diff --git a/server/mpm/event/config.m4 b/server/mpm/event/config.m4 index c891c75..351f1ac 100644 --- a/server/mpm/event/config.m4 +++ b/server/mpm/event/config.m4 @@ -7,8 +7,6 @@ elif test $have_threaded_sig_graceful != yes; then AC_MSG_RESULT(no - SIG_GRACEFUL cannot be used with a threaded MPM) elif test $ac_cv_have_threadsafe_pollset != yes; then AC_MSG_RESULT(no - APR_POLLSET_THREADSAFE is not supported) -elif test $apr_has_skiplist != yes; then - AC_MSG_RESULT(no - APR skiplist is not available, need APR 1.5.x or later) else AC_MSG_RESULT(yes) APACHE_MPM_SUPPORTED(event, yes, yes) diff --git a/server/mpm/event/config3.m4 b/server/mpm/event/config3.m4 index 8aa1631..fa9b8af 100644 --- a/server/mpm/event/config3.m4 +++ b/server/mpm/event/config3.m4 @@ -2,6 +2,6 @@ dnl ## XXX - Need a more thorough check of the proper flags to use APACHE_SUBST(MOD_MPM_EVENT_LDADD) -APACHE_MPM_MODULE(event, $enable_mpm_event, event.lo fdqueue.lo,[ +APACHE_MPM_MODULE(event, $enable_mpm_event, event.lo fdqueue.lo apr_skiplist.lo,[ AC_CHECK_FUNCS(pthread_kill) ], , [\$(MOD_MPM_EVENT_LDADD)]) diff --git a/server/mpm/event/apr_skiplist.c b/server/mpm/event/apr_skiplist.c new file mode 100644 index 0000000..b4696bd --- /dev/null +++ b/server/mpm/event/apr_skiplist.c @@ -0,0 +1,721 @@ +/* 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; +} diff --git a/server/mpm/event/apr_skiplist.h b/server/mpm/event/apr_skiplist.h new file mode 100644 index 0000000..f56ff22 --- /dev/null +++ b/server/mpm/event/apr_skiplist.h @@ -0,0 +1,263 @@ +/* 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. + */ + +#ifndef APR_SKIPLIST_H +#define APR_SKIPLIST_H +/** + * @file apr_skiplist.h + * @brief APR skip list implementation + */ + +#include "apr.h" +#include "apr_portable.h" +#include + +#ifdef __cplusplus +extern "C" { +#endif /* __cplusplus */ + +/** + * @defgroup apr_skiplist Skip list implementation + * Refer to http://en.wikipedia.org/wiki/Skip_list for information + * about the purpose of and ideas behind skip lists. + * @ingroup APR + * @{ + */ + +/** + * apr_skiplist_compare is the function type that must be implemented + * per object type that is used in a skip list for comparisons to maintain + * order. A value <0 indicates placement after this node; a value of 0 + * indicates collision with this exact node; a value >0 indicates placement + * before this node. + * */ +typedef int (*apr_skiplist_compare) (void *, void *); + +/** + * apr_skiplist_freefunc is the function type that must be implemented + * to handle elements as they are removed from a skip list. + */ +typedef void (*apr_skiplist_freefunc) (void *); + +/** Opaque structure used to represent the skip list */ +struct apr_skiplist; +/** Opaque structure used to represent the skip list */ +typedef struct apr_skiplist apr_skiplist; + +/** + * Opaque structure used to represent abstract nodes in the skip list + * (an abstraction above the raw elements which are collected in the + * skip list). + */ +struct apr_skiplistnode; +/** Opaque structure */ +typedef struct apr_skiplistnode apr_skiplistnode; + +/** + * Allocate memory using the same mechanism as the skip list. + * @param sl The skip list + * @param size The amount to allocate + * @remark If a pool was provided to apr_skiplist_init(), memory will + * be allocated from the pool or from a free list maintained with + * the skip list. Otherwise, memory will be allocated using the + * C standard library heap functions. + */ +APR_DECLARE(void *) apr_skiplist_alloc(apr_skiplist *sl, size_t size); + +/** + * Free memory using the same mechanism as the skip list. + * @param sl The skip list + * @param mem The object to free + * @remark If a pool was provided to apr_skiplist_init(), memory will + * be added to a free list maintained with the skip list and be available + * to operations on the skip list or to other calls to apr_skiplist_alloc(). + * Otherwise, memory will be freed using the C standard library heap + * functions. + */ +APR_DECLARE(void) apr_skiplist_free(apr_skiplist *sl, void *mem); + +/** + * Allocate a new skip list + * @param sl The pointer in which to return the newly created skip list + * @param p The pool from which to allocate the skip list (optional). + * @remark Unlike most APR functions, a pool is optional. If no pool + * is provided, the C standard library heap functions will be used instead. + */ +APR_DECLARE(apr_status_t) apr_skiplist_init(apr_skiplist **sl, apr_pool_t *p); + +/** + * Set the comparison functions to be used for searching the skip list. + * @param sl The skip list + * @param XXX1 FIXME + * @param XXX2 FIXME + * + * @remark If existing comparison functions are being replaced, the index + * will be replaced during this call. That is a potentially expensive + * operation. + */ +APR_DECLARE(void) apr_skiplist_set_compare(apr_skiplist *sl, apr_skiplist_compare XXX1, + apr_skiplist_compare XXX2); + +/** + * Set the indexing functions to the specified comparison functions and + * rebuild the index. + * @param sl The skip list + * @param XXX1 FIXME + * @param XXX2 FIXME + * + * @remark If an index already exists, it will not be replaced and the + * comparison functions will not be changed. + */ +APR_DECLARE(void) apr_skiplist_add_index(apr_skiplist *sl, apr_skiplist_compare XXX1, + apr_skiplist_compare