c_cpp 多线程

Posted 2021-05-14

#include "pch.h"
#include "barter.hpp"
#include "fps_stats.hpp"
#include <opencv2/opencv.hpp>
#include <string>
#include <list>
#include <thread>

enum ThreadState {
	Pause, Running, Quit
};

std::list<cv::Mat> frames;
cv::VideoCapture cap;
barter<cv::Mat> frame_barter;
std::atomic_int t_state{ ThreadState::Pause };

// thread function for video getting and show
void StreamThread(barter<cv::Mat> & frame_barter_, std::atomic_int & t_state_)
{
	auto frame = std::unique_ptr<cv::Mat>(new cv::Mat);
	for (;;) {
		// wait for a new frame to arrive
		while (t_state_ != ThreadState::Running) {
			if (t_state_ == ThreadState::Quit) return;
			std::this_thread::sleep_for(std::chrono::microseconds(30));
		}
		frame_barter_.exchange(frame);
		CV_Assert(frame);

		if (frame->empty())	continue;
		cv::imshow("R1", *frame);
		cv::waitKey(30);

		std::cout << "child thread's running" << std::endl;
	}
}


int main(int, char)
{
	cap.open(0);

	//open check
	if (!cap.isOpened()) {
		std::cerr << "Stream open failed : " << std::endl;
		return 1;
	}

	cv::setNumThreads(8);


	std::thread t1{ &StreamThread, std::ref(frame_barter), std::ref(t_state) };

	auto frame = std::unique_ptr<cv::Mat>(new cv::Mat);
	std::this_thread::sleep_for(std::chrono::seconds(1));
	std::cout << "cv::getNumThreads(): " << cv::getNumThreads() << std::endl;

	fps_stats fps{ "Video" };
	cap >> *frame;
	while (!frame->empty())
	{
		cv::imshow("Result", *frame);

		frame_barter.exchange(frame);
		t_state = ThreadState::Running;

		if (cv::waitKey(30) >= 0)
		{
			break;
		}
		cap >> *frame;
	}

	if (t1.joinable())
	{
		t_state = ThreadState::Quit;
		t1.join();
		std::cout << "t1 is joined" << std::endl;
	}

	return 0;
}