1160 lines
147 KiB
C
1160 lines
147 KiB
C
/*
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* Copyright (c) 2024
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* Gregory Burd <greg@burd.me>. All rights reserved.
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*
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* ISC License Permission to use, copy, modify, and/or distribute this software
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* for any purpose with or without fee is hereby granted, provided that the
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* above copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
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* REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
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* AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
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* INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
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* LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
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* OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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* PERFORMANCE OF THIS SOFTWARE.
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*
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* I'd like to thank others for thoughtfully licensing their work, the
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* community of software engineers succeeds when we work together.
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*
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* Portions of this code are derived from other copyrighted works:
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*
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* - MIT License
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* - https://github.com/greensky00/skiplist
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* 2017-2024 Jung-Sang Ahn <jungsang.ahn@gmail.com>
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* - https://github.com/paulross/skiplist
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* Copyright (c) 2017-2023 Paul Ross <paulross@uky.edu>
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* - https://github.com/JP-Ellis/rust-skiplist
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* Copyright (c) 2015 Joshua Ellis <github@jpellis.me>
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* - Public Domain
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* - https://gist.github.com/zhpengg/2873424
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* Zhipeng Li <zhpeng.is@gmail.com>
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*/
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#ifndef _SKIPLIST_H_
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#define _SKIPLIST_H_
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/*
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* This file defines a skiplist data structure.
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*
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* A skiplist is a way of storing sorted elements in such a way that they can be
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* accessed, inserted and removed, all in O(log(n)) on average.
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*
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* Conceptually, a skiplist is arranged as follows:
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*
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* <head> ----------> [2] --------------------------------------------------> [9] ---------->
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* <head> ----------> [2] ------------------------------------[7] ----------> [9] ---------->
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* <head> ----------> [2] ----------> [4] ------------------> [7] ----------> [9] --> [10] ->
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* <head> --> [1] --> [2] --> [3] --> [4] --> [5] --> [6] --> [7] --> [8] --> [9] --> [10] ->
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*
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* Each node contains at the very least a link to the next element in the list
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* (corresponding to the lowest level in the above diagram), but it can randomly
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* contain more links which skip further down the list (the towers in the above
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* diagram). This allows for the algorithm to move down the list faster than
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* having to visit every element.
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*
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* Conceptually, the skiplist can be thought of as a stack of linked lists. At
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* the very bottom is the full linked list with every element, and each layer
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* above corresponds to a linked list containing a random subset of the elements
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* from the layer immediately below it. The probability distribution that
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* determines this random subset can be customized, but typically a layer will
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* contain half the nodes from the layer below.
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*
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* This implementation maintains a doubly-linked list at the bottom layer to
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* support efficient iteration in either direction. There is also a guard
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* node at the tail rather than simply pointing to NULL.
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*
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* <head> <-> [1] <-> [2] <-> [3] <-> [4] <-> [5] <-> [6] <-> [7] <-> <tail>
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*
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* Safety:
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*
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* The ordered skiplist relies on a well-behaved comparison
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* function. Specifically, given some ordering function f(a, b), it must satisfy
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* the following properties:
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*
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* 1) Be well defined: f(a, b) should always return the same value
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* 2) Be anti-symmetric: f(a, b) == Greater if and only if f(b, a) == Less, and
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* f(a, b) == Equal == f(b, a).
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* 3) Be transitive: If f(a, b) == Greater and f(b, c) == Greater then f(a, c)
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* == Greater.
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*
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* Failure to satisfy these properties can result in unexpected behavior at
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* best, and at worst will cause a segfault, null deref, or some other bad
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* behavior.
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*
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* References for this implementation include, but are not limited to:
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*
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* - Skip lists: a probabilistic alternative to balanced trees
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* @article{10.1145/78973.78977,
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* author = {Pugh, William},
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* title = {Skip lists: a probabilistic alternative to balanced trees},
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* year = {1990}, issue_date = {June 1990},
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* publisher = {Association for Computing Machinery},
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* address = {New York, NY, USA},
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* volume = {33}, number = {6}, issn = {0001-0782},
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* url = {https://doi.org/10.1145/78973.78977},
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* doi = {10.1145/78973.78977},
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* journal = {Commun. ACM}, month = {jun}, pages = {668–676}, numpages = {9},
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* keywords = {trees, searching, data structures},
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* download = {https://www.cl.cam.ac.uk/teaching/2005/Algorithms/skiplists.pdf}
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* }
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*
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* - Tutorial: The Ubiquitous Skiplist, its Variants, and Applications in Modern Big Data Systems
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* @article{Vadrevu2023TutorialTU,
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* title={Tutorial: The Ubiquitous Skiplist, its Variants, and Applications in Modern Big Data Systems},
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* author={Venkata Sai Pavan Kumar Vadrevu and Lu Xing and Walid G. Aref},
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* journal={ArXiv},
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* year={2023},
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* volume={abs/2304.09983},
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* url={https://api.semanticscholar.org/CorpusID:258236678},
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* download={https://arxiv.org/pdf/2304.09983.pdf}
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||
* }
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*
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* - The Splay-List: A Distribution-Adaptive Concurrent Skip-List
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* @misc{aksenov2020splaylist,
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* title={The Splay-List: A Distribution-Adaptive Concurrent Skip-List},
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* author={Vitaly Aksenov and Dan Alistarh and Alexandra Drozdova and Amirkeivan Mohtashami},
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* year={2020},
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* eprint={2008.01009},
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* archivePrefix={arXiv},
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* primaryClass={cs.DC},
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* download={https://arxiv.org/pdf/2008.01009.pdf}
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* }
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*
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* - JellyFish: A Fast Skip List with MVCC},
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* @article{Yeon2020JellyFishAF,
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* title={JellyFish: A Fast Skip List with MVCC},
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* author={Jeseong Yeon and Leeju Kim and Youil Han and Hyeon Gyu Lee and Eunji Lee and Bryan Suk Joon Kim},
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* journal={Proceedings of the 21st International Middleware Conference},
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* year={2020},
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* url={https://api.semanticscholar.org/CorpusID:228086012}
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* }
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*/
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/*
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* Skiplist declarations.
