From acd2db46a9f1b1bee58ca5cdad1c933e38d2b27c Mon Sep 17 00:00:00 2001 From: Greg Burd Date: Tue, 26 Mar 2024 10:53:24 -0400 Subject: [PATCH] snapshot v2/p11; cleanup, still broken --- include/sl.h | 37 +++++++++++++++++++++---------------- 1 file changed, 21 insertions(+), 16 deletions(-) diff --git a/include/sl.h b/include/sl.h index ea97a4f..aa3d515 100644 --- a/include/sl.h +++ b/include/sl.h @@ -314,7 +314,7 @@ size_t level = 0; \ double probability = 0.5; \ \ - double random_value = (double)rand() / RAND_MAX; /* NOLINT(*-msc50-cpp) */ \ + double random_value = (double)(rand() / RAND_MAX); /* NOLINT(*-msc50-cpp) */ \ while (random_value < probability && level < max) { \ level++; \ probability *= 0.5; \ @@ -529,7 +529,7 @@ } \ \ /* (d) set duplicate flag */ \ - dest->field.sle.next[0] = (decl##_node_t *)is_dup; \ + dest->field.sle.next[1] = (decl##_node_t *)is_dup; \ \ /* (e) insert node into slh_pres list at head */ \ if (slist->slh_pres == NULL) \ @@ -564,6 +564,7 @@ { \ int rc = 0, n; \ size_t i; \ + decl##_node_t *prev = NULL; \ \ if (path == NULL) \ return 0; \ @@ -575,6 +576,10 @@ /* No need to preserve the head or tail sentry nodes. */ \ if (path[i] == slist->slh_head || path[i] == slist->slh_tail) \ continue; \ + /* No need to preserve a node more than once. */ \ + if (path[i] == prev) \ + continue; \ + prev = path[i]; \ \ /* When the generation of the node in the path is < the list's \ current generation, we must preserve it. */ \ @@ -1131,6 +1136,20 @@ * \ * Restores the Skiplist to generation `gen`. Once you restore `gen` you \ * can no longer access any generations > `gen`. \ + * \ + * ALGORITHM: \ + * iterate over the preserved nodes (slist->slh_pres) \ + * a) remove/free nodes with node->gen > gen from slist \ + * b) remove/free nodes > gen from slh_pres \ + * c) restore nodes == gen by... \ + * i) remove node from slh_pres list \ + * ii) _insert(node) or \ + * _insert_dup() if node->field.sle_next[1] != 0 (clear that) \ + * d) set slist's gen to `gen` \ + * \ + * NOTES: \ + * - Starting with slh_pres, the `node->field.sle.next[0]` form a \ + * singly-linked list. \ */ \ decl##_t *prefix##skip_restore_snapshot_##decl(decl##_t *slist, unsigned gen) \ { \ @@ -1143,20 +1162,6 @@ if (gen >= slist->gen || slist->slh_pres == NULL) \ return slist; \ \ - /* ALGORITHM: \ - * iterate over the preserved nodes (slist->slh_pres) \ - * a) remove nodes with node->gen > gen from slist \ - * b) remove nodes > gen from slh_pres and _free_node() \ - * c) restore nodes == gen by... \ - * i) remove node from slh_pres list \ - * ii) _insert(node) or \ - * _insert_dup() if node->field.sle_next[1] != 0 (clear that) \ - * d) set slist's gen to `gen` \ - * \ - * NOTES: \ - * - the `node->field.sle.next[0]` forms a singly-linked list. \ - */ \ - \ /* (a) */ \ SKIPLIST_FOREACH_H2T(decl, prefix, slist, node, i) \ { \