1) Fixed a significant bug in MutablePriorityQueue when setting

the indices allowing rescheduling of values in the middle of the queue.
2) Implemented a cache friendly variant - MutableSkipHeapPriorityQueue
   based on
   https://playfulprogramming.blogspot.com/2015/08/cache-optimizing-priority-queue.html
   https://github.com/rollbear/prio_queue/blob/master/prio_queue.hpp
This commit is contained in:
Vojtech Bubnik 2021-07-09 12:53:16 +02:00
parent c8a46c1f24
commit e4fd6a828f
3 changed files with 595 additions and 4 deletions

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@ -7,6 +7,7 @@ template<typename T, typename IndexSetter, typename LessPredicate, const bool Re
class MutablePriorityQueue
{
public:
// It is recommended to use make_mutable_priority_queue() for construction.
MutablePriorityQueue(IndexSetter &&index_setter, LessPredicate &&less_predicate) :
m_index_setter(std::forward<IndexSetter>(index_setter)),
m_less_predicate(std::forward<LessPredicate>(less_predicate))
@ -139,7 +140,7 @@ inline void MutablePriorityQueue<T, LessPredicate, IndexSetter, ResetIndexWhenRe
// switch nodes
if (! m_less_predicate(*parent, *child)) {
T tmp = *parent;
m_index_setter(*parent, childIdx);
m_index_setter(tmp, childIdx);
m_index_setter(*child, parentIdx);
m_heap[parentIdx] = *child;
m_heap[childIdx] = tmp;
@ -171,9 +172,268 @@ inline void MutablePriorityQueue<T, LessPredicate, IndexSetter, ResetIndexWhenRe
if (m_less_predicate(*parent, *child))
return;
// switch nodes
m_index_setter(*parent, childIdx);
m_index_setter(*child, parentIdx);
T tmp = *parent;
m_index_setter(tmp, childIdx);
m_index_setter(*child, parentIdx);
m_heap[parentIdx] = *child;
m_heap[childIdx] = tmp;
// shift down
parentIdx = childIdx;
parent = child;
}
}
// Binary heap addressing of a hierarchy of binary miniheaps by a higher level binary heap.
// Conceptually it works the same as a plain binary heap, however it is cache friendly.
// A binary block of "block_size" implements a binary miniheap of (block_size / 2) leaves and
// ((block_size / 2) - 1) nodes, thus wasting a single element. To make addressing simpler,
// the zero'th element inside each miniheap is wasted, thus for example a single element heap is
// 2 elements long and the 1st element starts at address 1.
//
// Mostly copied from the following great source:
// https://playfulprogramming.blogspot.com/2015/08/cache-optimizing-priority-queue.html
// https://github.com/rollbear/prio_queue/blob/master/prio_queue.hpp
// original source Copyright Björn Fahller 2015, Boost Software License, Version 1.0, http://www.boost.org/LICENSE_1_0.txt
template <std::size_t blocking>
struct SkipHeapAddressing
{
public:
static const constexpr std::size_t block_size = blocking;
static const constexpr std::size_t block_mask = block_size - 1;
static_assert((block_size & block_mask) == 0U, "block size must be 2^n for some integer n");
static inline std::size_t child_of(std::size_t node_no) noexcept {
if (! is_block_leaf(node_no))
// If not a leaf, then it is sufficient to just traverse down inside a miniheap.
// The following line is equivalent to, but quicker than
// return block_base(node_no) + 2 * block_offset(node_no);
return node_no + block_offset(node_no);
// Otherwise skip to a root of a child miniheap.
return (block_base(node_no) + 1 + child_no(node_no) * 2) * block_size + 1;
}
static inline std::size_t parent_of(std::size_t node_no) noexcept {
auto const node_root = block_base(node_no); // 16
if (! is_block_root(node_no))
// If not a block (miniheap) root, then it is sufficient to just traverse up inside a miniheap.
return node_root + block_offset(node_no) / 2;
// Otherwise skipping from a root of one miniheap into leaf of another miniheap.