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*/
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#ifndef SKIPLIST_MAX_HEIGHT
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#define SKIPLIST_MAX_HEIGHT 1
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#endif
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#define SKIPLIST_ENTRY(type) \
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struct __skiplist_entry { \
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struct __skiplist_idx { \
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struct type *prev, **next; \
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size_t cap, len; \
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} sle; \
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}
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/*
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* Skip List access methods.
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*/
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#define SKIP_FIRST(head) ((head)->slh_head)
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#define SKIP_LAST(head) ((head)->slh_tail)
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#define SKIP_NEXT(elm, field) ((elm)->field.sle.next[0])
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#define SKIP_PREV(elm, field) ((elm)->field.sle.prev)
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#define SKIP_EMPTY(head) ((head)->length == 0)
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/*
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* Skip List functions.
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*/
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#define SKIP_COMPARATOR(list, type, fn) \
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int __skip_cmp_##type(struct list *head, struct type *a, struct type *b, void *aux) \
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{ \
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if (a == b) \
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return 0; \
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if (a == (head)->slh_head || b == (head)->slh_tail) \
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return -1; \
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if (a == (head)->slh_tail || b == (head)->slh_head) \
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return 1; \
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fn \
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}
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#define SKIPLIST_DECL(decl, prefix, field, free_node_blk, update_node_blk, snap_node_blk, sizeof_entry_blk) \
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\
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/* Skiplist node type */ \
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typedef struct decl##_node decl##_node_t; \
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\
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/* Skiplist type */ \
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typedef struct decl { \
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size_t level, length, max; \
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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##_t; \
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\
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/* Snapshot of a Skiplist */ \
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typedef struct decl##_snap { \
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decl##_t list; \
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decl##_node_t *nodes; \
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size_t bytes; \
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} decl##_snap_t; \
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\
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/* Path taken to find an element in the Skiplist, path[0] is the match if \
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one exists */ \
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struct __##decl##_path { \
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size_t cap; \
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size_t len; \
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struct decl##_node **nodes; \
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}; \
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\
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typedef enum { SKIP_EQ = 0, SKIP_LTE = -1, SKIP_LT = -2, SKIP_GTE = 1, SKIP_GT = 2 } skip_pos_##decl_t; \
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\
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/* -- __skip_key_compare_ \
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* \
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* This function takes four arguments: \
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* - a reference to the Skiplist \
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* - the two nodes to compare, `a` and `b` \
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* - `aux` an additional auxiliary argument \
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* and returns: \
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* a < b : return -1 \
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* a == b : return 0 \
