haproxy/ebtree/eb32sctree.c

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/*
* 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 "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 */
}