1795 lines
234 KiB
C
1795 lines
234 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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* Skip List 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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#if defined(SKIPLIST_DEBUG)
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#ifndef SKIP_DEBUGF
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#define SKIP_DEBUGF
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#if defined(DEBUG) && DEBUG > 0
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#define __skip_debugf(...) \
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do { \
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fprintf(stderr, "%s:%d:%s(): ", __FILE__, __LINE__, __func__); \
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fprintf(stderr, __VA_ARGS__); \
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} while (0)
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#else
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#define __skip_debugf(fmt, args...) ((void)0)
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#endif
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#endif
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#endif
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/*
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* A Skip List contains elements, a portion of which is used to manage those
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* elements while the rest is defined by the use case for this declaration. The
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* house keeping portion is the SKIPLIST_ENTRY below. It maintains the array of
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* forward pointers to nodes and has a height (a zero-based count of levels, so
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* a height of `0` means one (1) level and a height of `4` means five (5)
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* levels).
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*/
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#define SKIPLIST_ENTRY(type) \
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struct __skiplist_##decl_entry { \
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struct type *sle_prev, **sle_next; \
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size_t sle_height, sle_gen; \
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}
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/*
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* Skip List node comparison function. This macro builds a function used when
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* comparing two nodes for equality. A portion of this function, `fn_blk`, is
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* the code you supply to compare two nodes as a block (starts with `{`, your
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* code, then `}`) that should compare the node referenced by `a` to the node
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* `b` as follows:
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*
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* When:
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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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* As stated earlier, 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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* Example for nodes with keys that are signed integeters (`int`):
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* {
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* (void)list;
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* (void)aux;
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* if (a->key < b->key)
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* return -1;
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* if (a->key > b->key)
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* return 1;
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* return 0;
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* }
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*
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* Note that the comparison function can also make use of the reference to the
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* list as well as a reference to a variable `aux` that you can point to
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* anything else required to perform your comparison. The auxiliary pointer
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* is unused for other purposes. You could even use it a pointer to a function
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* that chooses the proper comparison function for the two nodes in question.
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*
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* Example where the value of `decl` below is `ex`:
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* {
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* // Cast `aux` to a function that returns a function that properly compares
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* // `a` and `b`, for example if they were objects or different structs.
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* (skip_ex_cmp_t *(fn)(ex_node_t *, ex_node_t *)) =
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* (skip_ex_cmp_t *()(ex_node_t *, ex_node_t *))aux;
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*
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* // Use the `fn` pointed to by `aux` to get the comparison function.
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* skip_ex_cmp_t *cmp = fn(a, b);
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*
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* // Now call that function and return the proper result.
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* return cmp(list, a, b, aux);
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* }
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*/
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#define SKIP_COMPARATOR(list, decl, fn_blk) \
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int __skip_cmp_##decl(struct list *head, struct decl *a, struct decl *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_blk \
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}
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#define SKIPLIST_FOREACH_H2T(decl, prefix, list, elm, iter) \
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for (iter = 0, (elm) = prefix##skip_head_##decl(list); (elm) != NULL; iter++, (elm) = prefix##skip_next_node_##decl(list, elm))
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/* Iterate from tail to head over the nodes. */
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#define SKIPLIST_FOREACH_T2H(decl, prefix, list, elm, iter) \
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for (iter = prefix##skip_size_##decl(list), (elm) = prefix##skip_tailf_##decl(list); (elm) != NULL; \
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iter--, (elm) = prefix##skip_prev_node_##decl(list, elm))
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#define __SKIP_ENTRIES_T2B(field, elm) for (size_t lvl = elm->field.sle_height; lvl != (size_t)-1; lvl--)
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#define __SKIP_ENTRIES_T2B_FROM(field, elm, off) for (size_t lvl = off; lvl != (size_t)-1; lvl--)
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#define __SKIP_IS_LAST_ENTRY_T2B() if (lvl == 0)
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#define __SKIP_ENTRIES_B2T(field, elm) for (size_t lvl = 0; lvl < elm->field.sle_height + 1; lvl++)
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#define __SKIP_ENTRIES_B2T_FROM(field, elm, off) for (size_t lvl = off; lvl < elm->field.sle_height + 1; lvl++)
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#define __SKIP_IS_LAST_ENTRY_B2T() if (lvl + 1 == elm->field.sle_height)
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/*
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* Skip List declarations and access methods.
