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Code Issues Releases Wiki Activity

added a function for getting space for ancestor nodes in the node_chain,

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and use it within dns_rbt_findnode.

moved the guts of dns_rbt_deletename into its own function to clean up
the freeing of ancestor memory into just one location.

deletefromlevel required that ancestor_count be > 1, which would abort
trying to delete the root of the tree when the root had no children.
This commit is contained in:
David Lawrence
1999-01-31 18:43:57 +00:00
parent 97940a084c
commit 94231e2288
1 changed files with 98 additions and 68 deletions
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166
lib/dns/rbt.c
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@@ -22,6 +22,7 @@
#include <string.h>
#include <isc/assertions.h>
#include <isc/boolean.h>
#include <isc/error.h>
#include <isc/mem.h>
#include <isc/result.h>
@@ -49,6 +50,7 @@ struct node_chain {
*/
dns_rbtnode_t * levels[127];
int level_count;
isc_boolean_t mem_failure;
};
#ifndef MIN
@@ -83,6 +85,16 @@ struct node_chain {
#define FIRST_IS_LESS -1
#define FIRST_IS_MORE -2
/*
* For use in allocating space for the chain of ancestor nodes.
*
* The maximum number of ancestors is theoretically not limited by the
* data tree. This initial value of 24 ancestors would be able to scan
* the full height of a single level of 16,777,216 nodes, more than double
* the current size of .com.
*/
#define ANCESTOR_BLOCK 24
#ifdef DEBUG
#define inline
/*
@@ -111,6 +123,9 @@ static dns_result_t join_nodes(dns_rbt_t *rbt,
dns_rbtnode_t *node, dns_rbtnode_t *parent,
dns_rbtnode_t **rootp);
static inline dns_result_t get_ancestor_mem(isc_mem_t *mctx,
node_chain_t *chain);
static int cmp_label(dns_label_t *a, dns_label_t *b);
static inline int cmp_names_on_level(dns_name_t *a, dns_name_t *b);
static inline int cmp_names_for_depth(dns_name_t *a, dns_name_t *b);
@@ -127,6 +142,10 @@ static void dns_rbt_deletefromlevel(dns_rbt_t *rbt,
node_chain_t *chain);
static void dns_rbt_deletetree(dns_rbt_t *rbt, dns_rbtnode_t *node);
static dns_result_t zapnode_and_fixlevels(dns_rbt_t *rbt,
dns_rbtnode_t *node,
isc_boolean_t recurse,
node_chain_t *chain);
/*
* Initialize a red/black tree of trees.
@@ -453,7 +472,7 @@ dns_rbt_addname(dns_rbt_t *rbt, dns_name_t *name, void *data) {
*/
dns_rbtnode_t *
dns_rbt_findnode(dns_rbt_t *rbt, dns_name_t *name, node_chain_t *chain) {
dns_rbtnode_t *current, **ancestor_mem;
dns_rbtnode_t *current;
dns_name_t *search_name, *new_search_name, *current_name;
dns_name_t holder1, holder2;
int compared, current_labels, keep_labels, dont_count_root_label;
@@ -475,29 +494,16 @@ dns_rbt_findnode(dns_rbt_t *rbt, dns_name_t *name, node_chain_t *chain) {
current_name = &holder1;
if (chain != NULL) {
/*
* The maximum number of ancestors is theoretically
* not limited by the data tree. This initial value
* of 24 ancestors would be able to scan the full
* height of a single level of 16,777,216 nodes, more
* than double the current size of .com.
*/
chain->ancestor_maxitems = 24;
ancestor_mem = isc_mem_get(rbt->mctx,
chain->ancestor_maxitems *
sizeof(dns_rbtnode_t *));
if (ancestor_mem == NULL)
return (NULL); /* @@@ flag no memory! best way? */
chain->ancestors = ancestor_mem;
chain->ancestor_maxitems = 0;
chain->ancestor_count = 0;
ADD_ANCESTOR(chain, NULL);
chain->level_count = 0;
}
if (get_ancestor_mem(rbt->mctx, chain) != DNS_R_SUCCESS)
return (NULL);
ADD_ANCESTOR(chain, NULL);
}
while (current != NULL) {
dns_rbt_namefromnode(current, current_name);
compared = cmp_names_for_depth(search_name, current_name);
@@ -509,23 +515,9 @@ dns_rbt_findnode(dns_rbt_t *rbt, dns_name_t *name, node_chain_t *chain) {
* Expand the storage space for ancestors, if necessary.