// Address of a parent miniheap block. One miniheap branches at (block_size / 2) leaves to (block_size) miniheaps.
auto const parent_base = block_base(node_root / block_size - 1); // 0
// Index of a leaf of a parent miniheap, which is a parent of node_no.
auto const child = ((node_no - block_size) / block_size - parent_base) / 2;
return
// Address of a parent miniheap
parent_base +
// Address of a leaf of a parent miniheap
block_size / 2 + child; // 30
}
// Leafs are stored inside the second half of a block.
static inline bool is_block_leaf(std::size_t node_no) noexcept { return (node_no & (block_size >> 1)) != 0U; }
// Unused space aka padding to facilitate quick addressing.
static inline bool is_padding (std::size_t node_no) noexcept { return block_offset(node_no) == 0U; }
// Following methods are internal, but made public for unit tests.
//private:
// Address is a root of a block (of a miniheap).
static inline bool is_block_root(std::size_t node_no) noexcept { return block_offset(node_no) == 1U; }
// Offset inside a block (inside a miniheap).
static inline std::size_t block_offset (std::size_t node_no) noexcept { return node_no & block_mask; }
// Base address of a block (a miniheap).
static inline std::size_t block_base (std::size_t node_no) noexcept { return node_no & ~block_mask; }
// Index of a leaf.
static inline std::size_t child_no (std::size_t node_no) noexcept { assert(is_block_leaf(node_no)); return node_no & (block_mask >> 1); }
};
// Cache friendly variant of MutablePriorityQueue, implemented as a binary heap of binary miniheaps,
// building upon SkipHeapAddressing.
template<typename T, typename IndexSetter, typename LessPredicate, std::size_t blocking = 32, const bool ResetIndexWhenRemoved = false>
class MutableSkipHeapPriorityQueue
{
public:
using address = SkipHeapAddressing<blocking>;
// It is recommended to use make_miniheap_mutable_priority_queue() for construction.
MutableSkipHeapPriorityQueue(IndexSetter &&index_setter, LessPredicate &&less_predicate) :
m_index_setter(std::forward<IndexSetter>(index_setter)),
m_less_predicate(std::forward<LessPredicate>(less_predicate))
{}
~MutableSkipHeapPriorityQueue() { clear(); }
void clear();
// Reserve one unused element per miniheap.
void reserve(size_t cnt) { m_heap.reserve(cnt + ((cnt + (address::block_size - 1)) / (address::block_size - 1))); }
void push(const T &item);
void push(T &&item);
void pop();
T& top() { return m_heap[1]; }
void remove(size_t idx);
void update(size_t idx) { assert(! address::is_padding(idx)); T item = m_heap[idx]; remove(idx); push(item); }
// There is one padding element storead at each miniheap, thus lower the number of elements by the number of miniheaps.
size_t size() const noexcept { return m_heap.size() - (m_heap.size() + address::block_size - 1) / address::block_size; }
bool empty() const { return m_heap.empty(); }
protected:
void update_heap_up(size_t top, size_t bottom);
void update_heap_down(size_t top, size_t bottom);
void pop_back() noexcept {
assert(m_heap.size() > 1);
assert(! address::is_padding(m_heap.size() - 1));
m_heap.pop_back();
if (address::is_padding(m_heap.size() - 1))
m_heap.pop_back();
}
private:
std::vector<T> m_heap;
IndexSetter m_index_setter;
LessPredicate m_less_predicate;
};
template<typename T, std::size_t BlockSize, const bool ResetIndexWhenRemoved, typename IndexSetter, typename LessPredicate>
MutableSkipHeapPriorityQueue<T, IndexSetter, LessPredicate, BlockSize, ResetIndexWhenRemoved>
make_miniheap_mutable_priority_queue(IndexSetter &&index_setter, LessPredicate &&less_predicate)
{
return MutableSkipHeapPriorityQueue<T, IndexSetter, LessPredicate, BlockSize, ResetIndexWhenRemoved>(
std::forward<IndexSetter>(index_setter), std::forward<LessPredicate>(less_predicate));
}
template<class T, class LessPredicate, class IndexSetter, std::size_t blocking, const bool ResetIndexWhenRemoved>
inline void MutableSkipHeapPriorityQueue<T, LessPredicate, IndexSetter, blocking, ResetIndexWhenRemoved>::clear()
{
#ifdef NDEBUG
// Only mark as removed from the queue in release mode, if configured so.