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* a > b : return 1 \
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*/ \
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static int __skip_key_compare_##decl(decl##_t *slist, decl##_node_t *a, decl##_node_t *b, void *aux) \
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{ \
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if (a == b) \
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return 0; \
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if (a == slist->slh_head || b == slist->slh_tail) \
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return -1; \
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if (a == slist->slh_tail || b == slist->slh_head) \
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return 1; \
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return slist->cmp(slist, a, b, aux); \
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} \
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\
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/* -- __skip_toss_ \
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* A "coin toss" function that is critical to the proper operation of the \
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* Skiplist. For example, when `max = 6` this function returns 0 with \
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* probability 0.5, 1 with 0.25, 2 with 0.125, etc. until 6 with 0.5^7. \
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*/ \
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static int __skip_toss_##decl(size_t max) \
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{ \
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size_t level = 0; \
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double probability = 0.5; \
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\
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double random_value = (double)rand() / RAND_MAX; /* NOLINT(*-msc50-cpp) */ \
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while (random_value < probability && level < max) { \
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level++; \
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probability *= 0.5; \
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} \
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return level; \
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} \
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\
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/* -- skip_alloc_node_ */ \
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int prefix##skip_alloc_node_##decl(decl##_t *slist, decl##_node_t **node) \
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{ \
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decl##_node_t *n; \
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/* Calculate the size of the struct sle within decl##_node_t, multiply \
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by array size. (16/24 bytes on 32/64 bit systems) */ \
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size_t sle_arr_sz = sizeof(struct __skiplist_idx) * slist->max; \
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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.cap = slist->max; \
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n->field.sle.len = 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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return 0; \
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} \
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\
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/* -- skip_init_ \
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* \
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*/ \
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int prefix##skip_init_##decl(decl##_t *slist, int max, int (*cmp)(struct decl *, decl##_node_t *, decl##_node_t *, void *)) \
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{ \
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int rc = 0; \
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size_t i; \
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\
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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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if (SKIPLIST_MAX_HEIGHT > 1 && slist->max > SKIPLIST_MAX_HEIGHT) \
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return -1; \
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slist->cmp = cmp; \
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rc = prefix##skip_alloc_node_##decl(slist, &slist->slh_head); \
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if (rc) \
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goto fail; \
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rc = prefix##skip_alloc_node_##decl(slist, &slist->slh_tail); \
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if (rc) \
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goto fail; \
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\
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slist->slh_head->field.sle.len = 0; \
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for (i = 0; i < slist->max; i++) \
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slist->slh_head->field.sle.next[i] = slist->slh_tail; \
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slist->slh_head->field.sle.prev = NULL; \
