EchoServer.cpp

// SPDX-License-Identifier: LGPL-3.0-or-later
// Copyright © 2020-2021 Florian Fischer
#include <sys/socket.h>
#include <sys/types.h>

#include <atomic>
#include <cerrno>
#include <chrono>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <string>

#include "Common.hpp"
#include "Debug.hpp"
#include "Runtime.hpp"
#include "emper-config.h"
#include "io.hpp"

#ifdef EMPER_HAS_COMPARE_H
#include <compare>
#endif

const std::string HOST = "::";
const std::string PORT = "12345";

unsigned int computations_us = 0;

std::atomic<bool> quit = false;

auto main(int argc, char* argv[]) -> int {
	std::string host = HOST;
	std::string port = PORT;

	if (argc > 3) {
		std::cerr << "Usage: " << argv[0] << " [port] [computation_us]" << std::endl;
		exit(EXIT_FAILURE);
	}

	if (argc > 1) {
		port = std::string(argv[1]);
	}

	if (argc > 2) {
		computations_us = std::stoi(argv[2]);
	}

	std::cout << "Echoserver listening on " << host << ":" << port << std::endl;

	Runtime runtime;
	auto* listener = emper::io::tcp_listener(host, port, [](int socket) {
		// NOLINTNEXTLINE(modernize-avoid-c-arrays)
		char buf[1024];
		while (!quit.load(std::memory_order_consume)) {
			ssize_t bytes_recv = emper::io::recvAndWait(socket, buf, sizeof(buf), 0);
			if (unlikely(bytes_recv <= 0)) {
				// socket was shutdown
				if (bytes_recv < 0) {
					LOGE("server read failed:" << strerror(errno));
				}
				break;
			}

			if (unlikely(bytes_recv == 5 && strncmp("quit\n", buf, bytes_recv) == 0)) {
				quit = true;
				Runtime::getRuntime()->initiateTermination();
				break;
			}

			const auto start = std::chrono::steady_clock::now();
			const auto deadline = start + std::chrono::microseconds(computations_us);
			// TODO: The suppressed linter error below may be a false positive
			// reported by clang-tidy.
			// NOLINTNEXTLINE(modernize-use-nullptr)
			while (std::chrono::steady_clock::now() < deadline) {
			}

			ssize_t bytes_send = emper::io::sendAndWait(socket, buf, bytes_recv, MSG_NOSIGNAL, true);
			if (unlikely(bytes_recv != bytes_send)) {
				LOGE("server send failed: " << strerror(errno));
				break;
			}
		}

		emper::io::closeAndForget(socket);
	});

	if (!listener) {
		exit(EXIT_FAILURE);
	}

	runtime.scheduleFromAnywhere(*listener);

	runtime.waitUntilFinished();

	return EXIT_FAILURE;
}