if (ResetIndexWhenRemoved)
#endif /* NDEBUG */
{
for (size_t idx = 0; idx < m_heap.size(); ++ idx)
// Mark as removed from the queue.
if (! address::is_padding(idx))
m_index_setter(m_heap[idx], std::numeric_limits<size_t>::max());
}
m_heap.clear();
}
template<class T, class LessPredicate, class IndexSetter, std::size_t blocking, const bool ResetIndexWhenRemoved>
inline void MutableSkipHeapPriorityQueue<T, LessPredicate, IndexSetter, blocking, ResetIndexWhenRemoved>::push(const T &item)
{
if (address::is_padding(m_heap.size()))
m_heap.emplace_back(T());
size_t idx = m_heap.size();
m_heap.emplace_back(item);
m_index_setter(m_heap.back(), idx);
update_heap_up(1, idx);
}
template<class T, class LessPredicate, class IndexSetter, std::size_t blocking, const bool ResetIndexWhenRemoved>
inline void MutableSkipHeapPriorityQueue<T, LessPredicate, IndexSetter, blocking, ResetIndexWhenRemoved>::push(T &&item)
{
if (address::is_padding(m_heap.size()))
m_heap.emplace_back(T());
size_t idx = m_heap.size();
m_heap.emplace_back(std::move(item));
m_index_setter(m_heap.back(), idx);
update_heap_up(1, idx);
}
template<class T, class LessPredicate, class IndexSetter, std::size_t blocking, const bool ResetIndexWhenRemoved>
inline void MutableSkipHeapPriorityQueue<T, LessPredicate, IndexSetter, blocking, ResetIndexWhenRemoved>::pop()
{
assert(! m_heap.empty());
#ifdef NDEBUG
// Only mark as removed from the queue in release mode, if configured so.
if (ResetIndexWhenRemoved)
#endif /* NDEBUG */
{
// Mark as removed from the queue.
m_index_setter(m_heap.front(), std::numeric_limits<size_t>::max());
}
// Zero'th element is padding, thus non-empty queue must have at least two elements.
if (m_heap.size() > 2) {
m_heap[1] = m_heap.back();
this->pop_back();
m_index_setter(m_heap[1], 1);
update_heap_down(1, m_heap.size() - 1);
} else
m_heap.clear();
}
template<class T, class LessPredicate, class IndexSetter, std::size_t blocking, const bool ResetIndexWhenRemoved>
inline void MutableSkipHeapPriorityQueue<T, LessPredicate, IndexSetter, blocking, ResetIndexWhenRemoved>::remove(size_t idx)
{
assert(idx < m_heap.size());
assert(! address::is_padding(idx));
#ifdef NDEBUG
// Only mark as removed from the queue in release mode, if configured so.
if (ResetIndexWhenRemoved)
#endif /* NDEBUG */
{
// Mark as removed from the queue.