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*/
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#define SKIPLIST_DECL(decl, prefix, field, free_node_blk, update_node_blk, archive_node_blk, sizeof_entry_blk) \
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\
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/* Skip List node type */ \
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typedef struct decl##_node decl##_node_t; \
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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 slh_level, slh_length, slh_max, slh_gen; \
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int (*slh_cmp)(struct decl *, decl##_node_t *, decl##_node_t *, void *); \
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void *slh_aux; \
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decl##_node_t *slh_head; \
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decl##_node_t *slh_tail; \
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struct { \
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decl##_node_t *head; \
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decl##_node_t *tail; \
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size_t gen; \
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} slh_snap; \
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} decl##_t; \
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\
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/* Skip List comparison function type */ \
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typedef int (*skip_##decl##_cmp_t)(decl##_t *, decl##_node_t *, decl##_node_t *, void *); \
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\
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/* Used when positioning a cursor within a Skip List. */ \
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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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/** \
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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 Skip List \
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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 == NULL) \
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return -1; \
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if (b == NULL) \
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return 1; \
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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->slh_cmp(slist, a, b, aux); \
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} \
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\
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/** \
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* -- __skip_toss_ \
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* \
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* A "coin toss" function that is critical to the proper operation of the \
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* Skip List. 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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/** \
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* -- __skip_gen_ \
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* \
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* Returns the current generation for snapshot purposes. \
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*/ \
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static inline size_t __skip_gen_##decl(decl##_t *slist) \
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{ \
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return slist->slh_snap.gen; \
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} \
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\
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/** \
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* -- __skip_incr_gen_ \
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* \
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* Returns the current generation for snapshot purposes. \
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*/ \
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static inline size_t __skip_incr_gen_##decl(decl##_t *slist) \
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{ \
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return ++slist->slh_snap.gen; \
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} \
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\
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/** \
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* -- skip_alloc_node_ \
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* \
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* Allocates a new node on the heap and sets default values. \
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*/ \
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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_##decl_entry) * slist->slh_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_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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return 0; \
