freebsd-skq/contrib/apr/tables/apr_skiplist.c
2015-08-09 05:14:25 +00:00

722 lines
19 KiB
C

/* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
* Modified to use APR and APR pools.
* TODO: Is malloc() better? Will long running skiplists grow too much?
* Keep the skiplist_alloc() and skiplist_free() until we know
* Yeah, if using pools it means some bogus cycles for checks
* (and an useless function call for skiplist_free) which we
* can removed if/when needed.
*/
#include "apr_skiplist.h"
typedef struct {
apr_skiplistnode **data;
size_t size, pos;
apr_pool_t *p;
} apr_skiplist_q;
struct apr_skiplist {
apr_skiplist_compare compare;
apr_skiplist_compare comparek;
int height;
int preheight;
size_t size;
apr_skiplistnode *top;
apr_skiplistnode *bottom;
/* These two are needed for appending */
apr_skiplistnode *topend;
apr_skiplistnode *bottomend;
apr_skiplist *index;
apr_array_header_t *memlist;
apr_skiplist_q nodes_q,
stack_q;
apr_pool_t *pool;
};
struct apr_skiplistnode {
void *data;
apr_skiplistnode *next;
apr_skiplistnode *prev;
apr_skiplistnode *down;
apr_skiplistnode *up;
apr_skiplistnode *previndex;
apr_skiplistnode *nextindex;
apr_skiplist *sl;
};
static int get_b_rand(void)
{
static int ph = 32; /* More bits than we will ever use */
static int randseq;
if (ph > 31) { /* Num bits in return of rand() */
ph = 0;
randseq = rand();
}
return randseq & (1 << ph++);
}
typedef struct {
size_t size;
apr_array_header_t *list;
} memlist_t;
typedef struct {
void *ptr;
char inuse;
} chunk_t;
APR_DECLARE(void *) apr_skiplist_alloc(apr_skiplist *sl, size_t size)
{
if (sl->pool) {
void *ptr;
int found_size = 0;
int i;
chunk_t *newchunk;
memlist_t *memlist = (memlist_t *)sl->memlist->elts;
for (i = 0; i < sl->memlist->nelts; i++) {
if (memlist->size == size) {
int j;
chunk_t *chunk = (chunk_t *)memlist->list->elts;
found_size = 1;
for (j = 0; j < memlist->list->nelts; j++) {
if (!chunk->inuse) {
chunk->inuse = 1;
return chunk->ptr;
}
chunk++;
}
break; /* no free of this size; punt */
}
memlist++;
}
/* no free chunks */
ptr = apr_palloc(sl->pool, size);
if (!ptr) {
return ptr;
}
/*
* is this a new sized chunk? If so, we need to create a new
* array of them. Otherwise, re-use what we already have.