m_index_setter(m_heap[idx], std::numeric_limits<size_t>::max());
}
if (idx + 1 == m_heap.size()) {
this->pop_back();
return;
}
m_heap[idx] = m_heap.back();
m_index_setter(m_heap[idx], idx);
this->pop_back();
update_heap_down(idx, m_heap.size() - 1);
update_heap_up(1, idx);
}
template<class T, class LessPredicate, class IndexSetter, std::size_t blocking, const bool ResetIndexWhenRemoved>
inline void MutableSkipHeapPriorityQueue<T, LessPredicate, IndexSetter, blocking, ResetIndexWhenRemoved>::update_heap_up(size_t top, size_t bottom)
{
assert(! address::is_padding(top));
assert(! address::is_padding(bottom));
size_t childIdx = bottom;
T *child = &m_heap[childIdx];
for (;;) {
size_t parentIdx = address::parent_of(childIdx);
if (childIdx == 1 || parentIdx < top)
break;
T *parent = &m_heap[parentIdx];
// switch nodes
if (! m_less_predicate(*parent, *child)) {
T tmp = *parent;
m_index_setter(tmp, childIdx);
m_index_setter(*child, parentIdx);
m_heap[parentIdx] = *child;
m_heap[childIdx] = tmp;
}
// shift up
childIdx = parentIdx;
child = parent;
}
}
template<class T, class LessPredicate, class IndexSetter, std::size_t blocking, const bool ResetIndexWhenRemoved>
inline void MutableSkipHeapPriorityQueue<T, LessPredicate, IndexSetter, blocking, ResetIndexWhenRemoved>::update_heap_down(size_t top, size_t bottom)
{
assert(! address::is_padding(top));
assert(! address::is_padding(bottom));
size_t parentIdx = top;
T *parent = &m_heap[parentIdx];
for (;;) {
size_t childIdx = address::child_of(parentIdx);
if (childIdx > bottom)
break;
T *child = &m_heap[childIdx];
size_t child2Idx = childIdx + (address::is_block_leaf(parentIdx) ? address::block_size : 1);
if (child2Idx <= bottom) {
T *child2 = &m_heap[child2Idx];
if (! m_less_predicate(*child, *child2)) {
child = child2;
childIdx = child2Idx;
}
}
if (m_less_predicate(*parent, *child))
return;
// switch nodes
T tmp = *parent;
m_index_setter(tmp, childIdx);
m_index_setter(*child, parentIdx);
m_heap[parentIdx] = *child;
m_heap[childIdx] = tmp;
// shift down

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@ -12,6 +12,7 @@ add_executable(${_TEST_NAME}_tests
test_placeholder_parser.cpp
test_polygon.cpp
test_mutable_polygon.cpp
test_mutable_priority_queue.cpp
test_stl.cpp
test_meshsimplify.cpp
test_meshboolean.cpp

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@ -0,0 +1,330 @@
#include <catch2/catch.hpp>
#include <queue>
#include "libslic3r/MutablePriorityQueue.hpp"
// based on https://raw.githubusercontent.com/rollbear/prio_queue/master/self_test.cpp
// original source Copyright Björn Fahller 2015, Boost Software License, Version 1.0, http://www.boost.org/LICENSE_1_0.txt
TEST_CASE("Skip addressing", "[MutableSkipHeapPriorityQueue]") {
using skip_addressing = SkipHeapAddressing<8>;
SECTION("block root") {
REQUIRE(skip_addressing::is_block_root(1));
REQUIRE(skip_addressing::is_block_root(9));
REQUIRE(skip_addressing::is_block_root(17));
REQUIRE(skip_addressing::is_block_root(73));
REQUIRE(! skip_addressing::is_block_root(2));
REQUIRE(! skip_addressing::is_block_root(3));
REQUIRE(! skip_addressing::is_block_root(4));
REQUIRE(! skip_addressing::is_block_root(7));
REQUIRE(! skip_addressing::is_block_root(31));
}
SECTION("block leaf") {
REQUIRE(! skip_addressing::is_block_leaf(1));
REQUIRE(! skip_addressing::is_block_leaf(2));
REQUIRE(! skip_addressing::is_block_leaf(3));
REQUIRE(skip_addressing::is_block_leaf(4));
REQUIRE(skip_addressing::is_block_leaf(5));
REQUIRE(skip_addressing::is_block_leaf(6));
REQUIRE(skip_addressing::is_block_leaf(7));
REQUIRE(skip_addressing::is_block_leaf(28));