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} \
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\
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/** \
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* -- skip_init_ \
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* \
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* Initializes a Skip List to the deafault values, this must be called \
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* before using the list. \
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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->slh_length = 0; \
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slist->slh_max = (size_t)(max < 0 ? -max : max); \
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slist->slh_max = SKIPLIST_MAX_HEIGHT == 1 ? slist->slh_max : SKIPLIST_MAX_HEIGHT; \
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if (SKIPLIST_MAX_HEIGHT > 1 && slist->slh_max > SKIPLIST_MAX_HEIGHT) \
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return -1; \
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slist->slh_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_height = 0; \
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for (i = 0; i < slist->slh_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_height = slist->slh_max - 1; \
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for (i = 0; i < slist->slh_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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/** \
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* -- skip_free_node_ \
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* \
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|
* Properly releases heap memory allocated for use as a node. \
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|
* This function invokes the `free_node_blk` within which you \
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* should release any heap objects or other resources held by \
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|
* this node in the list. \
|
|
*/ \
|
|
void prefix##skip_free_node_##decl(decl##_node_t *node) \
|
|
{ \
|
|
free_node_blk; \
|
|
free(node); \
|
|
} \
|
|
\
|
|
/** \
|
|
* -- skip_size_ \
|
|
* \
|
|
* Returns the current size (length, count) of elements in the list. \
|
|
*/ \
|
|
int prefix##skip_size_##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_empty_ \
|
|
* \
|
|
* Release all nodes and their associated heap objects, but not the list \
|
|
* itself. The list is still valid, only empty. \
|
|
*/ \
|
|
void prefix##skip_empty_##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(node); \
|
|
node = next; \
|
|
} while (node != NULL); \
|
|
\
|
|
while (node) { \
|
|
next = node->field.sle_next[0]; \
|
|
if (next->field.sle_prev) \
|
|
free_node_blk; \
|
|
free(node); \
|
|
} \
|
|
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_size_##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_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 + 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_height; \
|
|
do { \
|
|
while (elm != slist->slh_tail && elm->field.sle_next[i] && __skip_key_compare_##decl(slist, elm->field.sle_next[i], n, slist->slh_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->slh_aux) == 0) { \
|
|
path[0] = elm; \
|
|
} \
|
|
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) \
|
|
{ \
|
|
int rc = 0; \
|
|
static decl##_node_t apath[SKIPLIST_MAX_HEIGHT + 1]; \
|
|
size_t i, len, loc = 0, cur_height, new_height; \
|
|
decl##_node_t *node, **path = (decl##_node_t **)&apath; \
|
|
\
|
|
if (slist == NULL || new == NULL) \
|
|
return ENOENT; \
|
|
\
|
|
/* Allocate a buffer, or use a static one. */ \
|
|
if (SKIPLIST_MAX_HEIGHT == 1) { \
|
|
path = malloc(sizeof(decl##_node_t *) * slist->slh_max + 1); \
|
|
if (path == NULL) \
|
|
return ENOMEM; \
|
|
} \
|
|
memset(path, 0, sizeof(decl##_node_t *) * slist->slh_max + 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]; \
|
|
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); \
|
|
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] = 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] != slist->slh_tail) { \
|
|
new->field.sle_next[i] = path[i + 1]->field.sle_next[i]; \
|
|
path[i + 1]->field.sle_next[i] = new; \
|
|
loc = path[i + 1] == 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] == 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]; \
|
|
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 this node's generation for snapshots. */ \
|
|
new->field.sle_gen = __skip_gen_##decl(slist); \
|
|
/* 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. \
|
|
* \
|
|
* 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_height; \
|
|
\
|
|
do { \
|
|
while (elm != slist->slh_tail && elm->field.sle_next[i] && __skip_key_compare_##decl(slist, elm->field.sle_next[i], n, slist->slh_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->slh_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 *query) \
|
|
{ \
|
|
int cmp; \
|
|
unsigned int i; \
|
|
decl##_node_t *elm = slist->slh_head; \
|
|
\
|
|
