From 1b61323231c7462c9def2aa17f5c330cb75f3eb9 Mon Sep 17 00:00:00 2001 From: Thomas Haller Date: Fri, 1 Oct 2021 16:10:39 +0200 Subject: [PATCH] Squashed 'src/c-rbtree/' content from commit 8aa7bd1828ee git-subtree-dir: src/c-rbtree git-subtree-split: 8aa7bd1828eedb19960f9eef98d15543ec9f34eb --- .editorconfig | 11 + .github/workflows/ci.yml | 33 ++ .gitmodules | 3 + AUTHORS | 39 ++ NEWS.md | 40 ++ README.md | 54 ++ meson.build | 19 + src/c-rbtree-private.h | 35 ++ src/c-rbtree.c | 1120 ++++++++++++++++++++++++++++++++++++++ src/c-rbtree.h | 437 +++++++++++++++ src/libcrbtree.sym | 21 + src/meson.build | 76 +++ src/test-api.c | 107 ++++ src/test-basic.c | 239 ++++++++ src/test-map.c | 277 ++++++++++ src/test-misc.c | 66 +++ src/test-parallel.c | 384 +++++++++++++ src/test-posix.c | 270 +++++++++ subprojects/c-stdaux | 1 + 19 files changed, 3232 insertions(+) create mode 100644 .editorconfig create mode 100644 .github/workflows/ci.yml create mode 100644 .gitmodules create mode 100644 AUTHORS create mode 100644 NEWS.md create mode 100644 README.md create mode 100644 meson.build create mode 100644 src/c-rbtree-private.h create mode 100644 src/c-rbtree.c create mode 100644 src/c-rbtree.h create mode 100644 src/libcrbtree.sym create mode 100644 src/meson.build create mode 100644 src/test-api.c create mode 100644 src/test-basic.c create mode 100644 src/test-map.c create mode 100644 src/test-misc.c create mode 100644 src/test-parallel.c create mode 100644 src/test-posix.c create mode 160000 subprojects/c-stdaux diff --git a/.editorconfig b/.editorconfig new file mode 100644 index 000000000..b10bb4f3f --- /dev/null +++ b/.editorconfig @@ -0,0 +1,11 @@ +root = true + +[*] +end_of_line = lf +insert_final_newline = true +trim_trailing_whitespace = true +charset = utf-8 + +[*.{c,h}] +indent_style = space +indent_size = 8 diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml new file mode 100644 index 000000000..c270c52ca --- /dev/null +++ b/.github/workflows/ci.yml @@ -0,0 +1,33 @@ +name: Continuous Integration + +on: + push: + pull_request: + schedule: + - cron: '0 0 * * *' + +jobs: + ci: + name: CI with Default Configuration + runs-on: ubuntu-latest + + steps: + - name: Fetch Sources + uses: actions/checkout@v2 + - name: Run through C-Util CI + uses: c-util/automation/src/ci-c-util@v1 + with: + m32: 1 + valgrind: 1 + + ci-ptrace: + name: Reduced CI with PTrace + runs-on: ubuntu-latest + env: + CRBTREE_TEST_PTRACE: '1' + + steps: + - name: Fetch Sources + uses: actions/checkout@v2 + - name: Run through C-Util CI + uses: c-util/automation/src/ci-c-util@v1 diff --git a/.gitmodules b/.gitmodules new file mode 100644 index 000000000..a86b29fd1 --- /dev/null +++ b/.gitmodules @@ -0,0 +1,3 @@ +[submodule "subprojects/c-stdaux"] + path = subprojects/c-stdaux + url = https://github.com/c-util/c-stdaux.git diff --git a/AUTHORS b/AUTHORS new file mode 100644 index 000000000..ed4e72e91 --- /dev/null +++ b/AUTHORS @@ -0,0 +1,39 @@ +LICENSE: + This project is dual-licensed under both the Apache License, Version + 2.0, and the GNU Lesser General Public License, Version 2.1+. + +AUTHORS-ASL: + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. + +AUTHORS-LGPL: + This program is free software; you can redistribute it and/or modify it + under the terms of the GNU Lesser General Public License as published + by the Free Software Foundation; either version 2.1 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public License + along with this program; If not, see . + +COPYRIGHT: (ordered alphabetically) + Copyright (C) 2015-2019 Red Hat, Inc. + +AUTHORS: (ordered alphabetically) + David Rheinsberg + Kay Sievers + Thomas Haller + Tom Gundersen diff --git a/NEWS.md b/NEWS.md new file mode 100644 index 000000000..d76a41290 --- /dev/null +++ b/NEWS.md @@ -0,0 +1,40 @@ +# c-rbtree - Intrusive Red-Black Tree Collection + +## CHANGES WITH 3: + + * Add more helpers. Add both a collection of iteratiors and helpers + for initializing a tree and checking if a tree is empty, without + explicitly accessing the data structure. + + Contributions from: David Herrmann + + - Berlin, 2017-08-13 + +## CHANGES WITH 2: + + * Relicense as ASL-2.0 to make c-rbtree useful for more projects. All + code is now fully available under the ASL-2.0. Nothing is covered by + the LGPL, anymore. + + * Switch build-system from Autotools to Meson. This simplifies the code + base significantly. The Meson Build System is now used by many other + projects, including GStreamer, Weston, and several Gnome packages. + See http://mesonbuild.com/ for more information. + + Contributions from: David Herrmann + + - Berlin, 2016-12-14 + +## CHANGES WITH 1: + + * Initial release of c-rbtree. + + * This projects provides an RB-Tree API, that is fully implemented in + ISO-C11 and has no external dependencies. Furthermore, tree + traversal, memory allocations, and key comparisons are completely + controlled by the API user. The implementation only provides the + RB-Tree specific rebalancing and coloring. + + Contributions from: David Herrmann, Kay Sievers, Tom Gundersen + + - Berlin, 2016-08-31 diff --git a/README.md b/README.md new file mode 100644 index 000000000..c725bbb8f --- /dev/null +++ b/README.md @@ -0,0 +1,54 @@ +c-rbtree +======== + +Intrusive Red-Black Tree Collection + +The c-rbtree project implements an intrusive collection based on red-black +trees in ISO-C11. Its API guarantees the user full control over its +data-structures, and rather limits itself to just the tree-specific rebalancing +and coloring operations. For API documentation, see the c-rbtree.h header file, +as well as the docbook comments for each function. + +### Project + + * **Website**: + * **Bug Tracker**: + +### Requirements + +The requirements for this project are: + + * `libc` (e.g., `glibc >= 2.16`) + +At build-time, the following software is required: + + * `meson >= 0.41` + * `pkg-config >= 0.29` + +### Build + +The meson build-system is used for this project. Contact upstream +documentation for detailed help. In most situations the following +commands are sufficient to build and install from source: + +```sh +mkdir build +cd build +meson setup .. +ninja +meson test +ninja install +``` + +No custom configuration options are available. + +### Repository: + + - **web**: + - **https**: `https://github.com/c-util/c-rbtree.git` + - **ssh**: `git@github.com:c-util/c-rbtree.git` + +### License: + + - **Apache-2.0** OR **LGPL-2.1-or-later** + - See AUTHORS file for details. diff --git a/meson.build b/meson.build new file mode 100644 index 000000000..c13194676 --- /dev/null +++ b/meson.build @@ -0,0 +1,19 @@ +project( + 'c-rbtree', + 'c', + version: '3', + license: 'Apache', + default_options: [ + 'c_std=c11' + ], +) +project_description = 'Intrusive Red-Black Tree Collection' + +add_project_arguments('-D_GNU_SOURCE', language: 'c') +mod_pkgconfig = import('pkgconfig') + +sub_cstdaux = subproject('c-stdaux') + +dep_cstdaux = sub_cstdaux.get_variable('libcstdaux_dep') + +subdir('src') diff --git a/src/c-rbtree-private.h b/src/c-rbtree-private.h new file mode 100644 index 000000000..c9befbf37 --- /dev/null +++ b/src/c-rbtree-private.h @@ -0,0 +1,35 @@ +#pragma once + +/* + * Private definitions + * This file contains private definitions for the RB-Tree implementation, but + * which are used by our test-suite. + */ + +#include +#include +#include "c-rbtree.h" + +/* + * Nodes + */ + +static inline void *c_rbnode_raw(CRBNode *n) { + return (void *)(n->__parent_and_flags & ~C_RBNODE_FLAG_MASK); +} + +static inline unsigned long c_rbnode_flags(CRBNode *n) { + return n->__parent_and_flags & C_RBNODE_FLAG_MASK; +} + +static inline _Bool c_rbnode_is_red(CRBNode *n) { + return c_rbnode_flags(n) & C_RBNODE_RED; +} + +static inline _Bool c_rbnode_is_black(CRBNode *n) { + return !(c_rbnode_flags(n) & C_RBNODE_RED); +} + +static inline _Bool c_rbnode_is_root(CRBNode *n) { + return c_rbnode_flags(n) & C_RBNODE_ROOT; +} diff --git a/src/c-rbtree.c b/src/c-rbtree.c new file mode 100644 index 000000000..2f0e608f9 --- /dev/null +++ b/src/c-rbtree.c @@ -0,0 +1,1120 @@ +/* + * RB-Tree Implementation + * This implements the insertion/removal of elements in RB-Trees. You're highly + * recommended to have an RB-Tree documentation at hand when reading this. Both + * insertion and removal can be split into a handful of situations that can + * occur. Those situations are enumerated as "Case 1" to "Case n" here, and + * follow closely the cases described in most RB-Tree documentations. This file + * does not explain why it is enough to handle just those cases, nor does it + * provide a proof of correctness. Dig out your algorithm 101 handbook if + * you're interested. + * + * This implementation is *not* straightforward. Usually, a handful of + * rotation, reparent, swap and link helpers can be used to implement the + * rebalance operations. However, those often perform unnecessary writes. + * Therefore, this implementation hard-codes all the operations. You're highly + * recommended to look at the two basic helpers before reading the code: + * c_rbnode_swap_child() + * c_rbnode_set_parent_and_flags() + * Those are the only helpers used, hence, you should really know what they do + * before digging into the code. + * + * For a highlevel documentation of the API, see the header file and docbook + * comments. + */ + +#include +#include +#include +#include +#include "c-rbtree.h" +#include "c-rbtree-private.h" + +/* + * We use the lower 2 bits of CRBNode pointers to store flags. Make sure + * CRBNode is 4-byte aligned, so the lower 2 bits are actually unused. We also + * sometimes store a pointer to the root-node, so make sure this one is also 4 + * byte aligned. + * Note that there are actually some architectures where `max_align_t` is 4, so + * we do not have much wiggle-room to extend this flag-set. + */ +static_assert(alignof(CRBNode) <= alignof(max_align_t), "Invalid RBNode alignment"); +static_assert(alignof(CRBNode) >= 4, "Invalid CRBNode alignment"); +static_assert(alignof(CRBTree) <= alignof(max_align_t), "Invalid RBTree alignment"); +static_assert(alignof(CRBTree) >= 4, "Invalid CRBTree alignment"); + +/** + * c_rbnode_leftmost() - return leftmost child + * @n: current node, or NULL + * + * This returns the leftmost child of @n. If @n is NULL, this will return NULL. + * In all other cases, this function returns a valid pointer. That is, if @n + * does not have any left children, this returns @n. + * + * Worst case runtime (n: number of elements in tree): O(log(n)) + * + * Return: Pointer to leftmost child, or NULL. + */ +_c_public_ CRBNode *c_rbnode_leftmost(CRBNode *n) { + if (n) + while (n->left) + n = n->left; + return n; +} + +/** + * c_rbnode_rightmost() - return rightmost child + * @n: current node, or NULL + * + * This returns the rightmost child of @n. If @n is NULL, this will return + * NULL. In all other cases, this function returns a valid pointer. That is, if + * @n does not have any right children, this returns @n. + * + * Worst case runtime (n: number of elements in tree): O(log(n)) + * + * Return: Pointer to rightmost child, or NULL. + */ +_c_public_ CRBNode *c_rbnode_rightmost(CRBNode *n) { + if (n) + while (n->right) + n = n->right; + return n; +} + +/** + * c_rbnode_leftdeepest() - return left-deepest child + * @n: current node, or NULL + * + * This returns the left-deepest child of @n. If @n is NULL, this will return + * NULL. In all other cases, this function returns a valid pointer. That is, if + * @n does not have any children, this returns @n. + * + * The left-deepest child is defined as the deepest child without any left + * (grand-...)siblings. + * + * Worst case runtime (n: number of elements in tree): O(log(n)) + * + * Return: Pointer to left-deepest child, or NULL. + */ +_c_public_ CRBNode *c_rbnode_leftdeepest(CRBNode *n) { + if (n) { + for (;;) { + if (n->left) + n = n->left; + else if (n->right) + n = n->right; + else + break; + } + } + return n; +} + +/** + * c_rbnode_rightdeepest() - return right-deepest child + * @n: current node, or NULL + * + * This returns the right-deepest child of @n. If @n is NULL, this will return + * NULL. In all other cases, this function returns a valid pointer. That is, if + * @n does not have any children, this returns @n. + * + * The right-deepest child is defined as the deepest child without any right + * (grand-...)siblings. + * + * Worst case runtime (n: number of elements in tree): O(log(n)) + * + * Return: Pointer to right-deepest child, or NULL. + */ +_c_public_ CRBNode *c_rbnode_rightdeepest(CRBNode *n) { + if (n) { + for (;;) { + if (n->right) + n = n->right; + else if (n->left) + n = n->left; + else + break; + } + } + return n; +} + +/** + * c_rbnode_next() - return next node + * @n: current node, or NULL + * + * An RB-Tree always defines a linear order of its elements. This function + * returns the logically next node to @n. If @n is NULL, the last node or + * unlinked, this returns NULL. + * + * Worst case runtime (n: number of elements in tree): O(log(n)) + * + * Return: Pointer to next node, or NULL. + */ +_c_public_ CRBNode *c_rbnode_next(CRBNode *n) { + CRBNode *p; + + if (!c_rbnode_is_linked(n)) + return NULL; + if (n->right) + return c_rbnode_leftmost(n->right); + + while ((p = c_rbnode_parent(n)) && n == p->right) + n = p; + + return p; +} + +/** + * c_rbnode_prev() - return previous node + * @n: current node, or NULL + * + * An RB-Tree always defines a linear order of its elements. This function + * returns the logically previous node to @n. If @n is NULL, the first node or + * unlinked, this returns NULL. + * + * Worst case runtime (n: number of elements in tree): O(log(n)) + * + * Return: Pointer to previous node, or NULL. + */ +_c_public_ CRBNode *c_rbnode_prev(CRBNode *n) { + CRBNode *p; + + if (!c_rbnode_is_linked(n)) + return NULL; + if (n->left) + return c_rbnode_rightmost(n->left); + + while ((p = c_rbnode_parent(n)) && n == p->left) + n = p; + + return p; +} + +/** + * c_rbnode_next_postorder() - return next node in post-order + * @n: current node, or NULL + * + * This returns the next node to @n, based on a left-to-right post-order + * traversal. If @n is NULL, the root node, or unlinked, this returns NULL. + * + * This implements a left-to-right post-order traversal: First visit the left + * child of a node, then the right, and lastly the node itself. Children are + * traversed recursively. + * + * This function can be used to implement a left-to-right post-order traversal: + * + * for (n = c_rbtree_first_postorder(t); n; n = c_rbnode_next_postorder(n)) + * visit(n); + * + * Worst case runtime (n: number of elements in tree): O(log(n)) + * + * Return: Pointer to next node, or NULL. + */ +_c_public_ CRBNode *c_rbnode_next_postorder(CRBNode *n) { + CRBNode *p; + + if (!c_rbnode_is_linked(n)) + return NULL; + + p = c_rbnode_parent(n); + if (p && n == p->left && p->right) + return c_rbnode_leftdeepest(p->right); + + return p; +} + +/** + * c_rbnode_prev_postorder() - return previous node in post-order + * @n: current node, or NULL + * + * This returns the previous node to @n, based on a left-to-right post-order + * traversal. That is, it is the inverse operation to c_rbnode_next_postorder(). + * If @n is NULL, the left-deepest node, or unlinked, this returns NULL. + * + * This function returns the logical previous node in a directed post-order + * traversal. That is, it effectively does a pre-order traversal (since a + * reverse post-order traversal is a pre-order traversal). This function does + * NOT do a right-to-left post-order traversal! In other words, the following + * invariant is guaranteed, if c_rbnode_next_postorder(n) is non-NULL: + * + * n == c_rbnode_prev_postorder(c_rbnode_next_postorder(n)) + * + * This function can be used to implement a right-to-left pre-order traversal, + * using the fact that a reverse post-order traversal is also a valid pre-order + * traversal: + * + * for (n = c_rbtree_last_postorder(t); n; n = c_rbnode_prev_postorder(n)) + * visit(n); + * + * This would effectively perform a right-to-left pre-order traversal: first + * visit a parent, then its right child, then its left child. Both children are + * traversed recursively. + * + * Worst case runtime (n: number of elements in tree): O(log(n)) + * + * Return: Pointer to previous node in post-order, or NULL. + */ +_c_public_ CRBNode *c_rbnode_prev_postorder(CRBNode *n) { + CRBNode *p; + + if (!c_rbnode_is_linked(n)) + return NULL; + if (n->right) + return n->right; + if (n->left) + return n->left; + + while ((p = c_rbnode_parent(n))) { + if (p->left && n != p->left) + return p->left; + n = p; + } + + return NULL; +} + +/** + * c_rbtree_first() - return first node + * @t: tree to operate on + * + * An RB-Tree always defines a linear order of its elements. This function + * returns the logically first node in @t. If @t is empty, NULL is returned. + * + * Fixed runtime (n: number of elements in tree): O(log(n)) + * + * Return: Pointer to first node, or NULL. + */ +_c_public_ CRBNode *c_rbtree_first(CRBTree *t) { + c_assert(t); + return c_rbnode_leftmost(t->root); +} + +/** + * c_rbtree_last() - return last node + * @t: tree to operate on + * + * An RB-Tree always defines a linear order of its elements. This function + * returns the logically last node in @t. If @t is empty, NULL is returned. + * + * Fixed runtime (n: number of elements in tree): O(log(n)) + * + * Return: Pointer to last node, or NULL. + */ +_c_public_ CRBNode *c_rbtree_last(CRBTree *t) { + c_assert(t); + return c_rbnode_rightmost(t->root); +} + +/** + * c_rbtree_first_postorder() - return first node in post-order + * @t: tree to operate on + * + * This returns the first node of a left-to-right post-order traversal. That + * is, it returns the left-deepest leaf. If the tree is empty, this returns + * NULL. + * + * This can also be interpreted as the last node of a right-to-left pre-order + * traversal. + * + * Fixed runtime (n: number of elements in tree): O(log(n)) + * + * Return: Pointer to first node in post-order, or NULL. + */ +_c_public_ CRBNode *c_rbtree_first_postorder(CRBTree *t) { + c_assert(t); + return c_rbnode_leftdeepest(t->root); +} + +/** + * c_rbtree_last_postorder() - return last node in post-order + * @t: tree to operate on + * + * This returns the last node of a left-to-right post-order traversal. That is, + * it always returns the root node, or NULL if the tree is empty. + * + * This can also be interpreted as the first node of a right-to-left pre-order + * traversal. + * + * Fixed runtime (n: number of elements in tree): O(1) + * + * Return: Pointer to last node in post-order, or NULL. + */ +_c_public_ CRBNode *c_rbtree_last_postorder(CRBTree *t) { + c_assert(t); + return t->root; +} + +static inline void c_rbtree_store(CRBNode **ptr, CRBNode *addr) { + /* + * We use volatile accesses whenever we STORE @left or @right members + * of a node. This guarantees that any parallel, lockless lookup gets + * to see those stores in the correct order, which itself guarantees + * that there're no temporary loops during tree rotation. + * Note that you still need to properly synchronize your accesses via + * seqlocks, rcu, whatever. We just guarantee that you get *some* + * result on a lockless traversal and never run into endless loops, or + * undefined behavior. + */ + *(volatile CRBNode **)ptr = addr; +} + +/* + * Set the flags and parent of a node. This should be treated as a simple + * assignment of the 'flags' and 'parent' fields of the node. No other magic is + * applied. But since both fields share its backing memory, this helper + * function is provided. + */ +static inline void c_rbnode_set_parent_and_flags(CRBNode *n, CRBNode *p, unsigned long flags) { + n->__parent_and_flags = (unsigned long)p | flags; +} + +/* + * Nodes in the tree do not separately store a point to the tree root. That is, + * there is no way to access the tree-root in O(1) given an arbitrary node. + * Fortunately, this is usually not required. The only situation where this is + * needed is when rotating the root-node itself. + * + * In case of the root node, c_rbnode_parent() returns NULL. We use this fact + * to re-use the parent-pointer storage of the root node to point to the + * CRBTree root. This way, we can rotate the root-node (or add/remove it) + * without requiring a separate tree-root pointer. + * + * However, to keep the tree-modification functions simple, we hide this detail + * whenever possible. This means, c_rbnode_parent() will continue to return + * NULL, and tree modifications will boldly reset the pointer to NULL on + * rotation. Hence, the only way to retain this pointer is to call + * c_rbnode_pop_root() on a possible root-node before rotating. This returns + * NULL if the node in question is not the root node. Otherwise, it returns the + * tree-root, and clears the pointer/flag from the node in question. This way, + * you can perform tree operations as usual. Afterwards, use + * c_rbnode_push_root() to restore the root-pointer on any possible new root. + */ +static inline CRBTree *c_rbnode_pop_root(CRBNode *n) { + CRBTree *t = NULL; + + if (c_rbnode_is_root(n)) { + t = c_rbnode_raw(n); + n->__parent_and_flags = c_rbnode_flags(n) & ~C_RBNODE_ROOT; + } + + return t; +} + +/* counter-part to c_rbnode_pop_root() */ +static inline CRBTree *c_rbnode_push_root(CRBNode *n, CRBTree *t) { + if (t) { + if (n) + n->__parent_and_flags = (unsigned long)t + | c_rbnode_flags(n) + | C_RBNODE_ROOT; + c_rbtree_store(&t->root, n); + } + + return NULL; +} + +/* + * This function partially swaps a child node with another one. That is, this + * function changes the parent of @old to point to @new. That is, you use it + * when swapping @old with @new, to update the parent's left/right pointer. + * This function does *NOT* perform a full swap, nor does it touch any 'parent' + * pointer. + * + * The sole purpose of this function is to shortcut left/right conditionals + * like this: + * + * if (old == old->parent->left) + * old->parent->left = new; + * else + * old->parent->right = new; + * + * That's it! If @old is the root node, this will do nothing. The caller must + * employ c_rbnode_pop_root() and c_rbnode_push_root(). + */ +static inline void c_rbnode_swap_child(CRBNode *old, CRBNode *new) { + CRBNode *p = c_rbnode_parent(old); + + if (p) { + if (p->left == old) + c_rbtree_store(&p->left, new); + else + c_rbtree_store(&p->right, new); + } +} + +/** + * c_rbtree_move() - move tree + * @to: destination tree + * @from: source tree + * + * This imports the entire tree from @from into @to. @to must be empty! @from + * will be empty afterwards. + * + * Note that this operates in O(1) time. Only the root-entry is updated to + * point to the new tree-root. + */ +_c_public_ void c_rbtree_move(CRBTree *to, CRBTree *from) { + CRBTree *t; + + c_assert(!to->root); + + if (from->root) { + t = c_rbnode_pop_root(from->root); + c_assert(t == from); + + to->root = from->root; + from->root = NULL; + + c_rbnode_push_root(to->root, to); + } +} + +static inline void c_rbtree_paint_terminal(CRBNode *n) { + CRBNode *p, *g, *gg, *x; + CRBTree *t; + + /* + * Case 4: + * This path assumes @n is red, @p is red, but the uncle is unset or + * black. This implies @g exists and is black. + * + * This case requires up to 2 rotations to restore the tree invariants. + * That is, it runs in O(1) time and fully restores the RB-Tree + * invariants, all at the cost of performing at mots 2 rotations. + */ + + p = c_rbnode_parent(n); + g = c_rbnode_parent(p); + gg = c_rbnode_parent(g); + + c_assert(c_rbnode_is_red(p)); + c_assert(c_rbnode_is_black(g)); + c_assert(p == g->left || !g->left || c_rbnode_is_black(g->left)); + c_assert(p == g->right || !g->right || c_rbnode_is_black(g->right)); + + if (p == g->left) { + if (n == p->right) { + /* + * We're the right red child of a red parent, which is + * a left child. Rotate on parent and consider us to be + * the old parent and the old parent to be us, making us + * the left child instead of the right child so we can + * handle it the same as below. Rotating two red nodes + * changes none of the invariants. + */ + x = n->left; + c_rbtree_store(&p->right, x); + c_rbtree_store(&n->left, p); + if (x) + c_rbnode_set_parent_and_flags(x, p, c_rbnode_flags(x)); + c_rbnode_set_parent_and_flags(p, n, c_rbnode_flags(p)); + p = n; + } + + /* 'n' is invalid from here on! */ + + /* + * We're the red left child of a red parent, black grandparent + * and uncle. Rotate parent on grandparent and switch their + * colors, making the parent black and the grandparent red. The + * root of this subtree was changed from the grandparent to the + * parent, but the color remained black, so the number of black + * nodes on each path stays the same. However, we got rid of + * the double red path as we are still the (red) child of the + * parent, which has now turned black. Note that had we been + * the right child, rather than the left child, we would now be + * the left child of the old grandparent, and we would still + * have a double red path. As the new grandparent remains + * black, we're done. + */ + x = p->right; + t = c_rbnode_pop_root(g); + c_rbtree_store(&g->left, x); + c_rbtree_store(&p->right, g); + c_rbnode_swap_child(g, p); + if (x) + c_rbnode_set_parent_and_flags(x, g, c_rbnode_flags(x) & ~C_RBNODE_RED); + c_rbnode_set_parent_and_flags(p, gg, c_rbnode_flags(p) & ~C_RBNODE_RED); + c_rbnode_set_parent_and_flags(g, p, c_rbnode_flags(g) | C_RBNODE_RED); + c_rbnode_push_root(p, t); + } else /* if (p == g->right) */ { /* same as above, but mirrored */ + if (n == p->left) { + x = n->right; + c_rbtree_store(&p->left, n->right); + c_rbtree_store(&n->right, p); + if (x) + c_rbnode_set_parent_and_flags(x, p, c_rbnode_flags(x)); + c_rbnode_set_parent_and_flags(p, n, c_rbnode_flags(p)); + p = n; + } + + x = p->left; + t = c_rbnode_pop_root(g); + c_rbtree_store(&g->right, x); + c_rbtree_store(&p->left, g); + c_rbnode_swap_child(g, p); + if (x) + c_rbnode_set_parent_and_flags(x, g, c_rbnode_flags(x) & ~C_RBNODE_RED); + c_rbnode_set_parent_and_flags(p, gg, c_rbnode_flags(p) & ~C_RBNODE_RED); + c_rbnode_set_parent_and_flags(g, p, c_rbnode_flags(g) | C_RBNODE_RED); + c_rbnode_push_root(p, t); + } +} + +static inline CRBNode *c_rbtree_paint_path(CRBNode *n) { + CRBNode *p, *g, *u; + + for (;;) { + p = c_rbnode_parent(n); + if (!p) { + /* + * Case 1: + * We reached the root. Mark it black and be done. As + * all leaf-paths share the root, the ratio of black + * nodes on each path stays the same. + */ + c_rbnode_set_parent_and_flags(n, c_rbnode_raw(n), c_rbnode_flags(n) & ~C_RBNODE_RED); + return NULL; + } else if (c_rbnode_is_black(p)) { + /* + * Case 2: + * The parent is already black. As our node is red, we + * did not change the number of black nodes on any + * path, nor do we have multiple consecutive red nodes. + * There is nothing to be done. + */ + return NULL; + } + + g = c_rbnode_parent(p); + u = (p == g->left) ? g->right : g->left; + if (!u || !c_rbnode_is_red(u)) { + /* + * Case 4: + * The parent is red, but its uncle is black. By + * rotating the parent above the uncle, we distribute + * the red nodes and thus restore the tree invariants. + * No recursive fixup will be needed afterwards. Hence, + * just let the caller know about @n and make them do + * the rotations. + */ + return n; + } + + /* + * Case 3: + * Parent and uncle are both red, and grandparent is black. + * Repaint parent and uncle black, the grandparent red and + * recurse into the grandparent. Note that this is the only + * recursive case. That is, this step restores the tree + * invariants for the sub-tree below @p (including @n), but + * needs to continue the re-coloring two levels up. + */ + c_rbnode_set_parent_and_flags(p, g, c_rbnode_flags(p) & ~C_RBNODE_RED); + c_rbnode_set_parent_and_flags(u, g, c_rbnode_flags(u) & ~C_RBNODE_RED); + c_rbnode_set_parent_and_flags(g, c_rbnode_raw(g), c_rbnode_flags(g) | C_RBNODE_RED); + n = g; + } +} + +static inline void c_rbtree_paint(CRBNode *n) { + /* + * When a new node is inserted into an RB-Tree, we always link it as a + * tail-node and paint it red. This way, the node will not violate the + * rb-tree invariants regarding the number of black nodes on all paths. + * + * However, a red node must never have another bordering red-node (ie., + * child or parent). Since the node is newly linked, it does not have + * any children. Therefore, all we need to do is fix the path upwards + * through all parents until we hit a black parent or can otherwise fix + * the coloring. + * + * This function first walks up the path from @n towards the tree root + * (done in c_rbtree_paint_path()). This recolors its parent/uncle, if + * possible, until it hits a sub-tree that cannot be fixed via + * re-coloring. After c_rbtree_paint_path() returns, there are two + * possible outcomes: + * + * 1) @n is NULL, in which case the tree invariants were + * restored by mere recoloring. Nothing is to be done. + * + * 2) @n is non-NULL, but points to a red ancestor of the + * original node. In this case we need to restore the tree + * invariants via a simple left or right rotation. This will + * be done by c_rbtree_paint_terminal(). + * + * As a summary, this function runs O(log(n)) re-coloring operations in + * the worst case, followed by O(1) rotations as final restoration. The + * amortized cost, however, is O(1), since re-coloring only recurses + * upwards if it hits a red uncle (which can only happen if a previous + * operation terminated its operation on that layer). + * While amortized painting of inserted nodes is O(1), finding the + * correct spot to link the node (before painting it) still requires a + * search in the binary tree in O(log(n)). + */ + n = c_rbtree_paint_path(n); + if (n) + c_rbtree_paint_terminal(n); +} + +/** + * c_rbnode_link() - link node into tree + * @p: parent node to link under + * @l: left/right slot of @p to link at + * @n: node to add + * + * This links @n into an tree underneath another node. The caller must provide + * the exact spot where to link the node. That is, the caller must traverse the + * tree based on their search order. Once they hit a leaf where to insert the + * node, call this function to link it and rebalance the tree. + * + * For this to work, the caller must provide a pointer to the parent node. If + * the tree might be empty, you must resort to c_rbtree_add(). + * + * In most cases you are better off using c_rbtree_add(). See there for details + * how tree-insertion works. + */ +_c_public_ void c_rbnode_link(CRBNode *p, CRBNode **l, CRBNode *n) { + c_assert(p); + c_assert(l); + c_assert(n); + c_assert(l == &p->left || l == &p->right); + + c_rbnode_set_parent_and_flags(n, p, C_RBNODE_RED); + c_rbtree_store(&n->left, NULL); + c_rbtree_store(&n->right, NULL); + c_rbtree_store(l, n); + + c_rbtree_paint(n); +} + +/** + * c_rbtree_add() - add node to tree + * @t: tree to operate one + * @p: parent node to link under, or NULL + * @l: left/right slot of @p (or root) to link at + * @n: node to add + * + * This links @n into the tree given as @t. The caller must provide the exact + * spot where to link the node. That is, the caller must traverse the tree + * based on their search order. Once they hit a leaf where to insert the node, + * call this function to link it and rebalance the tree. + * + * A typical insertion would look like this (@t is your tree, @n is your node): + * + * CRBNode **i, *p; + * + * i = &t->root; + * p = NULL; + * while (*i) { + * p = *i; + * if (compare(n, *i) < 0) + * i = &(*i)->left; + * else + * i = &(*i)->right; + * } + * + * c_rbtree_add(t, p, i, n); + * + * Once the node is linked into the tree, a simple lookup on the same tree can + * be coded like this: + * + * CRBNode *i; + * + * i = t->root; + * while (i) { + * int v = compare(n, i); + * if (v < 0) + * i = (*i)->left; + * else if (v > 0) + * i = (*i)->right; + * else + * break; + * } + * + * When you add nodes to a tree, the memory contents of the node do not matter. + * That is, there is no need to initialize the node via c_rbnode_init(). + * However, if you relink nodes multiple times during their lifetime, it is + * usually very convenient to use c_rbnode_init() and c_rbnode_unlink() (rather + * than c_rbnode_unlink_stale()). In those cases, you should validate that a + * node is unlinked before you call c_rbtree_add(). + */ +_c_public_ void c_rbtree_add(CRBTree *t, CRBNode *p, CRBNode **l, CRBNode *n) { + c_assert(t); + c_assert(l); + c_assert(n); + c_assert(!p || l == &p->left || l == &p->right); + c_assert(p || l == &t->root); + + c_rbnode_set_parent_and_flags(n, p, C_RBNODE_RED); + c_rbtree_store(&n->left, NULL); + c_rbtree_store(&n->right, NULL); + + if (p) + c_rbtree_store(l, n); + else + c_rbnode_push_root(n, t); + + c_rbtree_paint(n); +} + +static inline void c_rbnode_rebalance_terminal(CRBNode *p, CRBNode *previous) { + CRBNode *s, *x, *y, *g; + CRBTree *t; + + if (previous == p->left) { + s = p->right; + if (c_rbnode_is_red(s)) { + /* + * Case 2: + * We have a red node as sibling. Rotate it onto our + * side so we can later on turn it black. This way, we + * gain the additional black node in our path. + */ + t = c_rbnode_pop_root(p); + g = c_rbnode_parent(p); + x = s->left; + c_rbtree_store(&p->right, x); + c_rbtree_store(&s->left, p); + c_rbnode_swap_child(p, s); + c_rbnode_set_parent_and_flags(x, p, c_rbnode_flags(x) & ~C_RBNODE_RED); + c_rbnode_set_parent_and_flags(s, g, c_rbnode_flags(s) & ~C_RBNODE_RED); + c_rbnode_set_parent_and_flags(p, s, c_rbnode_flags(p) | C_RBNODE_RED); + c_rbnode_push_root(s, t); + s = x; + } + + x = s->right; + if (!x || c_rbnode_is_black(x)) { + y = s->left; + if (!y || c_rbnode_is_black(y)) { + /* + * Case 3+4: + * Our sibling is black and has only black + * children. Flip it red and turn parent black. + * This way we gained a black node in our path. + * Note that the parent must be red, otherwise + * it must have been handled by our caller. + */ + c_assert(c_rbnode_is_red(p)); + c_rbnode_set_parent_and_flags(s, p, c_rbnode_flags(s) | C_RBNODE_RED); + c_rbnode_set_parent_and_flags(p, c_rbnode_parent(p), c_rbnode_flags(p) & ~C_RBNODE_RED); + return; + } + + /* + * Case 5: + * Left child of our sibling is red, right one is black. + * Rotate on parent so the right child of our sibling is + * now red, and we can fall through to case 6. + */ + x = y->right; + c_rbtree_store(&s->left, y->right); + c_rbtree_store(&y->right, s); + c_rbtree_store(&p->right, y); + if (x) + c_rbnode_set_parent_and_flags(x, s, c_rbnode_flags(x) & ~C_RBNODE_RED); + x = s; + s = y; + } + + /* + * Case 6: + * The right child of our sibling is red. Rotate left and flip + * colors, which gains us an additional black node in our path, + * that was previously on our sibling. + */ + t = c_rbnode_pop_root(p); + g = c_rbnode_parent(p); + y = s->left; + c_rbtree_store(&p->right, y); + c_rbtree_store(&s->left, p); + c_rbnode_swap_child(p, s); + c_rbnode_set_parent_and_flags(x, s, c_rbnode_flags(x) & ~C_RBNODE_RED); + if (y) + c_rbnode_set_parent_and_flags(y, p, c_rbnode_flags(y)); + c_rbnode_set_parent_and_flags(s, g, c_rbnode_flags(p)); + c_rbnode_set_parent_and_flags(p, s, c_rbnode_flags(p) & ~C_RBNODE_RED); + c_rbnode_push_root(s, t); + } else /* if (previous == p->right) */ { /* same as above, but mirrored */ + s = p->left; + if (c_rbnode_is_red(s)) { + t = c_rbnode_pop_root(p); + g = c_rbnode_parent(p); + x = s->right; + c_rbtree_store(&p->left, x); + c_rbtree_store(&s->right, p); + c_rbnode_swap_child(p, s); + c_rbnode_set_parent_and_flags(x, p, c_rbnode_flags(x) & ~C_RBNODE_RED); + c_rbnode_set_parent_and_flags(s, g, c_rbnode_flags(s) & ~C_RBNODE_RED); + c_rbnode_set_parent_and_flags(p, s, c_rbnode_flags(p) | C_RBNODE_RED); + c_rbnode_push_root(s, t); + s = x; + } + + x = s->left; + if (!x || c_rbnode_is_black(x)) { + y = s->right; + if (!y || c_rbnode_is_black(y)) { + c_assert(c_rbnode_is_red(p)); + c_rbnode_set_parent_and_flags(s, p, c_rbnode_flags(s) | C_RBNODE_RED); + c_rbnode_set_parent_and_flags(p, c_rbnode_parent(p), c_rbnode_flags(p) & ~C_RBNODE_RED); + return; + } + + x = y->left; + c_rbtree_store(&s->right, y->left); + c_rbtree_store(&y->left, s); + c_rbtree_store(&p->left, y); + if (x) + c_rbnode_set_parent_and_flags(x, s, c_rbnode_flags(x) & ~C_RBNODE_RED); + x = s; + s = y; + } + + t = c_rbnode_pop_root(p); + g = c_rbnode_parent(p); + y = s->right; + c_rbtree_store(&p->left, y); + c_rbtree_store(&s->right, p); + c_rbnode_swap_child(p, s); + c_rbnode_set_parent_and_flags(x, s, c_rbnode_flags(x) & ~C_RBNODE_RED); + if (y) + c_rbnode_set_parent_and_flags(y, p, c_rbnode_flags(y)); + c_rbnode_set_parent_and_flags(s, g, c_rbnode_flags(p)); + c_rbnode_set_parent_and_flags(p, s, c_rbnode_flags(p) & ~C_RBNODE_RED); + c_rbnode_push_root(s, t); + } +} + +static inline CRBNode *c_rbnode_rebalance_path(CRBNode *p, CRBNode **previous) { + CRBNode *s, *nl, *nr; + + while (p) { + s = (*previous == p->left) ? p->right : p->left; + nl = s->left; + nr = s->right; + + /* + * If the sibling under @p is black and exclusively has black + * children itself (i.e., nephews/nieces in @nl/@nr), then we + * can easily re-color to fix this sub-tree, and continue one + * layer up. However, if that's not the case, we have tree + * rotations at our hands to move one of the black nodes into + * our path, then turning the red node black to fully restore + * the RB-Tree invariants again. This fixup will be done by the + * caller, so we just let them know where to do that. + */ + if (c_rbnode_is_red(s) || + (nl && c_rbnode_is_red(nl)) || + (nr && c_rbnode_is_red(nr))) + return p; + + /* + * Case 3+4: + * Sibling is black, and all nephews/nieces are black. Flip + * sibling red. This way the sibling lost a black node in its + * path, thus getting even with our path. However, paths not + * going through @p haven't been fixed up, hence we proceed + * recursively one layer up. + * Before we continue one layer up, there are two possible + * terminations: If the parent is red, we can turn it black. + * This terminates the rebalancing, since the entire point of + * rebalancing is that everything below @p has one black node + * less than everything else. Lastly, if there is no layer + * above, we hit the tree root and nothing is left to be done. + */ + c_rbnode_set_parent_and_flags(s, p, c_rbnode_flags(s) | C_RBNODE_RED); + if (c_rbnode_is_red(p)) { + c_rbnode_set_parent_and_flags(p, c_rbnode_parent(p), c_rbnode_flags(p) & ~C_RBNODE_RED); + return NULL; + } + + *previous = p; + p = c_rbnode_parent(p); + } + + return NULL; +} + +static inline void c_rbnode_rebalance(CRBNode *n) { + CRBNode *previous = NULL; + + /* + * Rebalance a tree after a node was removed. This function must be + * called on the parent of the leaf that was removed. It will first + * perform a recursive re-coloring on the parents of @n, until it + * either hits the tree-root, or a condition where a tree-rotation is + * needed to restore the RB-Tree invariants. + */ + + n = c_rbnode_rebalance_path(n, &previous); + if (n) + c_rbnode_rebalance_terminal(n, previous); +} + +/** + * c_rbnode_unlink_stale() - remove node from tree + * @n: node to remove + * + * This removes the given node from its tree. Once unlinked, the tree is + * rebalanced. + * + * This does *NOT* reset @n to being unlinked. If you need this, use + * c_rbtree_unlink(). + */ +_c_public_ void c_rbnode_unlink_stale(CRBNode *n) { + CRBTree *t; + + c_assert(n); + c_assert(c_rbnode_is_linked(n)); + + /* + * There are three distinct cases during node removal of a tree: + * * The node has no children, in which case it can simply be removed. + * * The node has exactly one child, in which case the child displaces + * its parent. + * * The node has two children, in which case there is guaranteed to + * be a successor to the node (successor being the node ordered + * directly after it). This successor is the leftmost descendant of + * the node's right child, so it cannot have a left child of its own. + * Therefore, we can simply swap the node with its successor (including + * color) and remove the node from its new place, which will be one of + * the first two cases. + * + * Whenever the node we removed was black, we have to rebalance the + * tree. Note that this affects the actual node we _remove_, not @n (in + * case we swap it). + */ + + if (!n->left && !n->right) { + /* + * Case 1.0 + * The node has no children, it is a leaf-node and we + * can simply unlink it. If it was also black, we have + * to rebalance. + */ + t = c_rbnode_pop_root(n); + c_rbnode_swap_child(n, NULL); + c_rbnode_push_root(NULL, t); + + if (c_rbnode_is_black(n)) + c_rbnode_rebalance(c_rbnode_parent(n)); + } else if (!n->left && n->right) { + /* + * Case 1.1: + * The node has exactly one child, and it is on the + * right. The child *must* be red (otherwise, the right + * path has more black nodes than the non-existing left + * path), and the node to be removed must hence be + * black. We simply replace the node with its child, + * turning the red child black, and thus no rebalancing + * is required. + */ + t = c_rbnode_pop_root(n); + c_rbnode_swap_child(n, n->right); + c_rbnode_set_parent_and_flags(n->right, c_rbnode_parent(n), c_rbnode_flags(n->right) & ~C_RBNODE_RED); + c_rbnode_push_root(n->right, t); + } else if (n->left && !n->right) { + /* + * Case 1.2: + * The node has exactly one child, and it is on the left. Treat + * it as mirrored case of Case 1.1 (i.e., replace the node by + * its child). + */ + t = c_rbnode_pop_root(n); + c_rbnode_swap_child(n, n->left); + c_rbnode_set_parent_and_flags(n->left, c_rbnode_parent(n), c_rbnode_flags(n->left) & ~C_RBNODE_RED); + c_rbnode_push_root(n->left, t); + } else /* if (n->left && n->right) */ { + CRBNode *s, *p, *c, *next = NULL; + + /* Cache possible tree-root during tree-rotations. */ + t = c_rbnode_pop_root(n); + + /* + * Case 1.3: + * We are dealing with a full interior node with a child on + * both sides. We want to find its successor and swap it, + * then remove the node similar to Case 1. For performance + * reasons we don't perform the full swap, but skip links + * that are about to be removed, anyway. + * + * First locate the successor, remember its child and the + * parent the original node should have been linked on, + * before being removed. Then link up both the successor's + * new children and old child. + * + * s: successor + * p: parent + * c: right (and only potential) child of successor + * next: next node to rebalance on + */ + s = n->right; + if (!s->left) { + /* + * The immediate right child is the successor, + * the successor's right child remains linked + * as before. + */ + p = s; + c = s->right; + } else { + s = c_rbnode_leftmost(s); + p = c_rbnode_parent(s); + c = s->right; + + /* + * The new parent pointer of the successor's + * child is set below. + */ + c_rbtree_store(&p->left, c); + + c_rbtree_store(&s->right, n->right); + c_rbnode_set_parent_and_flags(n->right, s, c_rbnode_flags(n->right)); + } + + /* + * In both the above cases, the successor's left child + * needs to be replaced with the left child of the node + * that is being removed. + */ + c_rbtree_store(&s->left, n->left); + c_rbnode_set_parent_and_flags(n->left, s, c_rbnode_flags(n->left)); + + /* + * As in cases 1.1 and 1.0 above, if successor was a + * black leaf, we need to rebalance the tree, otherwise + * it must have a red child, so simply recolor that black + * and continue. Note that @next must be stored here, as + * the original color of the successor is forgotten below. + */ + if (c) + c_rbnode_set_parent_and_flags(c, p, c_rbnode_flags(c) & ~C_RBNODE_RED); + else + next = c_rbnode_is_black(s) ? p : NULL; + + /* + * Update the successor, to inherit the parent and color + * from the node being removed. + */ + if (c_rbnode_is_red(n)) + c_rbnode_set_parent_and_flags(s, c_rbnode_parent(n), c_rbnode_flags(s) | C_RBNODE_RED); + else + c_rbnode_set_parent_and_flags(s, c_rbnode_parent(n), c_rbnode_flags(s) & ~C_RBNODE_RED); + + /* + * Update the parent of the node being removed. Note that this + * needs to happen after the parent of the successor is set + * above, as that call would clear the root pointer, if set. + */ + c_rbnode_swap_child(n, s); + + /* Possibly restore saved tree-root. */ + c_rbnode_push_root(s, t); + + if (next) + c_rbnode_rebalance(next); + } +} diff --git a/src/c-rbtree.h b/src/c-rbtree.h new file mode 100644 index 000000000..d4d0fe45c --- /dev/null +++ b/src/c-rbtree.h @@ -0,0 +1,437 @@ +#pragma once + +/** + * Standalone Red-Black-Tree Implementation in Standard ISO-C11 + * + * This library provides an RB-Tree API, that is fully implemented in ISO-C11 + * and has no external dependencies. Furthermore, tree traversal, memory + * allocations, and key comparisons are completely controlled by the API user. + * The implementation only provides the RB-Tree specific rebalancing and + * coloring. + * + * A tree is represented by the "CRBTree" structure. It contains a *single* + * field, which is a pointer to the root node. If NULL, the tree is empty. If + * non-NULL, there is at least a single element in the tree. + * + * Each node of the tree is represented by the "CRBNode" structure. It has + * three fields. The @left and @right members can be accessed by the API user + * directly to traverse the tree. The third member is a combination of the + * parent pointer and a set of flags. + * API users are required to embed the CRBNode object into their own objects + * and then use offsetof() (i.e., container_of() and friends) to turn CRBNode + * pointers into pointers to their own structure. + */ + +#ifdef __cplusplus +extern "C" { +#endif + +#include +#include +#include + +typedef struct CRBNode CRBNode; +typedef struct CRBTree CRBTree; + +/* implementation detail */ +#define C_RBNODE_RED (0x1UL) +#define C_RBNODE_ROOT (0x2UL) +#define C_RBNODE_FLAG_MASK (0x3UL) + +/** + * struct CRBNode - Node of a Red-Black Tree + * @__parent_and_flags: internal state + * @left: left child, or NULL + * @right: right child, or NULL + * + * Each node in an RB-Tree must embed a CRBNode object. This object contains + * pointers to its left and right child, which can be freely accessed by the + * API user at any time. They are NULL, if the node does not have a left/right + * child. + * + * The @__parent_and_flags field must never be accessed directly. It encodes + * the pointer to the parent node, and the color of the node. Use the accessor + * functions instead. + * + * There is no reason to initialize a CRBNode object before linking it. + * However, if you need a boolean state that tells you whether the node is + * linked or not, you should initialize the node via c_rbnode_init() or + * C_RBNODE_INIT. + */ +struct CRBNode { + union { + unsigned long __parent_and_flags; + /* enforce >=4-byte alignment for @__parent_and_flags */ + alignas(4) unsigned char __align_dummy; + }; + CRBNode *left; + CRBNode *right; +}; + +#define C_RBNODE_INIT(_var) { .