*/
if (!found_size) {
memlist = apr_array_push(sl->memlist);
memlist->size = size;
memlist->list = apr_array_make(sl->pool, 20, sizeof(chunk_t));
}
newchunk = apr_array_push(memlist->list);
newchunk->ptr = ptr;
newchunk->inuse = 1;
return ptr;
}
else {
return malloc(size);
}
}
APR_DECLARE(void) apr_skiplist_free(apr_skiplist *sl, void *mem)
{
if (!sl->pool) {
free(mem);
}
else {
int i;
memlist_t *memlist = (memlist_t *)sl->memlist->elts;
for (i = 0; i < sl->memlist->nelts; i++) {
int j;
chunk_t *chunk = (chunk_t *)memlist->list->elts;
for (j = 0; j < memlist->list->nelts; j++) {
if (chunk->ptr == mem) {
chunk->inuse = 0;
return;
}
chunk++;
}
memlist++;
}
}
}
static apr_status_t skiplist_qpush(apr_skiplist_q *q, apr_skiplistnode *m)
{
if (q->pos >= q->size) {
apr_skiplistnode **data;
size_t size = (q->pos) ? q->pos * 2 : 32;
if (q->p) {
data = apr_palloc(q->p, size * sizeof(*data));
if (data) {
memcpy(data, q->data, q->pos * sizeof(*data));
}
}
else {
data = realloc(q->data, size * sizeof(*data));
}
if (!data) {
return APR_ENOMEM;
}
q->data = data;
q->size = size;
}
q->data[q->pos++] = m;
return APR_SUCCESS;
}
static APR_INLINE apr_skiplistnode *skiplist_qpop(apr_skiplist_q *q)
{
return (q->pos > 0) ? q->data[--q->pos] : NULL;
}
static APR_INLINE void skiplist_qclear(apr_skiplist_q *q)
{
q->pos = 0;
}
static apr_skiplistnode *skiplist_new_node(apr_skiplist *sl)
{
apr_skiplistnode *m = skiplist_qpop(&sl->nodes_q);
if (!m) {
if (sl->pool) {
m = apr_palloc(sl->pool, sizeof *m);
}
else {
m = malloc(sizeof *m);
}
}
return m;
}
static apr_status_t skiplist_free_node(apr_skiplist *sl, apr_skiplistnode *m)
{
return skiplist_qpush(&sl->nodes_q, m);
}
static apr_status_t skiplisti_init(apr_skiplist **s, apr_pool_t *p)
{
apr_skiplist *sl;
if (p) {
sl = apr_pcalloc(p, sizeof(apr_skiplist));
sl->memlist = apr_array_make(p, 20, sizeof(memlist_t));
sl->pool = sl->nodes_q.p = sl->stack_q.p = p;
}
else {
sl = calloc(1, sizeof(apr_skiplist));
if (!sl) {
return APR_ENOMEM;
}
}
*s = sl;
return APR_SUCCESS;
}
static int indexing_comp(void *a, void *b)
{
void *ac = (void *) (((apr_skiplist *) a)->compare);
void *bc = (void *) (((apr_skiplist *) b)->compare);
return ((ac < bc) ? -1 : ((ac > bc) ? 1 : 0));
}
static int indexing_compk(void *ac, void *b)
{
void *bc = (void *) (((apr_skiplist *) b)->compare);
return ((ac < bc) ? -1 : ((ac > bc) ? 1 : 0));
}
APR_DECLARE(apr_status_t) apr_skiplist_init(apr_skiplist **s, apr_pool_t *p)
{
apr_skiplist *sl;
skiplisti_init(s, p);
sl = *s;
skiplisti_init(&(sl->index), p);
apr_skiplist_set_compare(sl->index, indexing_comp, indexing_compk);
return APR_SUCCESS;
}
APR_DECLARE(void) apr_skiplist_set_compare(apr_skiplist *sl,
apr_skiplist_compare comp,
apr_skiplist_compare compk)
{
if (sl->compare && sl->comparek) {
apr_skiplist_add_index(sl, comp, compk);
}
else {
sl->compare = comp;
sl->comparek = compk;
}
}
APR_DECLARE(void) apr_skiplist_add_index(apr_skiplist *sl,
apr_skiplist_compare comp,
apr_skiplist_compare compk)
{
apr_skiplistnode *m;
apr_skiplist *ni;
int icount = 0;
apr_skiplist_find(sl->index, (void *)comp, &m);
if (m) {
return; /* Index already there! */
}
skiplisti_init(&ni, sl->pool);
apr_skiplist_set_compare(ni, comp, compk);
