snapshot v2/p2; snap/restore/rm snap done
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7560920d2a
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0557b6d0a1
111
include/sl.h
111
include/sl.h
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@ -166,7 +166,7 @@
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struct __skiplist_##decl_entry { \
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struct __skiplist_##decl_idx { \
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struct type *prev, **next; \
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size_t height; \
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size_t height, gen; \
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} sle; \
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}
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@ -261,11 +261,12 @@
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\
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/* Skip List structure and type */ \
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typedef struct decl { \
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size_t level, length, max; \
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size_t level, length, max, gen; \
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int (*cmp)(struct decl *, decl##_node_t *, decl##_node_t *, void *); \
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void *aux; \
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decl##_node_t *slh_head; \
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decl##_node_t *slh_tail; \
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decl##_node_t *slh_pres; \
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} decl##_t; \
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\
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/* Skip List comparison function type */ \
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@ -324,6 +325,7 @@
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n = (decl##_node_t *)calloc(1, sizeof(decl##_node_t) + sle_arr_sz); \
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if (n == NULL) \
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return ENOMEM; \
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n->field.sle.gen = slist->gen; \
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n->field.sle.height = 0; \
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n->field.sle.next = (decl##_node_t **)((uintptr_t)n + sizeof(decl##_node_t)); \
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*node = n; \
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@ -338,6 +340,7 @@
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int rc = 0; \
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size_t i; \
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\
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slist->gen = 1; \
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slist->length = 0; \
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slist->max = (size_t)(max < 0 ? -max : max); \
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slist->max = SKIPLIST_MAX_HEIGHT == 1 ? slist->max : SKIPLIST_MAX_HEIGHT; \
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@ -721,8 +724,8 @@
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return -1; \
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} \
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\
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/* -- skip_remove_ */ \
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int prefix##skip_remove_##decl(decl##_t *slist, decl##_node_t *n) \
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/* -- skip_remove_node_ */ \
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int prefix##skip_remove_node_##decl(decl##_t *slist, decl##_node_t *n) \
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{ \
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static decl##_node_t apath[SKIPLIST_MAX_HEIGHT + 1]; \
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size_t i, len, level; \
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@ -814,35 +817,111 @@
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return 0; \
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} \
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\
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/* -- skip_snapshot_ TODO/WIP \
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/* -- skip_snapshot_ \
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* A snapshot is a read-only view of a Skip List at a point in time. Once \
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* taken, a snapshot must be restored or disposed. Any number of snapshots \
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* can be created. \
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*/ \
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decl##_t *prefix##skip_snapshot_##decl(decl##_t *slist) \
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size_t prefix##skip_snapshot_##decl(decl##_t *slist) \
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{ \
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decl##_t *snap; \
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\
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if (slist == NULL) \
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return 0; \
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\
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return snap; \
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return ++slist->gen; \
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} \
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\
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/* -- skip_restore_snapshot_ TODO/WIP */ \
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/* -- skip_restore_snapshot_ \
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* Restores the Skiplist to generation `gen`. Once you restore `gen` you \
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* can no longer access any generations > `gen`. \
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*/ \
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decl##_t *prefix##skip_restore_snapshot_##decl(decl##_t *slist, unsigned gen) \
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{ \
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((void)gen); \
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size_t i; \
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decl##_node_t *node, *next, *prev; \
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\
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if (slist == NULL) \
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return 0; \
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return NULL; \
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\
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if (gen >= slist->gen || slist->slh_pres == NULL) \
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return slist; \
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\
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/* ALGORITHM: \
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* iterate over the preserved nodes (slist->slh_pres) \
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* a) remove nodes with node->gen > gen from slist \
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* b) remove nodes > gen from slh_pres and _free_node() \
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* c) restore nodes == gen by... \
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* i) remove node from slh_pres list \
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* ii) _insert(node) or \
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* _insert_dup() if node->field.sle_next[1] != 0 (clear that) \
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* d) set slist's gen to `gen` \
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* \
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* NOTES: \
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* - the `node->field.sle.prev` in this context is actually the "next" \
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* node in the `slh_pres` singly-linked list \
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*/ \
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\
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SKIPLIST_EACH_H2T(decl, prefix, slist, node, i) \
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{ \
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((void)i); \
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if (node->field.sle.gen > gen) \
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prefix##skip_remove_node_##decl(slist, node); \
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} \
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\
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prev = NULL; \
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node = slist->slh_pres; \
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while (node) { \
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next = node->field.sle.prev; \
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if (node->field.sle.gen > gen) { \
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if (prev == NULL) \
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slist->slh_pres = next; \
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else \
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prev->field.sle.prev = next; \
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prefix##skip_free_node_##decl(node); \
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} \
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if (node->field.sle.gen == gen) { \
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if (node->field.sle.next[1] != 0) { \
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node->field.sle.next[1] = NULL; \
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prefix##skip_insert_dup_##decl(slist, node); \
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} else { \
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prefix##skip_insert_##decl(slist, node); \
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} \
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} \
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prev = node; \
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node = next; \
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} \
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slist->gen = gen; \
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return slist; \
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} \
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\
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/* -- skip_dispose_snapshot_ TODO/WIP */ \
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/* -- skip_dispose_snapshot_ \
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* Removes from history all snapshots equal to or newer than (>=) \
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* `gen`. \
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*/ \
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void prefix##skip_dispose_snapshot_##decl(decl##_t *slist, unsigned gen) \
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{ \
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((void)slist); \
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((void)gen); \
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decl##_node_t *node, *next, *prev; \
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\
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if (slist == NULL) \
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return; \
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\
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if (slist->slh_pres == NULL) \
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return; \
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\
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prev = NULL; \
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node = slist->slh_pres; \
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while (node) { \
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next = node->field.sle.prev; \
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if (node->field.sle.gen >= gen) { \
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if (prev == NULL) \
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slist->slh_pres = next; \
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else \
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prev->field.sle.prev = next; \
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prefix##skip_free_node_##decl(node); \
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} \
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prev = node; \
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node = next; \
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} \
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slist->gen = gen - 1; \
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} \
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\
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/* Archive of a Skip List */ \
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@ -1209,7 +1288,7 @@
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{ \
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decl##_node_t node; \
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node.key = key; \
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return prefix##skip_remove_##decl(slist, &node); \
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return prefix##skip_remove_node_##decl(slist, &node); \
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}
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#define SKIPLIST_DECL_DOT(decl, prefix, field) \
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