*/
if (chain != NULL &&
chain->ancestor_count == chain->ancestor_maxitems) {
int oldsize = chain->ancestor_maxitems *
sizeof(dns_rbtnode_t *);
chain->ancestor_maxitems += 24;
ancestor_mem = isc_mem_get(rbt->mctx,
chain->ancestor_maxitems *
sizeof(dns_rbtnode_t *));
if (ancestor_mem == NULL)
return (NULL); /* @@@ flag no mem! best way? */
memcpy(ancestor_mem, chain->ancestors, oldsize);
isc_mem_put(rbt->mctx, chain->ancestors, oldsize);
chain->ancestors = ancestor_mem;
}
chain->ancestor_count == chain->ancestor_maxitems &&
get_ancestor_mem(rbt->mctx, chain) != DNS_R_SUCCESS)
return (NULL);
/*
* Standard binary search tree movement.
@@ -624,10 +616,9 @@ dns_rbt_findname(dns_rbt_t *rbt, dns_name_t *name) {
*/
dns_result_t
dns_rbt_deletename(dns_rbt_t *rbt, dns_name_t *name, isc_boolean_t recurse) {
dns_rbtnode_t *node, *down, *parent, **rootp;
dns_rbtnode_t *node;
dns_result_t result;
node_chain_t chain;
int ancestor_memory_size;
REQUIRE(VALID_RBT(rbt));
REQUIRE(dns_name_isabsolute(name));
@@ -635,27 +626,45 @@ dns_rbt_deletename(dns_rbt_t *rbt, dns_name_t *name, isc_boolean_t recurse) {
/*
* Find the node, building the ancestor chain.
*
* @@@ When searching, the name might not have an exact match:
* When searching, the name might not have an exact match:
* consider a.b.a.com, b.b.a.com and c.b.a.com as the only
* elements of a tree, which would make layer 1 a single
* node tree of "b.a.com" and layer 2 a three node tree of
* a, b, and c. Deleting a.com would find only a partial depth
* match in the first layer. Should it be a requirement that
* that the name have been added with data? For now, it is.
* that the name to be deleted have data? For now, it is.
*
* @@@ how to ->dirty, ->locknum and ->references figure in?
*/
node = dns_rbt_findnode(rbt, name, &chain);
ancestor_memory_size = chain.ancestor_maxitems *
sizeof(dns_rbtnode_t *);
/*
* The guts of this routine are in a separate function (which
* is called only once, by this function) to make freeing the
* ancestor memory easier, since there are several different
* exit points from the level checking logic.
*/
result = zapnode_and_fixlevels(rbt, node, recurse, &chain);
if (node == NULL || DATA(node) == NULL) {
if (chain.ancestor_maxitems > 0)
isc_mem_put(rbt->mctx, chain.ancestors,
ancestor_memory_size); /* @@@ */
return (DNS_R_NOTFOUND);
}
chain.ancestor_maxitems * sizeof(dns_rbtnode_t *));
return (result);
}
static dns_result_t
zapnode_and_fixlevels(dns_rbt_t *rbt, dns_rbtnode_t *node,
isc_boolean_t recurse, node_chain_t *chain) {
dns_rbtnode_t *down, *parent, **rootp;
dns_result_t result;
if (node == NULL || DATA(node) == NULL)
if (chain->mem_failure)
return (DNS_R_NOMEMORY);
else
return (DNS_R_NOTFOUND);
down = DOWN(node);
@@ -669,7 +678,7 @@ dns_rbt_deletename(dns_rbt_t *rbt, dns_name_t *name, isc_boolean_t recurse) {
rbt->data_deleter(DATA(node));
DATA(node) = NULL;
if (LEFT(down) != NULL || RIGHT(down) != NULL) {
if (LEFT(down) != NULL || RIGHT(down) != NULL)
/*
* This node cannot be removed because it
* points down to a level that has more than
@@ -677,10 +686,7 @@ dns_rbt_deletename(dns_rbt_t *rbt, dns_name_t *name, isc_boolean_t recurse) {
* as the root for that level. All that
* could be done was to blast its data.
*/
isc_mem_put(rbt->mctx, chain.ancestors,
ancestor_memory_size); /* @@@ */
return (DNS_R_SUCCESS);
}
/*
* There is a down pointer to a level with a single
@@ -688,16 +694,13 @@ dns_rbt_deletename(dns_rbt_t *rbt, dns_name_t *name, isc_boolean_t recurse) {
* on this level.