XXX2); + +/** + * Return the list maintained by the skip list abstraction. + * @param sl The skip list + */ +APR_DECLARE(apr_skiplistnode *) apr_skiplist_getlist(apr_skiplist *sl); + +/** + * Return the next matching element in the skip list using the specified + * comparison function. + * @param sl The skip list + * @param data The value to search for + * @param iter A pointer to the returned skip list node representing the element + * found + * @param func The comparison function to use + */ +APR_DECLARE(void *) apr_skiplist_find_compare(apr_skiplist *sl, + void *data, + apr_skiplistnode **iter, + apr_skiplist_compare func); + +/** + * Return the next matching element in the skip list using the current comparison + * function. + * @param sl The skip list + * @param data The value to search for + * @param iter A pointer to the returned skip list node representing the element + * found + */ +APR_DECLARE(void *) apr_skiplist_find(apr_skiplist *sl, void *data, apr_skiplistnode **iter); + +/** + * Return the next element in the skip list. + * @param sl The skip list + * @param iter On entry, a pointer to the skip list node to start with; on return, + * a pointer to the skip list node representing the element returned + * @remark If iter points to a NULL value on entry, NULL will be returned. + */ +APR_DECLARE(void *) apr_skiplist_next(apr_skiplist *sl, apr_skiplistnode **iter); + +/** + * Return the previous element in the skip list. + * @param sl The skip list + * @param iter On entry, a pointer to the skip list node to start with; on return, + * a pointer to the skip list node representing the element returned + * @remark If iter points to a NULL value on entry, NULL will be returned. + */ +APR_DECLARE(void *) apr_skiplist_previous(apr_skiplist *sl, apr_skiplistnode **iter); + +/** + * Insert an element into the skip list using the specified comparison function + * if it does not already exist. + * @param sl The skip list + * @param data The element to insert + * @param comp The comparison function to use for placement into the skip list + */ +APR_DECLARE(apr_skiplistnode *) apr_skiplist_insert_compare(apr_skiplist *sl, + void *data, apr_skiplist_compare comp); + +/** + * Insert an element into the skip list using the existing comparison function + * if it does not already exist (as determined by the comparison function) + * @param sl The skip list + * @param data The element to insert + * @remark If no comparison function has been set for the skip list, the element + * will not be inserted and NULL will be returned. + */ +APR_DECLARE(apr_skiplistnode *) apr_skiplist_insert(apr_skiplist* sl, void *data); + +/** + * Remove an element from the skip list using the specified comparison function for + * locating the element. In the case of duplicates, the 1st entry will be removed. + * @param sl The skip list + * @param data The element to remove + * @param myfree A function to be called for each removed element + * @param comp The comparison function to use for placement into the skip list + * @remark If the element is not found, 0 will be returned. Otherwise, the heightXXX + * will be returned. + */ +APR_DECLARE(int) apr_skiplist_remove_compare(apr_skiplist *sl, void *data, + apr_skiplist_freefunc myfree, apr_skiplist_compare comp); + +/** + * Remove an element from the skip list using the existing comparison function for + * locating the element. In the case of duplicates, the 1st entry will be removed. + * @param sl The skip list + * @param data The element to remove + * @param myfree A function to be called for each removed element + * @remark If the element is not found, 0 will be returned. Otherwise, the heightXXX + * will be returned. + * @remark If no comparison function has been set for the skip list, the element + * will not be removed and 0 will be returned. + */ +APR_DECLARE(int) apr_skiplist_remove(apr_skiplist *sl, void *data, apr_skiplist_freefunc myfree); + +/** + * Remove all elements from the skip list. + * @param sl The skip list + * @param myfree A function to be called for each removed element + */ +APR_DECLARE(void) apr_skiplist_remove_all(apr_skiplist *sl, apr_skiplist_freefunc myfree); + +/** + * Remove each element from the skip list. + * @param sl The skip list + * @param myfree A function to be called for each removed element + */ +APR_DECLARE(void) apr_skiplist_destroy(apr_skiplist *sl, apr_skiplist_freefunc myfree); + +/** + * Return the first element in the skip list, removing the element from the skip list. + * @param sl The skip list + * @param myfree A function to be called for the removed element + * @remark NULL will be returned if there are no elements + */ +APR_DECLARE(void *) apr_skiplist_pop(apr_skiplist *sl, apr_skiplist_freefunc myfree); + +/** + * Return the first element in the skip list, leaving the element in the skip list. + * @param sl The skip list + * @remark NULL will be returned if there are no elements + */ +APR_DECLARE(void *) apr_skiplist_peek(apr_skiplist *sl); + +/** + * Merge two skip lists. XXX SEMANTICS + * @param sl1 One of two skip lists to be merged + * @param sl2 The other of two skip lists to be merged + */ +APR_DECLARE(apr_skiplist *) apr_skiplist_merge(apr_skiplist *sl1, apr_skiplist *sl2); + +/** @} */ + +#ifdef __cplusplus +} +#endif + +#endif /* ! APR_SKIPLIST_H */