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\
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slist->slh_tail->field.sle.len = slist->max; \
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for (i = 0; i < slist->max; i++) \
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slist->slh_tail->field.sle.next[i] = NULL; \
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slist->slh_tail->field.sle.prev = slist->slh_head; \
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\
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/* NOTE: Here's a testing aid, simply set `max` to a negative number to \
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* seed the PRNG in a predictable way and have reproducible random numbers. \
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*/ \
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if (max < 0) \
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srand(-max); \
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else \
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srand(((unsigned int)time(NULL) ^ getpid())); \
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fail:; \
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return rc; \
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} \
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\
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/* -- skip_free_node_ */ \
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void prefix##skip_free_node_##decl(decl##_node_t *node) \
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{ \
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free_node_blk; \
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free(node); \
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||
} \
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||
\
|
||
/* -- skip_size_ */ \
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int prefix##skip_size_##decl(decl##_t *slist) \
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{ \
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return slist->length; \
|
||
} \
|
||
\
|
||
/* -- skip_empty_ */ \
|
||
int prefix##skip_empty_##decl(decl##_t *slist) \
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||
{ \
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||
return slist->length == 0; \
|
||
} \
|
||
\
|
||
/* -- skip_head_ */ \
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||
decl##_node_t *prefix##skip_head_##decl(decl##_t *slist) \
|
||
{ \
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||
return slist->slh_head->field.sle.next[0] == slist->slh_tail ? NULL : slist->slh_head->field.sle.next[0]; \
|
||
} \
|
||
\
|
||
/* -- skip_tail_ */ \
|
||
decl##_node_t *prefix##skip_tail_##decl(decl##_t *slist) \
|
||
{ \
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||
return slist->slh_tail->field.sle.prev == slist->slh_head->field.sle.next[0] ? NULL : slist->slh_tail->field.sle.prev; \
|
||
} \
|
||
\
|
||
/* -- __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->max + 1` \
|
||
*/ \
|
||
static size_t __skip_locate_##decl(decl##_t *slist, decl##_node_t *n, decl##_node_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.len; \
|
||
do { \
|
||
while (elm && __skip_key_compare_##decl(slist, elm->field.sle.next[i], n, slist->aux) < 0) \
|
||
elm = elm->field.sle.next[i]; \
|
||
path[i + 1] = elm; \
|
||
len++; \
|
||
} while (i--); \
|
||
elm = elm->field.sle.next[0]; \
|
||
if (__skip_key_compare_##decl(slist, elm, n, slist->aux) == 0) { \
|
||
path[0] = elm; \
|
||
} \
|
||
return len; \
|
||
} \
|
||
\
|
||
/* -- __skip_insert_ */ \
|
||
static int __skip_insert_##decl(decl##_t *slist, decl##_node_t *n, int flags) \
|
||
{ \
|
||
static decl##_node_t apath[SKIPLIST_MAX_HEIGHT + 1]; \
|
||
size_t i, len, level; \
|
||
decl##_node_t *node, **path = (decl##_node_t **)&apath; \
|
||
\
|
||
if (slist == NULL || n == NULL) \
|
||
return ENOENT; \
|
||
\
|
||
/* Allocate a buffer */ \
|
||
if (SKIPLIST_MAX_HEIGHT == 1) { \
|
||
path = malloc(sizeof(decl##_node_t *) * slist->max + 1); \
|
||
if (path == NULL) \
|
||
return ENOMEM; \
|
||
} \
|
||
\
|
||
len = __skip_locate_##decl(slist, n, path); \
|
||
node = path[0]; \
|
||
if (len > 0) { \
|
||
if ((node != NULL) && (flags == 0)) { \
|
||
/* Don't insert, duplicate flag not set. */ \
|
||
return -1; \
|
||
} \
|
||
level = __skip_toss_##decl(slist->max - 1); \
|
||
n->field.sle.len = level + 1; \
|
||
for (i = 0; i <= level; i++) { \
|
||
if (i <= slist->slh_head->field.sle.len) { \
|
||
n->field.sle.next[i] = path[i + 1]->field.sle.next[i]; \
|
||
path[i + 1]->field.sle.next[i] = n; \
|
||
} else { \
|
||
n->field.sle.next[i] = slist->slh_tail; \
|
||
} \
|
||
} \
|
||
n->field.sle.prev = path[1]; \
|
||
if (n->field.sle.next[0] == slist->slh_tail) { \
|
||
slist->slh_tail->field.sle.prev = n; \
|
||
} \
|
||
if (level > slist->slh_head->field.sle.len) { \
|
||
slist->slh_head->field.sle.len = level; \
|
||
slist->slh_tail->field.sle.len = level; \
|
||
} \
|
||
slist->length++; \
|
||
\
|
||
if (SKIPLIST_MAX_HEIGHT == 1) \
|
||
free(path); \
|
||
} \
|
||
return 0; \
|
||
} \
|
||
\
|
||
/* -- skip_insert_ */ \
|
||
int prefix##skip_insert_##decl(decl##_t *slist, decl##_node_t *n) \
|
||
{ \
|
||
return __skip_insert_##decl(slist, n, 0); \
|
||
} \
|
||
\
|
||
/* -- skip_insert_dup_ */ \
|
||
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. \
|
||
* \
|
||
* NOTE: This differs from _locate() in that it avoids an alloc/free \
|
||
