diff --git a/examples/slm.c b/examples/slm.c index d59b1d2..cb4ba49 100644 --- a/examples/slm.c +++ b/examples/slm.c @@ -18,10 +18,10 @@ // Local demo application OPTIONS: // --------------------------------------------------------------------------- -#define TEST_ARRAY_SIZE 50 +#define TEST_ARRAY_SIZE 1000 #define VALIDATE -#define SNAPSHOTS -#define DOT +//define SNAPSHOTS +//define DOT #ifdef DOT size_t gen = 0; FILE *of = 0; @@ -182,7 +182,7 @@ SKIPLIST_DECL_DOT(esempio, api_, entries) void sprintf_esempio_node(esempio_node_t *node, char *buf) { - sprintf(buf, "%d:%s (hits: %lu)", node->key, node->value, node->entries.sle_hits); + sprintf(buf, "%d:%s (hits: %lu)", node->key, node->value, node->entries.sle_levels[0]->hits); //TODO sprintf(buf, "%d:%s", node->key, node->value); } @@ -224,6 +224,10 @@ int_to_roman_numeral(int num) res[0] = '0'; return res; } + if (num > 10000) { + sprintf(res, "The person you were looking for is not here, their mailbox is full, good bye."); + return res; + } while (num) { // while input number is not zero while (num / del[i]) { // while a number contains the largest key value possible strcat(res, sym[i]); // append the symbol for this key value to res string diff --git a/include/sl.h b/include/sl.h index 7a9fabf..15d6422 100644 --- a/include/sl.h +++ b/include/sl.h @@ -202,12 +202,15 @@ void __attribute__((format(printf, 4, 5))) __skip_diag_(const char *file, int li * zero-based count of levels, so a height of `0` means one (1) level and a * height of `4` means five (5) forward pointers (levels) in the node, [0-4). */ -#define SKIPLIST_ENTRY(decl) \ - struct __skiplist_##decl##_entry { \ - struct decl##_node *sle_prev, **sle_next; \ - size_t sle_height; \ - size_t sle_era; \ - size_t sle_hits; \ +#define SKIPLIST_ENTRY(decl) \ + struct __skiplist_##decl##_entry { \ + size_t sle_era; \ + size_t sle_height; \ + struct decl##_node *sle_prev; \ + struct __skiplist_##decl##_level { \ + struct decl##_node *next; \ + size_t hits; \ + } **sle_levels; \ } #define SKIPLIST_FOREACH_H2T(decl, prefix, list, elm, iter) \ @@ -231,982 +234,986 @@ void __attribute__((format(printf, 4, 5))) __skip_diag_(const char *file, int li /* Iterate over the subtree to the left (v, or 'lt') and right (u) or "CHu" and "CHv". */ #define __SKIP_SUBTREE_CHv(decl, field, list, path, nth) \ - for (decl##_node_t *elm = path[nth].node; elm->field.sle_next[path[nth].in] == path[nth].node; elm = elm->field.sle_prev) + for (decl##_node_t *elm = path[nth].node; elm->field.sle_levels[path[nth].in]->next == path[nth].node; elm = elm->field.sle_prev) #define __SKIP_SUBTREE_CHu(decl, field, list, path, nth) \ - for (decl##_node_t *elm = path[nth].node; elm != path[nth].node->field.sle_next[0]; elm = elm->field.sle_next[0]) + for (decl##_node_t *elm = path[nth].node; elm != path[nth].node->field.sle_levels[0]->next; elm = elm->field.sle_levels[0]->next) /* * Skiplist declarations and access methods. */ -#define SKIPLIST_DECL(decl, prefix, field, compare_entries_blk, free_entry_blk, update_entry_blk, archive_entry_blk, sizeof_entry_blk) \ - \ - /* Used when positioning a cursor within a Skiplist. */ \ - typedef enum { SKIP_EQ = 0, SKIP_LTE = -1, SKIP_LT = -2, SKIP_GTE = 1, SKIP_GT = 2 } skip_pos_##decl_t; \ - \ - /* Skiplist node type */ \ - typedef struct decl##_node decl##_node_t; \ - \ - /* Skiplist type. */ \ - typedef struct decl decl##_t; \ - \ - /* Skiplist structure */ \ - struct decl { \ - size_t slh_length, slh_max_height; \ - void *slh_aux; \ - decl##_node_t *slh_head; \ - decl##_node_t *slh_tail; \ - struct { \ - void (*free_entry)(decl##_node_t *); \ - int (*update_entry)(decl##_node_t *, void *); \ - int (*archive_entry)(decl##_node_t *, const decl##_node_t *); \ - size_t (*sizeof_entry)(decl##_node_t *); \ - int (*compare_entries)(decl##_t *, decl##_node_t *, decl##_node_t *, void *); \ - \ - /* Optional: Snapshots */ \ - int (*preserve_node)(decl##_t * slist, const decl##_node_t *src, decl##_node_t **preserved); \ - void (*release_snapshots)(decl##_t *); \ - size_t (*snapshot_current_era)(decl##_t *); \ - size_t (*snapshot_incr_era)(decl##_t *); \ - void (*snapshot_record_era)(decl##_t *, decl##_node_t *); \ - } slh_fns; \ - struct { \ - size_t era; \ - decl##_node_t *pres; \ - } slh_snap; \ - }; \ - \ - typedef struct __skiplist_path_##decl { \ - decl##_node_t *node; /* node traversed in the act of location */ \ - size_t in; /* level at which the node was intersected */ \ - size_t pu; /* sum of hits from intersection to level[1] */ \ - } __skiplist_path_##decl##_t; \ - \ - /** \ - * -- __skip_compare_entries_fn_ \ - * \ - * Wraps the `compare_entries_blk` code into `slh_fns.compare_entries`. \ - */ \ - static int __skip_compare_entries_fn_##decl(decl##_t *list, decl##_node_t *a, decl##_node_t *b, void *aux) \ - { \ - compare_entries_blk; \ - } \ - \ - /** \ - * -- __skip_free_entry_fn \ - * \ - * Wraps the `free_entry_blk` code into `slh_fns.free_entry`. \ - */ \ - static void __skip_free_entry_fn_##decl(decl##_node_t *node) \ - { \ - free_entry_blk; \ - } \ - \ - /** \ - * -- __skip_update_entry_fn_ \ - * \ - * Wraps the `update_entry_blk` code into `slh_fns.update_entry`. \ - */ \ - static int __skip_update_entry_fn_##decl(decl##_node_t *node, void *value) \ - { \ - int rc = 0; \ - update_entry_blk; \ - return rc; \ - } \ - \ - /** \ - * -- __skip_archive_entry_fn_ \ - * \ - * Wraps the `archive_entry_blk` code into `slh_fns.archive_entry`. \ - */ \ - static int __skip_archive_entry_fn_##decl(decl##_node_t *dest, const decl##_node_t *src) \ - { \ - int rc = 0; \ - archive_entry_blk; \ - return rc; \ - } \ - \ - /** \ - * -- __skip_sizeof_entry_fn_ \ - * \ - * Wraps the `sizeof_entry_blk` code into `slh_fns.sizeof_entry`. \ - */ \ - static size_t __skip_sizeof_entry_fn_##decl(decl##_node_t *node) \ - { \ - size_t bytes = 0; \ - sizeof_entry_blk; \ - return bytes; \ - } \ - \ - /** \ - * -- __skip_compare_nodes_ \ - * \ - * This function takes four arguments: \ - * - a reference to the Skiplist \ - * - the two nodes to compare, `a` and `b` \ - * - `aux` an additional auxiliary argument \ - * and returns: \ - * a < b : return -1 \ - * a == b : return 0 \ - * a > b : return 1 \ - */ \ - static int __skip_compare_nodes_##decl(decl##_t *slist, decl##_node_t *a, decl##_node_t *b, void *aux) \ - { \ - if (a == b) \ - return 0; \ - if (a == NULL) \ - return -1; \ - if (b == NULL) \ - return 1; \ - if (a == slist->slh_head || b == slist->slh_tail) \ - return -1; \ - if (a == slist->slh_tail || b == slist->slh_head) \ - return 1; \ - return slist->slh_fns.compare_entries(slist, a, b, aux); \ - } \ - \ - /** \ - * -- __skip_toss_ \ - * \ - * A "coin toss" function that is critical to the proper operation of the \ - * Skiplist. For example, when `max = 6` this function returns 0 with \ - * probability 0.5, 1 with 0.25, 2 with 0.125, etc. until 6 with 0.5^7. \ - */ \ - static int __skip_toss_##decl(size_t max) \ - { \ - size_t level = 0; \ - double probability = 0.5; \ - \ - double random_value = (double)rand() / RAND_MAX; /* NOLINT(*-msc50-cpp) */ \ - while (random_value < probability && level < max) { \ - level++; \ - probability *= 0.5; \ - } \ - return level; \ - } \ - \ - /** \ - * -- skip_alloc_node_ \ - * \ - * Allocates a new node on the heap and sets default values. \ - */ \ - int prefix##skip_alloc_node_##decl(decl##_t *slist, decl##_node_t **node) \ - { \ - decl##_node_t *n; \ - /* Calculate the size of the struct sle within decl##_node_t, multiply \ - by array size. (16/24 bytes on 32/64 bit systems) */ \ - size_t sle_arr_sz = sizeof(struct __skiplist_##decl##_entry) * slist->slh_max_height; \ - n = (decl##_node_t *)calloc(1, sizeof(decl##_node_t) + sle_arr_sz); \ - if (n == NULL) \ - return ENOMEM; \ - n->field.sle_height = 0; \ - n->field.sle_next = (decl##_node_t **)((uintptr_t)n + sizeof(decl##_node_t)); \ - *node = n; \ - return 0; \ - } \ - \ - /** \ - * -- skip_init_ \ - * \ - * Initializes a Skiplist to the deafault values, this must be called \ - * before using the list. \ - */ \ - int prefix##skip_init_##decl(decl##_t *slist, int max) \ - { \ - int rc = 0; \ - size_t i; \ - \ - slist->slh_length = 0; \ - slist->slh_max_height = SKIPLIST_MAX_HEIGHT == 1 ? (size_t)(max < 0 ? -max : max) : SKIPLIST_MAX_HEIGHT; \ - slist->slh_snap.era = 0; \ - slist->slh_fns.free_entry = __skip_free_entry_fn_##decl; \ - slist->slh_fns.update_entry = __skip_update_entry_fn_##decl; \ - slist->slh_fns.archive_entry = __skip_archive_entry_fn_##decl; \ - slist->slh_fns.sizeof_entry = __skip_sizeof_entry_fn_##decl; \ - slist->slh_fns.compare_entries = __skip_compare_entries_fn_##decl; \ - rc = prefix##skip_alloc_node_##decl(slist, &slist->slh_head); \ - if (rc) \ - goto fail; \ - rc = prefix##skip_alloc_node_##decl(slist, &slist->slh_tail); \ - if (rc) \ - goto fail; \ - \ - slist->slh_head->field.sle_height = floor(log(slist->slh_max_height) / M_LOG2E); \ - for (i = 0; i < slist->slh_max_height; i++) \ - slist->slh_head->field.sle_next[i] = slist->slh_tail; \ - slist->slh_head->field.sle_prev = NULL; \ - \ - slist->slh_tail->field.sle_height = slist->slh_head->field.sle_height; \ - for (i = 0; i < slist->slh_max_height; i++) \ - slist->slh_tail->field.sle_next[i] = NULL; \ - slist->slh_tail->field.sle_prev = slist->slh_head; \ - \ - /* NOTE: Here's a testing aid, simply set `max` to a negative number to \ - * seed the PRNG in a predictable way and have reproducible random numbers. \ - */ \ - if (max < 0) \ - srand(-max); \ - else \ - srand(((unsigned int)time(NULL) ^ getpid())); \ - fail:; \ - return rc; \ - } \ - \ - /** \ - * -- skip_free_node_ \ - * \ - * Properly releases heap memory allocated for use as a node. \ - * This function