/* Build the new index... This can be expensive! */
m = apr_skiplist_insert(sl->index, ni);
while (m->prev) {
m = m->prev;
icount++;
}
for (m = apr_skiplist_getlist(sl); m; apr_skiplist_next(sl, &m)) {
int j = icount - 1;
apr_skiplistnode *nsln;
nsln = apr_skiplist_insert(ni, m->data);
/* skip from main index down list */
while (j > 0) {
m = m->nextindex;
j--;
}
/* insert this node in the indexlist after m */
nsln->nextindex = m->nextindex;
if (m->nextindex) {
m->nextindex->previndex = nsln;
}
nsln->previndex = m;
m->nextindex = nsln;
}
}
static int skiplisti_find_compare(apr_skiplist *sl, void *data,
apr_skiplistnode **ret,
apr_skiplist_compare comp)
{
int count = 0;
apr_skiplistnode *m;
m = sl->top;
while (m) {
if (m->next) {
int compared = comp(data, m->next->data);
if (compared == 0) {
m = m->next;
while (m->down) {
m = m->down;
}
*ret = m;
return count;
}
if (compared > 0) {
m = m->next;
count++;
continue;
}
}
m = m->down;
count++;
}
*ret = NULL;
return count;
}
APR_DECLARE(void *) apr_skiplist_find_compare(apr_skiplist *sli, void *data,
apr_skiplistnode **iter,
apr_skiplist_compare comp)
{
apr_skiplistnode *m;
apr_skiplist *sl;
if (!comp) {
if (iter) {
*iter = NULL;
}
return NULL;
}
if (comp == sli->compare || !sli->index) {
sl = sli;
}
else {
apr_skiplist_find(sli->index, (void *)comp, &m);
if (!m) {
if (iter) {
*iter = NULL;
}
return NULL;
}
sl = (apr_skiplist *) m->data;
}
skiplisti_find_compare(sl, data, &m, sl->comparek);
if (iter) {
*iter = m;
}
return (m) ? m->data : NULL;
}
APR_DECLARE(void *) apr_skiplist_find(apr_skiplist *sl, void *data, apr_skiplistnode **iter)
{
return apr_skiplist_find_compare(sl, data, iter, sl->compare);
}
APR_DECLARE(apr_skiplistnode *) apr_skiplist_getlist(apr_skiplist *sl)
{
if (!sl->bottom) {
return NULL;
}
return sl->bottom->next;
}
APR_DECLARE(void *) apr_skiplist_next(apr_skiplist *sl, apr_skiplistnode **iter)
{
if (!*iter) {
return NULL;
}
*iter = (*iter)->next;
return (*iter) ? ((*iter)->data) : NULL;
}
APR_DECLARE(void *) apr_skiplist_previous(apr_skiplist *sl, apr_skiplistnode **iter)
{
if (!*iter) {
return NULL;
}
*iter = (*iter)->prev;
return (*iter) ? ((*iter)->data) : NULL;
}
static APR_INLINE int skiplist_height(const apr_skiplist *sl)
{
/* Skiplists (even empty) always have a top node, although this
* implementation defers its creation until the first insert, or
* deletes it with the last remove. We want the real height here.
*/
return sl->height ? sl->height : 1;
}
APR_DECLARE(apr_skiplistnode *) apr_skiplist_insert_compare(apr_skiplist *sl, void *data,
apr_skiplist_compare comp)
{
apr_skiplistnode *m, *p, *tmp, *ret = NULL;
int ch, nh = 1;
if (!comp) {
return NULL;
}
ch = skiplist_height(sl);
if (sl->preheight) {
while (nh < sl->preheight && get_b_rand()) {
nh++;
}
}
else {
while (nh <= ch && get_b_rand()) {
nh++;
}
}
/* Now we have in nh the height at which we wish to insert our new node,
* and in ch the current height: don't create skip paths to the inserted
* element until the walk down through the tree (which decrements ch)
* reaches nh. From there, any walk down pushes the current node on a
* stack (the node(s) after which we would insert) to pop back through
* for insertion later.
