(C++) How to use Payload Object to imiplement thread pool? - c++

Question

I saw this very well implemented thread pool: https://github.com/progschj/ThreadPool. I am wondering whether I can use a payload object instead. The idea is that instead of using a function pointer, use an object to describe the payload, which always contains a run function and a promise. The main thread then wait on the future of the promise.
Here is what I got:
#include <iostream>
#include <queue>
#include <thread>
#include <future>
#include <condition_variable>
#include <mutex>
class GenericPayload {
protected:
std::promise <int> m_returnCode;
public:
virtual void run() = 0;
std::future <int> getFuture() {
return m_returnCode.get_future();
}
};
class MyPayload:public GenericPayload {
private:
int m_input1;
int m_input2;
int m_result;
public:
MyPayload(int input1, int input2):m_input1(input1), m_input2(input2) {}
void run() {
m_result = m_input1 * m_input2;
m_returnCode.set_value(0);
}
int getResult() {
return m_result;
}
};
class ThreadPool {
private:
std::queue <GenericPayload *> payloads;
std::mutex queue_mutex;
std::condition_variable cv;
std::vector< std::thread > workers;
bool stop;
public:
ThreadPool(size_t threads)
: stop(false)
{
for(size_t i = 0;i<threads;++i)
workers.emplace_back(
[this]
{
for(;;)
{
GenericPayload *payload;
{
std::unique_lock<std::mutex> lock(this->queue_mutex);
this->cv.wait(lock,
[this]{ return this->stop || !this->payloads.empty(); });
if(this->stop)
return;
payload = this->payloads.front();
this->payloads.pop();
}
payload->run();
}
}
);
}
void addPayLoad (GenericPayload *payload) {
payloads.push(payload);
}
~ThreadPool()
{
{
std::unique_lock<std::mutex> lock(queue_mutex);
stop = true;
}
cv.notify_all();
for(std::thread &worker: workers)
worker.join();
}
};
int main() {
MyPayload myPayload(3, 5);
ThreadPool threadPool(2);
std::future <int> returnCode = myPayload.getFuture();
threadPool.addPayLoad(&myPayload);
returnCode.get();
std::cout << myPayload.getResult() << std::endl;
}
Is this the right way to do it though? I had to pass a pointer to the payload because 1. I want GenericPayload to be abstract and 2. std::promise is not copyable. Thx for any feedback.