__parent_and_flags = (unsigned long)&(_var) } + +CRBNode *c_rbnode_leftmost(CRBNode *n); +CRBNode *c_rbnode_rightmost(CRBNode *n); +CRBNode *c_rbnode_leftdeepest(CRBNode *n); +CRBNode *c_rbnode_rightdeepest(CRBNode *n); +CRBNode *c_rbnode_next(CRBNode *n); +CRBNode *c_rbnode_prev(CRBNode *n); +CRBNode *c_rbnode_next_postorder(CRBNode *n); +CRBNode *c_rbnode_prev_postorder(CRBNode *n); + +void c_rbnode_link(CRBNode *p, CRBNode **l, CRBNode *n); +void c_rbnode_unlink_stale(CRBNode *n); + +/** + * struct CRBTree - Red-Black Tree + * @root: pointer to the root node, or NULL + * + * Each Red-Black Tree is rooted in an CRBTree object. This object contains a + * pointer to the root node of the tree. The API user is free to access the + * @root member at any time, and use it to traverse the tree. + * + * To initialize an RB-Tree, set it to NULL / all zero. + */ +struct CRBTree { + union { + CRBNode *root; + /* enforce >=4-byte alignment for @root */ + alignas(4) unsigned char __align_dummy; + }; +}; + +#define C_RBTREE_INIT {} + +CRBNode *c_rbtree_first(CRBTree *t); +CRBNode *c_rbtree_last(CRBTree *t); +CRBNode *c_rbtree_first_postorder(CRBTree *t); +CRBNode *c_rbtree_last_postorder(CRBTree *t); + +void c_rbtree_move(CRBTree *to, CRBTree *from); +void c_rbtree_add(CRBTree *t, CRBNode *p, CRBNode **l, CRBNode *n); + +/** + * c_rbnode_init() - mark a node as unlinked + * @n: node to operate on + * + * This marks the node @n as unlinked. The node will be set to a valid state + * that can never happen if the node is linked in a tree. Furthermore, this + * state is fully known to the implementation, and as such handled gracefully + * in all cases. + * + * You are *NOT* required to call this on your node. c_rbtree_add() can handle + * uninitialized nodes just fine. However, calling this allows to use + * c_rbnode_is_linked() to check for the state of a node. Furthermore, + * iterators and accessors can be called on initialized (yet unlinked) nodes. + * + * Use the C_RBNODE_INIT macro if you want to initialize static variables. + */ +static inline void c_rbnode_init(CRBNode *n) { + *n = (CRBNode)C_RBNODE_INIT(*n); +} + +/** + * c_rbnode_entry() - get parent container of tree node + * @_what: tree node, or NULL + * @_t: type of parent container + * @_m: member name of tree node in @_t + * + * If the tree node @_what is embedded into a surrounding structure, this will + * turn the tree node pointer @_what into a pointer to the parent container + * (using offsetof(3), or sometimes called container_of(3)). + * + * If @_what is NULL, this will also return NULL. + * + * Return: Pointer to parent container, or NULL. + */ +#define c_rbnode_entry(_what, _t, _m) \ + ((_t *)(void *)(((unsigned long)(void *)(_what) ?: \ + offsetof(_t, _m)) - offsetof(_t, _m))) + +/** + * c_rbnode_parent() - return parent pointer + * @n node to access + * + * This returns a pointer to the parent of the given node @n. If @n does not + * have a parent, NULL is returned. If @n is not linked, @n itself is returned. + * + * You should not call this on unlinked or uninitialized nodes! If you do, you + * better know its semantics. + * + * Return: Pointer to parent. + */ +static inline CRBNode *c_rbnode_parent(CRBNode *n) { + return (n->__parent_and_flags & C_RBNODE_ROOT) ? + NULL : + (void *)(n->__parent_and_flags & ~C_RBNODE_FLAG_MASK); +} + +/** + * c_rbnode_is_linked() - check whether a node is linked + * @n: node to check, or NULL + * + * This checks whether the passed node is linked. If you pass NULL, or if the + * node is not linked into a tree, this will return false. Otherwise, this + * returns true. + * + * Note that you must have either linked the node or initialized it, before + * calling this function. Never call this function on uninitialized nodes. + * Furthermore, removing a node via c_rbnode_unlink_stale() does *NOT* mark the + * node as unlinked. You have to call c_rbnode_init() yourself after removal, or + * use the c_rbnode_unlink() helper. + * + * Return: true if the node is linked, false if not. + */ +static inline _Bool c_rbnode_is_linked(CRBNode *n) { + return n && c_rbnode_parent(n) != n; +} + +/** + * c_rbnode_unlink() - safely remove node from tree and reinitialize it + * @n: node to remove, or NULL + * + * This is almost the same as c_rbnode_unlink_stale(), but extends it slightly, to be + * more convenient to use in many cases: + * - if @n is unlinked or NULL, this is a no-op + * - @n is reinitialized after being removed + */ +static inline void c_rbnode_unlink(CRBNode *n) { + if (c_rbnode_is_linked(n)) { + c_rbnode_unlink_stale(n); + c_rbnode_init(n); + } +} + +/** + * c_rbtree_init() - initialize a new RB-Tree + * @t: tree to operate on + * + * This initializes a new, empty RB-Tree. An RB-Tree must be initialized before + * any other functions are called on it. Alternatively, you can zero its memory + * or assign C_RBTREE_INIT. + */ +static inline void c_rbtree_init(CRBTree *t) { + *t = (CRBTree)C_RBTREE_INIT; +} + +/** + * c_rbtree_is_empty() - check whether an RB-tree is empty + * @t: tree to operate on + * + * This checks whether the passed RB-Tree is empty. + * + * Return: True if tree is empty, false otherwise. + */ +static inline _Bool c_rbtree_is_empty(CRBTree *t) { + return !t->root; +} + +/** + * CRBCompareFunc - compare a node to a key + * @t: tree where the node is linked to + * @k: key to compare + * @n: node to compare + * + * If you use the tree-traversal helpers (which are optional), you need to + * provide this callback so they can compare nodes in a tree to the key you + * look for. + * + * The tree @t is provided as optional context to this callback. The key you + * look for is provided as @k, the current node that should be compared to is + * provided as @n. This function should work like strcmp(), that is, return <0 + * if @key orders before @n, 0 if both compare equal, and >0 if it orders after + * @n. + */ +typedef int (*CRBCompareFunc) (CRBTree *t, void *k, CRBNode *n); + +/** + * c_rbtree_find_node() - find node + * @t: tree to search through + * @f: comparison function + * @k: key to search for + * + * This searches through @t for a node that compares equal to @k. The function + * @f must be provided by the caller, which is used to compare nodes to @k. See + * the documentation of CRBCompareFunc for details. + * + * If there are multiple entries that compare equal to @k, this will return a + * pseudo-randomly picked node. If you need stable lookup functions for trees + * where duplicate entries are allowed, you better code your own lookup. + * + * Return: Pointer to matching node, or NULL. + */ +static inline CRBNode *c_rbtree_find_node(CRBTree *t, CRBCompareFunc f, const void *k) { + CRBNode *i; + + assert(t); + assert(f); + + i = t->root; + while (i) { + int v = f(t, (void *)k, i); + if (v < 0) + i = i->left; + else if (v > 0) + i = i->right; + else + return i; + } + + return NULL; +} + +/** + * c_rbtree_find_entry() - find entry + * @_t: tree to search through + * @_f: comparison function + * @_k: key to search for + * @_s: type of the structure that embeds the nodes + * @_m: name of the node-member in type @_t + * + * This is very similar to c_rbtree_find_node(), but instead of returning a + * pointer to the CRBNode, it returns a pointer to the surrounding object. This + * object must embed the CRBNode object. The type of the surrounding object + * must be given as @_s, and the name of the embedded CRBNode member as @_m. + * + * See c_rbtree_find_node() and c_rbnode_entry() for more details. + * + * Return: Pointer to found entry, NULL if not found. + */ +#define c_rbtree_find_entry(_t, _f, _k, _s, _m) \ + c_rbnode_entry(c_rbtree_find_node((_t), (_f), (_k)), _s, _m) + +/** + * c_rbtree_find_slot() - find slot to insert new node + * @t: tree to search through + * @f: comparison function + * @k: key to search for + * @p: output storage for parent pointer + * + * This searches through @t just like c_rbtree_find_node() does. However, + * instead of returning a pointer to a node that compares equal to @k, this + * searches for a slot to insert a node with key @k. A pointer to the slot is + * returned, and a pointer to the parent of the slot is stored in @p. Both + * can be passed directly to c_rbtree_add(), together with your node to insert. + * + * If there already is a node in the tree, that compares equal to @k, this will + * return NULL and store the conflicting node in @p. In all other cases, + * this will return a pointer (non-NULL) to the empty slot to insert the node + * at. @p will point to the parent node of that slot. + * + * If you want trees that allow duplicate nodes, you better code your own + * insertion function. + * + * Return: Pointer to slot to insert node, or NULL on conflicts. + */ +static inline CRBNode **c_rbtree_find_slot(CRBTree *t, CRBCompareFunc f, const void *k, CRBNode **p) { + CRBNode **i; + + assert(t); + assert(f); + assert(p); + + i = &t->root; + *p = NULL; + while (*i) { + int v = f(t, (void *)k, *i); + *p = *i; + if (v < 0) + i = &(*i)->left; + else if (v > 0) + i = &(*i)->right; + else + return NULL; + } + + return i; +} + +/** + * c_rbtree_for_each*() - iterators + * + * The c_rbtree_for_each*() macros provide simple for-loop wrappers to iterate + * an RB-Tree. They come in a set of flavours: + * + * - "entry": This combines c_rbnode_entry() with the loop iterator, so the + * iterator always has the type of the surrounding object, rather + * than CRBNode. + * + * - "safe": The loop iterator always keeps track of the next element to + * visit. This means, you can safely modify the current element, + * while retaining loop-integrity. + * You still must not touch any other entry of the tree. Otherwise, + * the loop-iterator will be corrupted. Also remember to only + * modify the tree in a way compatible with your iterator-order. + * That is, if you use in-order iteration (default), you can unlink + * your current object, including re-balancing the tree. However, + * if you use post-order, you must not trigger a tree rebalance + * operation, since it is not an invariant of post-order iteration. + * + * - "postorder": Rather than the default in-order iteration, this iterates + * the tree in post-order. + * + * - "unlink": This unlinks the current element from the tree before the loop + * code is run. Note that the tree is not rebalanced. That is, + * you must never break out of the loop. If you do so, the tree + * is corrupted. + */ + +#define c_rbtree_for_each(_iter, _tree) \ + for (_iter = c_rbtree_first(_tree); \ + _iter; \ + _iter = c_rbnode_next(_iter)) + +#define c_rbtree_for_each_entry(_iter, _tree, _m) \ + for (_iter = c_rbnode_entry(c_rbtree_first(_tree), __typeof__(*_iter), _m); \ + _iter; \ + _iter = c_rbnode_entry(c_rbnode_next(&_iter->_m), __typeof__(*_iter), _m)) + +#define c_rbtree_for_each_safe(_iter, _safe, _tree) \ + for (_iter = c_rbtree_first(_tree), _safe = c_rbnode_next(_iter); \ + _iter; \ + _iter = _safe, _safe = c_rbnode_next(_safe)) + +#define c_rbtree_for_each_entry_safe(_iter, _safe, _tree, _m) \ + for (_iter = c_rbnode_entry(c_rbtree_first(_tree), __typeof__(*_iter), _m), \ + _safe = _iter ? c_rbnode_entry(c_rbnode_next(&_iter->_m), __typeof__(*_iter), _m) : NULL; \ + _iter; \ + _iter = _safe, \ + _safe = _safe ? c_rbnode_entry(c_rbnode_next(&_safe->_m), __typeof__(*_iter), _m) : NULL) + +#define c_rbtree_for_each_postorder(_iter, _tree) \ + for (_iter = c_rbtree_first_postorder(_tree); \ + _iter; \ + _iter = c_rbnode_next_postorder(_iter)) \ + +#define c_rbtree_for_each_entry_postorder(_iter, _tree, _m) \ + for (_iter = c_rbnode_entry(c_rbtree_first_postorder(_tree), __typeof__(*_iter), _m); \ + _iter; \ + _iter = c_rbnode_entry(c_rbnode_next_postorder(&_iter->_m), __typeof__(*_iter), _m)) + +#define c_rbtree_for_each_safe_postorder(_iter, _safe, _tree) \ + for (_iter = c_rbtree_first_postorder(_tree), _safe = c_rbnode_next_postorder(_iter); \ + _iter; \ + _iter = _safe, _safe = c_rbnode_next_postorder(_safe)) + +#define c_rbtree_for_each_entry_safe_postorder(_iter, _safe, _tree, _m) \ + for (_iter = c_rbnode_entry(c_rbtree_first_postorder(_tree), __typeof__(*_iter), _m), \ + _safe = _iter ? c_rbnode_entry(c_rbnode_next_postorder(&_iter->_m), __typeof__(*_iter), _m) : NULL; \ + _iter; \ + _iter = _safe, \ + _safe = _safe ? c_rbnode_entry(c_rbnode_next_postorder(&_safe->_m), __typeof__(*_iter), _m) : NULL) + +#define c_rbtree_for_each_safe_postorder_unlink(_iter, _safe, _tree) \ + for (_iter = c_rbtree_first_postorder(_tree), _safe = c_rbnode_next_postorder(_iter); \ + _iter ? ((*_iter = (CRBNode)C_RBNODE_INIT(*_iter)), 1) : (((_tree)->root = NULL), 0); \ + _iter = _safe, _safe = c_rbnode_next_postorder(_safe)) \ + +#define c_rbtree_for_each_entry_safe_postorder_unlink(_iter, _safe, _tree, _m) \ + for (_iter = c_rbnode_entry(c_rbtree_first_postorder(_tree), __typeof__(*_iter), _m), \ + _safe = _iter ? c_rbnode_entry(c_rbnode_next_postorder(&_iter->_m), __typeof__(*_iter), _m) : NULL; \ + _iter ? ((_iter->_m = (CRBNode)C_RBNODE_INIT(_iter->_m)), 1) : (((_tree)->root = NULL), 0); \ + _iter = _safe, \ + _safe = _safe ? c_rbnode_entry(c_rbnode_next_postorder(&_safe->_m), __typeof__(*_iter), _m) : NULL) + +#ifdef __cplusplus +} +#endif diff --git a/src/libcrbtree.sym b/src/libcrbtree.sym new file mode 100644 index 000000000..e7b801b81 --- /dev/null +++ b/src/libcrbtree.sym @@ -0,0 +1,21 @@ +LIBCRBTREE_3 { +global: + c_rbnode_leftmost; + c_rbnode_rightmost; + c_rbnode_leftdeepest; + c_rbnode_rightdeepest; + c_rbnode_next; + c_rbnode_prev; + c_rbnode_next_postorder; + c_rbnode_prev_postorder; + c_rbnode_link; + c_rbnode_unlink_stale; + c_rbtree_first; + c_rbtree_last; + c_rbtree_first_postorder; + c_rbtree_last_postorder; + c_rbtree_add; + c_rbtree_move; +local: + *; +}; diff --git