REQUIRE(skip_addressing::is_block_leaf(29));
REQUIRE(skip_addressing::is_block_leaf(30));
REQUIRE(! skip_addressing::is_block_leaf(257));
REQUIRE(skip_addressing::is_block_leaf(255));
}
SECTION("Obtaining child") {
REQUIRE(skip_addressing::child_of(1) == 2);
REQUIRE(skip_addressing::child_of(2) == 4);
REQUIRE(skip_addressing::child_of(3) == 6);
REQUIRE(skip_addressing::child_of(4) == 9);
REQUIRE(skip_addressing::child_of(31) == 249);
}
SECTION("Obtaining parent") {
REQUIRE(skip_addressing::parent_of(2) == 1);
REQUIRE(skip_addressing::parent_of(3) == 1);
REQUIRE(skip_addressing::parent_of(6) == 3);
REQUIRE(skip_addressing::parent_of(7) == 3);
REQUIRE(skip_addressing::parent_of(9) == 4);
REQUIRE(skip_addressing::parent_of(17) == 4);
REQUIRE(skip_addressing::parent_of(33) == 5);
REQUIRE(skip_addressing::parent_of(29) == 26);
REQUIRE(skip_addressing::parent_of(1097) == 140);
}
}
template<size_t block_size = 16>
static auto make_test_priority_queue()
{
return make_miniheap_mutable_priority_queue<std::pair<int, size_t>, block_size, false>(
[](std::pair<int, size_t> &v, size_t idx){ v.second = idx; },
[](std::pair<int, size_t> &l, std::pair<int, size_t> &r){ return l.first < r.first; });
}
TEST_CASE("Mutable priority queue - basic tests", "[MutableSkipHeapPriorityQueue]") {
SECTION("a default constructed queue is empty") {
auto q = make_test_priority_queue();
REQUIRE(q.empty());
REQUIRE(q.size() == 0);
}
SECTION("an empty queue is not empty when one element is inserted") {
auto q = make_test_priority_queue();
q.push(std::make_pair(1, 0U));
REQUIRE(!q.empty());
REQUIRE(q.size() == 1);
}
SECTION("a queue with one element has it on top") {
auto q = make_test_priority_queue();
q.push(std::make_pair(8, 0U));
REQUIRE(q.top().first == 8);
}
SECTION("a queue with one element becomes empty when popped") {
auto q = make_test_priority_queue();
q.push(std::make_pair(9, 0U));
q.pop();
REQUIRE(q.empty());
REQUIRE(q.size() == 0);
}
SECTION("insert sorted stays sorted") {
auto q = make_test_priority_queue();
for (auto i : { 1, 2, 3, 4, 5, 6, 7, 8 })
q.push(std::make_pair(i, 0U));
REQUIRE(q.top().first == 1);
q.pop();
REQUIRE(q.top().first == 2);
q.pop();
REQUIRE(q.top().first == 3);
q.pop();
REQUIRE(q.top().first == 4);
q.pop();
REQUIRE(q.top().first == 5);
q.pop();
REQUIRE(q.top().first == 6);
q.pop();
REQUIRE(q.top().first == 7);
q.pop();
REQUIRE(q.top().first == 8);
q.pop();
REQUIRE(q.empty());
}
SECTION("randomly inserted elements are popped sorted") {
auto q = make_test_priority_queue();
std::random_device rd;
std::mt19937 gen(rd());
std::uniform_int_distribution<> dist(1, 100000);
int n[36000];
for (auto& i : n) {
i = dist(gen);
q.push(std::make_pair(i, 0U));
}
REQUIRE(!q.empty());
REQUIRE(q.size() == 36000);
std::sort(std::begin(n), std::end(n));
for (auto i : n) {
REQUIRE(q.top().first == i);
q.pop();
}
REQUIRE(q.empty());
}
}
TEST_CASE("Mutable priority queue - reshedule first", "[MutableSkipHeapPriorityQueue]") {
SECTION("reschedule top with highest prio leaves order unchanged") {
auto q = make_miniheap_mutable_priority_queue<std::pair<std::pair<int, int*>, size_t>, 4, false>(
[](std::pair<std::pair<int, int*>, size_t>& v, size_t idx) { v.second = idx; },
[](std::pair<std::pair<int, int*>, size_t>& l, std::pair<std::pair<int, int*>, size_t>& r) { return l.first.first < r.first.first; });
// 0 1 2 3 4 5 6 7 8
int nums[] = { 32, 1, 88, 16, 9, 11, 3, 22, 23 };
for (auto &i : nums)
q.push(std::make_pair(std::make_pair(i, &i), 0U));
REQUIRE(q.top().first.first == 1);
REQUIRE(q.top().first.second == &nums[1]);
REQUIRE(*q.top().first.second == 1);
// Update the top element.
