C++ by example - Channels

channels.cpp

#include <iostream>
#include <cassert>
#include <boost/asio.hpp>
#include <boost/thread.hpp>

constexpr int NTASK = 50;

int
main()
{
	boost::asio::io_service io_service;
	boost::asio::local::stream_protocol::socket tx(io_service), rx(io_service);
	boost::asio::local::connect_pair(tx, rx);
	boost::mutex guard;
	for (int id = 0; id < NTASK; ++id)
	{
		boost::async([&tx, &guard, id]() {
			auto bufs = boost::asio::buffer(&id, sizeof(int));
			boost::asio::write(tx, bufs);
			boost::mutex::scoped_lock scoped_lock(guard);
			std::cout << "task number " << id << " finished" << std::endl;
		});
	}
	int task_results[NTASK];
	for (int id = 0; id < NTASK; ++id)
	{
		auto bufs = boost::asio::buffer(&task_results[id], sizeof(int));
		boost::asio::async_read(rx, bufs,
			[id, &task_results](const boost::system::error_code & error, std::size_t bytes_transferred)
			{
				assert(!error);
				assert(bytes_transferred == sizeof(int));
				std::cout << "task number " << id << " reported (" << task_results[id] << ")" << std::endl;
			});
	}
	io_service.run();
	std::cout << "done" << std::endl;
}