[EchoServer] exit the echo server by terminate the runtime 

Since stats are printed in the Runtime destructor we can not simply call
exit() and have to properly terminate the Runtime.
When the echo server receives a "quit" message all active connections will
return and the Runtime will terminate if there is no work left.

apps/EchoServer.cpp

@@ -3,6 +3,7 @@
 #include <sys/socket.h>
 #include <sys/types.h>
 
+#include <atomic>
 #include <cerrno>
 #include <chrono>
 #include <cstdlib>
@@ -25,6 +26,8 @@ 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;
@@ -48,21 +51,20 @@ auto main(int argc, char* argv[]) -> int {
 	auto* listener = emper::io::tcp_listener(host, port, [](int socket) {
 		// NOLINTNEXTLINE(modernize-avoid-c-arrays)
 		char buf[1024];
-		for (;;) {
+		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));
 				}
-
-			finish:
-				emper::io::closeAndForget(socket);
-				return;
 			}
+			break;
 
 			if (unlikely(bytes_recv == 5 && strncmp("quit\n", buf, bytes_recv) == 0)) {
-				exit(EXIT_SUCCESS);
+				quit = true;
+				Runtime::getRuntime()->initiateTermination();
+				break;
 			}
 
 			const auto start = std::chrono::steady_clock::now();
@@ -76,9 +78,11 @@ auto main(int argc, char* argv[]) -> int {
 			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));
-				goto finish;
+				break;
 			}
 		}
+
+		emper::io::closeAndForget(socket);
 	});
 
 	if (!listener) {