if (slist == NULL || query == NULL) \
|
|
return NULL; \
|
|
\
|
|
i = slist->slh_head->field.sle_height; \
|
|
\
|
|
do { \
|
|
while (elm != slist->slh_tail && elm->field.sle_next[i] && __skip_key_compare_##decl(slist, elm->field.sle_next[i], query, slist->slh_aux) < 0) \
|
|
elm = elm->field.sle_next[i]; \
|
|
} while (i--); \
|
|
do { \
|
|
elm = elm->field.sle_next[0]; \
|
|
cmp = __skip_key_compare_##decl(slist, elm, query, slist->slh_aux); \
|
|
} while (cmp < 0); \
|
|
return elm; \
|
|
} \
|
|
\
|
|
/** \
|
|
* -- 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. \
|
|
* \
|
|
* 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 *query) \
|
|
{ \
|
|
int cmp; \
|
|
unsigned int i; \
|
|
decl##_node_t *elm = slist->slh_head; \
|
|
\
|
|
if (slist == NULL || query == NULL) \
|
|
return NULL; \
|
|
\
|
|
i = slist->slh_head->field.sle_height; \
|
|
\
|
|
do { \
|
|
while (elm != slist->slh_tail && elm->field.sle_next[i] && __skip_key_compare_##decl(slist, elm->field.sle_next[i], query, slist->slh_aux) < 0) \
|
|
elm = elm->field.sle_next[i]; \
|
|
} while (i--); \
|
|
do { \
|
|
elm = elm->field.sle_next[0]; \
|
|
cmp = __skip_key_compare_##decl(slist, elm, query, slist->slh_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 *query) \
|
|
{ \
|
|
int cmp; \
|
|
unsigned int i; \
|
|
decl##_node_t *elm = slist->slh_head; \
|
|
\
|
|
if (slist == NULL || query == NULL) \
|
|
return NULL; \
|
|
\
|
|
i = slist->slh_head->field.sle_height; \
|
|
\
|
|
do { \
|
|
while (elm != slist->slh_tail && elm->field.sle_next[i] && __skip_key_compare_##decl(slist, elm->field.sle_next[i], query, slist->slh_aux) < 0) \
|
|
elm = elm->field.sle_next[i]; \
|
|
} while (i--); \
|
|
elm = elm->field.sle_next[0]; \
|
|
if (__skip_key_compare_##decl(slist, elm, query, slist->slh_aux) == 0) { \
|
|
return elm; \
|
|
} else { \
|
|
do { \
|
|
elm = elm->field.sle_prev; \
|
|
cmp = __skip_key_compare_##decl(slist, elm, query, slist->slh_aux); \
|
|
} while (cmp >= 0); \
|
|
} \
|
|
return elm; \
|
|
} \
|
|
\
|
|
/** \
|
|
* -- 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. \
|
|
* \
|
|
* 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 *query) \
|
|
{ \
|
|
int cmp; \
|
|
unsigned int i; \
|
|
decl##_node_t *elm = slist->slh_head; \
|
|
\
|
|
if (slist == NULL || query == NULL) \
|
|
return NULL; \
|
|
\
|
|
i = slist->slh_head->field.sle_height; \
|
|
\
|
|
do { \
|
|
while (elm != slist->slh_tail && elm->field.sle_next[i] && __skip_key_compare_##decl(slist, elm->field.sle_next[i], query, slist->slh_aux) < 0) \
|
|
elm = elm->field.sle_next[i]; \
|
|
} while (i--); \
|
|
elm = elm->field.sle_next[0]; \
|
|
do { \
|
|
elm = elm->field.sle_prev; \
|
|
cmp = __skip_key_compare_##decl(slist, elm, query, slist->slh_aux); \
|
|
} while (cmp >= 0); \
|
|
return elm; \
|
|
} \
|
|
\
|
|
/** \
|
|
* -- skip_position_ \
|
|
* \
|
|
* Position a cursor relative to `n`. \
|
|
* \
|
|
* 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_##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_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) \
|
|
{ \
|
|
static decl##_node_t apath[SKIPLIST_MAX_HEIGHT + 1]; \
|
|
int rc = 0; \
|
|
decl##_node_t *node, **path = (decl##_node_t **)&apath; \
|
|
\
|
|
if (slist == NULL) \
|
|
return -1; \
|
|
\
|
|
/* Allocate a buffer, or use a static one. */ \
|
|
if (SKIPLIST_MAX_HEIGHT == 1) { \
|
|
path = malloc(sizeof(decl##_node_t *) * slist->slh_max + 1); \
|
|
if (path == NULL) \
|
|
return ENOMEM; \
|
|
} \
|
|
memset(path, 0, sizeof(decl##_node_t *) * slist->slh_max + 1); \
|
|
\
|
|
__skip_locate_##decl(slist, new, path); \
|
|
node = path[0]; \
|
|
\
|
|
if (SKIPLIST_MAX_HEIGHT == 1) \
|
|
free(path); \
|
|
\
|
|
if (node) { \
|
|
decl##_node_t *src = node, *dest = new; \
|
|
update_node_blk; \
|
|
node->field.sle_gen = __skip_gen_##decl(slist); \
|
|
return rc; \
|
|
} \
|
|
return -1; \
|
|
} \
|
|
\
|
|
/** \
|
|
* -- skip_remove_node_ \
|
|
* \
|
|
* Removes the node `n` from the `slist` if present. \
|
|
*/ \
|
|
int prefix##skip_remove_node_##decl(decl##_t *slist, decl##_node_t *n) \
|
|
{ \
|
|
size_t i, len, height; \
|
|
static decl##_node_t apath[SKIPLIST_MAX_HEIGHT + 1]; \
|
|
decl##_node_t *node, **path = (decl##_node_t **)&apath; \
|
|
\
|
|
if (slist == NULL || n == NULL) \
|
|
return -1; \
|
|
if (slist->slh_length == 0) \
|
|
return 0; \
|
|
\
|
|
/* Allocate a buffer */ \
|
|
if (SKIPLIST_MAX_HEIGHT == 1) { \
|
|
path = malloc(sizeof(decl##_node_t *) * slist->slh_max + 1); \
|
|
if (path == NULL) \
|
|
return ENOMEM; \
|
|
} \
|
|
memset(path, 0, sizeof(decl##_node_t *) * slist->slh_max + 1); \
|
|
\
|
|
/* Attempt to locate the node in the list. */ \
|
|
len = __skip_locate_##decl(slist, n, path); \
|
|
node = path[0]; \
|
|
if (node) { \
|
|
/* 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]->field.sle_next[i] != node) \
|
|
break; \
|
|
/* ... adjust the next pointer at that level. */ \
|
|
path[i + 1]->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]->field.sle_next[i] == slist->slh_tail) { \
|
|
height = path[i + 1]->field.sle_height; \
|
|
path[i + 1]->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 = n->field.sle_prev; \
|
|
} \
|
|
\
|
|