* for the path when SKIPLIST_MAX_HEIGHT == 1. \
|
||
*/ \
|
||
decl##_node_t *prefix##skip_position_eq_##decl(decl##_t *slist, decl##_node_t *n) \
|
||
{ \
|
||
unsigned int i; \
|
||
decl##_node_t *elm = slist->slh_head; \
|
||
\
|
||
if (slist == NULL || n == NULL) \
|
||
return NULL; \
|
||
\
|
||
i = slist->slh_head->field.sle.len; \
|
||
\
|
||
do { \
|
||
while (elm && __skip_key_compare_##decl(slist, elm->field.sle.next[i], n, slist->aux) < 0) \
|
||
elm = elm->field.sle.next[i]; \
|
||
} while (i--); \
|
||
elm = elm->field.sle.next[0]; \
|
||
if (__skip_key_compare_##decl(slist, elm, n, slist->aux) == 0) { \
|
||
return elm; \
|
||
} \
|
||
return NULL; \
|
||
} \
|
||
\
|
||
/* -- 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. \
|
||
* \
|
||
* NOTE: This differs from _locate() in that it avoids an alloc/free \
|
||
* for the path when SKIPLIST_MAX_HEIGHT == 1. \
|
||
*/ \
|
||
decl##_node_t *prefix##skip_position_gte_##decl(decl##_t *slist, decl##_node_t *n) \
|
||
{ \
|
||
int cmp; \
|
||
unsigned int i; \
|
||
decl##_node_t *elm = slist->slh_head; \
|
||
\
|
||
if (slist == NULL || n == NULL) \
|
||
return NULL; \
|
||
\
|
||
i = slist->slh_head->field.sle.len; \
|
||
\
|
||
do { \
|
||
while (elm && __skip_key_compare_##decl(slist, elm->field.sle.next[i], n, slist->aux) < 0) \
|
||
elm = elm->field.sle.next[i]; \
|
||
} while (i--); \
|
||
do { \
|
||
elm = elm->field.sle.next[0]; \
|
||
cmp = __skip_key_compare_##decl(slist, elm, n, slist->aux); \
|
||
} while (cmp < 0); \
|
||
return elm; \
|
||
} \
|
||
\
|
||
/* -- skip_position_gt TODO \
|
||
* 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. \
|
||
* \
|
||
* NOTE: This differs from _locate() in that it avoids an alloc/free \
|
||
* for the path when SKIPLIST_MAX_HEIGHT == 1. \
|
||
*/ \
|
||
decl##_node_t *prefix##skip_position_gt_##decl(decl##_t *slist, decl##_node_t *n) \
|
||
{ \
|
||
int cmp; \
|
||
unsigned int i; \
|
||
decl##_node_t *elm = slist->slh_head; \
|
||
\
|
||
if (slist == NULL || n == NULL) \
|
||
return NULL; \
|
||
\
|
||
i = slist->slh_head->field.sle.len; \
|
||
\
|
||
do { \
|
||
while (elm && __skip_key_compare_##decl(slist, elm->field.sle.next[i], n, slist->aux) < 0) \
|
||
elm = elm->field.sle.next[i]; \
|
||
} while (i--); \
|
||
do { \
|
||
elm = elm->field.sle.next[0]; \
|
||
cmp = __skip_key_compare_##decl(slist, elm, n, slist->aux); \
|
||
} while (cmp < 0); \
|
||
return elm; \
|
||
} \
|
||
\
|
||
/* -- 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. \
|
||
* \
|
||
* NOTE: This differs from _locate() in that it avoids an alloc/free \
|
||
* for the path when SKIPLIST_MAX_HEIGHT == 1. \
|
||
*/ \
|
||
decl##_node_t *prefix##skip_position_lte_##decl(decl##_t *slist, decl##_node_t *n) \
|
||
{ \
|
||
int cmp; \
|
||
unsigned int i; \
|
||
decl##_node_t *elm = slist->slh_head; \
|
||
\
|
||
if (slist == NULL || n == NULL) \
|
||
return NULL; \
|
||
\
|
||
i = slist->slh_head->field.sle.len; \
|
||
\
|
||
do { \
|
||
while (elm && __skip_key_compare_##decl(slist, elm->field.sle.next[i], n, slist->aux) < 0) \
|
||
elm = elm->field.sle.next[i]; \
|
||
} while (i--); \
|
||
elm = elm->field.sle.next[0]; \
|
||
if (__skip_key_compare_##decl(slist, elm, n, slist->aux) == 0) { \
|
||
return elm; \
|
||
} else { \
|
||
do { \
|
||
elm = elm->field.sle.prev; \
|
||
cmp = __skip_key_compare_##decl(slist, elm, n, slist->aux); \
|
||
} while (cmp > 0); \
|
||
} \
|
||
return elm; \
|
||
} \
|
||
\
|
||
/* -- skip_position_lt TODO \
|
||
* 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. \
|
||
* \
|
||
* NOTE: This differs from _locate() in that it avoids an alloc/free \
|
||
* for the path when SKIPLIST_MAX_HEIGHT == 1. \
|
||
*/ \
|
||
decl##_node_t *prefix##skip_position_lt_##decl(decl##_t *slist, decl##_node_t *n) \
|
||
{ \
|
||
int cmp; \
|
||
unsigned int i; \
|
||
decl##_node_t *elm = slist->slh_head; \
|
||
\
|
||
if (slist == NULL || n == NULL) \
|
||
return NULL; \
|
||
\
|
||
i = slist->slh_head->field.sle.len; \
|
||
\
|
||
do { \
|
||
while (elm && __skip_key_compare_##decl(slist, elm->field.sle.next[i], n, slist->aux) < 0) \
|
||
elm = elm->field.sle.next[i]; \
|
||
} while (i--); \
|
||
elm = elm->field.sle.next[0]; \
|
||
if (__skip_key_compare_##decl(slist, elm, n, slist->aux) == 0) { \
|
||
return elm; \
|
||
} else { \
|
||
do { \
|
||
elm = elm->field.sle.prev; \
|
||
cmp = __skip_key_compare_##decl(slist, elm, n, slist->aux); \
|
||
} while (cmp > 0); \
|
||
} \
|
||
return elm; \
|
||
} \
|
||
\
|
||
/* -- skip_position_ \
|
||
* Position a cursor relative to `n`. \
|
||
* This avoids an alloc/free for the path when SKIPLIST_MAX_HEIGHT == 1. \
|
||
*/ \
|
||
decl##_node_t *prefix##skip_position_##decl(decl##_t *slist, skip_pos_##decl_t op, decl##_node_t *n) \
|
||
{ \
|
||
decl##_node_t *node; \
|
||
\
|
||
switch (op) { \
|
||
case (SKIP_LT): \
|
||
node = prefix##skip_position_lt_##decl(slist, n); \
|
||
break; \
|
||
case (SKIP_LTE): \
|
||
node = prefix##skip_position_lte_##decl(slist, n); \
|
||
break; \
|
||
case (SKIP_GTE): \
|
||
node = prefix##skip_position_gte_##decl(slist, n); \
|
||
break; \
|
||
case (SKIP_GT): \
|
||
node = prefix##skip_position_gt_##decl(slist, n); \
|
||
break; \
|
||
default: \
|
||
case (SKIP_EQ): \
|
||
node = prefix##skip_position_eq_##decl(slist, n); \
|
||
break; \
|
||
} \
|
||
return node; \
|
||
} \
|
||
\
|
||
/* -- skip_update_ \
|
||
* Locates a node in the list that equals the `new` node and then \
|
||
