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Diffstat (limited to '')
| -rw-r--r-- | src/eb32sctree.c | 472 |
1 files changed, 472 insertions, 0 deletions
diff --git a/src/eb32sctree.c b/src/eb32sctree.c new file mode 100644 index 0000000..af6a539 --- /dev/null +++ b/src/eb32sctree.c @@ -0,0 +1,472 @@ +/* + * Elastic Binary Trees - exported functions for operations on 32bit nodes. + * Version 6.0.6 with backports from v7-dev + * (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 + */ + +/* Consult eb32sctree.h for more details about those functions */ + +#include <import/eb32sctree.h> + + +/* This function is used to build a tree of duplicates by adding a new node to + * a subtree of at least 2 entries. + */ +struct eb32sc_node *eb32sc_insert_dup(struct eb_node *sub, struct eb_node *new, unsigned long scope) +{ + struct eb32sc_node *eb32; + struct eb_node *head = sub; + eb_troot_t *new_left = eb_dotag(&new->branches, EB_LEFT); + eb_troot_t *new_rght = eb_dotag(&new->branches, EB_RGHT); + eb_troot_t *new_leaf = eb_dotag(&new->branches, EB_LEAF); + + /* first, identify the deepest hole on the right branch */ + while (eb_gettag(head->branches.b[EB_RGHT]) != EB_LEAF) { + struct eb_node *last = head; + + head = container_of(eb_untag(head->branches.b[EB_RGHT], EB_NODE), + struct eb_node, branches); + + if (unlikely(head->bit > last->bit + 1)) { + /* there's a hole here, we must assign the top of the + * following sub-tree to <sub> and mark all intermediate + * nodes with the scope mask. + */ + do { + eb32 = container_of(sub, struct eb32sc_node, node); + if (!(eb32->node_s & scope)) + eb32->node_s |= scope; + + sub = container_of(eb_untag(sub->branches.b[EB_RGHT], EB_NODE), + struct eb_node, branches); + } while (sub != head); + } + + eb32 = container_of(head, struct eb32sc_node, node); + if (!(eb32->node_s & scope)) + eb32->node_s |= scope; + } + + /* Here we have a leaf attached to (head)->b[EB_RGHT] */ + if (head->bit < -1) { + /* A hole exists just before the leaf, we insert there */ + new->bit = -1; + sub = container_of(eb_untag(head->branches.b[EB_RGHT], EB_LEAF), + struct eb_node, branches); + head->branches.b[EB_RGHT] = eb_dotag(&new->branches, EB_NODE); + + new->node_p = sub->leaf_p; + new->leaf_p = new_rght; + sub->leaf_p = new_left; + new->branches.b[EB_LEFT] = eb_dotag(&sub->branches, EB_LEAF); + new->branches.b[EB_RGHT] = new_leaf; + eb32 = container_of(new, struct eb32sc_node, node); + eb32->node_s = container_of(sub, struct eb32sc_node, node)->leaf_s | scope; + return eb32; + } else { + int side; + /* No hole was found before a leaf. We have to insert above + * <sub>. Note that we cannot be certain that <sub> is attached + * to the right of its parent, as this is only true if <sub> + * is inside the dup tree, not at the head. + */ + new->bit = sub->bit - 1; /* install at the lowest level */ + side = eb_gettag(sub->node_p); + head = container_of(eb_untag(sub->node_p, side), struct eb_node, branches); + head->branches.b[side] = eb_dotag(&new->branches, EB_NODE); + + new->node_p = sub->node_p; + new->leaf_p = new_rght; + sub->node_p = new_left; + new->branches.b[EB_LEFT] = eb_dotag(&sub->branches, EB_NODE); + new->branches.b[EB_RGHT] = new_leaf; + eb32 = container_of(new, struct eb32sc_node, node); + eb32->node_s = container_of(sub, struct eb32sc_node, node)->node_s | scope; + return eb32; + } +} + +/* Insert eb32sc_node <new> into subtree starting at node root <root>. Only + * new->key needs be set with the key. The eb32sc_node is returned. This + * implementation does NOT support unique trees. + */ +struct eb32sc_node *eb32sc_insert(struct eb_root *root, struct eb32sc_node *new, unsigned long scope) +{ + struct eb32sc_node *old; + unsigned int side; + eb_troot_t *troot, **up_ptr; + u32 newkey; /* caching the key saves approximately one cycle */ + eb_troot_t *new_left, *new_rght; + eb_troot_t *new_leaf; + int old_node_bit; + unsigned long old_scope; + + side = EB_LEFT; + troot = root->b[EB_LEFT]; + 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 */ + new->node_s = scope; + new->leaf_s = scope; + 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. <newkey> carries the key being inserted. + */ + newkey = new->key; + + while (1) { + if (eb_gettag(troot) == EB_LEAF) { + /* insert above a leaf */ + old = container_of(eb_untag(troot, EB_LEAF), + struct eb32sc_node, node.branches); + new->node.node_p = old->node.leaf_p; + up_ptr = &old->node.leaf_p; + old_scope = old->leaf_s; + break; + } + + /* OK we're walking down this link */ + old = container_of(eb_untag(troot, EB_NODE), + struct eb32sc_node, node.branches); + old_node_bit = old->node.bit; + + /* our new node will be found