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This commit is contained in:
Robin Dietzel 2023-11-01 17:05:01 +01:00
parent 9cf2d0b952
commit e942e95712
2 changed files with 183 additions and 8 deletions
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4
task1/main.cpp
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@ -63,9 +63,9 @@ auto main(int argc, char *argv[]) -> int {
fmt::print("Sorted {} entries within {} ms in sequential\n", dataset_seq.size(), delay_ms.count());
static constexpr int nthreads = 16;
const int nthreads = std::thread::hardware_concurrency();
t1 = std::chrono::high_resolution_clock::now();
algo::MergeSort_v2::sort(dataset_par.begin(), dataset_par.end(), [](int32_t a, int32_t b) {
algo::MergeSort_mt::sort(dataset_par, [](int32_t a, int32_t b) {
return (a > b);
}, nthreads);
t2 = std::chrono::high_resolution_clock::now();

187
task1/mergesort.h
View File

@ -4,6 +4,8 @@
#include <algorithm>
#include <thread>
#include <mutex>
#include <future>
#include <ranges>
namespace algo {
@ -84,15 +86,42 @@ namespace algo {
class MergeSort_v2 {
private:
template<typename Iterator, typename Comparator>
template<typename Container, typename Comparator>
static auto
mt_merge() {
mt_merge(Container left, Container right, Comparator cmp) -> Container {
//using Iterator = typename std::iterator_traits<Container>::value_type;
Container output;
auto lefti = left.begin();
auto righti = right.begin();
while (lefti < left.end() && righti < right.end()) {
if (cmp(*lefti, *righti)) {
output.emplace_back(std::move(*lefti));
lefti++;
} else {
output.emplace_back(std::move(*righti));
righti++;
}
}
while (lefti < left.end()) {
output.emplace_back(std::move(*lefti));
lefti++;
}
while (righti < right.end()) {
output.emplace_back(std::move(*righti));
righti++;
}
return output;
}
template<typename Iterator, typename Comparator>
static auto
merge(Iterator start, Iterator middle, Iterator end, Comparator cmp, Iterator output_start, std::recursive_mutex &dataset_guard) -> void {
merge(Iterator start, Iterator middle, Iterator end, Comparator cmp, Iterator output_start,
std::recursive_mutex &dataset_guard) -> void {
Iterator start_m = start;
Iterator begin = output_start;
Iterator start2 = middle + 1;
@ -131,6 +160,69 @@ namespace algo {
}
template<typename Container, typename Iterator, typename Comparator>
static auto mt_split(Container &output_vec, Iterator start, Iterator end, Comparator cmp, Iterator output_start,
int &nthreads, std::recursive_mutex &dataset_guard, std::mutex &depth_guard) -> void {
Iterator mid = start;
Iterator to_start = output_start;
if (std::distance(start, end) < 1) {
return;
}
bool rem_threads;
{
std::lock_guard guard(depth_guard); //RAII guard
rem_threads = nthreads > 1;
}
if (rem_threads) {
{
std::lock_guard guard(depth_guard); //RAII guard
nthreads -= 2;
}
std::advance(mid, std::distance(start, end) / 2);
std::thread t1([&]() {
mt_split(output_vec, start, mid, cmp, output_start, nthreads, dataset_guard, depth_guard);
});
std::advance(output_start, std::distance(start, mid + 1));
std::thread t2([&]() {
mt_split(output_vec, mid + 1, end, cmp, output_start, nthreads, dataset_guard, depth_guard);
});
//merge everything together starting from the complete beginning
t1.join();
t2.join();
std::vector<int> left;
left.assign(start, mid);
std::vector<int> right;
right.assign(mid + 1, end);
mt_merge(left, right, cmp);
} else {
//move mid iterator litterally to the mid
std::advance(mid, std::distance(start, end) / 2);
//sort the first half within an recursion
mt_split(output_vec, start, mid, cmp, output_start, nthreads, dataset_guard, depth_guard);