invokes the `free_node_blk` within which you \ - * should release any heap objects or other resources held by \ - * this node in the list. \ - */ \ - void prefix##skip_free_node_##decl(decl##_t *slist, decl##_node_t *node) \ - { \ - slist->slh_fns.free_entry(node); \ - free(node); \ - } \ - \ - /** \ - * -- skip_length_ \ - * \ - * Returns the current length of the list. \ - */ \ - int prefix##skip_length_##decl(decl##_t *slist) \ - { \ - return slist->slh_length; \ - } \ - \ - /** \ - * -- skip_is_empty_ \ - * \ - * Returns non-zero when the list is empty. \ - */ \ - int prefix##skip_is_empty_##decl(decl##_t *slist) \ - { \ - return slist->slh_length == 0; \ - } \ - \ - /** \ - * -- skip_head_ \ - * \ - * Returns the node containing the first (smallest) element in the \ - * list which can be used to traverse the list. \ - */ \ - decl##_node_t *prefix##skip_head_##decl(decl##_t *slist) \ - { \ - return slist->slh_head->field.sle_next[0] == slist->slh_tail ? NULL : slist->slh_head->field.sle_next[0]; \ - } \ - \ - /** \ - * -- skip_tail_ \ - * \ - * Returns the node containing the last (largest) element in the \ - * list which can be used to traverse the list. \ - */ \ - decl##_node_t *prefix##skip_tail_##decl(decl##_t *slist) \ - { \ - return slist->slh_tail->field.sle_prev == slist->slh_head->field.sle_next[0] ? NULL : slist->slh_tail->field.sle_prev; \ - } \ - \ - /** \ - * -- skip_next_node_ \ - * \ - * A node reference can be thought of as a cursor. This moves the cursor \ - * to the next node in the list or returns NULL if the next is the tail. \ - */ \ - decl##_node_t *prefix##skip_next_node_##decl(decl##_t *slist, decl##_node_t *n) \ - { \ - if (slist == NULL || n == NULL) \ - return NULL; \ - if (n->field.sle_next[0] == slist->slh_tail) \ - return NULL; \ - return n->field.sle_next[0]; \ - } \ - \ - /** \ - * -- skip_prev_node_ \ - * \ - * A node reference can be thought of as a cursor. This moves the cursor \ - * to the previous node in the list or returns NULL if the previous node \ - * is the head. \ - */ \ - decl##_node_t *prefix##skip_prev_node_##decl(decl##_t *slist, decl##_node_t *n) \ - { \ - if (slist == NULL || n == NULL) \ - return NULL; \ - if (n->field.sle_prev == slist->slh_head) \ - return NULL; \ - return n->field.sle_prev; \ - } \ - \ - /** \ - * -- skip_release_ \ - * \ - * Release all nodes and their associated heap objects, but not the list \ - * itself. The list is still valid, only empty. \ - */ \ - void prefix##skip_release_##decl(decl##_t *slist) \ - { \ - decl##_node_t *node, *next; \ - \ - if (slist == NULL) \ - return; \ - if (prefix##skip_is_empty_##decl(slist)) \ - return; \ - node = prefix##skip_head_##decl(slist); \ - do { \ - next = prefix##skip_next_node_##decl(slist, node); \ - prefix##skip_free_node_##decl(slist, node); \ - node = next; \ - } while (node != NULL); \ - \ - while (node) { \ - next = node->field.sle_next[0]; \ - if (next->field.sle_prev) \ - slist->slh_fns.free_entry(node); \ - free(node); \ - } \ - if (slist->slh_fns.snapshot_incr_era) \ - slist->slh_fns.snapshot_incr_era(slist); \ - return; \ - } \ - \ - /** \ - * -- skip_to_array_ \ - * \ - * Returns a heap allocated array of nodes in the order they exist. \ - * This isn't maintained by the list, if you add/remove nodes it is \ - * no longer accurate. At [-1] is the length of the array. \ - * NOTE: Caller must deallocate. \ - */ \ - decl##_node_t **prefix##skip_to_array_##decl(decl##_t *slist) \ - { \ - size_t nth, len = prefix##skip_length_##decl(slist); \ - decl##_node_t *node, **nodes = NULL; \ - nodes = (decl##_node_t **)calloc(sizeof(decl##_node_t *), len + 1); \ - if (nodes != NULL) { \ - nodes[0] = (decl##_node_t *)(uintptr_t)len; \ - nodes++; \ - SKIPLIST_FOREACH_H2T(decl, prefix, slist, node, nth) \ - { \ - nodes[nth] = node; \ - } \ - } \ - return nodes; \ - } \ - \ - /** \ - * -- __skip_adjust_hit_counts_ TODO \ - * \ - * On delete we check the hit counts across all nodes and next[] pointers \ - * and find the smallest counter then subtract that + 1 from all hit \ - * counters. \ - * \ - */ \ - static void __skip_adjust_hit_counts_##decl(decl##_t *slist) \ - { \ - ((void)slist); \ - } \ - \ - /** \ - * -- __skip_rebalence_ \ - * \ - * Restore balance to our list by adjusting heights and forward pointers \ - * according to the algorithm put forth in "The Splay-List: A \ - * Distribution-Adaptive Concurrent Skip-List". \ - * \ - */ \ - static void __skip_rebalence_##decl(decl##_t *slist, size_t len, __skiplist_path_##decl##_t path[]) \ - { \ - size_t i, j, u_hits, hits_CHu = 0, hits_CHv = 0, delta_height, new_height, cur_hits, prev_hits; \ - double k_threshold, m_total_hits, asc_cond, dsc_cond; \ - \ - /* Total hits, `k`, accross all nodes. */ \ - m_total_hits = slist->slh_head->field.sle_next[slist->slh_head->field.sle_height]->field.sle_hits; \ - \ - /* Height of the head node, should be close to floor(log(max_height)). */ \ - k_threshold = slist->slh_head->field.sle_height + 1; \ - \ - /* Moving backwards along the path... \ - * - path[0] contains a match, if there was one \ - * - path[1..len] will be the nodes traversed along the way \ - * - path[len] is where the locate() terminated, just before path[0] \ - * if there was a match \ - */ \ - for (i = 1; i < len; i++) { \ - if (path[i].node == slist->slh_head || path[i].node == slist->slh_tail) \ - continue; \ - \ - __SKIP_SUBTREE_CHu(decl, field, slist, path, i) \ - { \ - hits_CHu += elm->field.sle_hits; \ - } \ - __SKIP_SUBTREE_CHv(decl, field, slist, path, i) \ - { \ - hits_CHv += elm->field.sle_hits; \ - } \ - u_hits = hits_CHu + hits_CHv; \ - \ - /* (a) Check the decent condition: \ - * u_hits <= m_total_hits / (2 ^ (k_threshold - height of node)) \ - * When met should induce: \ - * 1) traverse the path backward, and... \ - * 2) propagate path[i].level[i] hits backward along path, and... \ - * 3) adjust any forward pointers along the way, then... \ - * 4) lower the path[i]'s node height by 1 \ - */ \ - delta_height = k_threshold - path[i].node->field.sle_height + 1; \ - dsc_cond = m_total_hits / pow(2.0, delta_height); \ - if (u_hits <= dsc_cond && path[i].node->field.sle_height > 0) { \ - if (path[i - 1].node->field.sle_prev != slist->slh_head) { \ - /* 1) go backwards along path from where we are until head */ \ - j = i; \ - cur_hits = path[j].node->field.sle_next[path[j].in]->field.sle_hits; \ - do { \ - /* 2) propagate hits */ \ - prev_hits = path[j - 1].node->field.sle_next[path[j - 1].in]->field.sle_hits; \ - path[j - 1].node->field.sle_next[path[j - 1].in]->field.sle_hits += cur_hits; \ - cur_hits = prev_hits; \ - /* 3) adjust forward pointers */ \ - if (path[j - 1].node->field.sle_next[j] == path[i].node) \ - path[j - 1].node->field.sle_next[j] = path[i].node->field.sle_next[j]; \ - } while (j-- > 1); \ - /* 4) reduce height by one */ \ - path[i].node->field.sle_height--; \ - /* TODO: remove me */ \ - __skip_integrity_check_##decl(slist, 0); \ - prefix##skip_dot_##decl(of, slist, gen, "dsc_cond", sprintf_##decl##_node); \ - } \ - } \ - /* (b) Check the ascent condition: \ - * path[i].pu + node_hits > hits total / (2 ^ (height of head - height of node - 1)) \ - * When met should induce: \ - * 1) check the ascent condition, then iff true ... \ - * 2) add a level, and ... \ - * 3) set its hits to the prev node at intersection height \ - * 4) set prev node hits to 0 and forward to this new level \ - */ \ - /* 1) check ascent condition */ \ - asc_cond = m_total_hits / pow(2.0, delta_height == 0 ? 0 : delta_height - 1); \ - if (path[i - 1].pu > asc_cond && path[i].node->field.sle_height < slist->slh_max_height - 1) { \ - /* 2) increase height by one */ \ - new_height = path[i].node->field.sle_height++; \ - /* 3) update hit counter */ \ - path[i].node->field.sle_next[new_height]->field.sle_hits += path[i - 1].node->field.sle_next[path[i - 1].in]->field.sle_hits; \ - /* 4) reset the prev node hits to 0 */ \ - path[i - 1].node->field.sle_next[path[i - 1].in]->field.sle_hits = 0; \ - if (path[i - 1].in != 0) \ - path[i - 1].node->field.sle_next[path[i - 1].in]->field.sle_next[path[i - 1].in] = path[i].node; \ - /* TODO: remove me */ \ - __skip_integrity_check_##decl(slist, 0); \ - prefix##skip_dot_##decl(of, slist, gen, "asc_cond", sprintf_##decl##_node); \ - } \ - } \ - } \ - \ - /** \ - * -- __skip_locate_ \ - * \ - * Locates a node that matches another node updating `path` and then \ - * returning the length of that path + 1 to the node and the matching \ - * node in path[0], or NULL at path[0] where there wasn't a match. \ - * sizeof(path) should be `slist->slh_max_height + 1` \ - */ \ - static size_t __skip_locate_##decl(decl##_t *slist, decl##_node_t *n, __skiplist_path_##decl##_t path[]) \ - { \ - unsigned int i; \ - size_t len = 0; \ - decl##_node_t *elm = slist->slh_head; \ - \ - if (slist == NULL || n == NULL) \ - return 0; \ - \ - /* Find the node that matches `node` or NULL. */ \ - i = slist->slh_head->field.sle_height; \ - do { \ - path[i + 1].pu = 0; \ - while (elm != slist->slh_tail && elm->field.sle_next[i] && __skip_compare_nodes_##decl(slist, elm->field.sle_next[i], n, slist->slh_aux) < 0) { \ - elm = elm->field.sle_next[i]; \ - path[i + 1].in = i; \ - path[i + 1].pu += elm->field.sle_next[path[i + 1].in]->field.sle_hits; \ - } \ - path[i + 1].node = elm; \ - path[i + 1].node->field.sle_next[path[i + 1].in]->field.sle_hits++; \ - len++; \ - } while (i--); \ - elm = elm->field.sle_next[0]; \ - if (__skip_compare_nodes_##decl(slist, elm, n, slist->slh_aux) == 0) { \ - path[0].node = elm; \ - path[0].node->field.sle_hits++; \ - __skip_rebalence_##decl(slist, len, path); \ - } \ - return len; \ - } \ - \ - /** \ - * -- __skip_insert_ \ - * \ - * Inserts the node `new` into the list `slist`, when `flags` is non-zero \ - * duplicate keys are allowed. Duplicates are grouped together by key but \ - * are otherwise unordered. \ - */ \ - static int __skip_insert_##decl(decl##_t *slist, decl##_node_t *new, int flags) \ - { \ - static __skiplist_path_##decl##_t apath[SKIPLIST_MAX_HEIGHT + 1]; \ - int rc = 0; \ - size_t i, len, loc = 0, cur_height, new_height; \ - decl##_node_t *node; \ - __skiplist_path_##decl##_t *path = apath; \ - \ - if (slist == NULL || new == NULL) \ - return ENOENT; \ - \ - /* Allocate a buffer, or use a static one. */ \ - if (SKIPLIST_MAX_HEIGHT == 1) { \ - path = malloc(sizeof(__skiplist_path_##decl##_t) * slist->slh_max_height + 1); \ - if (path == NULL) \ - return ENOMEM; \ - } \ - memset(path, 0, sizeof(__skiplist_path_##decl##_t) * slist->slh_max_height + 1); \ - \ - /* Find a `path` to `new` in the list and a match (`path[0]`) if it exists. */ \ - len = __skip_locate_##decl(slist, new, path); \ - node = path[0].node; \ - if (len > 0) { \ - if ((node != NULL) && (flags == 0)) { \ - /* Don't insert, duplicate if flag not set. */ \ - return -1; \ - } \ - /* Coin toss to determine level of this new node [0, max) */ \ - cur_height = slist->slh_head->field.sle_height; \ - new_height = __skip_toss_##decl(slist->slh_max_height); \ - new->field.sle_height = new_height; \ - /* Trim the path to at most the new height for the new node. */ \ - if (new_height > cur_height) { \ - for (i = cur_height + 1; i <= new_height; i++) { \ - path[i + 1].node = slist->slh_tail; \ - } \ - } \ - /* Ensure all next[] point to tail. */ \ - __SKIP_ENTRIES_B2T(field, new) \ - { \ - new->field.sle_next[lvl] = slist->slh_tail; \ - } \ - /* Adjust all forward pointers for each element in the path. */ \ - for (i = 0; i <= new_height; i++) { \ - /* The tail's next[i] is always NULL, we don't want that in the \ - next[i] for our new node. Also, don't set the tail's next[i] \ - because it is always NULL. */ \ - if (path[i + 1].node != slist->slh_tail) { \ - new->field.sle_next[i] = path[i + 1].node->field.sle_next[i]; \ - path[i + 1].node->field.sle_next[i] = new; \ - loc = path[i + 1].node == slist->slh_head ? i : loc; \ - } else { \ - new->field.sle_next[i] = slist->slh_tail; \ - } \ - } \ - /* Ensure all slh_head->next[] above loc point to tail. */ \ - if (path[1].node == slist->slh_head) { \ - __SKIP_ENTRIES_B2T_FROM(field, slist->slh_head, loc + 1) \ - { \ - slist->slh_head->field.sle_next[lvl] = slist->slh_tail; \ - } \ - } \ - /* Adujust the previous pointers in the nodes. */ \ - new->field.sle_prev = path[1].node; \ - new->field.sle_next[0]->field.sle_prev = new; \ - /* Account for insert at tail. */ \ - if (new->field.sle_next[0] == slist->slh_tail) { \ - slist->slh_tail->field.sle_prev = new; \ - } \ - /* Adjust the head/tail boundary node heights if necessary. */ \ - if (new_height > cur_height) { \ - slist->slh_head->field.sle_height = new_height; \ - slist->slh_tail->field.sle_height = new_height; \ - } \ - /* Record the era for this node to enable snapshots. */ \ - if (slist->slh_fns.snapshot_record_era) \ - slist->slh_fns.snapshot_record_era(slist, new); \ - /* Set hits for rebalencing to 1 when new born. */ \ - new->field.sle_hits = 1; \ - /* Increase our list length (aka. size, count, etc.) by one. */ \ - slist->slh_length++; \ - \ - if (SKIPLIST_MAX_HEIGHT == 1) \ - free(path); \ - } \ - return rc; \ - } \ - \ - /** \ - * -- skip_insert_ \ - * \ - * Insert into the list `slist` the node `n`. \ - */ \ - int prefix##skip_insert_##decl(decl##_t *slist, decl##_node_t *n) \ - { \ - return __skip_insert_##decl(slist, n, 0); \ - } \ - \ - /** \ - * -- skip_insert_dup_ \ - * \ - * Inserts into `slist` the node `n` even if that node's key already \ - * exists in the list. \ - */ \ - int prefix##skip_insert_dup_##decl(decl##_t *slist, decl##_node_t *n) \ - { \ - return __skip_insert_##decl(slist, n, 1); \ - } \ - \ - /** \ - * -- skip_position_eq_ \ - * \ - * Find a node that matches the node `n`. This differs from the locate() \ - * API in that it does not return the path to the node, only the match. \ - */ \ - decl##_node_t *prefix##skip_position_eq_##decl(decl##_t *slist, decl##_node_t *query) \ - { \ - static __skiplist_path_##decl##_t apath[SKIPLIST_MAX_HEIGHT + 1]; \ - decl##_node_t *node = NULL; \ - __skiplist_path_##decl##_t *path = apath; \ - \ - /* Allocate a buffer, or use a static one. */ \ - if (SKIPLIST_MAX_HEIGHT == 1) { \ - path = malloc(sizeof(__skiplist_path_##decl##_t) * slist->slh_max_height + 1); \ - if (path == NULL) \ - goto done; \ - } \ - memset(path, 0, sizeof(__skiplist_path_##decl##_t) * slist->slh_max_height + 1); \ - \ - /* Find a `path` to `new` in the list and a match (`path[0]`) if it exists. */ \ - __skip_locate_##decl(slist, query, path); \ - node = path[0].node; \ - done:; \ - if (SKIPLIST_MAX_HEIGHT == 1) \ - free(path); \ - \ - return node; \ - } \ - \ - /** \ - * -- skip_position_gte \ - * \ - * Position and return a cursor at the first node that is equal to \ - * or greater than the provided node `n`, otherwise if the largest \ - * key is less than the key in `n` return NULL. \ - */ \ - decl##_node_t *prefix##skip_position_gte_##decl(decl##_t *slist, decl##_node_t *query) \ - { \ - static __skiplist_path_##decl##_t apath[SKIPLIST_MAX_HEIGHT + 1]; \ - int cmp; \ - decl##_node_t *node; \ - __skiplist_path_##decl##_t *path = apath; \ - \ - /* Allocate a buffer, or use a static one. */ \ - if (SKIPLIST_MAX_HEIGHT == 1) { \ - path = malloc(sizeof(__skiplist_path_##decl##_t) * slist->slh_max_height + 1); \ - if (path == NULL) \ - goto done; \ - } \ - memset(path, 0, sizeof(__skiplist_path_##decl##_t) * slist->slh_max_height + 1); \ - \ - /* Find a `path` to `new` in the list and a match (`path[0]`) if it exists. */ \ - __skip_locate_##decl(slist, query, path); \ - node = path[1].node; \ - do { \ - node = node->field.sle_next[0]; \ - cmp = __skip_compare_nodes_##decl(slist, node, query, slist->slh_aux); \ - } while (cmp < 0); \ - \ - done:; \ - if (SKIPLIST_MAX_HEIGHT == 1) \ - free(path); \ - \ - return node; \ - } \ - \ - /** \ - * -- skip_position_gt_ \ - * \ - * Position and return a cursor at the first node that is greater than \ - * the provided node `n`. If the largestkey is less than the key in `n` \ - * return NULL. \ - */ \ - decl##_node_t *prefix##skip_position_gt_##decl(decl##_t *slist, decl##_node_t *query) \ - { \ - static __skiplist_path_##decl##_t apath[SKIPLIST_MAX_HEIGHT + 1]; \ - int cmp; \ - decl##_node_t *node; \ - __skiplist_path_##decl##_t *path = apath; \ - \ - /* Allocate a buffer, or use a static one. */ \ - if (SKIPLIST_MAX_HEIGHT == 1) { \ - path = malloc(sizeof(__skiplist_path_##decl##_t) * slist->slh_max_height + 1); \ - if (path == NULL) \ - goto done; \ - } \ - memset(path, 0, sizeof(__skiplist_path_##decl##_t) * slist->slh_max_height + 1); \ - \ - /* Find a `path` to `new` in the list and a match (`path[0]`) if it exists. */ \ - __skip_locate_##decl(slist, query, path); \ - node = path[1].node; \ - if (node == slist->slh_tail) \ - goto done; \ - do { \ - node = node->field.sle_next[0]; \ - cmp = __skip_compare_nodes_##decl(slist, node, query, slist->slh_aux); \ - } while (cmp <= 0 && node != slist->slh_tail); \ - \ - done:; \ - if (SKIPLIST_MAX_HEIGHT == 1) \ - free(path); \ - \ - return node; \ - } \ - \ - /** \ - * -- skip_position_lte \ - * \ - * Position and return a cursor at the last node that is less than \ - * or equal to node `n`. \ - * Return NULL if nothing is less than or equal. \ - */ \ - decl##_node_t *prefix##skip_position_lte_##decl(decl##_t *slist, decl##_node_t *query) \ - { \ - static __skiplist_path_##decl##_t apath[SKIPLIST_MAX_HEIGHT + 1]; \ - decl##_node_t *node; \ - __skiplist_path_##decl##_t *path = apath; \ - \ - /* Allocate a buffer, or use a static one. */ \ - if (SKIPLIST_MAX_HEIGHT == 1) { \ - path = malloc(sizeof(__skiplist_path_##decl##_t) * slist->slh_max_height + 1); \ - if (path == NULL) \ - goto done; \ - } \ - memset(path, 0, sizeof(__skiplist_path_##decl##_t) * slist->slh_max_height + 1); \ - \ - /* Find a `path` to `new` in the list and a match (`path[0]`) if it exists. */ \ - __skip_locate_##decl(slist, query, path); \ - node = path[0].node; \ - if (node) \ - goto done; \ - node = path[1].node; \ - \ - done:; \ - if (SKIPLIST_MAX_HEIGHT == 1) \ - free(path); \ - \ - return node; \ - } \ - \ - /** \ - * -- skip_position_lt_ \ - * \ - * Position and return a cursor at the last node that is less than \ - * to the node `n`. Return NULL if nothing is less than or equal. \ - */ \ - decl##_node_t *prefix##skip_position_lt_##decl(decl##_t *slist, decl##_node_t *query) \ - { \ - static __skiplist_path_##decl##_t apath[SKIPLIST_MAX_HEIGHT + 1]; \ - decl##_node_t *node; \ - __skiplist_path_##decl##_t *path = apath; \ - \ - /* Allocate a buffer, or use a static one. */ \ - if (SKIPLIST_MAX_HEIGHT == 1) { \ - path = malloc(sizeof(__skiplist_path_##decl##_t) * slist->slh_max_height + 1); \ - if (path == NULL) \ - goto done; \ - } \ - memset(path, 0, sizeof(__skiplist_path_##decl##_t) * slist->slh_max_height + 1); \ - \ - /* Find a `path` to `new` in the list and a match (`path[0]`) if it exists. */ \ - __skip_locate_##decl(slist, query, path); \ - node = path[1].node; \ - \ - done:; \ - if (SKIPLIST_MAX_HEIGHT == 1) \ - free(path); \ - \ - return node; \ - } \ - \ - /** \ - * -- skip_position_ \ - * \ - * Position a cursor relative to `n`. \ - */ \ - decl##_node_t *prefix##skip_position_##decl(decl##_t *slist, skip_pos_##decl_t op, decl##_node_t *query) \ - { \ - decl##_node_t *node; \ - \ - switch (op) { \ - case (SKIP_LT): \ - node = prefix##skip_position_lt_##decl(slist, query); \ - break; \ - case (SKIP_LTE): \ - node = prefix##skip_position_lte_##decl(slist, query); \ - break; \ - case (SKIP_GTE): \ - node = prefix##skip_position_gte_##decl(slist, query); \ - break; \ - case (SKIP_GT): \ - node = prefix##skip_position_gt_##decl(slist, query); \ - break; \ - default: \ - case (SKIP_EQ): \ - node = prefix##skip_position_eq_##decl(slist, query); \ - break; \ - } \ - return node; \ - } \ - \ - /** \ - * -- skip_update_ \ - * \ - * Locates a node in the list that equals the `new` node and then \ - * uses the `update_entry_blk` to update the contents. \ - * \ - * WARNING: Do not update the portion of the node used for ordering \ - * (e.g. `key`) unless you really know what you're doing. \ - */ \ - int prefix##skip_update_##decl(decl##_t *slist, decl##_node_t *query, void *value) \ - { \ - static __skiplist_path_##decl##_t apath[SKIPLIST_MAX_HEIGHT + 1]; \ - int rc = 0, np; \ - decl##_node_t *node; \ - __skiplist_path_##decl##_t *path = apath; \ - \ - if (slist == NULL) \ - return -1; \ - \ - /* Allocate a buffer, or use a static one. */ \ - if (SKIPLIST_MAX_HEIGHT == 1) { \ - path = malloc(sizeof(__skiplist_path_##decl##_t) * slist->slh_max_height + 1); \ - if (path == NULL) \ - return ENOMEM; \ - } \ - memset(path, 0, sizeof(__skiplist_path_##decl##_t) * slist->slh_max_height + 1); \ - \ - __skip_locate_##decl(slist, query, path); \ - node = path[0].node; \ - \ - if (SKIPLIST_MAX_HEIGHT == 1) \ - free(path); \ - \ - if (node == NULL) \ - return -1; \ - \ - /* If the optional snapshots feature is configured, use it now. \ - Snapshots preserve the node if it is younger than our snapshot \ - moment. */ \ - if (slist->slh_fns.preserve_node) { \ - np = slist->slh_fns.preserve_node(slist, node, NULL); \ - if (np > 0) \ - return np; \ - } \ - \ - slist->slh_fns.update_entry(node, value); \ - \ - /* Record the era for this node to enable snapshots. */ \ - if (slist->slh_fns.snapshot_record_era) \ - slist->slh_fns.snapshot_record_era(slist, node); \ - \ - return rc; \ - } \ - \ - /** \ - * -- skip_remove_node_ \ - * \ - * Removes the node `n` from the `slist` if present. \ - */ \ - int prefix##skip_remove_node_##decl(decl##_t *slist, decl##_node_t *query) \ - { \ - static __skiplist_path_##decl##_t apath[SKIPLIST_MAX_HEIGHT + 1]; \ - int np = 0; \ - size_t i, len, height; \ - decl##_node_t *node; \ - __skiplist_path_##decl##_t *path = apath; \ - \ - if (slist == NULL || query == NULL) \ - return -1; \ - if (slist->slh_length == 0) \ - return 0; \ - \ - /* Allocate a buffer */ \ - if (SKIPLIST_MAX_HEIGHT == 1) { \ - path = malloc(sizeof(__skiplist_path_##decl##_t) * slist->slh_max_height + 1); \ - if (path == NULL) \ - return ENOMEM; \ - } \ - memset(path, 0, sizeof(__skiplist_path_##decl##_t) * slist->slh_max_height + 1); \ - \ - /* Attempt to locate the node in the list. */ \ - len = __skip_locate_##decl(slist, query, path); \ - node = path[0].node; \ - if (node) { \ - /* If the optional snapshots feature is configured, use it now. \ - Snapshots preserve the node if it is younger than our snapshot \ - moment, this node is about to be removed. */ \ - if (slist->slh_fns.preserve_node) { \ - np = slist->slh_fns.preserve_node(slist, node, NULL); \ - if (np > 0) \ - return np; \ - } \ - /* We found it, set the next->prev to the node->prev keeping in mind \ - that the next node might be the tail). */ \ - node->field.sle_next[0]->field.sle_prev = node->field.sle_prev; \ - /* Walk the path, stop when the next node is not the one we're \ - removing. At each step along our walk... */ \ - for (i = 0; i < len; i++) { \ - if (path[i + 1].node->field.sle_next[i] != node) \ - break; \ - /* ... adjust the next pointer at that level. */ \ - path[i + 1].node->field.sle_next[i] = node->field.sle_next[i]; \ - /* Adjust the height so we're only pointing at the tail once at \ - the top so we don't waste steps later when searching. */ \ - if (path[i + 1].node->field.sle_next[i] == slist->slh_tail) { \ - height = path[i + 1].node->field.sle_height; \ - path[i + 1].node->field.sle_height = height - 1; \ - } \ - } \ - /* Account for delete at tail. */ \ - if (node->field.sle_next[0] == slist->slh_tail) { \ - slist->slh_tail->field.sle_prev = query->field.sle_prev; \ - } \ - \ - if (SKIPLIST_MAX_HEIGHT == 1) \ - free(path); \ - \ - slist->slh_fns.free_entry(node); \ - \ - /* Reduce the height of the head node. */ \ - i = 0; \ - while (slist->slh_head->field.sle_next[i] != slist->slh_tail && i < slist->slh_head->field.sle_height) \ - i++; \ - slist->slh_head->field.sle_height = i; \ - slist->slh_tail->field.sle_height = i; \ - \ - slist->slh_length--; \ - __skip_adjust_hit_counts_##decl(slist); \ - } \ - return 0; \ - } \ - \ - /** \ - * -- skip_free_ \ - * \ - * Release all nodes and their associated heap objects. The list reference \ - * is no longer valid after this call. To make it valid again call _init(). \ - */ \ - void prefix##skip_free_##decl(decl##_t *slist) \ - { \ - if (slist == NULL) \ - return; \ - \ - prefix##skip_release_##decl(slist); \ - \ - free(slist->slh_head); \ - free(slist->slh_tail); \ +#define SKIPLIST_DECL(decl, prefix, field, compare_entries_blk, free_entry_blk, update_entry_blk, archive_entry_blk, sizeof_entry_blk) \ + \ + /* Used when positioning a cursor within a Skiplist. */ \ + typedef enum { SKIP_EQ = 0, SKIP_LTE = -1, SKIP_LT = -2, SKIP_GTE = 1, SKIP_GT = 2 } skip_pos_##decl_t; \ + \ + /* Skiplist node type */ \ + typedef struct decl##_node decl##_node_t; \ + \ + /* Skiplist type. */ \ + typedef struct decl decl##_t; \ + \ + /* Skiplist structure */ \ + struct decl { \ + size_t slh_length, slh_max_height; \ + void *slh_aux; \ + decl##_node_t *slh_head; \ + decl##_node_t *slh_tail; \ + struct { \ + void (*free_entry)(decl##_node_t *); \ + int (*update_entry)(decl##_node_t *, void *); \ + int (*archive_entry)(decl##_node_t *, const decl##_node_t *); \ + size_t (*sizeof_entry)(decl##_node_t *); \ + int (*compare_entries)(decl##_t *, decl##_node_t *, decl##_node_t *, void *); \ + \ + /* Optional: Snapshots */ \ + int (*preserve_node)(decl##_t * slist, const decl##_node_t *src, decl##_node_t **preserved); \ + void (*release_snapshots)(decl##_t *); \ + size_t (*snapshot_current_era)(decl##_t *); \ + size_t (*snapshot_incr_era)(decl##_t *); \ + void (*snapshot_record_era)(decl##_t *, decl##_node_t *); \ + } slh_fns; \ + struct { \ + size_t era; \ + decl##_node_t *pres; \ + } slh_snap; \ + }; \ + \ + typedef struct __skiplist_path_##decl { \ + decl##_node_t *node; /* node traversed in the act of location */ \ + size_t in; /* level at which the node was intersected */ \ + size_t pu; /* sum of hits from intersection to level[1] */ \ + } __skiplist_path_##decl##_t; \ + \ + /** \ + * -- __skip_compare_entries_fn_ \ + * \ + * Wraps the `compare_entries_blk` code into `slh_fns.compare_entries`. \ + */ \ + static int __skip_compare_entries_fn_##decl(decl##_t *list, decl##_node_t *a, decl##_node_t *b, void *aux) \ + { \ + compare_entries_blk; \ + } \ + \ + /** \ + * -- __skip_free_entry_fn \ + * \ + * Wraps the `free_entry_blk` code into `slh_fns.free_entry`. \ + */ \ + static void __skip_free_entry_fn_##decl(decl##_node_t *node) \ + { \ + free_entry_blk; \ + } \ + \ + /** \ + * -- __skip_update_entry_fn_ \ + * \ + * Wraps the `update_entry_blk` code into `slh_fns.update_entry`. \ + */ \ + static int __skip_update_entry_fn_##decl(decl##_node_t *node, void *value) \ + { \ + int rc = 0; \ + update_entry_blk; \ + return rc; \ + } \ + \ + /** \ + * -- __skip_archive_entry_fn_ \ + * \ + * Wraps the `archive_entry_blk` code into `slh_fns.archive_entry`. \ + */ \ + static int __skip_archive_entry_fn_##decl(decl##_node_t *dest, const decl##_node_t *src) \ + { \ + int rc = 0; \ + archive_entry_blk; \ + return rc; \ + } \ + \ + /** \ + * -- __skip_sizeof_entry_fn_ \ + * \ + * Wraps the `sizeof_entry_blk` code into `slh_fns.sizeof_entry`. \ + */ \ + static size_t __skip_sizeof_entry_fn_##decl(decl##_node_t *node) \ + { \ + size_t bytes = 0; \ + sizeof_entry_blk; \ + return bytes; \ + } \ + \ + /** \ + * -- __skip_compare_nodes_ \ + * \ + * This function takes four arguments: \ + * - a reference to the Skiplist \ + * - the two nodes to compare, `a` and `b` \ + * - `aux` an additional auxiliary argument \ + * and returns: \ + * a < b : return -1 \ + * a == b : return 0 \ + * a > b : return 1 \ + */ \ + static int __skip_compare_nodes_##decl(decl##_t *slist, decl##_node_t *a, decl##_node_t *b, void *aux) \ + { \ + if (a == b) \ + return 0; \ + if (a == NULL) \ + return -1; \ + if (b == NULL) \ + return 1; \ + if (a == slist->slh_head || b == slist->slh_tail) \ + return -1; \ + if (a == slist->slh_tail || b == slist->slh_head) \ + return 1; \ + return slist->slh_fns.compare_entries(slist, a, b, aux); \ + } \ + \ + /** \ + * -- __skip_toss_ \ + * \ + * A "coin toss" function that is critical to the proper operation of the \ + * Skiplist. For example, when `max = 6` this function returns 0 with \ + * probability 0.5, 1 with 0.25, 2 with 0.125, etc. until 6 with 0.5^7. \ + */ \ + static int __skip_toss_##decl(size_t max) \ + { \ + size_t level = 0; \ + double probability = 0.5; \ + \ + double random_value = (double)rand() / RAND_MAX; /* NOLINT(*-msc50-cpp) */ \ + while (random_value < probability && level < max) { \ + level++; \ + probability *= 0.5; \ + } \ + return level; \ + } \ + \ + /** \ + * -- skip_alloc_node_ \ + * \ + * Allocates a new node on the heap and sets default values. \ + */ \ + int prefix##skip_alloc_node_##decl(decl##_t *slist, decl##_node_t **node) \ + { \ + decl##_node_t *n; \ + /* Calculate the size of the struct sle within decl##_node_t, multiply \ + by array size. (16/24 bytes on 32/64 bit systems) */ \ + size_t