q.top().first.first = 2;
q.update(1);
REQUIRE(q.top().first.first == 2);
REQUIRE(q.top().first.second == &nums[1]);
q.pop();
REQUIRE(q.top().first.first == 3);
REQUIRE(q.top().first.second == &nums[6]);
q.pop();
REQUIRE(q.top().first.first == 9);
REQUIRE(q.top().first.second == &nums[4]);
q.pop();
REQUIRE(q.top().first.first == 11);
REQUIRE(q.top().first.second == &nums[5]);
q.pop();
REQUIRE(q.top().first.first == 16);
REQUIRE(q.top().first.second == &nums[3]);
q.pop();
REQUIRE(q.top().first.first == 22);
REQUIRE(q.top().first.second == &nums[7]);
q.pop();
REQUIRE(q.top().first.first == 23);
REQUIRE(q.top().first.second == &nums[8]);
q.pop();
REQUIRE(q.top().first.first == 32);
REQUIRE(q.top().first.second == &nums[0]);
q.pop();
REQUIRE(q.top().first.first == 88);
REQUIRE(q.top().first.second == &nums[2]);
q.pop();
REQUIRE(q.empty());
}
SECTION("reschedule to mid range moves element to correct place") {
auto q = make_miniheap_mutable_priority_queue<std::pair<std::pair<int, int*>, size_t>, 4, false>(
[](std::pair<std::pair<int, int*>, size_t>& v, size_t idx) { v.second = idx; },
[](std::pair<std::pair<int, int*>, size_t>& l, std::pair<std::pair<int, int*>, size_t>& r) { return l.first.first < r.first.first; });
// 0 1 2 3 4 5 6 7 8
int nums[] = { 32, 1, 88, 16, 9, 11, 3, 22, 23 };
for (auto& i : nums)
q.push(std::make_pair(std::make_pair(i, &i), 0U));
REQUIRE(q.top().first.first == 1);
REQUIRE(q.top().first.second == &nums[1]);
REQUIRE(*q.top().first.second == 1);
// Update the top element.
q.top().first.first = 12;
q.update(1);
REQUIRE(q.top().first.first == 3);
REQUIRE(q.top().first.second == &nums[6]);
q.pop();
REQUIRE(q.top().first.first == 9);
REQUIRE(q.top().first.second == &nums[4]);
q.pop();
REQUIRE(q.top().first.first == 11);
REQUIRE(q.top().first.second == &nums[5]);
q.pop();
REQUIRE(q.top().first.first == 12);
REQUIRE(q.top().first.second == &nums[1]);
q.pop();
REQUIRE(q.top().first.first == 16);
REQUIRE(q.top().first.second == &nums[3]);
q.pop();
REQUIRE(q.top().first.first == 22);
REQUIRE(q.top().first.second == &nums[7]);
q.pop();
REQUIRE(q.top().first.first == 23);
REQUIRE(q.top().first.second == &nums[8]);
q.pop();
REQUIRE(q.top().first.first == 32);
REQUIRE(q.top().first.second == &nums[0]);
q.pop();
REQUIRE(q.top().first.first == 88);
REQUIRE(q.top().first.second == &nums[2]);
q.pop();
REQUIRE(q.empty());
}
SECTION("reschedule to last moves element to correct place", "heap")
{
auto q = make_miniheap_mutable_priority_queue<std::pair<std::pair<int, int*>, size_t>, 4, false>(
[](std::pair<std::pair<int, int*>, size_t>& v, size_t idx) { v.second = idx; },
[](std::pair<std::pair<int, int*>, size_t>& l, std::pair<std::pair<int, int*>, size_t>& r) { return l.first.first < r.first.first; });
// 0 1 2 3 4 5 6 7 8
int nums[] = { 32, 1, 88, 16, 9, 11, 3, 22, 23 };
for (auto& i : nums)
q.push(std::make_pair(std::make_pair(i, &i), 0U));
REQUIRE(q.top().first.first == 1);
REQUIRE(q.top().first.second == &nums[1]);
REQUIRE(*q.top().first.second == 1);
// Update the top element.
