[EchoServer] implement random computation in range

apps/EchoServer.cpp

@@ -14,6 +14,7 @@
 #include "Common.hpp"
 #include "Debug.hpp"
 #include "Runtime.hpp"
+#include "Worker.hpp"
 #include "emper-config.h"
 #include "io.hpp"
 
@@ -26,6 +27,7 @@ static const std::string PORT = "12345";
 static const int BACKLOG = 1024;
 
 static unsigned int computations_us = 0;
+static unsigned int max_computations_us = 0;
 
 static std::atomic<bool> quit = false;
 
@@ -33,8 +35,9 @@ 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;
+	if (argc > 4) {
+		std::cerr << "Usage: " << argv[0] << " [port] [computations_us] [max_computations_us]"
+							<< std::endl;
 		exit(EXIT_FAILURE);
 	}
 
@@ -46,7 +49,19 @@ auto main(int argc, char* argv[]) -> int {
 		computations_us = std::stoi(argv[2]);
 	}
 
-	std::cout << "Echoserver listening on " << host << ":" << port << std::endl;
+	if (argc > 3) {
+		max_computations_us = std::stoi(argv[3]);
+		if (max_computations_us < computations_us)
+			DIE_MSG("max_computations_us must be bigger than computations_us");
+	}
+
+	std::cout << "Echoserver listening on " << host << ":" << port;
+	if (computations_us) {
+		std::cout << " with " << computations_us;
+		if (max_computations_us) std::cout << " - " << max_computations_us;
+		std::cout << " us computations";
+	}
+	std::cout << std::endl;
 
 	Runtime runtime;
 	auto serverFunc = [](int socket) {
@@ -68,12 +83,20 @@ auto main(int argc, char* argv[]) -> int {
 				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) {
+			if (computations_us) {
+				unsigned int computation = computations_us;
+				if (max_computations_us) {
+					// Worker::rand is always positiv. Why does it return int?
+					computation += Worker::rand() % (max_computations_us - computations_us);
+				}
+
+				const auto start = std::chrono::steady_clock::now();
+				const auto deadline = start + std::chrono::microseconds(computation);
+				// 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);