if (SKIPLIST_MAX_HEIGHT == 1) \
|
|
free(path); \
|
|
\
|
|
free_node_blk; \
|
|
\
|
|
/* Reduce the height of the header. */ \
|
|
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--; \
|
|
} \
|
|
return 0; \
|
|
} \
|
|
\
|
|
/** \
|
|
* -- skip_destroy_ \
|
|
* \
|
|
* 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_destroy_##decl(decl##_t *slist) \
|
|
{ \
|
|
if (slist == NULL) \
|
|
return; \
|
|
\
|
|
prefix##skip_empty_##decl(slist); \
|
|
\
|
|
free(slist->slh_head); \
|
|
free(slist->slh_tail); \
|
|
return; \
|
|
} \
|
|
\
|
|
/** \
|
|
* -- skip_snap_head_ \
|
|
* \
|
|
* Returns the node containing the first (smallest) element in the \
|
|
* snapshot which can be used to traverse the list. \
|
|
*/ \
|
|
decl##_node_t *prefix##skip_snap_head_##decl(decl##_t *slist) \
|
|
{ \
|
|
return slist->slh_snap.head->field.sle_next[0] == slist->slh_snap.tail ? NULL : slist->slh_snap.head->field.sle_next[0]; \
|
|
} \
|
|
\
|
|
/** \
|
|
* -- skip_snap_tail_ \
|
|
* \
|
|
* Returns the node containing the last (largest) element in the \
|
|
* snapshot which can be used to traverse the list. \
|
|
*/ \
|
|
decl##_node_t *prefix##skip_snap_tail_##decl(decl##_t *slist) \
|
|
{ \
|
|
return slist->slh_snap.tail->field.sle_prev == slist->slh_snap.head->field.sle_next[0] ? NULL : slist->slh_snap.tail->field.sle_prev; \
|
|
} \
|
|
\
|
|
/** \
|
|
* -- skip_release_snapshot_ \
|
|
* \
|
|
* ALGORITHM: \
|
|
* A snapshot starts with a copy of the head and the tail of the list. \
|
|
* Those can be free'd here as our last step. We record a generation, which \
|
|
* is a monatomically growing unsigned int, at the time of the snapshot, \
|
|
* nodes inserted or mutated have there generation updated. To find the \
|
|
* nodes in the list that are only referenced by the snapshot we can perform \
|
|
* a "mergesort" like traversal of both the snapshot and the live list. For \
|
|
* each node, if the keys match and the nodes are not equal (same address in \
|
|
* memory) and we've reached a node greater than the snap node then we can \
|
|
* free the node in the snap. Duplicates complicate this a bit. \
|
|
*/ \
|
|
void prefix##skip_release_snapshot_##decl(decl##_t *slist) \
|
|
{ \
|
|
int cmp; \
|
|
size_t nth, cnt = 0; \
|
|
decl##_node_t *sn, *ln, *node, *next; \
|
|
\
|
|
if (slist == NULL) \
|
|
return; \
|
|
\
|
|
sn = prefix##skip_snap_head_##decl(slist); \
|
|
SKIPLIST_FOREACH_H2T(decl, prefix, slist, ln, nth) \
|
|
{ \
|
|
goto top_of_loop; \
|
|
sn_forward_only:; \
|
|
sn = sn->field.sle_next[0]; \
|
|
if (sn == slist->slh_snap.tail) \
|
|
break; \
|
|
top_of_loop:; \
|
|
/* When a node is referenced by both, keep going. */ \
|
|
if (ln == sn) \
|
|
goto both_sn_and_ln_forward; \
|
|
\
|
|
cmp = slist->slh_cmp(slist, sn, ln, slist->slh_aux); \
|
|
/* When the `sn` > the `ln`, move forward `ln` only. */ \
|
|
if (cmp > 0) \
|
|
goto ln_forward_only; \
|
|
/* When the `sn` < the `ln`, move both forward. */ \
|
|
if (cmp < 0) { \
|
|
sn = sn->field.sle_next[0]; \
|
|
if (sn == slist->slh_snap.tail) \
|
|
break; \
|
|
goto sn_forward_only; \
|
|
} \
|
|
/* When nodes match but have different addresses... */ \
|
|
if (cmp == 0) { \
|
|
/* ... we could have: \
|
|
a) a duplicate, or \
|
|
b) a copied a node, but not it's value, because it was \
|
|
adjacent to some mutated node (it was in the `path[]` \
|
|
during an insert, update, or delete), or \
|
|
c) ...? \
|
|
*/ \
|
|
cnt++; \
|
|
} \
|
|
/* ln forward only */ \
|
|
goto ln_forward_only; \
|
|
\
|
|
ln_forward_only:; \
|
|
continue; \
|
|
both_sn_and_ln_forward:; \
|
|
sn = sn->field.sle_next[0]; \
|
|
if (sn == slist->slh_snap.tail) \
|
|
break; \
|
|
} \
|
|
/* If `sn` isn't at tail then there are a few more nodes to release. */ \
|
|
while (sn != slist->slh_snap.tail) { \
|
|
node = sn; \
|
|
free_node_blk; \
|
|
next = sn->field.sle_next[0]; \
|
|
free(sn); \
|
|
sn = next; \
|
|
} \
|
|
} \
|
|
\
|
|
/** \
|
|
* -- __skip_preserve_node_ \
|
|
* \
|
|
* Preserve given node in the slh_pres list. \
|
|
*/ \
|
|
static int __skip_preserve_node_##decl(decl##_t *slist, const decl##_node_t *src, decl##_node_t **preserved) \
|
|
{ \
|
|
int rc = 0; \
|
|
decl##_node_t *dest; \
|
|
\
|
|
if (slist == NULL || src == NULL) \
|
|
return 0; \
|
|
\
|
|
/* (a) alloc */ \
|
|
rc = prefix##skip_alloc_node_##decl(slist, &dest); \
|
|
if (rc) \
|
|
return rc; \
|
|
\
|
|
/* (b) shallow copy */ \
|
|
memcpy(dest, src, sizeof(decl##_node_t)); \
|
|
\
|
|
if (!(src == slist->slh_head || src == slist->slh_tail)) { \
|
|
/* (d) deep copy */ \
|
|
archive_node_blk; \
|
|
if (rc) { \
|
|
prefix##skip_free_node_##decl(dest); \
|
|
return rc; \
|
|
} \
|
|
} \
|
|
\
|
|
*preserved = dest; \
|
|
\
|
|
return rc; \
|
|
} \
|
|
\
|
|
/** \
|
|
* -- skip_restore_snapshot_ TODO/WIP \
|
|
* \
|
|
* Restores the Skiplist to the snapshot. \
|
|
*/ \
|
|
decl##_t *prefix##skip_restore_snapshot_##decl(decl##_t *slist) \
|
|
{ \
|
|
((void)slist); \
|
|
return NULL; \
|
|
} \
|
|
\
|
|
/** \
|
|
* -- skip_snapshot_ \
|
|
* \
|
|
* A snapshot is a read-only view of a Skip List at a point in time. Once \
|
|
* taken, a snapshot must be restored or released. Any number of snapshots \
|
|
* can be created. \
