ + if (npfx1 == old_node_bit) { + root = &old->node.branches; + side = EB_LEFT; + troot = root->b[side]; + continue; + } + + /* cover nodes are always walked through on the right */ + side = EB_RGHT; + bit = old_node_bit >> 1; /* recheck that bit */ + root = &old->node.branches; + troot = root->b[side]; + continue; + } + + /* we don't want to skip bits for further comparisons, so we must limit <bit>. + * However, since we're going down around <old_node_bit>, we know it will be + * properly matched, so we can skip this bit. + */ + old_node_bit >>= 1; + bit = old_node_bit + 1; + + /* walk down */ + root = &old->node.branches; + side = old_node_bit & 7; + side ^= 7; + side = (nkey[old_node_bit >> 3] >> side) & 1; + troot = root->b[side]; + } + + /* Right here, we have 4 possibilities : + * - the tree does not contain any leaf matching the + * key, and we have new->key < old->key. We insert + * new above old, on the left ; + * + * - the tree does not contain any leaf matching the + * key, and we have new->key > old->key. We insert + * new above old, on the right ; + * + * - the tree does contain the key with the same prefix + * length. We add the new key next to it as a first + * duplicate (since it was alone). + * + * The last two cases can easily be partially merged. + * + * - the tree contains a leaf matching the key, we have + * to insert above it as a cover node. The leaf with + * the shortest prefix becomes the left subtree and + * the leaf with the longest prefix becomes the right + * one. The cover node gets the min of both prefixes + * as its new bit. + */ + + /* first we want to ensure that we compare the correct bit, which means + * the largest common to both nodes. + */ + if (bit > npfx) + bit = npfx; + if (bit > old->node.pfx) + bit = old->node.pfx; + + new->node.bit = (bit << 1) + 1; /* assume normal node by default */ + + /* if one prefix is included in the second one, we don't compare bits + * because they won't necessarily match, we just proceed with a cover + * node insertion. + */ + diff = 0; + if (bit < old->node.pfx && bit < npfx) + diff = cmp_bits(nkey, old->key, bit); + + if (diff == 0) { + /* Both keys match. Either it's a duplicate entry or we have to + * put the shortest prefix left and the largest one right below + * a new cover node. By default, diff==0 means we'll be inserted + * on the right. + */ + new->node.bit--; /* anticipate cover node insertion */ + if (npfx == old->node.pfx) { + new->node.bit = -1; /* mark as new dup tree, just in case */ + + if (unlikely(eb_gettag(root_right))) { + /* we refuse to duplicate this key if the tree is + * tagged as containing only unique keys. + */ + return old; + } + + if (eb_gettag(troot) != EB_LEAF) { + /* there was already a dup tree below */ + struct eb_node *ret; + ret = eb_insert_dup(&old->node, &new->node); + return container_of(ret, struct ebmb_node, node); + } + /* otherwise fall through to insert first duplicate */ + } + /* otherwise we just rely on the tests below to select the right side */ + else if (npfx < old->node.pfx) + diff = -1; /* force insertion to left side */ + } + + insert_above: + 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); + + if (diff >= 0) { + new->node.branches.b[EB_LEFT] = troot; + new->node.branches.b[EB_RGHT] = new_leaf; + new->node.leaf_p = new_rght; + *up_ptr = new_left; + } + else { + new->node.branches.b[EB_LEFT] = new_leaf; + new->node.branches.b[EB_RGHT] = troot; + new->node.leaf_p = new_left; + *up_ptr = new_rght; + } + + root->b[side] = eb_dotag(&new->node.branches, EB_NODE); + return new; +} + + + +#endif /* _EBMBTREE_H */ + |