//move output iterator
std::advance(output_start, std::distance(start, mid + 1));
//sort the second half within a recursion
mt_split(output_vec, mid + 1, end, cmp, output_start, nthreads, dataset_guard, depth_guard);
std::vector<int> left;
left.assign(start, mid);
std::vector<int> right;
right.assign(mid + 1, end);
mt_merge(left, right, cmp);
}
}
template<typename Container, typename Iterator, typename Comparator>
static auto ms_split(Container &output_vec, Iterator start, Iterator end, Comparator cmp, Iterator output_start,
int &nthreads, std::recursive_mutex &dataset_guard, std::mutex &depth_guard) -> void {
@ -149,12 +241,16 @@ namespace algo {
std::advance(mid, std::distance(start, end) / 2);
//sort the first half within an recursion
std::thread t1([&]() { ms_split(output_vec, start, mid, cmp, output_start, nthreads, dataset_guard, depth_guard); });
std::thread t1([&]() {
ms_split(output_vec, start, mid, cmp, output_start, nthreads, dataset_guard, depth_guard);
});
//move output iteratoroutput_vec, start, mid, cmp, output_start
std::advance(output_start, std::distance(start, mid + 1));
//sort the second half within a recursion
std::thread t2([&]() { ms_split(output_vec, mid + 1, end, cmp, output_start, nthreads, dataset_guard, depth_guard); });
std::thread t2([&]() {
ms_split(output_vec, mid + 1, end, cmp, output_start, nthreads, dataset_guard, depth_guard);
});
//merge everything together starting from the complete beginning
@ -186,8 +282,87 @@ namespace algo {
std::recursive_mutex dataset_guard;
std::mutex depth_guard;
ms_split(temporary_dataset, start, end - 1, cmp, temporary_dataset.begin(), nthreads, dataset_guard, depth_guard);
mt_split(temporary_dataset, start, end - 1, cmp, temporary_dataset.begin(), nthreads, dataset_guard,
depth_guard);
}
};
class MergeSort_mt {
template<typename T, typename Comparator>
static auto
merge(typename std::vector<T>::iterator mid, std::vector<T> &left, std::vector<T> &right,
Comparator cmp, std::mutex &mut) {
{
std::lock_guard lock(mut);
auto l = left.begin();
auto r = right.begin();
while (l < left.end() && r < right.end()) {
if (cmp(*l, *r)) {
*mid = *l;
l++;
} else {
*mid = *r;
r++;
}
mid++;
}
while (l < left.end()) {
*mid = *l;
mid++;
l++;
}
while (r < right.end()) {
*mid = *r;
mid++;
r++;
}
}
}
template<typename T, typename Comparator>
static auto split(std::vector<T> &data, std::vector<T> &outdata, Comparator cmp, int depth, int &num_threads, std::mutex &mut) {
if (data.size() <= 1) {
return;
}
auto mid = data.begin();
std::advance(mid, std::distance(data.begin(), data.end()) / 2);
std::vector<T> left(std::make_move_iterator(data.begin()), std::make_move_iterator(mid));
std::vector<T> right(std::make_move_iterator(mid), std::make_move_iterator(data.end()));
if (depth < num_threads) {
std::thread left_thread([&]() { split(left, outdata, cmp, depth + 1, num_threads, mut); });
std::thread right_thread([&]() { split(right, outdata, cmp, depth + 1, num_threads, mut); });
left_thread.join();
right_thread.join();
} else {
split(left, outdata, cmp, depth + 1, num_threads, mut);
split(right, outdata, cmp, depth + 1, num_threads, mut);
}
mid = outdata.begin();
std::advance(mid, std::distance(outdata.begin(), outdata.end())/2);
merge(mid, left, right, cmp, mut);
}
public:
template<typename T, typename Comparator>
static auto
sort(std::vector<T> &data, Comparator cmp, int num_threads = std::thread::hardware_concurrency()) -> void {
std::vector<T> local_result = data;
std::mutex local_result_lock;
split(data, local_result, cmp, 0, num_threads, local_result_lock);
data = local_result;
}
};
}