|
|
*/ \
|
|
size_t prefix##skip_snapshot_##decl(decl##_t *slist) \
|
|
{ \
|
|
int rc; \
|
|
decl##_node_t *head, *tail; \
|
|
\
|
|
if (slist == NULL) \
|
|
return 0; \
|
|
/* (a) preserve the head node */ \
|
|
rc = __skip_preserve_node_##decl(slist, slist->slh_head, &head); \
|
|
if (rc > 0) \
|
|
return rc; \
|
|
/* (b) preserve the tail node */ \
|
|
rc = __skip_preserve_node_##decl(slist, slist->slh_tail, &tail); \
|
|
if (rc > 0) { \
|
|
prefix##skip_free_node_##decl(head); \
|
|
return rc; \
|
|
} \
|
|
/* (c) update any references in the new head's next[] array to point to \
|
|
the new tail; update the prev field in the new tail to the new head \
|
|
for similar reasons. */ \
|
|
__SKIP_ENTRIES_B2T(field, head) \
|
|
{ \
|
|
if (head->field.sle_next[lvl] == slist->slh_tail) \
|
|
head->field.sle_next[lvl] = tail; \
|
|
} \
|
|
if (tail->field.sle_prev == slist->slh_head) \
|
|
tail->field.sle_prev = head; \
|
|
/* (d) release previous snapshot, assign the new one */ \
|
|
if (slist->slh_snap.head != NULL) \
|
|
prefix##skip_release_snapshot_##decl(slist); \
|
|
slist->slh_snap.head = head; \
|
|
slist->slh_snap.tail = tail; \
|
|
slist->slh_snap.gen = __skip_incr_gen_##decl(slist); \
|
|
return slist->slh_gen; \
|
|
}
|
|
|
|
#define SKIPLIST_INTEGRITY_CHECK(decl, prefix, field) \
|
|
/** \
|
|
* -- __skip_integrity_failure_ \
|
|
*/ \
|
|
static void __attribute__((format(printf, 1, 2))) __skip_integrity_failure_##decl(const char *fmt, ...) \
|
|
{ \
|
|
va_list args; \
|
|
__skip_debugf(fmt, args); \
|
|
} \
|
|
\
|
|
/** \
|
|
* -- __skip_integrity_check_ \
|
|
*/ \
|
|
static int __skip_integrity_check_##decl(decl##_t *slist, int flags) \
|
|
{ \
|
|
size_t n = 0; \
|
|
unsigned long nth, n_err = 0; \
|
|
decl##_node_t *node, *prev, *next; \
|
|
struct __skiplist_##decl_entry *this; \
|
|
\
|
|
if (slist == NULL) { \
|
|
__skip_integrity_failure_##decl("slist was NULL, nothing to check\n"); \
|
|
n_err++; \
|
|
return n_err; \
|
|
} \
|
|
\
|
|
/* Check the Skiplist header (slh) */ \
|
|
\
|
|
if (slist->slh_head == NULL) { \
|
|
__skip_integrity_failure_##decl("skiplist slh_head is NULL\n"); \
|
|
n_err++; \
|
|
return n_err; \
|
|
} \
|
|
\
|
|
if (slist->slh_tail == NULL) { \
|
|
__skip_integrity_failure_##decl("skiplist slh_tail is NULL\n"); \
|
|
n_err++; \
|
|
return n_err; \
|
|
} \
|
|
\
|
|
if (slist->slh_cmp == NULL) { \
|
|
__skip_integrity_failure_##decl("skiplist comparison function (cmp) is NULL\n"); \
|
|
n_err++; \
|
|
return n_err; \
|
|
} \
|
|
\
|
|
if (slist->slh_max < 1) { \
|
|
__skip_integrity_failure_##decl("skiplist max level must be 1 at minimum\n"); \
|
|
n_err++; \
|
|
if (flags) \
|
|
return n_err; \
|
|
} \
|
|
\
|
|
if (slist->slh_level >= slist->slh_max) { \
|
|
/* level is 0-based, max of 12 means level cannot be > 11 */ \
|
|
__skip_integrity_failure_##decl("skiplist level %lu in header was >= max %lu\n", slist->slh_level, slist->slh_max); \
|
|
n_err++; \
|
|
if (flags) \
|
|
return n_err; \
|
|
} \
|
|
\
|
|
if (SKIPLIST_MAX_HEIGHT < 1) { \
|
|
__skip_integrity_failure_##decl("SKIPLIST_MAX_HEIGHT cannot be less than 1\n"); \
|
|
n_err++; \
|
|
if (flags) \
|
|
return n_err; \
|
|
} \
|
|
\
|
|
if (SKIPLIST_MAX_HEIGHT > 1 && slist->slh_max > SKIPLIST_MAX_HEIGHT) { \
|
|
__skip_integrity_failure_##decl("slist->slh_max %lu cannot be greater than SKIPLIST_MAX_HEIGHT %lu\n", slist->slh_max, \
|
|
(size_t)SKIPLIST_MAX_HEIGHT); \
|
|
n_err++; \
|
|
if (flags) \
|
|
return n_err; \
|
|
} \
|
|
\
|
|
node = slist->slh_head; \
|
|
__SKIP_ENTRIES_B2T(field, node) \
|
|
{ \
|
|
if (node->field.sle_next[lvl] == 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) \
|
|
break; \
|
|
} \
|
|
n++; \
|
|
__SKIP_ENTRIES_B2T_FROM(field, node, n) \
|
|
{ \
|
|
if (node->field.sle_next[lvl] == 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) { \
|
|
__skip_integrity_failure_##decl("after internal nodes, the head's %lu next node should always be the tail\n", lvl); \
|
|
n_err++; \
|
|
if (flags) \
|
|
return n_err; \
|
|
} \
|
|
} \
|
|
\
|
|
if (slist->slh_length > 0 && slist->slh_tail->field.sle_prev == slist->slh_head) { \
|
|
__skip_integrity_failure_##decl("slist->slh_length is 0, but tail->prev == head, not an internal node\n"); \
|
|
n_err++; \
|
|
if (flags) \
|
|
return n_err; \
|
|
} \
|
|
\
|
|
/* Validate the head node */ \
|
|
\
|
|
/* Validate the tail node */ \
|
|
\
|
|
/* Validate each node */ \
|
|
SKIPLIST_FOREACH_H2T(decl, prefix, slist, node, nth) \
|
|
{ \
|
|
this = &node->field; \
|
|
\
|
|
if (this->sle_height >= slist->slh_max) { \
|
|
__skip_integrity_failure_##decl("the %luth node's [%p] height %lu is >= max %lu\n", nth, (void *)node, this->sle_height, slist->slh_max); \
|
|
n_err++; \
|
|
if (flags) \
|
|
return n_err; \
|
|
} \
|
|
\
|
|
if (this->sle_next == NULL) { \
|
|
__skip_integrity_failure_##decl("the %luth node's [%p] next field should never NULL\n", nth, (void *)node); \
|
|
n_err++; \
|
|
if (flags) \
|
|
return n_err; \
|
|
} \
|
|
\
|
|
if (this->sle_prev == NULL) { \
|
|
__skip_integrity_failure_##decl("the %luth node [%p] prev field should never NULL\n", nth, (void *)node); \
|
|
n_err++; \
|
|
if (flags) \
|
|
return n_err; \
|
|
} \