* uses the `update_node_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 *new) \
|
||
{ \
|
||
decl##_node_t *node; \
|
||
\
|
||
if (slist == NULL || new == NULL) \
|
||
return -1; \
|
||
\
|
||
node = prefix##skip_position_eq_##decl(slist, new); \
|
||
if (node) { \
|
||
update_node_blk; \
|
||
return 0; \
|
||
} \
|
||
return -1; \
|
||
} \
|
||
\
|
||
/* -- skip_remove_ */ \
|
||
int prefix##skip_remove_##decl(decl##_t *slist, decl##_node_t *n) \
|
||
{ \
|
||
static decl##_node_t apath[SKIPLIST_MAX_HEIGHT + 1]; \
|
||
size_t i, len, level; \
|
||
decl##_node_t *node, **path = (decl##_node_t **)&apath; \
|
||
\
|
||
if (slist == NULL || n == NULL) \
|
||
return -1; \
|
||
if (slist->length == 0) \
|
||
return 0; \
|
||
\
|
||
/* Allocate a buffer */ \
|
||
if (SKIPLIST_MAX_HEIGHT == 1) { \
|
||
path = malloc(sizeof(decl##_node_t *) * slist->max + 1); \
|
||
if (path == NULL) \
|
||
return ENOMEM; \
|
||
} \
|
||
\
|
||
len = __skip_locate_##decl(slist, n, path); \
|
||
node = path[0]; \
|
||
if (node) { \
|
||
node->field.sle.next[0]->field.sle.prev = node->field.sle.prev; \
|
||
for (i = 1; i <= len; i++) { \
|
||
if (path[i]->field.sle.next[i - 1] != node) \
|
||
break; \
|
||
path[i]->field.sle.next[i - 1] = node->field.sle.next[i - 1]; \
|
||
if (path[i]->field.sle.next[i - 1] == slist->slh_tail) { \
|
||
level = path[i]->field.sle.len; \
|
||
path[i]->field.sle.len = level - 1; \
|
||
} \
|
||
} \
|
||
if (SKIPLIST_MAX_HEIGHT == 1) \
|
||
free(path); \
|
||
free_node_blk; \
|
||
\
|
||
/* Find all levels in the first element in the list that point \
|
||
at the tail and shrink the level. */ \
|
||
i = 0; \
|
||
node = slist->slh_head; \
|
||
while (node->field.sle.next[i] != slist->slh_tail && i++ < slist->slh_head->field.sle.len) \
|
||
; \
|
||
slist->slh_head->field.sle.len = i; \
|
||
slist->slh_tail->field.sle.len = i; \
|
||
slist->length--; \
|
||
} \
|
||
return 0; \
|
||
} \
|
||
\
|
||
/* -- skip_next_node_ */ \
|
||
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_ */ \
|
||
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_destroy_ */ \
|
||
int prefix##skip_destroy_##decl(decl##_t *slist) \
|
||
{ \
|
||
decl##_node_t *node, *next; \
|
||
\
|
||
if (slist == NULL) \
|
||
return 0; \
|
||
if (prefix##skip_size_##decl(slist) == 0) \
|
||
return 0; \
|
||
node = prefix##skip_head_##decl(slist); \
|
||
do { \
|
||
next = prefix##skip_next_node_##decl(slist, node); \
|
||
prefix##skip_free_node_##decl(node); \
|
||
node = next; \
|
||
} while (node != NULL); \
|
||
\
|
||
free(slist->slh_head); \
|
||
free(slist->slh_tail); \
|
||
return 0; \
|
||
} \
|
||
\
|
||
/* -- skip_snapshot_ TODO/WIP \
|
||
* A snapshot is a read-only view of a Skiplist at a point in \
|
||
* time. Once taken, a snapshot must be restored or disposed. \
|
||
* Any number of snapshots can be created. \
|
||
* \
|
||
* NOTE: There are many fancy algorithms for this, for now \
|
||
* this implementation will simply create a copy of the nodes. \
|
||
*/ \
|
||
decl##_snap_t *prefix##skip_snapshot_##decl(decl##_t *slist) \
|
||
{ \
|
||
size_t bytes, i; \
|
||
decl##_snap_t *snap; \
|
||
decl##_node_t *node, *new; \
|
||
\
|
||
if (slist == NULL) \
|
||
return 0; \
|
||
\
|
||
bytes = sizeof(decl##_snap_t) + (slist->length * sizeof(decl##_node_t)); \
|
||
snap = (decl##_snap_t *)calloc(1, bytes); \
|
||
if (snap == NULL) \
|
||
return NULL; \
|
||
\
|
||
snap->bytes = bytes; \
|
||
snap->list.length = slist->length; \
|
||
snap->list.max = slist->max; \
|
||
snap->nodes = (decl##_node_t *)(snap + sizeof(decl##_snap_t)); \
|
||
\
|
||
i = 0; \
|
||
node = prefix##skip_head_##decl(slist); \
|
||
while (node) { \
|
||
decl##_node_t *n = (decl##_node_t *)snap->nodes + (i++ * sizeof(decl##_node_t)); \
|
||
new = (decl##_node_t *)&n; \
|
||
snap_node_blk; \
|
||
node = prefix##skip_next_node_##decl(slist, node); \
|
||
} \
|
||
return snap; \
|
||
} \
|
||
\
|
||
/* -- skip_restore_snapshot_ TODO/WIP */ \
|
||
decl##_t *prefix##skip_restore_snapshot_##decl(decl##_snap_t *snap, int (*cmp)(decl##_t * head, decl##_node_t * a, decl##_node_t * b, void *aux)) \
|
||
{ \
|
||
int rc; \
|
||
size_t i; \
|
||
decl##_t *slist; \
|
||
decl##_node_t *node, *new; \
|
||
\
|
||
if (snap == NULL || cmp == NULL) \
|
||
return 0; \
|
||
slist = (decl##_t *)calloc(1, sizeof(decl##_t)); \
|
||
if (slist == NULL) \
|
||
return NULL; \
|
||
\
|
||
slist->cmp = cmp; \
|
||
slist->max = snap->list.max; \
|
||
\
|
||
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.len = 0; \
|
||
for (i = 0; i < slist->max; i++) \
|
||
slist->slh_head->field.sle.next[i] = slist->slh_tail; \
|
||
slist->slh_head->field.sle.prev = NULL; \
|
||
\
|
||
slist->slh_tail->field.sle.len = slist->max; \
|
||
for (i = 0; i < slist->max; i++) \
|
||
slist->slh_tail->field.sle.next[i] = NULL; \
|
||
slist->slh_tail->field.sle.prev = slist->slh_head; \
|
||
\
|
||
i = 0; \
|
||
while (snap->list.length > 0) { \
|
||
decl##_node_t *n = (decl##_node_t *)snap->nodes + (i++ * sizeof(decl##_node_t)); \
|
||
node = (decl##_node_t *)&n; \
|
||
rc = prefix##skip_alloc_node_##decl(slist, &new); \
|
||
snap_node_blk; \
|
||
__skip_insert_##decl(slist, new, 1); \
|
||
snap->list.length--; \
|
||
} \
|
||
return slist; \
|
||
fail:; \
|
||
if (slist->slh_head) \
|
||
free(slist->slh_head); \
|
||
if (slist->slh_tail) \
|
||
free(slist->slh_tail); \
|
||
return NULL; \
|
||
} \
|
||
\
|
||
/* -- skip_dispose_snapshot_ TODO/WIP */ \
|
||
void prefix##skip_dispose_snapshot_##decl(decl##_snap_t *snap) \
|
||
{ \
|
||