sle_arr_sz = sizeof(struct __skiplist_##decl##_level) * slist->slh_max_height; \ + n = (decl##_node_t *)calloc(1, sizeof(decl##_node_t) + sle_arr_sz); \ + if (n == NULL) \ + return ENOMEM; \ + n->field.sle_height = 0; \ + n->field.sle_levels = (struct __skiplist_##decl##_level **)((uintptr_t)n + sizeof(decl##_node_t)); \ + *node = n; \ + return 0; \ + } \ + \ + /** \ + * -- skip_init_ \ + * \ + * Initializes a Skiplist to the deafault values, this must be called \ + * before using the list. \ + */ \ + int prefix##skip_init_##decl(decl##_t *slist, int max) \ + { \ + int rc = 0; \ + size_t i; \ + \ + slist->slh_length = 0; \ + slist->slh_max_height = SKIPLIST_MAX_HEIGHT == 1 ? (size_t)(max < 0 ? -max : max) : SKIPLIST_MAX_HEIGHT; \ + slist->slh_snap.era = 0; \ + slist->slh_fns.free_entry = __skip_free_entry_fn_##decl; \ + slist->slh_fns.update_entry = __skip_update_entry_fn_##decl; \ + slist->slh_fns.archive_entry = __skip_archive_entry_fn_##decl; \ + slist->slh_fns.sizeof_entry = __skip_sizeof_entry_fn_##decl; \ + slist->slh_fns.compare_entries = __skip_compare_entries_fn_##decl; \ + rc = prefix##skip_alloc_node_##decl(slist, &slist->slh_head); \ + if (rc) \ + goto fail; \ + rc = prefix##skip_alloc_node_##decl(slist, &slist->slh_tail); \ + if (rc) \ + goto fail; \ + \ + slist->slh_head->field.sle_height = floor(log(slist->slh_max_height) / M_LOG2E); \ + for (i = 0; i < slist->slh_max_height; i++) \ + slist->slh_head->field.sle_levels[i]->next = slist->slh_tail; \ + slist->slh_head->field.sle_prev = NULL; \ + \ + slist->slh_tail->field.sle_height = slist->slh_head->field.sle_height; \ + for (i = 0; i < slist->slh_max_height; i++) \ + slist->slh_tail->field.sle_levels[i]->next = NULL; \ + slist->slh_tail->field.sle_prev = slist->slh_head; \ + \ + /* NOTE: Here's a testing aid, simply set `max` to a negative number to \ + * seed the PRNG in a predictable way and have reproducible random numbers. \ + */ \ + if (max < 0) \ + srand(-max); \ + else \ + srand(((unsigned int)time(NULL) ^ getpid())); \ + fail:; \ + return rc; \ + } \ + \ + /** \ + * -- skip_free_node_ \ + * \ + * Properly releases heap memory allocated for use as a node. \ + * This function invokes the `free_node_blk` within which you \ + * should release any heap objects or other resources held by \ + * this node in the list. \ + */ \ + void prefix##skip_free_node_##decl(decl##_t *slist, decl##_node_t *node) \ + { \ + slist->slh_fns.free_entry(node); \ + free(node); \ + } \ + \ + /** \ + * -- skip_length_ \ + * \ + * Returns the current length of the list. \ + */ \ + int prefix##skip_length_##decl(decl##_t *slist) \ + { \ + return slist->slh_length; \ + } \ + \ + /** \ + * -- skip_is_empty_ \ + * \ + * Returns non-zero when the list is empty. \ + */ \ + int prefix##skip_is_empty_##decl(decl##_t *slist) \ + { \ + return slist->slh_length == 0; \ + } \ + \ + /** \ + * -- skip_head_ \ + * \ + * Returns the node containing the first (smallest) element in the \ + * list which can be used to traverse the list. \ + */ \ + decl##_node_t *prefix##skip_head_##decl(decl##_t *slist) \ + { \ + return slist->slh_head->field.sle_levels[0]->next == slist->slh_tail ? NULL : slist->slh_head->field.sle_levels[0]->next; \ + } \ + \ + /** \ + * -- skip_tail_ \ + * \ + * Returns the node containing the last (largest) element in the \ + * list which can be used to traverse the list. \ + */ \ + decl##_node_t *prefix##skip_tail_##decl(decl##_t *slist) \ + { \ + return slist->slh_tail->field.sle_prev == slist->slh_head->field.sle_levels[0]->next ? NULL : slist->slh_tail->field.sle_prev; \ + } \ + \ + /** \ + * -- skip_next_node_ \ + * \ + * A node reference can be thought of as a cursor. This moves the cursor \ + * to the next node in the list or returns NULL if the next is the tail. \ + */ \ + decl##_node_t *prefix##skip_next_node_##decl(decl##_t *slist, decl##_node_t *n) \ + { \ + if (slist == NULL || n == NULL) \ + return NULL; \ + if (n->field.sle_levels[0]->next == slist->slh_tail) \ + return NULL; \ + return n->field.sle_levels[0]->next; \ + } \ + \ + /** \ + * -- skip_prev_node_ \ + * \ + * A node reference can be thought of as a cursor. This moves the cursor \ + * to the previous node in the list or returns NULL if the previous node \ + * is the head. \ + */ \ + decl##_node_t *prefix##skip_prev_node_##decl(decl##_t *slist, decl##_node_t *n) \ + { \ + if (slist == NULL || n == NULL) \ + return NULL; \ + if (n->field.sle_prev == slist->slh_head) \ + return NULL; \ + return n->field.sle_prev; \ + } \ + \ + /** \ + * -- skip_release_ \ + * \ + * Release all nodes and their associated heap objects, but not the list \ + * itself. The list is still valid, only empty. \ + */ \ + void prefix##skip_release_##decl(decl##_t *slist) \ + { \ + decl##_node_t *node, *next; \ + \ + if (slist == NULL) \ + return; \ + if (prefix##skip_is_empty_##decl(slist)) \ + return; \ + node = prefix##skip_head_##decl(slist); \ + do { \ + next = prefix##skip_next_node_##decl(slist, node); \ + prefix##skip_free_node_##decl(slist, node); \ + node = next; \ + } while (node != NULL); \ + \ + while (node) { \ + next = node->field.sle_levels[0]->next; \ + if (next->field.sle_prev) \ + slist->slh_fns.free_entry(node); \ + free(node); \ + } \ + if (slist->slh_fns.snapshot_incr_era) \ + slist->slh_fns.snapshot_incr_era(slist); \ + return; \ + } \ + \ + /** \ + * -- skip_to_array_ \ + * \ + * Returns a heap allocated array of nodes in the order they exist. \ + * This isn't maintained by the list, if you add/remove nodes it is \ + * no longer accurate. At [-1] is the length of the array. \ + * NOTE: Caller must deallocate. \ + */ \ + decl##_node_t **prefix##skip_to_array_##decl(decl##_t *slist) \ + { \ + size_t nth, len = prefix##skip_length_##decl(slist); \ + decl##_node_t *node, **nodes = NULL; \ + nodes = (decl##_node_t **)calloc(sizeof(decl##_node_t *), len + 1); \ + if (nodes != NULL) { \ + nodes[0] = (decl##_node_t *)(uintptr_t)len; \ + nodes++; \ + SKIPLIST_FOREACH_H2T(decl, prefix, slist, node, nth) \ + { \ + nodes[nth] = node; \ + } \ + } \ + return nodes; \ + } \ + \ + /** \ + * -- __skip_adjust_hit_counts_ TODO \ + * \ + * On delete we check the hit counts across all nodes and next[] pointers \ + * and find the smallest counter then subtract that + 1 from all hit \ + * counters. \ + * \ + */ \ + static void __skip_adjust_hit_counts_##decl(decl##_t *slist) \ + { \ + ((void)slist); \ + } \ + \ + /** \ + * -- __skip_rebalence_ \ + * \ + * Restore balance to our list by adjusting heights and forward pointers \ + * according to the algorithm put forth in "The Splay-List: A \ + * Distribution-Adaptive Concurrent Skip-List". \ + * \ + */ \ + static void __skip_rebalence_##decl(decl##_t *slist, size_t len, __skiplist_path_##decl##_t path[]) \ + { \ + size_t i, j, u_hits, hits_CHu = 0, hits_CHv = 0, delta_height, new_height, cur_hits, prev_hits; \ + double k_threshold, m_total_hits, asc_cond, dsc_cond; \ + \ + return; \ + /* Total hits, `k`, accross all nodes. */ \ + m_total_hits = slist->slh_head->field.sle_levels[slist->slh_head->field.sle_height]->hits; \ + \ + /* Height of the head node, should be close to floor(log(max_height)). */ \ + k_threshold = slist->slh_head->field.sle_height + 1; \ + \ + /* Moving backwards along the path... \ + * - path[0] contains a match, if there was one \ + * - path[1..len] will be the nodes traversed along the way \ + * - path[len] is where the locate() terminated, just before path[0] \ + * if there was a match \ + */ \ + for (i = 1; i < len; i++) { \ + if (path[i].node == slist->slh_head || path[i].node == slist->slh_tail) \ + continue; \ + \ + __SKIP_SUBTREE_CHu(decl, field, slist, path, i) \ + { \ + hits_CHu += elm->field.sle_levels[i]->hits; \ + } \ + __SKIP_SUBTREE_CHv(decl, field, slist, path, i) \ + { \ + hits_CHv += elm->field.sle_levels[i]->hits; \ + } \ + u_hits = hits_CHu + hits_CHv; \ + \ + /* (a) Check the decent condition: \ + * u_hits <= m_total_hits / (2 ^ (k_threshold - height of node)) \ + * When met should induce: \ + * 1) traverse the path backward, and... \ + * 2) propagate path[i].level[i] hits backward along path, and... \ + * 3) adjust any forward pointers along the way, then... \ + * 4) lower the path[i]'s node height by 1 \ + */ \ + delta_height = k_threshold - path[i].node->field.sle_height + 1; \ + dsc_cond = m_total_hits / pow(2.0, delta_height); \ + if (u_hits <= dsc_cond && path[i].node->field.sle_height > 0) { \ + if (path[i - 1].node->field.sle_prev != slist->slh_head) { \ + /* 1) go backwards along path from where we are until head */ \ + j = i; \ + cur_hits = path[j].node->field.sle_levels[path[j].in]->hits; \ + do { \ + /* 2) propagate hits */ \ + prev_hits = path[j - 1].node->field.sle_levels[path[j - 1].in]->hits; \ + path[j - 1].node->field.sle_levels[path[j - 1].in]->hits += cur_hits; \ + cur_hits = prev_hits; \ + /* 3) adjust forward pointers */ \ + if (path[j - 1].node->field.sle_levels[j]->next == path[i].node) \ + path[j - 1].node->field.sle_levels[j]->next = path[i].node->field.sle_levels[j]->next; \ + } while (j-- > 1); \ + /* 4) reduce height by one */ \ + path[i].node->field.sle_height--; \ + /* TODO: remove me \ + __skip_integrity_check_##decl(slist, 0); \ + prefix##skip_dot_##decl(of, slist, gen, "dsc_cond", sprintf_##decl##_node); \ + */ \ + } \ + } \ + /* (b) Check the ascent condition: \ + * path[i].pu + node_hits > hits total / (2 ^ (height of head - height of node - 1)) \ + * When met should induce: \ + * 1) check the ascent condition, then iff true ... \ + * 2) add a level, and ... \ + * 3) set its hits to the prev node at intersection height \ + * 4) set prev node hits to 0 and forward to this new level \ + */ \ + /* 1) check ascent condition */ \ + asc_cond = m_total_hits / pow(2.0, delta_height == 0 ? 