|
|
\
|
|
__SKIP_ENTRIES_B2T(field, node) \
|
|
{ \
|
|
if (this->sle_next[lvl] == NULL) { \
|
|
__skip_integrity_failure_##decl("the %luth 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) \
|
|
break; \
|
|
} \
|
|
n++; \
|
|
__SKIP_ENTRIES_B2T_FROM(field, node, n) \
|
|
{ \
|
|
if (this->sle_next[lvl] == NULL) { \
|
|
__skip_integrity_failure_##decl("after the %lunth the %luth 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) { \
|
|
__skip_integrity_failure_##decl("after the %lunth the %luth node's next[%lu] should point to the tail\n", n, nth, lvl); \
|
|
n_err++; \
|
|
if (flags) \
|
|
return n_err; \
|
|
} \
|
|
} \
|
|
\
|
|
decl##_node_t *a = (decl##_node_t *)(uintptr_t)this->sle_next; \
|
|
decl##_node_t *b = (decl##_node_t *)(intptr_t)((uintptr_t)node + sizeof(decl##_node_t)); \
|
|
if (a != b) { \
|
|
__skip_integrity_failure_##decl("the %luth node's [%p] next field isn't at the proper offset relative to the node\n", nth, (void *)node); \
|
|
n_err++; \
|
|
if (flags) \
|
|
return n_err; \
|
|
} \
|
|
\
|
|
next = this->sle_next[0]; \
|
|
prev = this->sle_prev; \
|
|
if (__skip_key_compare_##decl(slist, node, node, slist->slh_aux) != 0) { \
|
|
__skip_integrity_failure_##decl("the %luth node [%p] is not equal to itself\n", nth, (void *)node); \
|
|
n_err++; \
|
|
if (flags) \
|
|
return n_err; \
|
|
} \
|
|
\
|
|
if (__skip_key_compare_##decl(slist, node, prev, slist->slh_aux) < 0) { \
|
|
__skip_integrity_failure_##decl("the %luth node [%p] is not greater than the prev node [%p]\n", nth, (void *)node, (void *)prev); \
|
|
n_err++; \
|
|
if (flags) \
|
|
return n_err; \
|
|
} \
|
|
\
|
|
if (__skip_key_compare_##decl(slist, node, next, slist->slh_aux) > 0) { \
|
|
__skip_integrity_failure_##decl("the %luth node [%p] is not less than the next node [%p]\n", nth, (void *)node, (void *)next); \
|
|
n_err++; \
|
|
if (flags) \
|
|
return n_err; \
|
|
} \
|
|
\
|
|
if (__skip_key_compare_##decl(slist, prev, node, slist->slh_aux) > 0) { \
|
|
__skip_integrity_failure_##decl("the prev node [%p] is not less than the %luth node [%p]\n", (void *)prev, nth, (void *)node); \
|
|
n_err++; \
|
|
if (flags) \
|
|
return n_err; \
|
|
} \
|
|
\
|
|
if (__skip_key_compare_##decl(slist, next, node, slist->slh_aux) < 0) { \
|
|
__skip_integrity_failure_##decl("the next node [%p] is not greater than the %luth node [%p]\n", (void *)next, nth, (void *)node); \
|
|
n_err++; \
|
|
if (flags) \
|
|
return n_err; \
|
|
} \
|
|
} \
|
|
\
|
|
if (slist->slh_length != nth) { \
|
|
__skip_integrity_failure_slex("slist->slh_length (%lu) doesn't match the count (%lu) of nodes between the head and tail\n", slist->slh_length, \
|
|
nth); \
|
|
n_err++; \
|
|
if (flags) \
|
|
return n_err; \
|
|
} \
|
|
\
|
|
return 0; \
|
|
}
|
|
|
|
#define SKIPLIST_KV_ACCESS(decl, prefix, key, ktype, value, vtype, qblk, rblk) \
|
|
/** \
|
|
* skip_get_ -- \
|
|
* \
|
|
* Get the value for the given key. In the presence of duplicate keys this \
|
|
* returns the value from the first duplicate. \
|
|
*/ \
|
|
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; \
|
|
} \
|
|
\
|
|
/** \
|
|
* skip_contains_ -- \
|
|
* \
|
|
* Returns true if there is at least one match for the `key` in the list. \
|
|
*/ \
|
|
int prefix##skip_contains_##decl(decl##_t *slist, ktype key) \
|
|
{ \
|
|
decl##_node_t *node, query; \
|
|
\
|
|
qblk; \
|
|
node = prefix##skip_position_eq_##decl(slist, &query); \
|
|
if (node) \
|
|
return 1; \
|
|
return 0; \
|
|
} \
|
|
\
|
|
/** \
|
|
* skip_pos_ -- \
|
|
* \
|
|
* Position a "cursor" (get a "node") from the list that satisfies the \
|
|
* condition (`op`) or return NULL if the condition cannot be satisfied. \
|
|
* The condition is a skip_pos_##decl_t enum type: \
|
|
* \
|
|
* SKIP_GT -> greater than \
|
|
* SKIP_GTE -> greater than or equal to \
|
|
* SKIP_EQ -> equal to \
|
|
* SKIP_LTE -> less than or equal to \
|
|
* SKIP_LT -> less than \
|
|
* \
|
|
*/ \
|
|
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; \
|
|
} \
|
|
\
|
|
/** \
|
|
* skip_put_ -- \
|
|
* \
|
|
* Inserts `key` into the list within a node that contains `value`. \
|
|
*/ \
|
|
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; \
|
|
} \
|
|
\
|
|
/** \
|
|
* skip_dup_ -- \
|
|
* \
|
|
* Inserts `key` into the list allowing for duplicates within a node that \
|
|
* contains `value`. \
|
|
*/ \
|
|
int prefix##skip_dup_##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_dup_##decl(slist, node); \
|
|
if (rc) \
|
|
prefix##skip_free_node_##decl(node); \
|
|
return rc; \
|
|
} \
|
|
\
|
|
/** \
|
|
* skip_set_ -- \
|
|
* \
|
|
* Updates in-place the node to contain the new `value`. In the presence of \
|
|
* duplicate keys in the list, the first key's value will be updated. \
|
|
*/ \
|
|
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); \
|
|
} \
|
|
\
|
|
/** \
|
|
* skip_del_ -- \
|
|
* \
|
|
* Removes the node from the list with a matching `key`. In the presence of \
|
|
* duplicate keys in the list, this will remove the first duplicate. \
|
|
*/ \
|
|
int prefix##skip_del_##decl(decl##_t *slist, ktype key) \
|
|
{ \
|
|
decl##_node_t node; \
|
|
node.key = key; \
|
|