through this one, we must mark it */ + if ((old->node_s | scope) != old->node_s) + old->node_s |= scope; + + /* 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. + */ + + if ((old_node_bit < 0) || /* we're above a duplicate tree, stop here */ + (((new->key ^ old->key) >> old_node_bit) >= EB_NODE_BRANCHES)) { + /* 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; + old_scope = old->node_s; + break; + } + + /* walk down */ + root = &old->node.branches; + side = (newkey >> old_node_bit) & EB_NODE_BRANCH_MASK; + 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); + + /* We need the common higher bits between new->key and old->key. + * What differences are there between new->key and the node here ? + * NOTE that bit(new) is always < bit(root) because highest + * bit of new->key and old->key are identical here (otherwise they + * would sit on different branches). + */ + + // note that if EB_NODE_BITS > 1, we should check that it's still >= 0 + new->node.bit = flsnz(new->key ^ old->key) - EB_NODE_BITS; + new->leaf_s = scope; + new->node_s = old_scope | scope; + + if (new->key == old->key) { + new->node.bit = -1; /* mark as new dup tree, just in case */ + + if (eb_gettag(troot) != EB_LEAF) { + /* there was already a dup tree below */ + return eb32sc_insert_dup(&old->node, &new->node, scope); + } + /* otherwise fall through */ + } + + if (new->key >= old->key) { + 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 lowest key in the tree <root>, which is + * equal to or greater than <x>. NULL is returned is no key matches. + */ +struct eb32sc_node *eb32sc_lookup_ge(struct eb_root *root, u32 x, unsigned long scope) +{ + struct eb32sc_node *node; + eb_troot_t *troot; + + troot = root->b[EB_LEFT]; + if (unlikely(troot == NULL)) + return NULL; + + while (1) { + if ((eb_gettag(troot) == EB_LEAF)) { + /* We reached a leaf, which means that the whole upper + * parts were common. We will return either the current + * node or its next one if the former is too small. + */ + node = container_of(eb_untag(troot, EB_LEAF), + struct eb32sc_node, node.branches); + if ((node->leaf_s & scope) && node->key >= x) + return node; + /* return next */ + troot = node->node.leaf_p; + break; + } + node = container_of(eb_untag(troot, EB_NODE), + struct eb32sc_node, node.branches); + + if (node->node.bit < 0) { + /* We're at the top of a dup tree. Either we got a + * matching value and we return the leftmost node, or + * we don't and we skip the whole subtree to return the + * next node after the subtree. Note that since we're + * at the top of the dup tree, we can simply return the + * next node without first trying to escape from the + * tree. + */ + if ((node->node_s & scope) && node->key >= x) + troot = eb_dotag(&node->node.branches, EB_LEFT); + else + troot = node->node.node_p; + break; + } + + if (((x ^ node->key) >> node->node.bit) >= EB_NODE_BRANCHES) { + /* No more common bits at all. Either this node is too + * large and we need to get its lowest value, or it is too + * small, and we need to get the next value. + */ + if ((node->node_s & scope) && (node->key >> node->node.bit) > (x >> node->node.bit)) + troot = eb_dotag(&node->node.branches, EB_LEFT); + else + troot = node->node.node_p; + break; + } + troot = node->node.branches.b[(x >> node->node.bit) & EB_NODE_BRANCH_MASK]; + } + + /* If we get here, it means we want to report next node after the + * current one which is not below. <troot> is already initialised + * to the parent's branches. + */ + return eb32sc_next_with_parent(troot, scope); +} + +/* + * Find the first occurrence of the lowest key in the tree <root> which is + * equal to or greater than <x>, matching scope <scope>. If not found, it loops + * back to the beginning of the tree. NULL is returned is no key matches. + */ +struct eb32sc_node *eb32sc_lookup_ge_or_first(struct eb_root *root, u32 x, unsigned long scope) +{ + struct eb32sc_node *eb32; + eb_troot_t *troot; + + troot = root->b[EB_LEFT]; + if (unlikely(troot == NULL)) + return NULL; + + while (1) { + if ((eb_gettag(troot) == EB_LEAF)) { + /* We reached a leaf, which means that the whole upper + * parts were common. We will return either the current + * node or its next one if the former is too small. + */ + eb32 = container_of(eb_untag(troot, EB_LEAF), + struct eb32sc_node, node.branches); + if ((eb32->leaf_s & scope) && eb32->key >= x) + return eb32; + /* return next */ + troot = eb32->node.leaf_p; + break; + } + eb32 = container_of(eb_untag(troot, EB_NODE), + struct eb32sc_node, node.branches); + + if (eb32->node.bit < 0) { + /* We're at the top of a dup tree. Either we got a + * matching value and we return the leftmost node, or + * we don't and we skip the whole subtree to return the + * next node after the subtree. Note that since we're + * at the top of the dup tree, we can simply return the + * next node without first trying to escape from the + * tree. + */ + if ((eb32->node_s & scope) && eb32->key >= x) + troot = eb_dotag(&eb32->node.branches, EB_LEFT); + else + troot = eb32->node.node_p; + break; + } + + if (((x ^ eb32->key) >> eb32->node.bit) >= EB_NODE_BRANCHES) { + /* No more common bits at all. Either this node is too + * large and we need to get its lowest value, or it is too + * small, and we need to get the next value. + */ + if ((eb32->node_s & scope) && (eb32->key >> eb32->node.bit) > (x >> eb32->node.bit)) + troot = eb_dotag(&eb32->node.branches, EB_LEFT); + else + troot = eb32->node.node_p; + break; + } + troot = eb32->node.branches.b[(x >> eb32->node.bit) & EB_NODE_BRANCH_MASK]; + } + + /* If we get here, it means we want to report next node after the + * current one which is not below. <troot> is already initialised + * to the parent's branches. + */ + eb32 = eb32sc_next_with_parent(troot, scope); + if (!eb32) + eb32 = eb32sc_walk_down_left(root->b[EB_LEFT], scope); + + return eb32; +} + +/* Removes a leaf node from the tree if it was still in it. Marks the node + * as unlinked. + */ +void eb32sc_delete(struct eb32sc_node *eb32) +{ + struct eb_node *node = &eb32->node; + unsigned int pside, gpside, sibtype; + struct eb_node *parent; + struct eb_root *gparent; + unsigned long scope; + + if (!node->leaf_p) + return; + + /* we need the parent, our side, and the grand parent */ + pside = eb_gettag(node->leaf_p); + parent = eb_root_to_node(eb_untag(node->leaf_p, pside)); + + /* We likely have to release the parent link, unless it's the root, + * in which case we only set our branch to NULL. Note that we can + * only be attached to the root by its left branch. + */ + + if (eb_clrtag(parent->branches.b[EB_RGHT]) == NULL) { + /* we're just below the root, it's trivial. */ + parent->branches.b[EB_LEFT] = NULL; + goto delete_unlink; + } + + /* To release our parent, we have to identify our sibling, and reparent + * it directly to/from the grand parent. Note that the sibling can + * either be a link or a leaf. + */ + + gpside = eb_gettag(parent->node_p); + gparent = eb_untag(parent->node_p, gpside); + + gparent->b[gpside] = parent->branches.b[!pside]; + sibtype = eb_gettag(gparent->b[gpside]); + + if (sibtype == EB_LEAF) { + eb_root_to_node(eb_untag(gparent->b[gpside], EB_LEAF))->leaf_p = + eb_dotag(gparent, gpside); + } else { + eb_root_to_node(eb_untag(gparent->b[gpside], EB_NODE))->node_p = + eb_dotag(gparent, gpside); + } + /* Mark the parent unused. Note that we do not check if the parent is + * our own node, but that's not a problem because if it is, it will be + * marked unused at the same time, which we'll use below to know we can + * safely remove it. + */ + parent->node_p = NULL; + + /* The parent node has been detached, and is currently unused. It may + * belong to another node, so we cannot remove it that way. Also, our + * own node part might still be used. so we can use this spare node + * to replace ours if needed. + */ + + /* If our link part is unused, we can safely exit now */ + if (!node->node_p) + goto delete_unlink; + + /* From now on, <node> and <parent> are necessarily different, and the + * <node>'s node part is in use. By definition, <parent> is at least + * below <node>, so keeping its key for the bit string is OK. However + * its scope must be enlarged to cover the new branch it absorbs. + */ + + parent->node_p = node->node_p; + parent->branches = node->branches; + parent->bit = node->bit; + + /* We must now update the new node's parent... */ + gpside = eb_gettag(parent->node_p); + gparent = eb_untag(parent->node_p, gpside); + gparent->b[gpside] = eb_dotag(&parent->branches, EB_NODE); + + /* ... and its branches */ + scope = 0; + for (pside = 0; pside <= 1; pside++) { + if (eb_gettag(parent->branches.b[pside]) == EB_NODE) { + eb_root_to_node(eb_untag(parent->branches.b[pside], EB_NODE))->node_p = + eb_dotag(&parent->branches, pside); + scope |= container_of(eb_untag(parent->branches.b[pside], EB_NODE), struct eb32sc_node, node.branches)->node_s; + } else { + eb_root_to_node(eb_untag(parent->branches.b[pside], EB_LEAF))->leaf_p = + eb_dotag(&parent->branches, pside); + scope |= container_of(eb_untag(parent->branches.b[pside], EB_LEAF), struct eb32sc_node, node.branches)->leaf_s; + } + } + container_of(parent, struct eb32sc_node, node)->node_s = scope; + + delete_unlink: + /* Now the node has been completely unlinked */ + node->leaf_p = NULL; + return; /* tree is not empty yet */ +} |