a/src/meson.build b/src/meson.build new file mode 100644 index 000000000..d0b4d63ce --- /dev/null +++ b/src/meson.build @@ -0,0 +1,76 @@ +# +# target: libcrbtree.so +# + +libcrbtree_symfile = join_paths(meson.current_source_dir(), 'libcrbtree.sym') + +libcrbtree_deps = [ + dep_cstdaux, +] + +libcrbtree_private = static_library( + 'crbtree-private', + [ + 'c-rbtree.c', + ], + c_args: [ + '-fvisibility=hidden', + '-fno-common', + ], + dependencies: libcrbtree_deps, + pic: true, +) + +libcrbtree_shared = shared_library( + 'crbtree', + objects: libcrbtree_private.extract_all_objects(), + dependencies: libcrbtree_deps, + install: not meson.is_subproject(), + soversion: 0, + link_depends: libcrbtree_symfile, + link_args: [ + '-Wl,--no-undefined', + '-Wl,--version-script=@0@'.format(libcrbtree_symfile), + ], +) + +libcrbtree_dep = declare_dependency( + include_directories: include_directories('.'), + link_with: libcrbtree_private, + dependencies: libcrbtree_deps, + version: meson.project_version(), +) + +if not meson.is_subproject() + install_headers('c-rbtree.h') + + mod_pkgconfig.generate( + libraries: libcrbtree_shared, + version: meson.project_version(), + name: 'libcrbtree', + filebase: 'libcrbtree', + description: project_description, + ) +endif + +# +# target: test-* +# + +test_api = executable('test-api', ['test-api.c'], link_with: libcrbtree_shared) +test('API Symbol Visibility', test_api) + +test_basic = executable('test-basic', ['test-basic.c'], dependencies: libcrbtree_dep) +test('Basic API Behavior', test_basic) + +test_map = executable('test-map', ['test-map.c'], dependencies: libcrbtree_dep) +test('Generic Map', test_map) + +test_misc = executable('test-misc', ['test-misc.c'], dependencies: libcrbtree_dep) +test('Miscellaneous', test_misc) + +test_parallel = executable('test-parallel', ['test-parallel.c'], dependencies: libcrbtree_dep) +test('Lockless Parallel Readers', test_parallel) + +test_posix = executable('test-posix', ['test-posix.c'], dependencies: libcrbtree_dep) +test('Posix tsearch(3p) Comparison', test_posix) diff --git a/src/test-api.c b/src/test-api.c new file mode 100644 index 000000000..295f6b9b4 --- /dev/null +++ b/src/test-api.c @@ -0,0 +1,107 @@ +/* + * Tests for Public API + * This test, unlikely the others, is linked against the real, distributed, + * shared library. Its sole purpose is to test for symbol availability. + */ + +#undef NDEBUG +#include +#include +#include +#include +#include "c-rbtree.h" + +typedef struct TestNode { + CRBNode rb; +} TestNode; + +static void test_api(void) { + CRBTree t = C_RBTREE_INIT, t2 = C_RBTREE_INIT; + CRBNode *i, *is, n = C_RBNODE_INIT(n), m = C_RBNODE_INIT(m); + TestNode *ie, *ies; + + assert(c_rbtree_is_empty(&t)); + assert(!c_rbnode_is_linked(&n)); + assert(!c_rbnode_entry(NULL, TestNode, rb)); + + /* init, is_linked, add, link, {unlink{,_stale}} */ + + c_rbtree_add(&t, NULL, &t.root, &n); + assert(c_rbnode_is_linked(&n)); + + c_rbnode_link(&n, &n.left, &m); + assert(c_rbnode_is_linked(&m)); + + c_rbnode_unlink(&m); + assert(!c_rbnode_is_linked(&m)); + + c_rbtree_add(&t, NULL, &t.root, &n); + assert(c_rbnode_is_linked(&n)); + + c_rbnode_link(&n, &n.left, &m); + assert(c_rbnode_is_linked(&m)); + + c_rbnode_unlink_stale(&m); + assert(c_rbnode_is_linked(&m)); /* @m wasn't touched */ + + c_rbnode_init(&n); + assert(!c_rbnode_is_linked(&n)); + + c_rbnode_init(&m); + assert(!c_rbnode_is_linked(&m)); + + c_rbtree_init(&t); + assert(c_rbtree_is_empty(&t)); + + /* move */ + + c_rbtree_move(&t2, &t); + + /* first, last, leftmost, rightmost, next, prev */ + + assert(!c_rbtree_first(&t)); + assert(!c_rbtree_last(&t)); + assert(&n == c_rbnode_leftmost(&n)); + assert(&n == c_rbnode_rightmost(&n)); + assert(!c_rbnode_next(&n)); + assert(!c_rbnode_prev(&n)); + + /* postorder traversal */ + + assert(!c_rbtree_first_postorder(&t)); + assert(!c_rbtree_last_postorder(&t)); + assert(&n == c_rbnode_leftdeepest(&n)); + assert(&n == c_rbnode_rightdeepest(&n)); + assert(!c_rbnode_next_postorder(&n)); + assert(!c_rbnode_prev_postorder(&n)); + + /* iterators */ + + c_rbtree_for_each(i, &t) + assert(!i); + c_rbtree_for_each_safe(i, is, &t) + assert(!i); + c_rbtree_for_each_entry(ie, &t, rb) + assert(!ie); + c_rbtree_for_each_entry_safe(ie, ies, &t, rb) + assert(!ie); + + c_rbtree_for_each_postorder(i, &t) + assert(!i); + c_rbtree_for_each_safe_postorder(i, is, &t) + assert(!i); + c_rbtree_for_each_entry_postorder(ie, &t, rb) + assert(!ie); + c_rbtree_for_each_entry_safe_postorder(ie, ies, &t, rb) + assert(!ie); + + c_rbtree_for_each_safe_postorder_unlink(i, is, &t) + assert(!i); + c_rbtree_for_each_entry_safe_postorder_unlink(ie, ies, &t, rb) + assert(!ie); +} + +int main(int argc, char **argv) { + test_api(); + return 0; +} diff --git a/src/test-basic.c b/src/test-basic.c new file mode 100644 index 000000000..8fee64682 --- /dev/null +++ b/src/test-basic.c @@ -0,0 +1,239 @@ +/* + * Tests for Basic Tree Operations + * This test does some basic tree operations and verifies their correctness. It + * validates the RB-Tree invariants after each operation, to guarantee the + * stability of the tree. + * + * For testing purposes, we use the memory address of a node as its key, and + * order nodes in ascending order. + */ + +#undef NDEBUG +#include +#include +#include +#include +#include +#include +#include "c-rbtree.h" +#include "c-rbtree-private.h" + +static size_t validate(CRBTree *t) { + unsigned int i_black, n_black; + CRBNode *n, *p, *o; + size_t count = 0; + + c_assert(t); + c_assert(!t->root || c_rbnode_is_black(t->root)); + + /* traverse to left-most child, count black nodes */ + i_black = 0; + n = t->root; + while (n && n->left) { + if (c_rbnode_is_black(n)) + ++i_black; + n = n->left; + } + n_black = i_black; + + /* + * Traverse tree and verify correctness: + * 1) A node is either red or black + * 2) The root is black + * 3) All leaves are black + * 4) Every red node must have two black child nodes + * 5) Every path to a leaf contains the same number of black nodes + * + * Note that NULL nodes are considered black, which is why we don't + * check for 3). + */ + o = NULL; + while (n) { + ++count; + + /* verify natural order */ + c_assert(n > o); + o = n; + + /* verify consistency */ + c_assert(!n->right || c_rbnode_parent(n->right) == n); + c_assert(!n->left || c_rbnode_parent(n->left) == n); + + /* verify 2) */ + if (!c_rbnode_parent(n)) + c_assert(c_rbnode_is_black(n)); + + if (c_rbnode_is_red(n)) { + /* verify 4) */ + c_assert(!n->left || c_rbnode_is_black(n->left)); + c_assert(!n->right || c_rbnode_is_black(n->right)); + } else { + /* verify 1) */ + c_assert(c_rbnode_is_black(n)); + } + + /* verify 5) */ + if (!n->left && !n->right) + c_assert(i_black == n_black); + + /* get next node */ + if (n->right) { + n = n->right; + if (c_rbnode_is_black(n)) + ++i_black; + + while (n->left) { + n = n->left; + if (c_rbnode_is_black(n)) + ++i_black; + } + } else { + while ((p = c_rbnode_parent(n)) && n == p->right) { + n = p; + if (c_rbnode_is_black(p->right)) + --i_black; + } + + n = p; + if (p && c_rbnode_is_black(p->left)) + --i_black; + } + } + + return count; +} + +static void insert(CRBTree *t, CRBNode *n) { + CRBNode **i, *p; + + c_assert(t); + c_assert(n); + c_assert(!c_rbnode_is_linked(n)); + + i = &t->root; + p = NULL; + while (*i) { + p = *i; + if (n < *i) { + i = &(*i)->left; + } else { + c_assert(n > *i); + i = &(*i)->right; + } + } + + c_rbtree_add(t, p, i, n); +} + +static void shuffle(CRBNode **nodes, size_t n_memb) { + unsigned int i, j; + CRBNode *t; + + for (i = 0; i < n_memb; ++i) { + j = rand() % n_memb; + t = nodes[j]; + nodes[j] = nodes[i]; + nodes[i] = t; + } +} + +static void test_shuffle(void) { + CRBNode *nodes[512]; + CRBTree t = {}; + unsigned int i, j; + size_t n; + + /* allocate and initialize all nodes */ + for (i = 0; i < sizeof(nodes) / sizeof(*nodes); ++i) { + nodes[i] = malloc(sizeof(*nodes[i])); + c_assert(nodes[i]); + c_rbnode_init(nodes[i]); + } + + /* shuffle nodes and validate *empty* tree */ + shuffle(nodes, sizeof(nodes) / sizeof(*nodes)); + n = validate(&t); + c_assert(n == 0); + + /* add all nodes and validate after each insertion */ + for (i = 0; i < sizeof(nodes) / sizeof(*nodes); ++i) { + insert(&t, nodes[i]); + n = validate(&t); + c_assert(n == i + 1); + } + + /* shuffle nodes again */ + shuffle(nodes, sizeof(nodes) / sizeof(*nodes)); + + /* remove all nodes (in different order) and validate on each round */ + for (i = 0; i < sizeof(nodes) / sizeof(*nodes); ++i) { + c_rbnode_unlink(nodes[i]); + n = validate(&t); + c_assert(n == sizeof(nodes) / sizeof(*nodes) - i - 1); + } + + /* shuffle nodes and validate *empty* tree again */ + shuffle(nodes, sizeof(nodes) / sizeof(*nodes)); + n = validate(&t); + c_assert(n == 0); + + /* add all nodes again */ + for (i = 0; i < sizeof(nodes) / sizeof(*nodes); ++i) { + insert(&t, nodes[i]); + n = validate(&t); + c_assert(n == i + 1); + } + + /* 4 times, remove half of the nodes and add them again */ + for (j = 0; j < 4; ++j) { + /* shuffle nodes again */ + shuffle(nodes, sizeof(nodes) / sizeof(*nodes)); + + /* remove half of the nodes */ + for (i = 0; i < sizeof(nodes) / sizeof(*nodes) / 2; ++i) { + c_rbnode_unlink(nodes[i]); + n = validate(&t); + c_assert(n == sizeof(nodes) / sizeof(*nodes) - i - 1); + } + + /* shuffle the removed half */ + shuffle(nodes, sizeof(nodes) / sizeof(*nodes) / 2); + + /* add the removed half again */ + for (i = 0; i < sizeof(nodes) / sizeof(*nodes) / 2; ++i) { + insert(&t, nodes[i]); + n = validate(&t); + c_assert(n == sizeof(nodes) / sizeof(*nodes) / 2 + i + 1); + } + } + + /* shuffle nodes again */ + shuffle(nodes, sizeof(nodes) / sizeof(*nodes)); + + /* remove all */ + for (i = 0; i < sizeof(nodes) / sizeof(*nodes); ++i) { + c_rbnode_unlink(nodes[i]); + n = validate(&t); + c_assert(n == sizeof(nodes) / sizeof(*nodes) - i - 1); + } + + /* free nodes again */ + for (i = 0; i < sizeof(nodes) / sizeof(*nodes); ++i) + free(nodes[i]); +} + +int main(int argc, char **argv) { + unsigned int i; + + /* we want stable tests, so use fixed seed */ + srand(0xdeadbeef); + + /* + * The tests are pseudo random; run them multiple times, each run will + * have different orders and thus different results. + */ + for (i = 0; i < 4; ++i) + test_shuffle(); + + return 0; +} diff --git a/src/test-map.c b/src/test-map.c new file mode 100644 index 000000000..48a300d6f --- /dev/null +++ b/src/test-map.c @@ -0,0 +1,277 @@ +/* + * RB-Tree based Map + * This implements a basic Map between integer keys and objects. It uses the + * lookup and insertion helpers, rather than open-coding it. + */ + +#undef NDEBUG +#include +#include +#include +#include +#include +#include +#include "c-rbtree.h" +#include "c-rbtree-private.h" + +typedef struct { + unsigned long key; + unsigned int marker; + CRBNode rb; +} Node; + +#define node_from_rb(_rb) ((Node *)((char *)(_rb) - offsetof(Node, rb))) + +static int test_compare(CRBTree *t, void *k, CRBNode *n) { + unsigned long key = (unsigned long)k; + Node *node = node_from_rb(n); + + return (key < node->key) ? -1 : (key > node->key) ? 