*/
m = sl->top;
while (m) {
if (m->next) {
int compared = comp(data, m->next->data);
if (compared == 0) {
/* Keep the existing element(s) */
skiplist_qclear(&sl->stack_q);
return NULL;
}
if (compared > 0) {
m = m->next;
continue;
}
}
if (ch <= nh) {
/* push on stack */
skiplist_qpush(&sl->stack_q, m);
}
m = m->down;
ch--;
}
/* Pop the stack and insert nodes */
p = NULL;
while ((m = skiplist_qpop(&sl->stack_q))) {
tmp = skiplist_new_node(sl);
tmp->next = m->next;
if (m->next) {
m->next->prev = tmp;
}
m->next = tmp;
tmp->prev = m;
tmp->up = NULL;
tmp->nextindex = tmp->previndex = NULL;
tmp->down = p;
if (p) {
p->up = tmp;
}
else {
/* This sets ret to the bottom-most node we are inserting */
ret = tmp;
}
tmp->data = data;
tmp->sl = sl;
p = tmp;
}
/* Now we are sure the node is inserted, grow our tree to 'nh' tall */
for (; sl->height < nh; sl->height++) {
m = skiplist_new_node(sl);
tmp = skiplist_new_node(sl);
m->up = m->prev = m->nextindex = m->previndex = NULL;
m->next = tmp;
m->down = sl->top;
m->data = NULL;
m->sl = sl;
if (sl->top) {
sl->top->up = m;
}
else {
sl->bottom = sl->bottomend = m;
}
sl->top = sl->topend = tmp->prev = m;
tmp->up = tmp->next = tmp->nextindex = tmp->previndex = NULL;
tmp->down = p;
tmp->data = data;
tmp->sl = sl;
if (p) {
p->up = tmp;
}
else {
/* This sets ret to the bottom-most node we are inserting */
ret = tmp;
}
p = tmp;
}
if (sl->index != NULL) {
/*
* this is a external insertion, we must insert into each index as
* well
*/
apr_skiplistnode *ni, *li;
li = ret;
for (p = apr_skiplist_getlist(sl->index); p; apr_skiplist_next(sl->index, &p)) {
apr_skiplist *sli = (apr_skiplist *)p->data;
ni = apr_skiplist_insert_compare(sli, ret->data, sli->compare);
li->nextindex = ni;
ni->previndex = li;
li = ni;
}
}
sl->size++;
return ret;
}
APR_DECLARE(apr_skiplistnode *) apr_skiplist_insert(apr_skiplist *sl, void *data)
{
return apr_skiplist_insert_compare(sl, data, sl->compare);
}
#if 0
void skiplist_print_struct(apr_skiplist * sl, char *prefix)
{
apr_skiplistnode *p, *q;
fprintf(stderr, "Skiplist Structure (height: %d)\n", sl->height);
p = sl->bottom;
while (p) {
q = p;
fprintf(stderr, prefix);
while (q) {
fprintf(stderr, "%p ", q->data);
q = q->up;
}
fprintf(stderr, "\n");
p = p->next;
}
}
#endif
static int skiplisti_remove(apr_skiplist *sl, apr_skiplistnode *m, apr_skiplist_freefunc myfree)
{
apr_skiplistnode *p;
if (!m) {
return 0;
}
if (m->nextindex) {
skiplisti_remove(m->nextindex->sl, m->nextindex, NULL);
}
while (m->up) {
m = m->up;
}
while (m) {
p = m;
p->prev->next = p->next;/* take me out of the list */
if (p->next) {
p->next->prev = p->prev; /* take me out of the list */
}
m = m->down;
/* This only frees the actual data in the bottom one */
if (!m && myfree && p->data) {
myfree(p->data);
}
skiplist_free_node(sl, p);
}
sl->size--;
while (sl->top && sl->top->next == NULL) {
/* While the row is empty and we are not on the bottom row */
p = sl->top;
sl->top = sl->top->down;/* Move top down one */