0 : delta_height - 1); \ + if (path[i - 1].pu > asc_cond && path[i].node->field.sle_height < slist->slh_max_height - 1) { \ + /* 2) increase height by one */ \ + new_height = path[i].node->field.sle_height++; \ + /* 3) update hit counter */ \ + path[i].node->field.sle_levels[new_height]->hits += path[i - 1].node->field.sle_levels[path[i - 1].in]->hits; \ + /* 4) reset the prev node hits to 0 */ \ + path[i - 1].node->field.sle_levels[path[i - 1].in]->hits = 0; \ + if (path[i - 1].in != 0) \ + path[i - 1].node->field.sle_levels[path[i - 1].in]->next->field.sle_levels[path[i - 1].in]->next = path[i].node; \ + /* TODO: remove me \ + __skip_integrity_check_##decl(slist, 0); \ + prefix##skip_dot_##decl(of, slist, gen, "asc_cond", sprintf_##decl##_node); \ + */ \ + } \ + } \ + } \ + \ + /** \ + * -- __skip_locate_ \ + * \ + * Locates a node that matches another node updating `path` and then \ + * returning the length of that path + 1 to the node and the matching \ + * node in path[0], or NULL at path[0] where there wasn't a match. \ + * sizeof(path) should be `slist->slh_max_height + 1` \ + */ \ + static size_t __skip_locate_##decl(decl##_t *slist, decl##_node_t *n, __skiplist_path_##decl##_t path[]) \ + { \ + unsigned int i; \ + size_t len = 0; \ + decl##_node_t *elm = slist->slh_head; \ + \ + if (slist == NULL || n == NULL) \ + return 0; \ + \ + /* Find the node that matches `node` or NULL. */ \ + i = slist->slh_head->field.sle_height; \ + do { \ + path[i + 1].pu = 0; \ + while (elm != slist->slh_tail && elm->field.sle_levels[i]->next && \ + __skip_compare_nodes_##decl(slist, elm->field.sle_levels[i]->next, n, slist->slh_aux) < 0) { \ + elm = elm->field.sle_levels[i]->next; \ + path[i + 1].in = i; \ + path[i + 1].pu += elm->field.sle_levels[path[i + 1].in]->hits; \ + } \ + path[i + 1].node = elm; \ + path[i + 1].node->field.sle_levels[path[i + 1].in]->hits++; \ + len++; \ + } while (i--); \ + elm = elm->field.sle_levels[0]->next; \ + if (__skip_compare_nodes_##decl(slist, elm, n, slist->slh_aux) == 0) { \ + path[0].node = elm; \ + path[0].node->field.sle_levels[0]->hits++; \ + __skip_rebalence_##decl(slist, len, path); \ + } \ + return len; \ + } \ + \ + /** \ + * -- __skip_insert_ \ + * \ + * Inserts the node `new` into the list `slist`, when `flags` is non-zero \ + * duplicate keys are allowed. Duplicates are grouped together by key but \ + * are otherwise unordered. \ + */ \ + static int __skip_insert_##decl(decl##_t *slist, decl##_node_t *new, int flags) \ + { \ + static __skiplist_path_##decl##_t apath[SKIPLIST_MAX_HEIGHT + 1]; \ + int rc = 0; \ + size_t i, len, loc = 0, cur_height, new_height; \ + decl##_node_t *node; \ + __skiplist_path_##decl##_t *path = apath; \ + \ + if (slist == NULL || new == NULL) \ + return ENOENT; \ + \ + /* Allocate a buffer, or use a static one. */ \ + if (SKIPLIST_MAX_HEIGHT == 1) { \ + path = malloc(sizeof(__skiplist_path_##decl##_t) * slist->slh_max_height + 1); \ + if (path == NULL) \ + return ENOMEM; \ + } \ + memset(path, 0, sizeof(__skiplist_path_##decl##_t) * slist->slh_max_height + 1); \ + \ + /* Find a `path` to `new` in the list and a match (`path[0]`) if it exists. */ \ + len = __skip_locate_##decl(slist, new, path); \ + node = path[0].node; \ + if (len > 0) { \ + if ((node != NULL) && (flags == 0)) { \ + /* Don't insert, duplicate if flag not set. */ \ + return -1; \ + } \ + /* Coin toss to determine level of this new node [0, max) */ \ + cur_height = slist->slh_head->field.sle_height; \ + new_height = __skip_toss_##decl(slist->slh_max_height); \ + new->field.sle_height = new_height; \ + /* Trim the path to at most the new height for the new node. */ \ + if (new_height > cur_height) { \ + for (i = cur_height + 1; i <= new_height; i++) { \ + path[i + 1].node = slist->slh_tail; \ + } \ + } \ + /* Ensure all next[] point to tail. */ \ + __SKIP_ENTRIES_B2T(field, new) \ + { \ + new->field.sle_levels[lvl]->next = slist->slh_tail; \ + } \ + /* Adjust all forward pointers for each element in the path. */ \ + for (i = 0; i <= new_height; i++) { \ + /* The tail's next[i] is always NULL, we don't want that in the \ + next[i] for our new node. Also, don't set the tail's next[i] \ + because it is always NULL. */ \ + if (path[i + 1].node != slist->slh_tail) { \ + new->field.sle_levels[i]->next = path[i + 1].node->field.sle_levels[i]->next; \ + path[i + 1].node->field.sle_levels[i]->next = new; \ + loc = path[i + 1].node == slist->slh_head ? i : loc; \ + } else { \ + new->field.sle_levels[i]->next = slist->slh_tail; \ + } \ + } \ + /* Ensure all slh_head->next[] above loc point to tail. */ \ + if (path[1].node == slist->slh_head) { \ + __SKIP_ENTRIES_B2T_FROM(field, slist->slh_head, loc + 1) \ + { \ + slist->slh_head->field.sle_levels[lvl]->next = slist->slh_tail; \ + } \ + } \ + /* Adujust the previous pointers in the nodes. */ \ + new->field.sle_prev = path[1].node; \ + new->field.sle_levels[0]->next->field.sle_prev = new; \ + /* Account for insert at tail. */ \ + if (new->field.sle_levels[0]->next == slist->slh_tail) { \ + slist->slh_tail->field.sle_prev = new; \ + } \ + /* Adjust the head/tail boundary node heights if necessary. */ \ + if (new_height > cur_height) { \ + slist->slh_head->field.sle_height = new_height; \ + slist->slh_tail->field.sle_height = new_height; \ + } \ + /* Record the era for this node to enable snapshots. */ \ + if (slist->slh_fns.snapshot_record_era) \ + slist->slh_fns.snapshot_record_era(slist, new); \ + /* Set hits for rebalencing to 1 when new born. */ \ + new->field.sle_levels[new_height]->hits = 1; \ + /* Increase our list length (aka. size, count, etc.) by one. */ \ + slist->slh_length++; \ + \ + if (SKIPLIST_MAX_HEIGHT == 1) \ + free(path); \ + } \ + return rc; \ + } \ + \ + /** \ + * -- skip_insert_ \ + * \ + * Insert into the list `slist` the node `n`. \ + */ \ + int prefix##skip_insert_##decl(decl##_t *slist, decl##_node_t *n) \ + { \ + return __skip_insert_##decl(slist, n, 0); \ + } \ + \ + /** \ + * -- skip_insert_dup_ \ + * \ + * Inserts into `slist` the node `n` even if that node's key already \ + * exists in the list. \ + */ \ + int prefix##skip_insert_dup_##decl(decl##_t *slist, decl##_node_t *n) \ + { \ + return __skip_insert_##decl(slist, n, 1); \ + } \ + \ + /** \ + * -- skip_position_eq_ \ + * \ + * Find a node that matches the node `n`. This differs from the locate() \ + * API in that it does not return the path to the node, only the match. \ + */ \ + decl##_node_t *prefix##skip_position_eq_##decl(decl##_t *slist, decl##_node_t *query) \ + { \ + static __skiplist_path_##decl##_t apath[SKIPLIST_MAX_HEIGHT + 1]; \ + decl##_node_t *node = NULL; \ + __skiplist_path_##decl##_t *path = apath; \ + \ + /* Allocate a buffer, or use a static one. */ \ + if (SKIPLIST_MAX_HEIGHT == 1) { \ + path = malloc(sizeof(__skiplist_path_##decl##_t) * slist->slh_max_height + 1); \ + if (path == NULL) \ + goto done; \ + } \ + memset(path, 0, sizeof(__skiplist_path_##decl##_t) * slist->slh_max_height + 1); \ + \ + /* Find a `path` to `new` in the list and a match (`path[0]`) if it exists. */ \ + __skip_locate_##decl(slist, query, path); \ + node = path[0].node; \ + done:; \ + if (SKIPLIST_MAX_HEIGHT == 1) \ + free(path); \ + \ + return node; \ + } \ + \ + /** \ + * -- skip_position_gte \ + * \ + * Position and return a cursor at the first node that is equal to \ + * or greater than the provided node `n`, otherwise if the largest \ + * key is less than the key in `n` return NULL. \ + */ \ + decl##_node_t *prefix##skip_position_gte_##decl(decl##_t *slist, decl##_node_t *query) \ + { \ + static __skiplist_path_##decl##_t apath[SKIPLIST_MAX_HEIGHT + 1]; \ + int cmp; \ + decl##_node_t *node; \ + __skiplist_path_##decl##_t *path = apath; \ + \ + /* Allocate a buffer, or use a static one. */ \ + if (SKIPLIST_MAX_HEIGHT == 1) { \ + path = malloc(sizeof(__skiplist_path_##decl##_t) * slist->slh_max_height + 1); \ + if (path == NULL) \ + goto done; \ + } \ + memset(path, 0, sizeof(__skiplist_path_##decl##_t) * slist->slh_max_height + 1); \ + \ + /* Find a `path` to `new` in the list and a match (`path[0]`) if it exists. */ \ + __skip_locate_##decl(slist, query, path); \ + node = path[1].node; \ + do { \ + node = node->field.sle_levels[0]->next; \ + cmp = __skip_compare_nodes_##decl(slist, node, query, slist->slh_aux); \ + } while (cmp < 0); \ + \ + done:; \ + if (SKIPLIST_MAX_HEIGHT == 1) \ + free(path); \ + \ + return node; \ + } \ + \ + /** \ + * -- skip_position_gt_ \ + * \ + * Position and return a cursor at the first node that is greater than \ + * the provided node `n`. If the largestkey is less than the key in `n` \ + * return NULL. \ + */ \ + decl##_node_t *prefix##skip_position_gt_##decl(decl##_t *slist, decl##_node_t *query) \ + { \ + static __skiplist_path_##decl##_t apath[SKIPLIST_MAX_HEIGHT + 1]; \ + int cmp; \ + decl##_node_t *node; \ + __skiplist_path_##decl##_t *path = apath; \ + \ + /* Allocate a buffer, or use a static one. */ \ + if (SKIPLIST_MAX_HEIGHT == 1) { \ + path = malloc(sizeof(__skiplist_path_##decl##_t) * slist->slh_max_height + 1); \ + if (path == NULL) \ + goto done; \ + } \ + memset(path, 0, sizeof(__skiplist_path_##decl##_t) * slist->slh_max_height + 1); \ + \ + /* Find a `path` to `new` in the list and a match (`path[0]`) if it exists. */ \ + __skip_locate_##decl(slist, query, path); \ + node = path[1].node; \ + if (node == slist->slh_tail) \ + goto done; \ + do { \ + node = node->field.sle_levels[0]->next; \ + cmp = __skip_compare_nodes_##decl(slist, node, query, slist->slh_aux); \ + } while (cmp <= 0 && node != slist->slh_tail); \ + \ + done:; \ + if (SKIPLIST_MAX_HEIGHT == 1) \ + free(path); \ + \ + return node; \ + } \ + \ + /** \ + * -- skip_position_lte \ + * \ + * Position and return a cursor at the last node that is less than \ + * or equal to node `n`. \ + * Return NULL if nothing is less than or equal. \ + */ \ + decl##_node_t *prefix##skip_position_lte_##decl(decl##_t *slist, decl##_node_t *query) \ + { \ + static __skiplist_path_##decl##_t apath[SKIPLIST_MAX_HEIGHT + 1]; \ + decl##_node_t *node; \ + __skiplist_path_##decl##_t *path = apath; \ + \ + /* Allocate a buffer, or use a static one. */ \ + if (SKIPLIST_MAX_HEIGHT == 1) { \ + path = malloc(sizeof(__skiplist_path_##decl##_t) * slist->slh_max_height + 1); \ + if (path == NULL) \ + goto done; \ + } \ + memset(path, 0, sizeof(__skiplist_path_##decl##_t) * slist->slh_max_height + 1); \ + \ + /* Find a `path` to `new` in the list and a match (`path[0]`) if it exists. */ \ + __skip_locate_##decl(slist, query, path); \ + node = path[0].node; \ + if (node) \ + goto done; \ + node = path[1].node; \ + \ + done:; \ + if (SKIPLIST_MAX_HEIGHT == 1) \ + free(path); \ + \ + return node; \ + } \ + \ + /** \ + * -- skip_position_lt_ \ + * \ + * Position and return a cursor at the last node that is less than \ + * to the node `n`. Return NULL if nothing is less than or equal. \ + */ \ + decl##_node_t *prefix##skip_position_lt_##decl(decl##_t *slist, decl##_node_t *query) \ + { \ + static __skiplist_path_##decl##_t apath[SKIPLIST_MAX_HEIGHT + 1]; \ + decl##_node_t *node; \ + __skiplist_path_##decl##_t *path = apath; \ + \ + /* Allocate a buffer, or use a static one. */ \ + if (SKIPLIST_MAX_HEIGHT == 1) { \ + path = malloc(sizeof(__skiplist_path_##decl##_t) * slist->slh_max_height + 1); \ + if (path == NULL) \ + goto done; \ + } \ + memset(path, 0, sizeof(__skiplist_path_##decl##_t) * slist->slh_max_height + 1); \ + \ + /* Find a `path` to `new` in the list and a match (`path[0]`) if it exists. */ \ + __skip_locate_##decl(slist, query, path); \ + node = path[1].node; \ + \ + done:; \ + if (SKIPLIST_MAX_HEIGHT == 1) \ + free(path); \ + \ + return node; \ + } \ + \ + /** \ + * -- skip_position_ \ + * \ + * Position a cursor relative to `n`. \ + */ \ + decl##_node_t *prefix##skip_position_##decl(decl##_t *slist, skip_pos_##decl_t op, decl##_node_t *query) \ + { \ + decl##_node_t *node; \ + \ + switch (op) { \ + case (SKIP_LT): \ + node = prefix##skip_position_lt_##decl(slist, query); \ + break; \ + case (SKIP_LTE): \ + node = prefix##skip_position_lte_##decl(slist, query); \ + break; \ + case (SKIP_GTE): \ + node = prefix##skip_position_gte_##decl(slist, query); \ + break; \ + case (SKIP_GT): \ + node = prefix##skip_position_gt_##decl(slist, query); \ + break; \ + default: \ + case (SKIP_EQ): \ + node = prefix##skip_position_eq_##decl(slist, query); \ + break; \ + } \ + return node; \ + } \ + \ + /** \ + * -- skip_update_ \ + * \ + * Locates a node in the list that equals the `new` node and then \ + * uses the `update_entry_blk` to update the contents. \ + * \ + * WARNING: Do not update the portion of the node used for ordering \ + * (e.g. `key`) unless you really know what you're doing. \ + */ \ + int prefix##skip_update_##decl(decl##_t *slist, decl##_node_t *query, void *value) \ + { \ + static __skiplist_path_##decl##_t apath[SKIPLIST_MAX_HEIGHT + 1]; \ + int rc = 0, np; \ + decl##_node_t *node; \ + __skiplist_path_##decl##_t *path = apath; \ + \ + if (slist == NULL) \ + return -1; \ + \ + /* Allocate a buffer, or use a static one. */ \ + if (SKIPLIST_MAX_HEIGHT == 1) { \ + path = malloc(sizeof(__skiplist_path_##decl##_t) * slist->slh_max_height + 1); \ + if (path == NULL) \ + return ENOMEM; \ + } \ + memset(path, 0, sizeof(__skiplist_path_##decl##_t) * slist->slh_max_height + 1); \ + \ + __skip_locate_##decl(slist, query, path); \ + node = path[0].node; \ + \ + if (SKIPLIST_MAX_HEIGHT == 1) \ + free(path); \ + \ + if (node == NULL) \ + return -1; \ + \ + /* If the optional snapshots feature is configured, use it now. \ + Snapshots preserve the node if it is younger than our snapshot \ + moment. */ \ + if (slist->slh_fns.preserve_node) { \ + np = slist->slh_fns.preserve_node(slist, node, NULL); \ + if (np > 0) \ + return np; \ + } \ + \ + slist->slh_fns.update_entry(node, value); \ + \ + /* Record the era for this node to enable snapshots. */ \ + if (slist->slh_fns.snapshot_record_era) \ + slist->slh_fns.snapshot_record_era(slist, node); \ + \ + return rc; \ + } \ + \ + /** \ + * -- skip_remove_node_ \ + * \ + * Removes the node `n` from the `slist` if present. \ + */ \ + int prefix##skip_remove_node_##decl(decl##_t *slist, decl##_node_t *query) \ + { \ + static __skiplist_path_##decl##_t apath[SKIPLIST_MAX_HEIGHT + 1]; \ + int np = 0; \ + size_t i, len, height; \ + decl##_node_t *node; \ + __skiplist_path_##decl##_t *path = apath; \ + \ + if (slist == NULL || query == NULL) \ + return -1; \ + if (slist->slh_length == 0) \ + return 0; \ + \ + /* Allocate a buffer */ \ + if (SKIPLIST_MAX_HEIGHT == 1) { \ + path = malloc(sizeof(__skiplist_path_##decl##_t) * slist->slh_max_height + 1); \ + if (path == NULL) \ + return ENOMEM; \ + } \ + memset(path, 0, sizeof(__skiplist_path_##decl##_t) * slist->slh_max_height + 1); \ + \ + /* Attempt to locate the node in the list. */ \ + len = __skip_locate_##decl(slist, query, path); \ + node = path[0].node; \ + if (node) { \ + /* If the optional snapshots feature is configured, use it now. \ + Snapshots preserve the node if it is younger than our snapshot \ + moment, this node is about to be removed. */ \ + if (slist->slh_fns.preserve_node) { \ + np = slist->slh_fns.preserve_node(slist, node, NULL); \ + if (np > 0) \ + return np; \ + } \ + /* We found it, set the next->prev to the node->prev keeping in mind \ + that the next node might be the tail). */ \ + node->field.sle_levels[0]->next->field.sle_prev = node->field.sle_prev; \ + /* Walk the path, stop when the next node is not the one we're \ + removing. At each step along our walk... */ \ + for (i = 0; i < len; i++) { \ + if (path[i + 1].node->field.sle_levels[i]->next != node) \ + break; \ + /* ... adjust the next pointer at that level. */ \ + path[i + 1].node->field.sle_levels[i]->next = node->field.sle_levels[i]->next; \ + /* Adjust the height so we're only pointing at the tail once at \ + the top so we don't waste steps later when searching. */ \ + if (path[i + 1].node->field.sle_levels[i]->next == slist->slh_tail) { \ + height = path[i + 1].node->field.sle_height; \ + path[i + 1].node->field.sle_height = height - 1; \ + } \ + } \ + /* Account for delete at tail. */ \ + if (node->field.sle_levels[0]->next == slist->slh_tail) { \ + slist->slh_tail->field.sle_prev = query->field.sle_prev; \ + } \ + \ + if (SKIPLIST_MAX_HEIGHT == 1) \ + free(path); \ + \ + slist->slh_fns.free_entry(node); \ + \ + /* Reduce the height of the head node. */ \ + i = 0; \ + while (slist->slh_head->field.sle_levels[i]->next != slist->slh_tail && i < slist->slh_head->field.sle_height) \ + i++; \ + slist->slh_head->field.sle_height = i; \ + slist->slh_tail->field.sle_height = i; \ + \ + slist->slh_length--; \ + __skip_adjust_hit_counts_##decl(slist); \ + } \ + return 0; \ + } \ + \ + /** \ + * -- skip_free_ \ + * \ + * Release all nodes and their associated heap objects. The list reference \ + * is no longer valid after this call. To make it valid again call _init(). \ + */ \ + void prefix##skip_free_##decl(decl##_t *slist) \ + { \ + if (slist == NULL) \ + return; \ + \ + prefix##skip_release_##decl(slist); \ + \ + free(slist->slh_head); \ + free(slist->slh_tail); \ } #define SKIPLIST_DECL_SNAPSHOTS(decl, prefix, field) \ @@ -1235,7 +1242,7 @@ void __attribute__((format(printf, 4, 5))) __skip_diag_(const char *file, int li \ node = slist->slh_snap.pres; \ while (node) { \ - next = node->field.sle_next[0]; \ + next = node->field.sle_levels[0]->next; \ prefix##skip_free_node_##decl(slist, node); \ node = next; \ } \ @@ -1271,14 +1278,14 @@ void __attribute__((format(printf, 4, 5))) __skip_diag_(const char *file, int li return 0; \ \ /* (a) alloc, ... */ \ - size_t sle_arr_sz = sizeof(struct __skiplist_##decl##_entry) * slist->slh_max_height; \ + size_t sle_arr_sz = sizeof(struct __skiplist_##decl##_level) * slist->slh_max_height; \ rc = prefix##skip_alloc_node_##decl(slist, &dest); \ if (rc) \ return rc; \ \ - /* (b) shallow copy, fix sle_next pointer, ... */ \ + /* (b) shallow copy, fix sle_levels pointer, ... */ \ memcpy(dest, src, sizeof(decl##_node_t) + sle_arr_sz); \ - dest->field.sle_next = (decl##_node_t **)((uintptr_t)dest + sizeof(decl##_node_t)); \ + dest->field.sle_levels = (struct __skiplist_##decl##_level **)((uintptr_t)dest + sizeof(decl##_node_t)); \ \ /* ... if we're not preserving the head or the tail, ... */ \ if (!