1 : 0; +} + +static void shuffle(Node **nodes, size_t n_memb) { + unsigned int i, j; + Node *t; + + for (i = 0; i < n_memb; ++i) { + j = rand() % n_memb; + t = nodes[j]; + nodes[j] = nodes[i]; + nodes[i] = t; + } +} + +static void test_map(void) { + CRBNode **slot, *p, *safe_p; + CRBTree t = {}; + Node *n, *safe_n, *nodes[2048]; + unsigned long i, v; + + /* allocate and initialize all nodes */ + for (i = 0; i < sizeof(nodes) / sizeof(*nodes); ++i) { + nodes[i] = malloc(sizeof(*nodes[i])); + c_assert(nodes[i]); + nodes[i]->key = i; + nodes[i]->marker = 0; + c_rbnode_init(&nodes[i]->rb); + } + + /* shuffle nodes */ + shuffle(nodes, sizeof(nodes) / sizeof(*nodes)); + + /* add all nodes, and verify that each node is linked */ + for (i = 0; i < sizeof(nodes) / sizeof(*nodes); ++i) { + c_assert(!c_rbnode_is_linked(&nodes[i]->rb)); + c_assert(!c_rbtree_find_entry(&t, test_compare, (void *)nodes[i]->key, Node, rb)); + + slot = c_rbtree_find_slot(&t, test_compare, (void *)nodes[i]->key, &p); + c_assert(slot); + c_rbtree_add(&t, p, slot, &nodes[i]->rb); + + c_assert(c_rbnode_is_linked(&nodes[i]->rb)); + c_assert(nodes[i] == c_rbtree_find_entry(&t, test_compare, (void *)nodes[i]->key, Node, rb)); + } + + /* verify in-order traversal works */ + i = 0; + v = 0; + for (p = c_rbtree_first(&t); p; p = c_rbnode_next(p)) { + ++i; + c_assert(!node_from_rb(p)->marker); + node_from_rb(p)->marker = 1; + + c_assert(v <= node_from_rb(p)->key); + v = node_from_rb(p)->key; + + c_assert(!c_rbnode_next(p) || p == c_rbnode_prev(c_rbnode_next(p))); + } + c_assert(i == sizeof(nodes) / sizeof(*nodes)); + + /* verify reverse in-order traversal works */ + i = 0; + v = -1; + for (p = c_rbtree_last(&t); p; p = c_rbnode_prev(p)) { + ++i; + c_assert(node_from_rb(p)->marker); + node_from_rb(p)->marker = 0; + + c_assert(v >= node_from_rb(p)->key); + v = node_from_rb(p)->key; + } + c_assert(i == sizeof(nodes) / sizeof(*nodes)); + + /* verify post-order traversal works */ + i = 0; + for (p = c_rbtree_first_postorder(&t); p; p = c_rbnode_next_postorder(p)) { + ++i; + c_assert(!node_from_rb(p)->marker); + c_assert(!c_rbnode_parent(p) || !node_from_rb(c_rbnode_parent(p))->marker); + c_assert(!p->left || node_from_rb(p->left)->marker); + c_assert(!p->right || node_from_rb(p->right)->marker); + node_from_rb(p)->marker = 1; + + c_assert(!c_rbnode_next_postorder(p) || p == c_rbnode_prev_postorder(c_rbnode_next_postorder(p))); + } + c_assert(i == sizeof(nodes) / sizeof(*nodes)); + + /* verify pre-order (inverse post-order) traversal works */ + i = 0; + for (p = c_rbtree_last_postorder(&t); p; p = c_rbnode_prev_postorder(p)) { + ++i; + c_assert(node_from_rb(p)->marker); + c_assert(!c_rbnode_parent(p) || !node_from_rb(c_rbnode_parent(p))->marker); + c_assert(!p->left || node_from_rb(p->left)->marker); + c_assert(!p->right || node_from_rb(p->right)->marker); + node_from_rb(p)->marker = 0; + } + c_assert(i == sizeof(nodes) / sizeof(*nodes)); + + /* verify in-order traversal works via helper */ + i = 0; + v = 0; + c_rbtree_for_each(p, &t) { + ++i; + c_assert(!node_from_rb(p)->marker); + node_from_rb(p)->marker = 1; + + c_assert(v <= node_from_rb(p)->key); + v = node_from_rb(p)->key; + + c_assert(!c_rbnode_next(p) || p == c_rbnode_prev(c_rbnode_next(p))); + } + c_assert(i == sizeof(nodes) / sizeof(*nodes)); + + /* verify in-order traversal works via entry-helper */ + i = 0; + v = 0; + c_rbtree_for_each_entry(n, &t, rb) { + ++i; + c_assert(n->marker); + n->marker = 0; + + c_assert(v <= n->key); + v = n->key; + } + c_assert(i == sizeof(nodes) / sizeof(*nodes)); + + /* verify post-order traversal works via helper */ + i = 0; + c_rbtree_for_each_postorder(p, &t) { + ++i; + c_assert(!node_from_rb(p)->marker); + c_assert(!c_rbnode_parent(p) || !node_from_rb(c_rbnode_parent(p))->marker); + c_assert(!p->left || node_from_rb(p->left)->marker); + c_assert(!p->right || node_from_rb(p->right)->marker); + node_from_rb(p)->marker = 1; + + c_assert(!c_rbnode_next_postorder(p) || p == c_rbnode_prev_postorder(c_rbnode_next_postorder(p))); + } + c_assert(i == sizeof(nodes) / sizeof(*nodes)); + + /* verify post-order traversal works via entry-helper */ + i = 0; + c_rbtree_for_each_entry_postorder(n, &t, rb) { + ++i; + c_assert(n->marker); + c_assert(!c_rbnode_parent(&n->rb) || node_from_rb(c_rbnode_parent(&n->rb))->marker); + c_assert(!n->rb.left || !node_from_rb(n->rb.left)->marker); + c_assert(!n->rb.right || !node_from_rb(n->rb.right)->marker); + n->marker = 0; + } + c_assert(i == sizeof(nodes) / sizeof(*nodes)); + + /* shuffle nodes again */ + shuffle(nodes, sizeof(nodes) / sizeof(*nodes)); + + /* remove all nodes (in different order) */ + for (i = 0; i < sizeof(nodes) / sizeof(*nodes); ++i) { + c_assert(c_rbnode_is_linked(&nodes[i]->rb)); + c_assert(nodes[i] == c_rbtree_find_entry(&t, test_compare, (void *)nodes[i]->key, Node, rb)); + + c_rbnode_unlink(&nodes[i]->rb); + + c_assert(!c_rbnode_is_linked(&nodes[i]->rb)); + c_assert(!c_rbtree_find_entry(&t, test_compare, (void *)nodes[i]->key, Node, rb)); + } + c_assert(c_rbtree_is_empty(&t)); + + /* add all nodes again */ + for (i = 0; i < sizeof(nodes) / sizeof(*nodes); ++i) { + slot = c_rbtree_find_slot(&t, test_compare, (void *)nodes[i]->key, &p); + c_assert(slot); + c_rbtree_add(&t, p, slot, &nodes[i]->rb); + } + + /* remove all nodes via helper */ + i = 0; + c_rbtree_for_each_safe(p, safe_p, &t) { + ++i; + c_rbnode_unlink(p); + } + c_assert(i == sizeof(nodes) / sizeof(*nodes)); + c_assert(c_rbtree_is_empty(&t)); + + /* add all nodes again */ + for (i = 0; i < sizeof(nodes) / sizeof(*nodes); ++i) { + slot = c_rbtree_find_slot(&t, test_compare, (void *)nodes[i]->key, &p); + c_assert(slot); + c_rbtree_add(&t, p, slot, &nodes[i]->rb); + } + + /* remove all nodes via entry-helper */ + i = 0; + c_rbtree_for_each_entry_safe(n, safe_n, &t, rb) { + ++i; + c_rbnode_unlink(&n->rb); + } + c_assert(i == sizeof(nodes) / sizeof(*nodes)); + c_assert(c_rbtree_is_empty(&t)); + + /* add all nodes again */ + for (i = 0; i < sizeof(nodes) / sizeof(*nodes); ++i) { + slot = c_rbtree_find_slot(&t, test_compare, (void *)nodes[i]->key, &p); + c_assert(slot); + c_rbtree_add(&t, p, slot, &nodes[i]->rb); + } + + /* remove all nodes via unlink-helper */ + i = 0; + c_rbtree_for_each_safe_postorder_unlink(p, safe_p, &t) { + ++i; + c_assert(!c_rbnode_is_linked(p)); + } + c_assert(i == sizeof(nodes) / sizeof(*nodes)); + c_assert(c_rbtree_is_empty(&t)); + + /* add all nodes again */ + for (i = 0; i < sizeof(nodes) / sizeof(*nodes); ++i) { + slot = c_rbtree_find_slot(&t, test_compare, (void *)nodes[i]->key, &p); + c_assert(slot); + c_rbtree_add(&t, p, slot, &nodes[i]->rb); + } + + /* remove all nodes via entry-unlink-helper */ + i = 0; + c_rbtree_for_each_entry_safe_postorder_unlink(n, safe_n, &t, rb) { + ++i; + c_assert(!c_rbnode_is_linked(&n->rb)); + } + c_assert(i == sizeof(nodes) / sizeof(*nodes)); + c_assert(c_rbtree_is_empty(&t)); + + /* free nodes again */ + for (i = 0; i < sizeof(nodes) / sizeof(*nodes); ++i) { + c_assert(!nodes[i]->marker); + free(nodes[i]); + } + + c_assert(c_rbtree_is_empty(&t)); +} + +int main(int argc, char **argv) { + /* we want stable tests, so use fixed seed */ + srand(0xdeadbeef); + + test_map(); + return 0; +} diff --git a/src/test-misc.c b/src/test-misc.c new file mode 100644 index 000000000..ac2717cdc --- /dev/null +++ b/src/test-misc.c @@ -0,0 +1,66 @@ +/* + * Tests for Miscellaneous Tree Operations + * This test contains all of the minor tests that did not fit anywhere else. + */ + +#undef NDEBUG +#include +#include +#include +#include +#include +#include "c-rbtree.h" +#include "c-rbtree-private.h" + +static void insert(CRBTree *t, CRBNode *n) { + CRBNode **i, *p; + + c_assert(t); + c_assert(n); + c_assert(!c_rbnode_is_linked(n)); + + i = &t->root; + p = NULL; + while (*i) { + p = *i; + if (n < *i) { + i = &(*i)->left; + } else { + c_assert(n > *i); + i = &(*i)->right; + } + } + + c_rbtree_add(t, p, i, n); +} + +static void test_move(void) { + CRBTree t1 = C_RBTREE_INIT, t2 = C_RBTREE_INIT; + CRBNode n[128]; + unsigned int i; + + for (i = 0; i < sizeof(n) / sizeof(*n); ++i) { + n[i] = (CRBNode)C_RBNODE_INIT(n[i]); + insert(&t1, &n[i]); + } + + c_assert(!c_rbtree_is_empty(&t1)); + c_assert(c_rbtree_is_empty(&t2)); + + c_rbtree_move(&t2, &t1); + + c_assert(c_rbtree_is_empty(&t1)); + c_assert(!c_rbtree_is_empty(&t2)); + + while (t2.root) + c_rbnode_unlink(t2.root); + + c_assert(c_rbtree_is_empty(&t1)); + c_assert(c_rbtree_is_empty(&t2)); +} + +int main(int argc, char **argv) { + test_move(); + + return 0; +} diff --git a/src/test-parallel.c b/src/test-parallel.c new file mode 100644 index 000000000..1388722bf --- /dev/null +++ b/src/test-parallel.c @@ -0,0 +1,384 @@ +/* + * Tests Lockless Tree Lookups + * The RB-Tree implementation supports lockless tree lookups on shared + * data-structures. While it does not guarantee correct results (you might skip + * entire sub-trees), it does guarantee valid behavior (the traversal is + * guaranteed to end and produce some valid result). + * This test uses ptrace to run tree operations step-by-step in a separate + * process, and after each instruction verify the pseudo-validity of the tree. + * This means, a tree must only have valid left/right pointers (or NULL), and + * must not contain any loops in those pointers. + * + * This test runs two processes with a shared context and tree. It runs them in + * this order: + * + * | PARENT | CHILD | + * +--------------------+-----------+ + * ~ ~ ~ + * test_parent_start + * test_child1 + * test_parent_middle + * test_child2 + * test_parent_end + * ~ ~ ~ + * +--------------------+-----------+ + * + * Additionally, on each TRAP of CHILD, the parent runs test_parent_step(). The + * ptrace infrastructure generates a TRAP after each instruction, so this test + * is very CPU aggressive in the parent. + */ + +#undef NDEBUG +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include "c-rbtree.h" +#include "c-rbtree-private.h" + +typedef struct { + CRBNode rb; + bool visited; +} TestNode; + +typedef struct { + size_t mapsize; + char *map; + CRBTree *tree; + TestNode *node_mem; + CRBNode **nodes; + CRBNode **cache; + size_t n_nodes; +} TestContext; + +/* avoid ptrace-sigstop by using SIGKILL errors in traced children */ +#define child_assert(_expr) ((void)(!!(_expr) ? 1 : (raise(SIGKILL), 0))) + +static int compare(CRBTree *t, void *k, CRBNode *n) { + return (char *)n - (char *)k; +} + +static void shuffle(CRBNode **nodes, size_t n_memb) { + unsigned int i, j; + CRBNode *t; + + for (i = 0; i < n_memb; ++i) { + j = rand() % n_memb; + t = nodes[j]; + nodes[j] = nodes[i]; + nodes[i] = t; + } +} + +static void toggle_visit(CRBNode *n, bool set) { + c_rbnode_entry(n, TestNode, rb)->visited = set; +} + +static bool fetch_visit(CRBNode *n) { + return c_rbnode_entry(n, TestNode, rb)->visited; +} + +static void test_child1(TestContext *ctx) { + CRBNode *p, **slot; + size_t i; + + for (i = 0; i < ctx->n_nodes; ++i) { + child_assert(!c_rbnode_is_linked(ctx->nodes[i])); + slot = c_rbtree_find_slot(ctx->tree, compare, ctx->nodes[i], &p); + c_rbtree_add(ctx->tree, p, slot, ctx->nodes[i]); + } +} + +static void test_child2(TestContext *ctx) { + size_t i; + + for (i = 0; i < ctx->n_nodes; ++i) { + child_assert(c_rbnode_is_linked(ctx->nodes[i])); + c_rbnode_unlink(ctx->nodes[i]); + } +} + +static void test_parent_start(TestContext *ctx) { + size_t i; + + /* + * Generate a tree with @n_nodes entries. We store the entries in + * @ctx->node_mem, generate a randomized access-map in @ctx->nodes + * (i.e., an array of pointers to entries in @ctx->node_mem, but in + * random order), and a temporary cache for free use in the parent. + * + * All this is stored in a MAP_SHARED memory region so it is equivalent + * in child and parent. + */ + + ctx->n_nodes = 32; + ctx->mapsize = sizeof(CRBTree); + ctx->mapsize += ctx->n_nodes * sizeof(TestNode); + ctx->mapsize += ctx->n_nodes * sizeof(CRBNode*); + ctx->mapsize += ctx->n_nodes * sizeof(CRBNode*); + + ctx->map = mmap(NULL, ctx->mapsize, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANON, -1, 0); + c_assert(ctx->map != MAP_FAILED); + + ctx->tree = (void *)ctx->map; + ctx->node_mem = (void *)(ctx->tree + 1); + ctx->nodes = (void *)(ctx->node_mem + ctx->n_nodes); + ctx->cache = (void *)(ctx->nodes + ctx->n_nodes); + + for (i = 0; i < ctx->n_nodes; ++i) { + ctx->nodes[i] = &ctx->node_mem[i].rb; + c_rbnode_init(ctx->nodes[i]); + } + + shuffle(ctx->nodes, ctx->n_nodes); +} + +static void test_parent_middle(TestContext *ctx) { + size_t i; + + shuffle(ctx->nodes, ctx->n_nodes); + + for (i = 0; i < ctx->n_nodes; ++i) + child_assert(c_rbnode_is_linked(ctx->nodes[i])); +} + +static void test_parent_end(TestContext *ctx) { + size_t i; + int r; + + for (i = 0; i < ctx->n_nodes; ++i) + c_assert(!c_rbnode_is_linked(ctx->nodes[i])); + + r = munmap(ctx->map, ctx->mapsize); + c_assert(r >= 0); +} + +static void test_parent_step(TestContext *ctx) { + size_t i, i_level; + CRBNode *n, *p; + + n = ctx->tree->root; + i_level = 0; + + while (n) { + /* verify that we haven't visited @n, yet */ + c_assert(!fetch_visit(n)); + + /* verify @n is a valid node */ + for (i = 0; i < ctx->n_nodes; ++i) + if (n == ctx->nodes[i]) + break; + c_assert(i < ctx->n_nodes); + + /* pre-order traversal and marker for cycle detection */ + if (n->left) { + toggle_visit(n, true); + ctx->cache[i_level++] = n; + n = n->left; + } else if (n->right) { + toggle_visit(n, true); + ctx->cache[i_level++] = n; + n = n->right; + } else { + while (i_level > 0) { + p = ctx->cache[i_level - 1]; + if (p->right && n != p->right) { + n = p->right; + break; + } + --i_level; + n = p; + toggle_visit(n, false); + } + if (i_level == 0) + break; + } + } +} + +static int test_parallel_child(TestContext *ctx) { + int r; + + /* + * Make parent trace us and enter stopped state. In case of EPERM, we + * are either ptraced already, or are not privileged to run ptrace. + * Exit via 0xdf to signal this condition to our parent. + */ + r = ptrace(PTRACE_TRACEME, 0, 0, 0); + if (r < 0 && errno == EPERM) + return 0xdf; + + child_assert(r >= 0); + + /* SIGUSR1 to signal readiness */ + r = raise(SIGUSR1); + child_assert(r >= 0); + + /* run first part */ + test_child1(ctx); + + /* SIGURG to cause re-shuffle */ + r = raise(SIGURG); + child_assert(r >= 0); + + /* run second part */ + test_child2(ctx); + + /* SIGUSR2 to signal end */ + r = raise(SIGUSR2); + child_assert(r >= 0); + + /* return known exit code to parent */ + return 0xef; +} + +static int test_parallel(void) { + TestContext ctx = {}; + int r, pid, status; + uint64_t n_instr, n_event; + + /* create shared area for tree verification */ + test_parent_start(&ctx); + + /* run child */ + pid = fork(); + c_assert(pid >= 0); + if (pid == 0) { + r = test_parallel_child(&ctx); + _exit(r); + } + + /* + * After setup, the child immediately enters TRACE-operation and raises + * SIGUSR1. Once continued, the child performs the pre-configured tree + * operations. When done, it raises SIGUSR2, and then exits. + * + * Here in the parent we catch all trace-stops of the child via waitpid + * until we get no more such stop-events. Based on the stop-event we + * get, we verify child-state, STEP it, or perform other state tracking. + * We repeat this as long as we catch trace-stops from the child. + */ + n_instr = 0; + n_event = 0; + for (r = waitpid(pid, &status, 0); + r == pid && WIFSTOPPED(status); + r = waitpid(pid, &status, 0)) { + + switch (WSTOPSIG(status)) { + case SIGUSR1: + n_event |= 0x1; + + /* step child */ + r = ptrace(PTRACE_SINGLESTEP, pid, 0, 0); + + /* + * Some architectures (e.g., armv7hl) do not implement + * SINGLESTEP, but return EIO. Skip the entire test in + * this case. + */ + if (r < 0 && errno == EIO) + return 77; + + c_assert(r >= 0); + break; + + case SIGURG: + n_event |= 0x2; + test_parent_middle(&ctx); + + /* step child */ + r = ptrace(PTRACE_SINGLESTEP, pid, 0, 0); + c_assert(r >= 0); + break; + + case SIGUSR2: + n_event |= 0x4; + test_parent_end(&ctx); + + /* continue child */ + r = ptrace(PTRACE_CONT, pid, 0, 0); + c_assert(r >= 0); + break; + + case SIGTRAP: + ++n_instr; + test_parent_step(&ctx); + + /* step repeatedly as long as we get SIGTRAP */ + r = ptrace(PTRACE_SINGLESTEP, pid, 0, 0); + c_assert(r >= 0); + break; + + default: + c_assert(0); + break; + } + } + + /* verify our child exited cleanly */ + c_assert(r == pid); + c_assert(!!WIFEXITED(status)); + + /* + * 0xdf is signalled if ptrace is not allowed or we are already + * ptraced. In this case we skip the test. + * + * 0xef is signalled on success. + * + * In any other case something went wobbly and we should fail hard. + */ + switch (WEXITSTATUS(status)) { + case 0xef: + break; + case 0xdf: + return 77; + default: + c_assert(0); + break; + } + + /* verify we hit all child states */ + c_assert(n_event & 0x1); + c_assert(n_event & 0x2); + c_assert(n_event & 0x4); + c_assert(n_instr > 0); + + return 0; +} + +int main(int argc, char **argv) { + unsigned int i; + int r; + + if (!getenv("CRBTREE_TEST_PTRACE")) + return 77; + + /* we want stable tests, so use fixed seed */ + srand(0xdeadbeef); + + /* + * The tests are pseudo random; run them multiple times, each run will + * have different orders and thus different results. + */ + for (i = 0; i < 4; ++i) { + r = test_parallel(); + if (r) + return r; + } + + return 0; +} diff --git a/src/test-posix.c b/src/test-posix.c new file mode 100644 index 000000000..ee100ec52 --- /dev/null +++ b/src/test-posix.c @@ -0,0 +1,270 @@ +/* + * Tests to compare against POSIX RB-Trees + * POSIX provides balanced binary trees via the tsearch(3p) API. glibc + * implements them as RB-Trees. This file compares the performance of both. + * + * The semantic differences are: + * + * o The tsearch(3p) API does memory allocation of node structures itself, + * rather than allowing the caller to embed it. + * + * o The c-rbtree API exposes the tree structure, allowing efficient tree + * operations. Furthermore, it allows tree creation/deletion without taking + * the expensive insert/remove paths. For instance, imagine you want to + * create an rb-tree from a set of objects you have. With c-rbtree you can + * do that without a single rotation or tree-restructuring in O(n), while + * tsearch(3p) requires O(n log n). + * + * o The tsearch(3p) API requires one pointer-chase on each node access. This + * is inherent to the design as it does not allow embedding the node in the + * parent object. This slows down the API considerably. + * + * o The tsearch(3p) API does not allow multiple entries with the same key. + * + * o The tsearch(3p) API requires node lookup during removal. This does not + * affect the worst-case runtime, but does reduce absolute performance. + * + * o The tsearch(3p) API does not allow O(1) tests whether a node is linked + * or not. It requires a separate state variable per node. + * + * o The tsearch(3p) API does not allow walking the tree with context. The + * only accessor twalk(3p) provides no tree context nor caller context to + * the callback function. + * + * o The glibc implementation of tsearch(3p) uses RB-Trees without parent + * pointers. Hence, tree traversal requires back-tracking. Performance is + * similar, but it reduces memory consumption (though, at the same time it + * stores the key pointer, and allocates the node on the heap, so overall + * the memory consumption is higher still). + * But the more important issue is, a node itself is not enough context as + * tree iterator, but the full depth parent pointers are needed as well. + */ + +#undef NDEBUG +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include "c-rbtree.h" +#include "c-rbtree-private.h" + +typedef struct { + int key; + CRBNode rb; +} Node; + +#define node_from_rb(_rb) ((Node *)((char *)(_rb) - offsetof(Node, rb))) +#define node_from_key(_key) ((Node *)((char *)(_key) - offsetof(Node, key))) + +static void shuffle(Node **nodes, size_t n_memb) { + unsigned int i, j; + Node *t; + + for (i = 0; i < n_memb; ++i) { + j = rand() % n_memb; + t = nodes[j]; + nodes[j] = nodes[i]; + nodes[i] = t; + } +} + +static int compare(CRBTree *t, void *k, CRBNode *n) { + int key = (int)(unsigned long)k; + Node *node = node_from_rb(n); + + return key - node->key; +} + +static uint64_t now(void) { + struct timespec ts; + int r; + + r = clock_gettime(CLOCK_THREAD_CPUTIME_ID, &ts); + c_assert(r >= 0); + return ts.tv_sec * UINT64_C(1000000000) + ts.tv_nsec; +} + +/* + * POSIX tsearch(3p) based RB-Tree API + * + * This implements a small rb-tree API alongside c-rbtree but based on + * tsearch(3p) and friends. + * + * Note that we don't care for OOM here, nor do we implement all the same + * features as c-rbtree. This just does basic insertion, removal, and lookup + * without any conflict detection. + * + * This also hard-codes 'Node' as object type that can be stored in the tree. + */ + +typedef struct PosixRBTree PosixRBTree; + +struct PosixRBTree { + void *root; +}; + +static int posix_rbtree_compare(const void *a, const void *b) { + return *(const int *)a - *(const int *)b; +} + +static void posix_rbtree_add(PosixRBTree *t, const Node *node) { + void *res; + + res = tsearch(&node->key, &t->root, posix_rbtree_compare); + c_assert(*(int **)res == &node->key); +} + +static void posix_rbtree_remove(PosixRBTree *t, const Node *node) { + void *res; + + res = tdelete(&node->key, &t->root, posix_rbtree_compare); + c_assert(res); +} + +static Node *posix_rbtree_find(PosixRBTree *t, int key) { + void *res; + + res = tfind(&key, &t->root, posix_rbtree_compare); + return res ? node_from_key(*(int **)res) : NULL; +} + +static void posix_rbtree_visit(const void *n, const VISIT o, const int depth) { + static int v; + + /* HACK: twalk() has no context; use static context; reset on root */ + if (depth == 0 && (o == preorder || o == leaf)) + v = 0; + + switch (o) { + case postorder: + case leaf: + c_assert(v <= node_from_key(*(int **)n)->key); + v = node_from_key(*(int **)n)->key; + break; + default: + break; + } +} + +static void posix_rbtree_traverse(PosixRBTree *t) { + twalk(t->root, posix_rbtree_visit); +} + +/* + * Comparison between c-rbtree and tsearch(3p) + * + * Based on the tsearch(3p) API above, this now implements some comparisons + * between c-rbtree and the POSIX API. + * + * The semantic differences are explained above. This does mostly performance + * comparisons. + */ + +static void test_posix(void) { + uint64_t ts, ts_c1, ts_c2, ts_c3, ts_c4; + uint64_t ts_p1, ts_p2, ts_p3, ts_p4; + PosixRBTree pt = {}; + CRBNode **slot, *p; + CRBTree t = {}; + Node *nodes[2048]; + unsigned long i; + int v; + + /* allocate and initialize all nodes */ + for (i = 0; i < sizeof(nodes) / sizeof(*nodes); ++i) { + nodes[i] = malloc(sizeof(*nodes[i])); + c_assert(nodes[i]); + nodes[i]->key = i; + c_rbnode_init(&nodes[i]->rb); + } + + /* shuffle nodes */ + shuffle(nodes, sizeof(nodes) / sizeof(*nodes)); + + /* add all nodes, and verify that each node is linked */ + ts = now(); + for (i = 0; i < sizeof(nodes) / sizeof(*nodes); ++i) { + slot = c_rbtree_find_slot(&t, compare, (void *)(unsigned long)nodes[i]->key, &p); + c_assert(slot); + c_rbtree_add(&t, p, slot, &nodes[i]->rb); + } + ts_c1 = now() - ts; + + ts = now(); + for (i = 0; i < sizeof(nodes) / sizeof(*nodes); ++i) + posix_rbtree_add(&pt, nodes[i]); + ts_p1 = now() - ts; + + /* shuffle nodes again */ + shuffle(nodes, sizeof(nodes) / sizeof(*nodes)); + + /* traverse tree in-order */ + ts = now(); + i = 0; + v = 0; + for (p = c_rbtree_first(&t); p; p = c_rbnode_next(p)) { + ++i; + + c_assert(v <= node_from_rb(p)->key); + v = node_from_rb(p)->key; + } + c_assert(i == sizeof(nodes) / sizeof(*nodes)); + ts_c2 = now() - ts; + + ts = now(); + posix_rbtree_traverse(&pt); + ts_p2 = now() - ts; + + /* shuffle nodes again */ + shuffle(nodes, sizeof(nodes) / sizeof(*nodes)); + + /* lookup all nodes (in different order) */ + ts = now(); + for (i = 0; i < sizeof(nodes) / sizeof(*nodes); ++i) + c_assert(nodes[i] == c_rbtree_find_entry(&t, compare, + (void *)(unsigned long)nodes[i]->key, + Node, rb)); + ts_c3 = now() - ts; + + ts = now(); + for (i = 0; i < sizeof(nodes) / sizeof(*nodes); ++i) + c_assert(nodes[i] == posix_rbtree_find(&pt, nodes[i]->key)); + ts_p3 = now() - ts; + + /* shuffle nodes again */ + shuffle(nodes, sizeof(nodes) / sizeof(*nodes)); + + /* remove all nodes (in different order) */ + ts = now(); + for (i = 0; i < sizeof(nodes) / sizeof(*nodes); ++i) + c_rbnode_unlink(&nodes[i]->rb); + ts_c4 = now() - ts; + + ts = now(); + for (i = 0; i < sizeof(nodes) / sizeof(*nodes); ++i) + posix_rbtree_remove(&pt, nodes[i]); + ts_p4 = now() - ts; + + /* free nodes again */ + for (i = 0; i < sizeof(nodes) / sizeof(*nodes); ++i) + free(nodes[i]); + + fprintf(stderr, " insertion traversal lookup removal\n"); + fprintf(stderr, " c-rbtree: %8"PRIu64"ns %8"PRIu64"ns %8"PRIu64"ns %8"PRIu64"ns\n", + ts_c1, ts_c2, ts_c3, ts_c4); + fprintf(stderr, "tsearch(3p): %8"PRIu64"ns %8"PRIu64"ns %8"PRIu64"ns %8"PRIu64"ns\n", + ts_p1, ts_p2, ts_p3, ts_p4); +} + +int main(int argc, char **argv) { + /* we want stable tests, so use fixed seed */ + srand(0xdeadbeef); + + test_posix(); + return 0; +} diff --git a/subprojects/c-stdaux b/subprojects/c-stdaux new file mode 160000 index 000000000..c5f166d02 --- /dev/null +++ b/subprojects/c-stdaux @@ -0,0 +1 @@ +Subproject commit c5f166d02ff68af5cdcbad1bdcea2cb134e34ce4