*/
rootp = chain.level_count > 0 ?
&DOWN(chain.levels[chain.level_count - 1]) :
rootp = chain->level_count > 0 ?
&DOWN(chain->levels[chain->level_count - 1]) :
&rbt->root;
parent = chain.ancestors[chain.ancestor_count - 1];
parent = chain->ancestors[chain->ancestor_count - 1];
result = join_nodes(rbt, node, parent, rootp);
isc_mem_put(rbt->mctx, chain.ancestors,
ancestor_memory_size); /* @@@ */
return (result);
}
}
@@ -707,7 +710,7 @@ dns_rbt_deletename(dns_rbt_t *rbt, dns_name_t *name, isc_boolean_t recurse) {
* have one to start, or because it was recursively removed).
* So now the node needs to be removed from this level.
*/
dns_rbt_deletefromlevel(rbt, node, &chain);
dns_rbt_deletefromlevel(rbt, node, chain);
if (rbt->data_deleter != NULL)
rbt->data_deleter(DATA(node));
@@ -724,13 +727,13 @@ dns_rbt_deletename(dns_rbt_t *rbt, dns_name_t *name, isc_boolean_t recurse) {
* merged. The focus for exploring this criteria is shifted up one
* level.
*/
node = chain.level_count > 0 ?
chain.levels[chain.level_count - 1] : NULL;
node = chain->level_count > 0 ?
chain->levels[chain->level_count - 1] : NULL;
if (node != NULL && DATA(node) == NULL &&
LEFT(DOWN(node)) == NULL && RIGHT(DOWN(node)) == NULL) {
rootp = chain.level_count > 1 ?
&DOWN(chain.levels[chain.level_count - 2]) :
rootp = chain->level_count > 1 ?
&DOWN(chain->levels[chain->level_count - 2]) :
&rbt->root;
/*
* The search to find the original node went through the
@@ -746,14 +749,13 @@ dns_rbt_deletename(dns_rbt_t *rbt, dns_name_t *name, isc_boolean_t recurse) {
* In the second case, ancestor_count - 1 is remaining_node,
* - 2, is NULL and - 3 is the parent of current_node.
*/
parent = chain.ancestors[chain.ancestor_count - 1] == NULL ?
chain.ancestors[chain.ancestor_count - 2] :
chain.ancestors[chain.ancestor_count - 3];
parent = chain->ancestors[chain->ancestor_count - 1] == NULL ?
chain->ancestors[chain->ancestor_count - 2] :
chain->ancestors[chain->ancestor_count - 3];
result = join_nodes(rbt, node, parent, rootp);
}
isc_mem_put(rbt->mctx, chain.ancestors, ancestor_memory_size);/* @@@ */
return (result);
}
@@ -863,6 +865,34 @@ join_nodes(dns_rbt_t *rbt,
return (result);
}
static inline dns_result_t
get_ancestor_mem(isc_mem_t *mctx, node_chain_t *chain) {
dns_rbtnode_t **ancestor_mem;
int oldsize, newsize;
oldsize = chain->ancestor_maxitems * sizeof(dns_rbtnode_t *);
newsize = oldsize + ANCESTOR_BLOCK * sizeof(dns_rbtnode_t *);
ancestor_mem = isc_mem_get(mctx, newsize);
if (ancestor_mem == NULL) {
chain->mem_failure = ISC_TRUE;
return (DNS_R_NOMEMORY);
}
chain->mem_failure = ISC_FALSE;
if (oldsize > 0) {
memcpy(ancestor_mem, chain->ancestors, oldsize);
isc_mem_put(mctx, chain->ancestors, oldsize);
}
chain->ancestors = ancestor_mem;
chain->ancestor_maxitems += ANCESTOR_BLOCK;
return (DNS_R_SUCCESS);
}
static inline void
rotate_left(dns_rbtnode_t *node, dns_rbtnode_t *parent, dns_rbtnode_t **rootp) {
dns_rbtnode_t *child;
@@ -1040,7 +1070,7 @@ dns_rbt_deletefromlevel(dns_rbt_t *rbt, dns_rbtnode_t *delete,
REQUIRE(VALID_RBT(rbt));
REQUIRE(delete);
REQUIRE(chain->ancestor_count > 1);
REQUIRE(chain->ancestor_count > 0);
parent = chain->ancestors[chain->ancestor_count - 1];