return prefix##skip_remove_node_##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 size_t __skip_dot_width_##decl(decl##_t *slist, decl##_node_t *from, decl##_node_t *to) \
|
|
{ \
|
|
size_t w = 1; \
|
|
decl##_node_t *n = to; \
|
|
\
|
|
if (from == NULL || to == NULL) \
|
|
return 0; \
|
|
\
|
|
while (n->field.sle_prev != from) { \
|
|
w++; \
|
|
n = prefix##skip_prev_node_##decl(slist, n); \
|
|
} \
|
|
\
|
|
return w; \
|
|
} \
|
|
\
|
|
static inline void __skip_dot_write_node_##decl(FILE *os, size_t nsg, decl##_node_t *node) \
|
|
{ \
|
|
if (node) \
|
|
fprintf(os, "\"node%lu %p\"", nsg, (void *)node); \
|
|
else \
|
|
fprintf(os, "\"node%lu NULL\"", nsg); \
|
|
} \
|
|
\
|
|
/* -- __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 width; \
|
|
decl##_node_t *next; \
|
|
\
|
|
__skip_dot_write_node_##decl(os, nsg, node); \
|
|
fprintf(os, " [label = \""); \
|
|
fflush(os); \
|
|
__SKIP_ENTRIES_T2B(field, node) \
|
|
{ \
|
|
next = (node->field.sle_next[lvl] == slist->slh_tail) ? NULL : node->field.sle_next[lvl]; \
|
|
width = __skip_dot_width_##decl(slist, node, next ? next : slist->slh_tail); \
|
|
fprintf(os, " { <w%lu> %lu | <f%lu> ", lvl, width, lvl); \
|
|
if (next) \
|
|
fprintf(os, "%p } |", (void *)next); \
|
|
else \
|
|
fprintf(os, "0x0 } |"); \
|
|
fflush(os); \
|
|
} \
|
|
if (fn) { \
|
|
fn(node, buf); \
|
|
fprintf(os, " <f0> \u219F %lu \u226B %s \"\n", node->field.sle_height + 1, buf); \
|
|
} else { \
|
|
fprintf(os, " <f0> \u219F %lu \"\n", node->field.sle_height); \
|
|
} \
|
|
fprintf(os, "shape = \"record\"\n"); \
|
|
fprintf(os, "];\n"); \
|
|
fflush(os); \
|
|
\
|
|
/* Now edges */ \
|
|
__SKIP_ENTRIES_B2T(field, node) \
|
|
{ \
|
|
next = (node->field.sle_next[lvl] == slist->slh_tail) ? NULL : node->field.sle_next[lvl]; \
|
|
__skip_dot_write_node_##decl(os, nsg, node); \
|
|
fprintf(os, ":f%lu -> ", lvl); \
|
|
__skip_dot_write_node_##decl(os, nsg, next); \
|
|
fprintf(os, ":w%lu [];\n", lvl); \
|
|
fflush(os); \
|
|
} \
|
|
} \
|
|
\
|
|
/* -- _skip_dot_finish_ \
|
|
* Finalize the DOT file of the internal representation. \
|
|
*/ \
|
|
void prefix##skip_dot_end_##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%lu> | ", 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%lu -> HeadNode%lu [style=invis];\n", i, i); \
|
|
} \
|
|
nsg = 0; \
|
|
} \
|
|
fprintf(os, "}\n"); \
|
|
} \
|
|
\
|
|
/* -- skip_dot_ \
|
|
* Create a DOT file of the internal representation of the \
|
|
* Skip List 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, char *msg, skip_sprintf_node_##decl##_t fn) \
|
|
{ \
|
|
int letitgo = 0; \
|
|
size_t width, i; \
|
|
decl##_node_t *node, *next; \
|
|
\
|
|
if (slist == NULL || fn == NULL) \
|
|
return nsg; \
|
|
if (__skip_integrity_check_##decl(slist, 1) != 0) { \
|
|
perror("Skiplist failed integrity checks, impossible to diagram."); \
|
|
return -1; \
|
|
} \
|
|
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%lu {\n", nsg); \
|
|
fprintf(os, "style=dashed\n"); \
|
|
fprintf(os, "label=\"Skiplist iteration %lu", nsg); \
|
|
if (msg) \
|
|
fprintf(os, ", %s", msg); \
|
|
fprintf(os, "\"\n\n"); \
|
|
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) \
|
|
letitgo = 1; \
|
|
\
|
|
/* Write out the fields */ \
|
|
node = slist->slh_head; \
|
|
if (letitgo) { \
|
|
__SKIP_ENTRIES_T2B(field, node) \
|
|
{ \
|
|
next = (node->field.sle_next[lvl] == slist->slh_tail) ? NULL : node->field.sle_next[lvl]; \
|
|
width = __skip_dot_width_##decl(slist, node, next ? next : slist->slh_tail); \
|
|
fprintf(os, "{ %lu | <f%lu> ", width, lvl); \
|
|
if (next) \
|
|
fprintf(os, "%p }", (void *)next); \
|
|
else \
|
|
fprintf(os, "0x0 }"); \
|
|
__SKIP_IS_LAST_ENTRY_T2B() continue; \
|
|
fprintf(os, " | "); \
|
|
} \
|
|
} else { \
|
|
fprintf(os, "Empty HeadNode"); \
|
|
} \
|
|
fprintf(os, "\"\n"); \
|
|
fprintf(os, "shape = \"record\"\n"); \
|
|
fprintf(os, "];\n"); \
|
|
fflush(os); \
|
|
\
|
|
/* Edges for head node */ \
|
|
node = slist->slh_head; \
|
|
if (letitgo) { \
|
|
node = slist->slh_head; \
|
|
__SKIP_ENTRIES_B2T(field, node) \
|
|
{ \
|
|
next = (node->field.sle_next[lvl] == slist->slh_tail) ? NULL : node->field.sle_next[lvl]; \
|
|
fprintf(os, "\"HeadNode%lu\":f%lu -> ", nsg, lvl); \
|
|
__skip_dot_write_node_##decl(os, nsg, next); \
|
|
fprintf(os, ":w%lu [];\n", lvl); \
|
|
} \
|
|
fprintf(os, "\n"); \
|
|
} \
|
|
fflush(os); \
|
|
\
|
|
/* Now all nodes via level 0, if non-empty */ \
|
|
node = slist->slh_head; \
|
|
if (letitgo) { \
|
|
SKIPLIST_FOREACH_H2T(decl, prefix, slist, next, i) \
|
|
{ \
|
|
((void)i); \
|
|
__skip_dot_node_##decl(os, slist, next, nsg, fn); \
|
|
fflush(os); \
|
|
} \
|
|
fprintf(os, "\n"); \
|
|
} \
|
|
fflush(os); \
|
|
\
|
|
/* The tail, sentinal node */ \
|
|
if (letitgo) { \
|
|
__skip_dot_write_node_##decl(os, nsg, NULL); \
|
|
fprintf(os, " [label = \""); \
|
|
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]; \
|
|
fprintf(os, "<w%lu> 0x0", lvl); \
|
|
__SKIP_IS_LAST_ENTRY_T2B() continue; \
|
|
fprintf(os, " | "); \
|
|
} \
|
|
fprintf(os, "\" shape = \"record\"];\n"); \
|
|
} \
|
|
\
|
|
/* End: "subgraph cluster0 {" */ \
|
|
fprintf(os, "}\n\n"); \
|
|
nsg += 1; \
|
|
fflush(os); \
|
|
\
|
|
return nsg; \
|
|
}
|
|
|
|
#endif /* _SKIPLIST_H_ */
|