decl##_node_t *node; \
|
||
\
|
||
node = (decl##_node_t *)snap->nodes; \
|
||
while (snap->list.length > 0) { \
|
||
free_node_blk; \
|
||
node += sizeof(decl##_node_t); \
|
||
snap->list.length--; \
|
||
} \
|
||
free(snap); \
|
||
} \
|
||
\
|
||
/* -- skip_serialize_ TODO/WIP \
|
||
* Similar to snapshot, but includes the values and encodes them \
|
||
* in a portable manner. \
|
||
*/ \
|
||
decl##_snap_t *prefix##skip_serialize_##decl(decl##_t *slist) \
|
||
{ \
|
||
size_t size, bytes, i; \
|
||
decl##_snap_t *snap; \
|
||
decl##_node_t *node, *new; \
|
||
\
|
||
if (slist == NULL) \
|
||
return 0; \
|
||
\
|
||
bytes = sizeof(decl##_snap_t) + (slist->length * sizeof(decl##_node_t)); \
|
||
node = prefix##skip_head_##decl(slist); \
|
||
while (node) { \
|
||
sizeof_entry_blk; \
|
||
bytes += sizeof(size_t); \
|
||
bytes += size; \
|
||
node = prefix##skip_next_node_##decl(slist, node); \
|
||
} \
|
||
snap = (decl##_snap_t *)calloc(1, bytes); \
|
||
if (snap == NULL) \
|
||
return NULL; \
|
||
\
|
||
snap->bytes = bytes; \
|
||
snap->list.length = slist->length; \
|
||
snap->list.max = slist->max; \
|
||
snap->nodes = (decl##_node_t *)(snap + sizeof(decl##_snap_t)); \
|
||
\
|
||
i = 0; \
|
||
node = prefix##skip_head_##decl(slist); \
|
||
while (node) { \
|
||
decl##_node_t *n = (decl##_node_t *)snap->nodes + (i++ * sizeof(decl##_node_t)); \
|
||
new = (decl##_node_t *)&n; \
|
||
snap_node_blk; \
|
||
node = prefix##skip_next_node_##decl(slist, node); \
|
||
} \
|
||
return snap; \
|
||
} \
|
||
\
|
||
/* -- skip_deserialize_snapshot_ TODO/WIP */ \
|
||
decl##_t *prefix##skip_deserialize_##decl(decl##_snap_t *snap, int (*cmp)(decl##_t * head, decl##_node_t * a, decl##_node_t * b, void *aux)) \
|
||
{ \
|
||
int rc; \
|
||
size_t i; \
|
||
decl##_t *slist; \
|
||
decl##_node_t *node, *new; \
|
||
\
|
||
if (snap == NULL || cmp == NULL) \
|
||
return 0; \
|
||
slist = (decl##_t *)calloc(1, sizeof(decl##_t)); \
|
||
if (slist == NULL) \
|
||
return NULL; \
|
||
\
|
||
slist->cmp = cmp; \
|
||
slist->max = snap->list.max; \
|
||
\
|
||
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.len = 0; \
|
||
for (i = 0; i < slist->max; i++) \
|
||
slist->slh_head->field.sle.next[i] = slist->slh_tail; \
|
||
slist->slh_head->field.sle.prev = NULL; \
|
||
\
|
||
slist->slh_tail->field.sle.len = slist->max; \
|
||
for (i = 0; i < slist->max; i++) \
|
||
slist->slh_tail->field.sle.next[i] = NULL; \
|
||
slist->slh_tail->field.sle.prev = slist->slh_head; \
|
||
\
|
||
i = 0; \
|
||
while (snap->list.length > 0) { \
|
||
decl##_node_t *n = (decl##_node_t *)snap->nodes + (i++ * sizeof(decl##_node_t)); \
|
||
node = (decl##_node_t *)&n; \
|
||
rc = prefix##skip_alloc_node_##decl(slist, &new); \
|
||
snap_node_blk; \
|
||
__skip_insert_##decl(slist, new, 1); \
|
||
snap->list.length--; \
|
||
} \
|
||
return slist; \
|
||
fail:; \
|
||
if (slist->slh_head) \
|
||
free(slist->slh_head); \
|
||
if (slist->slh_tail) \
|
||
free(slist->slh_tail); \
|
||
return NULL; \
|
||
} \
|
||
\
|
||
/* -- __skip_integrity_check_ TODO */ \
|
||
static int __skip_integrity_check_##decl(decl##_t *slist) \
|
||
{ \
|
||
((void)slist); \
|
||
return 0; \
|
||
}
|
||
|
||
#define SKIPLIST_KV_ACCESS(decl, prefix, ktype, vtype, qblk, rblk) \
|
||
vtype prefix##skip_get_##decl(decl##_t *slist, ktype key) \
|
||
{ \
|
||
decl##_node_t *node, query; \
|
||
\
|
||
qblk; \
|
||
node = prefix##skip_position_eq_##decl(slist, &query); \
|
||
if (node) { \
|
||
rblk; \
|
||
} \
|
||
return (vtype)0; \
|
||
} \
|
||
\
|
||
decl##_node_t *prefix##skip_pos_##decl(decl##_t *slist, skip_pos_##decl_t op, ktype key) \
|
||
{ \
|
||
decl##_node_t *node, query; \
|
||
\
|
||
qblk; \
|
||
node = prefix##skip_position_##decl(slist, op, &query); \
|
||
if (node != slist->slh_head && node != slist->slh_tail) \
|
||
return node; \
|
||
return NULL; \
|
||
} \
|
||
\
|
||
int prefix##skip_put_##decl(decl##_t *slist, ktype key, vtype value) \
|
||
{ \
|
||
int rc; \
|
||
decl##_node_t *node; \
|
||
rc = prefix##skip_alloc_node_##decl(slist, &node); \
|
||
if (rc) \
|
||
return rc; \
|
||
node->key = key; \
|
||
node->value = value; \
|
||
rc = prefix##skip_insert_##decl(slist, node); \
|
||
if (rc) \
|
||
prefix##skip_free_node_##decl(node); \
|
||
return rc; \
|
||
} \
|
||
\
|
||
int prefix##skip_set_##decl(decl##_t *slist, ktype key, vtype value) \
|
||
{ \
|
||
decl##_node_t node; \
|
||
node.key = key; \
|
||
node.value = value; \
|
||
return prefix##skip_update_##decl(slist, &node); \
|
||
} \
|
||
\
|
||
int prefix##skip_del_##decl(decl##_t *slist, ktype key) \
|
||
{ \
|
||
decl##_node_t node; \
|
||
node.key = key; \
|
||
return prefix##skip_remove_##decl(slist, &node); \
|
||
}
|
||
|
||
#define SKIPLIST_DECL_DOT(decl, prefix, field) \
|
||
\
|
||
/* A type for a function that writes into a char[2048] buffer \
|
||
* a description of the value within the node. */ \
|
||
typedef void (*skip_sprintf_node_##decl##_t)(decl##_node_t *, char *); \
|
||
\
|
||
/* -- __skip_dot_node_ \
|
||
* Writes out a fragment of a DOT file representing a node. \
|
||
*/ \
|
||
static void __skip_dot_node_##decl(FILE *os, decl##_t *slist, decl##_node_t *node, size_t nsg, skip_sprintf_node_##decl##_t fn) \
|
||
{ \
|
||
char buf[2048]; \
|
||
size_t level, height = node->field.sle.len; \
|
||
decl##_node_t *next; \
|
||
\
|
||
fprintf(os, "\"node%zu %p\"", nsg, (void *)node); \
|
||
fprintf(os, " [label = \""); \
|
||
level = height; \
|
||
while (level--) { \
|
||