if (sl->top) {
sl->top->up = NULL; /* Make it think its the top */
}
skiplist_free_node(sl, p);
sl->height--;
}
if (!sl->top) {
sl->bottom = sl->bottomend = NULL;
sl->topend = NULL;
}
return skiplist_height(sl);
}
APR_DECLARE(int) apr_skiplist_remove_compare(apr_skiplist *sli,
void *data,
apr_skiplist_freefunc myfree, apr_skiplist_compare comp)
{
apr_skiplistnode *m;
apr_skiplist *sl;
if (!comp) {
return 0;
}
if (comp == sli->comparek || !sli->index) {
sl = sli;
}
else {
apr_skiplist_find(sli->index, (void *)comp, &m);
if (!m) {
return 0;
}
sl = (apr_skiplist *) m->data;
}
skiplisti_find_compare(sl, data, &m, comp);
if (!m) {
return 0;
}
while (m->previndex) {
m = m->previndex;
}
return skiplisti_remove(sl, m, myfree);
}
APR_DECLARE(int) apr_skiplist_remove(apr_skiplist *sl, void *data, apr_skiplist_freefunc myfree)
{
return apr_skiplist_remove_compare(sl, data, myfree, sl->comparek);
}
APR_DECLARE(void) apr_skiplist_remove_all(apr_skiplist *sl, apr_skiplist_freefunc myfree)
{
/*
* This must remove even the place holder nodes (bottom though top)
* because we specify in the API that one can free the Skiplist after
* making this call without memory leaks
*/
apr_skiplistnode *m, *p, *u;
m = sl->bottom;
while (m) {
p = m->next;
if (myfree && p && p->data) {
myfree(p->data);
}
do {
u = m->up;
skiplist_free_node(sl, m);
m = u;
} while (m);
m = p;
}
sl->top = sl->bottom = NULL;
sl->topend = sl->bottomend = NULL;
sl->height = 0;
sl->size = 0;
}
APR_DECLARE(void *) apr_skiplist_pop(apr_skiplist *a, apr_skiplist_freefunc myfree)
{
apr_skiplistnode *sln;
void *data = NULL;
sln = apr_skiplist_getlist(a);
if (sln) {
data = sln->data;
skiplisti_remove(a, sln, myfree);
}
return data;
}
APR_DECLARE(void *) apr_skiplist_peek(apr_skiplist *a)
{
apr_skiplistnode *sln;
sln = apr_skiplist_getlist(a);
if (sln) {
return sln->data;
}
return NULL;
}
static void skiplisti_destroy(void *vsl)
{
apr_skiplist_destroy(vsl, NULL);
}
APR_DECLARE(void) apr_skiplist_destroy(apr_skiplist *sl, apr_skiplist_freefunc myfree)
{
while (apr_skiplist_pop(sl->index, skiplisti_destroy) != NULL)
;
apr_skiplist_remove_all(sl, myfree);
if (!sl->pool) {
while (sl->nodes_q.pos)
free(sl->nodes_q.data[--sl->nodes_q.pos]);
free(sl->nodes_q.data);
free(sl->stack_q.data);
free(sl);
}
}
APR_DECLARE(apr_skiplist *) apr_skiplist_merge(apr_skiplist *sl1, apr_skiplist *sl2)
{
/* Check integrity! */
apr_skiplist temp;
struct apr_skiplistnode *b2;
if (sl1->bottomend == NULL || sl1->bottomend->prev == NULL) {
apr_skiplist_remove_all(sl1, NULL);
temp = *sl1;
*sl1 = *sl2;
*sl2 = temp;
/* swap them so that sl2 can be freed normally upon return. */
return sl1;
}
if(sl2->bottom == NULL || sl2->bottom->next == NULL) {
apr_skiplist_remove_all(sl2, NULL);
return sl1;
}
/* This is what makes it brute force... Just insert :/ */
b2 = apr_skiplist_getlist(sl2);
while (b2) {
apr_skiplist_insert(sl1, b2->data);
apr_skiplist_next(sl2, &b2);
}
apr_skiplist_remove_all(sl2, NULL);
return sl1;
}