(src == slist->slh_head || src == slist->slh_tail)) { \ @@ -1291,7 +1298,7 @@ void __attribute__((format(printf, 4, 5))) __skip_diag_(const char *file, int li } \ \ /* (d) is this a duplicate? */ \ - if (__skip_compare_nodes_##decl(slist, dest, dest->field.sle_next[0], slist->slh_aux) == 0 || \ + if (__skip_compare_nodes_##decl(slist, dest, dest->field.sle_levels[0]->next, slist->slh_aux) == 0 || \ __skip_compare_nodes_##decl(slist, dest, dest->field.sle_prev, slist->slh_aux) == 0) \ is_dup = (decl##_node_t *)0x1; \ \ @@ -1299,20 +1306,20 @@ void __attribute__((format(printf, 4, 5))) __skip_diag_(const char *file, int li dest->field.sle_prev = NULL; \ __SKIP_ALL_ENTRIES_B2T(field, dest) \ { \ - dest->field.sle_next[lvl] = NULL; \ + dest->field.sle_levels[lvl]->next = NULL; \ } \ \ /* (f) set duplicate flag */ \ - dest->field.sle_next[1] = (decl##_node_t *)is_dup; \ + dest->field.sle_levels[1]->next = (decl##_node_t *)is_dup; \ \ /* (g) insert node into slh_pres list at head */ \ if (slist->slh_snap.pres == NULL) { \ - dest->field.sle_next[0] = NULL; \ + dest->field.sle_levels[0]->next = NULL; \ slist->slh_snap.pres = dest; \ } else { \ /* The next[0] pointer forms the singly-linked list when \ preserved. */ \ - dest->field.sle_next[0] = slist->slh_snap.pres; \ + dest->field.sle_levels[0]->next = slist->slh_snap.pres; \ slist->slh_snap.pres = dest; \ } \ \ @@ -1352,11 +1359,11 @@ void __attribute__((format(printf, 4, 5))) __skip_diag_(const char *file, int li * c) restore nodes == era by... \ * i) remove node from slh_pres list \ * ii) _insert(node) or \ - * _insert_dup() if node->field.sle_next[1] != 0 (clear that) \ + * _insert_dup() if node->field.sle_levels[1] != 0 (clear that) \ * d) set slist's era to `era` \ * \ * NOTES: \ - * - Starting with slh_pres, the `node->field.sle_next[0]` form a \ + * - Starting with slh_pres, the `node->field.sle_levels[0]->next` form a \ * singly-linked list. \ */ \ decl##_t *prefix##skip_restore_snapshot_##decl(decl##_t *slist, size_t era) \ @@ -1387,12 +1394,12 @@ void __attribute__((format(printf, 4, 5))) __skip_diag_(const char *file, int li if (node->field.sle_era > era) { \ /* remove node from slh_snap.pres list */ \ if (slist->slh_snap.pres == node) \ - slist->slh_snap.pres = node->field.sle_next[0]; \ + slist->slh_snap.pres = node->field.sle_levels[0]->next; \ else { \ - if (node->field.sle_next[0] == NULL) \ - prev->field.sle_next[0] = NULL; \ + if (node->field.sle_levels[0]->next == NULL) \ + prev->field.sle_levels[0]->next = NULL; \ else \ - prev->field.sle_next[0] = node->field.sle_next[0]; \ + prev->field.sle_levels[0]->next = node->field.sle_levels[0]->next; \ } \ \ prefix##skip_free_node_##decl(slist, node); \ @@ -1403,24 +1410,24 @@ void __attribute__((format(printf, 4, 5))) __skip_diag_(const char *file, int li if (node->field.sle_era == era) { \ /* remove node from slh_snap.pres list */ \ if (slist->slh_snap.pres == node) \ - slist->slh_snap.pres = node->field.sle_next[0]; \ + slist->slh_snap.pres = node->field.sle_levels[0]->next; \ else { \ - if (node->field.sle_next[0] == NULL) \ - prev->field.sle_next[0] = NULL; \ + if (node->field.sle_levels[0]->next == NULL) \ + prev->field.sle_levels[0]->next = NULL; \ else \ - prev->field.sle_next[0] = node->field.sle_next[0]; \ + prev->field.sle_levels[0]->next = node->field.sle_levels[0]->next; \ } \ \ node->field.sle_prev = NULL; \ - if (node->field.sle_next[1] != 0) { \ - node->field.sle_next[1] = NULL; \ + if (node->field.sle_levels[1] != 0) { \ + node->field.sle_levels[1] = NULL; \ prefix##skip_insert_dup_##decl(slist, node); \ } else { \ prefix##skip_insert_##decl(slist, node); \ } \ } \ prev = node; \ - node = node->field.sle_next[0]; \ + node = node->field.sle_levels[0]->next; \ } \ \ /* (d) */ \ @@ -1547,12 +1554,12 @@ void __attribute__((format(printf, 4, 5))) __skip_diag_(const char *file, int li \ slist->slh_head->field.sle_height = 0; \ for (i = 0; i < slist->slh_max_height; i++) \ - slist->slh_head->field.sle_next[i] = slist->slh_tail; \ + slist->slh_head->field.sle_levels[i]->next = slist->slh_tail; \ slist->slh_head->field.sle_prev = NULL; \ \ slist->slh_tail->field.sle_height = slist->slh_max_height; \ for (i = 0; i < slist->slh_max_height; i++) \ - slist->slh_tail->field.sle_next[i] = NULL; \ + slist->slh_tail->field.sle_levels[i]->next = NULL; \ slist->slh_tail->field.sle_prev = slist->slh_head; \ \ i = 0; \ @@ -1678,26 +1685,26 @@ void __attribute__((format(printf, 4, 5))) __skip_diag_(const char *file, int li node = slist->slh_head; \ __SKIP_ENTRIES_B2T(field, node) \ { \ - if (node->field.sle_next[lvl] == NULL) { \ + if (node->field.sle_levels[lvl]->next == NULL) { \ __skip_integrity_failure_##decl("the head's %lu next node should not be NULL\n", lvl); \ n_err++; \ if (flags) \ return n_err; \ } \ n = lvl; \ - if (node->field.sle_next[lvl] == slist->slh_tail) \ + if (node->field.sle_levels[lvl]->next == slist->slh_tail) \ break; \ } \ n++; \ __SKIP_ENTRIES_B2T_FROM(field, node, n) \ { \ - if (node->field.sle_next[lvl] == NULL) { \ + if (node->field.sle_levels[lvl]->next == NULL) { \ __skip_integrity_failure_##decl("the head's %lu next node should not be NULL\n", lvl); \ n_err++; \ if (flags) \ return n_err; \ } \ - if (node->field.sle_next[lvl] != slist->slh_tail) { \ + if (node->field.sle_levels[lvl]->next != slist->slh_tail) { \ __skip_integrity_failure_##decl("after internal nodes, the head's %lu next node should always be the tail\n", lvl); \ n_err++; \ if (flags) \ @@ -1728,7 +1735,7 @@ void __attribute__((format(printf, 4, 5))) __skip_diag_(const char *file, int li return n_err; \ } \ \ - if (this->sle_next == NULL) { \ + if (this->sle_levels == NULL) { \ __skip_integrity_failure_##decl("the %lu node's [%p] next field should never be NULL\n", nth, (void *)node); \ n_err++; \ if (flags) \ @@ -1744,25 +1751,25 @@ void __attribute__((format(printf, 4, 5))) __skip_diag_(const char *file, int li \ __SKIP_ENTRIES_B2T(field, node) \ { \ - if (this->sle_next[lvl] == NULL) { \ + if (this->sle_levels[lvl]->next == NULL) { \ __skip_integrity_failure_##decl("the %lu node's next[%lu] should not be NULL\n", nth, lvl); \ n_err++; \ if (flags) \ return n_err; \ } \ n = lvl; \ - if (this->sle_next[lvl] == slist->slh_tail) \ + if (this->sle_levels[lvl]->next == slist->slh_tail) \ break; \ } \ n++; \ __SKIP_ENTRIES_B2T_FROM(field, node, n) \ { \ - if (this->sle_next[lvl] == NULL) { \ + if (this->sle_levels[lvl]->next == NULL) { \ __skip_integrity_failure_##decl("after the %lunth the %lu node's next[%lu] should not be NULL\n", n, nth, lvl); \ n_err++; \ if (flags) \ return n_err; \ - } else if (this->sle_next[lvl] != slist->slh_tail) { \ + } else if (this->sle_levels[lvl]->next != slist->slh_tail) { \ __skip_integrity_failure_##decl("after the %lunth the %lu node's next[%lu] should point to the tail\n", n, nth, lvl); \ n_err++; \ if (flags) \ @@ -1770,7 +1777,7 @@ void __attribute__((format(printf, 4, 5))) __skip_diag_(const char *file, int li } \ } \ \ - decl##_node_t *a = (decl##_node_t *)(uintptr_t)this->sle_next; \ + decl##_node_t *a = (decl##_node_t *)(uintptr_t)this->sle_levels; \ decl##_node_t *b = (decl##_node_t *)(intptr_t)((uintptr_t)node + sizeof(decl##_node_t)); \ if (a != b) { \ __skip_integrity_failure_##decl("the %lu node's [%p] next field isn't at the proper offset relative to the node\n", nth, (void *)node); \ @@ -1779,7 +1786,7 @@ void __attribute__((format(printf, 4, 5))) __skip_diag_(const char *file, int li return n_err; \ } \ \ - next = this->sle_next[0]; \ + next = this->sle_levels[0]->next; \ prev = this->sle_prev; \ if (__skip_compare_nodes_##decl(slist, node, node, slist->slh_aux) != 0) { \ __skip_integrity_failure_##decl("the %lu node [%p] is not equal to itself\n", nth, (void *)node); \ @@ -2002,7 +2009,7 @@ void __attribute__((format(printf, 4, 5))) __skip_diag_(const char *file, int li fflush(os); \ __SKIP_ENTRIES_T2B(field, node) \ { \ - next = (node->field.sle_next[lvl] == slist->slh_tail) ? NULL : node->field.sle_next[lvl]; \ + next = (node->field.sle_levels[lvl]->next == slist->slh_tail) ? NULL : node->field.sle_levels[lvl]->next; \ width = __skip_dot_width_##decl(slist, node, next ? next : slist->slh_tail); \ fprintf(os, " { %lu | ", lvl, width, lvl); \ if (next) \ @@ -2024,7 +2031,7 @@ void __attribute__((format(printf, 4, 5))) __skip_diag_(const char *file, int li /* Now edges */ \ __SKIP_ENTRIES_B2T(field, node) \ { \ - next = (node->field.sle_next[lvl] == slist->slh_tail) ? NULL : node->field.sle_next[lvl]; \ + next = (node->field.sle_levels[lvl]->next == slist->slh_tail) ? NULL : node->field.sle_levels[lvl]->next; \ __skip_dot_write_node_##decl(os, nsg, node); \ fprintf(os, ":f%lu -> ", lvl); \ __skip_dot_write_node_##decl(os, nsg, next); \ @@ -2103,7 +2110,7 @@ void __attribute__((format(printf, 4, 5))) __skip_diag_(const char *file, int li fprintf(os, "\"HeadNode%lu\" [\n", nsg); \ fprintf(os, "label = \""); \ \ - if (slist->slh_head->field.sle_height || slist->slh_head->field.sle_next[0] != slist->slh_tail) \ + if (slist->slh_head->field.sle_height || slist->slh_head->field.sle_levels[0]->next != slist->slh_tail) \ letitgo = 1; \ \ /* Write out the fields */ \ @@ -2111,7 +2118,7 @@ void __attribute__((format(printf, 4, 5))) __skip_diag_(const char *file, int li if (letitgo) { \ __SKIP_ENTRIES_T2B(field, node) \ { \ - next = (node->field.sle_next[lvl] == slist->slh_tail) ? NULL : node->field.sle_next[lvl]; \ + next = (node->field.sle_levels[lvl]->next == slist->slh_tail) ? NULL : node->field.sle_levels[lvl]->next; \ width = __skip_dot_width_##decl(slist, node, next ? next : slist->slh_tail); \ fprintf(os, "{ %lu | ", width, lvl); \ if (next) \ @@ -2135,7 +2142,7 @@ void __attribute__((format(printf, 4, 5))) __skip_diag_(const char *file, int li node = slist->slh_head; \ __SKIP_ENTRIES_B2T(field, node) \ { \ - next = (node->field.sle_next[lvl] == slist->slh_tail) ? NULL : node->field.sle_next[lvl]; \ + next = (node->field.sle_levels[lvl]->next == slist->slh_tail) ? NULL : node->field.sle_levels[lvl]->next; \ fprintf(os, "\"HeadNode%lu\":f%lu -> ", nsg, lvl); \ __skip_dot_write_node_##decl(os, nsg, next); \ fprintf(os, ":w%lu [];\n", lvl); \ @@ -2164,7 +2171,7 @@ void __attribute__((format(printf, 4, 5))) __skip_diag_(const char *file, int li node = slist->slh_tail; \ size_t th = slist->slh_head->field.sle_height; \ for (size_t lvl = th; lvl != (size_t)-1; lvl--) { \ - next = (node->field.sle_next[lvl] == slist->slh_tail) ? NULL : node->field.sle_next[lvl]; \ + next = (node->field.sle_levels[lvl]->next == slist->slh_tail) ? NULL : node->field.sle_levels[lvl]->next; \ fprintf(os, " 0x0", lvl); \ __SKIP_IS_LAST_ENTRY_T2B() continue; \ fprintf(os, " | "); \