fprintf(os, " { <w%zu> | <f%zu> %p } |", level, level, (void *)node->field.sle.next[level]); \
|
||
} \
|
||
if (fn) { \
|
||
fn(node, buf); \
|
||
fprintf(os, " <f0> %s\"\n", buf); \
|
||
} else { \
|
||
fprintf(os, " <f0> ?\"\n"); \
|
||
} \
|
||
fprintf(os, "shape = \"record\"\n"); \
|
||
fprintf(os, "];\n"); \
|
||
\
|
||
/* Now edges */ \
|
||
level = 0; \
|
||
for (level = 0; level < height; level++) { \
|
||
fprintf(os, "\"node%zu %p\"", nsg, (void *)node); \
|
||
fprintf(os, ":f%zu -> ", level); \
|
||
fprintf(os, "\"node%zu %p\"", nsg, (void *)node->field.sle.next[level]); \
|
||
fprintf(os, ":w%zu [];\n", level); \
|
||
} \
|
||
next = prefix##skip_next_node_##decl(slist, node); \
|
||
if (next) \
|
||
__skip_dot_node_##decl(os, slist, next, nsg, fn); \
|
||
} \
|
||
\
|
||
/* -- __skip_dot_finish_ \
|
||
* Finalize the DOT file of the internal representation. \
|
||
*/ \
|
||
static void __skip_dot_finish_##decl(FILE *os, size_t nsg) \
|
||
{ \
|
||
size_t i; \
|
||
if (nsg > 0) { \
|
||
/* Link the nodes together with an invisible node. \
|
||
* node0 [shape=record, label = "<f0> | <f1> | <f2> | <f3> | \
|
||
* <f4> | <f5> | <f6> | <f7> | <f8> | ", style=invis, width=0.01]; \
|
||
*/ \
|
||
fprintf(os, "node0 [shape=record, label = \""); \
|
||
for (i = 0; i < nsg; ++i) { \
|
||
fprintf(os, "<f%zu> | ", i); \
|
||
} \
|
||
fprintf(os, "\", style=invis, width=0.01];\n"); \
|
||
\
|
||
/* Now connect nodes with invisible edges \
|
||
* \
|
||
* node0:f0 -> HeadNode [style=invis]; \
|
||
* node0:f1 -> HeadNode1 [style=invis]; \
|
||
*/ \
|
||
for (i = 0; i < nsg; ++i) { \
|
||
fprintf(os, "node0:f%zu -> HeadNode%zu [style=invis];\n", i, i); \
|
||
} \
|
||
nsg = 0; \
|
||
} \
|
||
fprintf(os, "}\n"); \
|
||
} \
|
||
\
|
||
/* -- skip_dot_start_ */ \
|
||
static int __skip_dot_start_##decl(FILE *os, decl##_t *slist, size_t nsg, skip_sprintf_node_##decl##_t fn) \
|
||
{ \
|
||
size_t level; \
|
||
decl##_node_t *head, *tail; \
|
||
if (nsg == 0) { \
|
||
fprintf(os, "digraph Skiplist {\n"); \
|
||
fprintf(os, "label = \"Skiplist.\"\n"); \
|
||
fprintf(os, "graph [rankdir = \"LR\"];\n"); \
|
||
fprintf(os, "node [fontsize = \"12\" shape = \"ellipse\"];\n"); \
|
||
fprintf(os, "edge [];\n\n"); \
|
||
} \
|
||
fprintf(os, "subgraph cluster%zu {\n", nsg); \
|
||
fprintf(os, "style=dashed\n"); \
|
||
fprintf(os, "label=\"Skip list iteration %zu\"\n\n", nsg); \
|
||
fprintf(os, "\"HeadNode%zu\" [\n", nsg); \
|
||
fprintf(os, "label = \""); \
|
||
\
|
||
/* Write out the fields */ \
|
||
head = slist->slh_head; \
|
||
if (SKIP_EMPTY(slist)) \
|
||
fprintf(os, "Empty HeadNode"); \
|
||
else { \
|
||
level = head->field.sle.len - 1; \
|
||
do { \
|
||
decl##_node_t *node = head->field.sle.next[level]; \
|
||
fprintf(os, "{ <f%zu> %p }", level, (void *)node); \
|
||
if (level && head->field.sle.next[level] != slist->slh_tail) \
|
||
fprintf(os, " | "); \
|
||
} while (level-- && head->field.sle.next[level] != slist->slh_tail); \
|
||
} \
|
||
fprintf(os, "\"\n"); \
|
||
fprintf(os, "shape = \"record\"\n"); \
|
||
fprintf(os, "];\n"); \
|
||
\
|
||
/* Edges for head node */ \
|
||
decl##_node_t *node = slist->slh_head; \
|
||
for (level = 0; level < slist->slh_head->field.sle.len; level++) { \
|
||
if (node->field.sle.next[level] == slist->slh_tail) \
|
||
break; \
|
||
fprintf(os, "\"HeadNode%zu\":f%zu -> ", nsg, level); \
|
||
fprintf(os, "\"node%zu %p\"", nsg, (void *)node->field.sle.next[level]); \
|
||
fprintf(os, ":w%zu [];\n", level); \
|
||
} \
|
||
fprintf(os, "\n"); \
|
||
\
|
||
/* Now all nodes via level 0, if non-empty */ \
|
||
node = prefix##skip_head_##decl(slist); \
|
||
if (node) \
|
||
__skip_dot_node_##decl(os, slist, node, nsg, fn); \
|
||
fprintf(os, "\n"); \
|
||
\
|
||
/* The tail, sentinal node */ \
|
||
tail = slist->slh_tail; \
|
||
if (!SKIP_EMPTY(slist)) { \
|
||
fprintf(os, "\"node%zu %p\" [label = \"", nsg, (void *)slist->slh_tail); \
|
||
level = tail->field.sle.len - 1; \
|
||
do { \
|
||
fprintf(os, "<w%zu> %p", level, (void *)node->field.sle.prev); \
|
||
if (level && node->field.sle.prev != slist->slh_head) \
|
||
fprintf(os, " | "); \
|
||
} while (level-- && node->field.sle.prev != slist->slh_head); \
|
||
fprintf(os, "\" shape = \"record\"];\n"); \
|
||
} \
|
||
\
|
||
/* End: "subgraph cluster0 {" */ \
|
||
fprintf(os, "}\n\n"); \
|
||
nsg += 1; \
|
||
\
|
||
return nsg; \
|
||
} \
|
||
\
|
||
/* -- skip_dot_ \
|
||
* Create a DOT file of the internal representation of the \
|
||
* Skiplist on the provided file descriptor (default: STDOUT). \
|
||
* \
|
||
* To view the output: \
|
||
* $ dot -Tps filename.dot -o outfile.ps \
|
||
* You can change the output format by varying the value after -T and \
|
||
* choosing an appropriate filename extension after -o. \
|
||
* See: https://graphviz.org/docs/outputs/ for the format options. \
|
||
* \
|
||
* https://en.wikipedia.org/wiki/DOT_(graph_description_language) \
|
||
*/ \
|
||
int prefix##skip_dot_##decl(FILE *os, decl##_t *slist, size_t nsg, skip_sprintf_node_##decl##_t fn) \
|
||
{ \
|
||
if (__skip_integrity_check_##decl(slist) != 0) { \
|
||
perror("Skiplist failed integrity checks, impossible to diagram."); \
|
||
return -1; \
|
||
} \
|
||
if (os == NULL) \
|
||
os = stdout; \
|
||
if (!os) { \
|
||
perror("Failed to open output file, unable to write DOT file."); \
|
||
return -1; \
|
||
} \
|
||
__skip_dot_start_##decl(os, slist, nsg, fn); \
|
||
__skip_dot_finish_##decl(os, nsg); \
|
||
return 0; \
|
||
}
|
||
|
||
#endif /* _SKIPLIST_H_ */
|