q.top().first.first = 89;
q.update(1);
REQUIRE(q.top().first.first == 3);
REQUIRE(q.top().first.second == &nums[6]);
q.pop();
REQUIRE(q.top().first.first == 9);
REQUIRE(q.top().first.second == &nums[4]);
q.pop();
REQUIRE(q.top().first.first == 11);
REQUIRE(q.top().first.second == &nums[5]);
q.pop();
REQUIRE(q.top().first.first == 16);
REQUIRE(q.top().first.second == &nums[3]);
q.pop();
REQUIRE(q.top().first.first == 22);
REQUIRE(q.top().first.second == &nums[7]);
q.pop();
REQUIRE(q.top().first.first == 23);
REQUIRE(q.top().first.second == &nums[8]);
q.pop();
REQUIRE(q.top().first.first == 32);
REQUIRE(q.top().first.second == &nums[0]);
q.pop();
REQUIRE(q.top().first.first == 88);
REQUIRE(q.top().first.second == &nums[2]);
q.pop();
REQUIRE(q.top().first.first == 89);
REQUIRE(q.top().first.second == &nums[1]);
q.pop();
REQUIRE(q.empty());
}
SECTION("reschedule top of 2 elements to last") {
auto q = make_test_priority_queue<8>();
q.push(std::make_pair(1, 0U));
q.push(std::make_pair(2, 0U));
REQUIRE(q.top().first == 1);
// Update the top element.
q.top().first = 3;
q.update(1);
REQUIRE(q.top().first == 2);
}
SECTION("reschedule top of 3 elements left to 2nd") {
auto q = make_test_priority_queue<8>();
q.push(std::make_pair(1, 0U));
q.push(std::make_pair(2, 0U));
q.push(std::make_pair(4, 0U));
REQUIRE(q.top().first == 1);
// Update the top element.
q.top().first = 3;
q.update(1);
REQUIRE(q.top().first == 2);
}
SECTION("reschedule top of 3 elements right to 2nd") {
auto q = make_test_priority_queue<8>();
q.push(std::make_pair(1, 0U));
q.push(std::make_pair(4, 0U));
q.push(std::make_pair(2, 0U));
REQUIRE(q.top().first == 1);
// Update the top element.
q.top().first = 3;
q.update(1);
REQUIRE(q.top().first == 2);
}
SECTION("reschedule top random gives same resultas pop/push") {
std::random_device rd;
std::mt19937 gen(rd());
std::uniform_int_distribution<unsigned> dist(1, 100000);
auto pq = make_test_priority_queue<8>();
std::priority_queue<int, std::vector<int>, std::greater<>> stdq;
for (size_t outer = 0; outer < 100; ++ outer) {
int num = gen();
pq.push(std::make_pair(num, 0U));
stdq.push(num);
for (size_t inner = 0; inner < 100; ++ inner) {
int newval = gen();
// Update the top element.
pq.top().first = newval;
pq.update(1);
stdq.pop();
stdq.push(newval);
auto n = pq.top().first;
auto sn = stdq.top();
REQUIRE(sn == n);
}
}
}
}