Created
May 26, 2024 12:01
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#pragma once | |
#include <functional> | |
#include <future> | |
#include <atomic> | |
#include <mutex> | |
#include <queue> | |
#include <vector> | |
#include <thread> | |
#include <condition_variable> | |
#define FNTYPE void*(void) | |
class Threadpool { | |
public: | |
Threadpool() : worker_count(std::thread::hardware_concurrency() ? std::thread::hardware_concurrency() * 2 : 10) { run(); } | |
Threadpool(std::size_t c) : worker_count(c) { run(); } | |
~Threadpool() { shutdown(); } | |
std::future<void*> spawn(std::function<FNTYPE> fn) { | |
std::packaged_task<FNTYPE> task { fn }; | |
auto future = task.get_future(); | |
{ | |
std::lock_guard<std::mutex> tl(tasks_lock); | |
tasks.push(std::move(task)); | |
} | |
tasks_cv.notify_one(); | |
return future; | |
} | |
void shutdown() { | |
{ | |
// Counter intuitive lock but required for the condition_variable to be notified correctly | |
// See: https://stackoverflow.com/questions/38147825/ | |
std::lock_guard<std::mutex> lock(tasks_lock); | |
running.store(false); | |
} | |
tasks_cv.notify_all(); // Wake up all threads to finish up and exit | |
for (auto& t : workers) { | |
if (t.joinable()) { | |
t.join(); | |
} | |
} | |
} | |
private: | |
std::vector<std::thread> workers; | |
std::queue<std::packaged_task<FNTYPE>> tasks; | |
std::mutex tasks_lock; | |
std::condition_variable tasks_cv; | |
std::atomic<bool> running { true }; | |
std::size_t worker_count; | |
void run() { | |
for (std::size_t i = 0; i < worker_count; ++i) { | |
workers.emplace_back([&](){ | |
while (true) { | |
std::packaged_task<FNTYPE> task; | |
{ | |
std::unique_lock<std::mutex> ul(tasks_lock); | |
tasks_cv.wait(ul, [&](){ return !tasks.empty() || !running.load(); }); | |
if (!running.load() && tasks.empty()) { | |
return; | |
} | |
task = std::move(tasks.front()); | |
tasks.pop(); | |
} | |
if (task.valid()) { | |
task(); | |
} | |
} | |
}); | |
} | |
} | |
}; | |
#undef FNTYPE |
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