[IO] add execution time option to EchoClient

Benchmark results using a maximum execution time does not suffer from really slow outliers.
Specifying execution time and iterations is not allowed.

apps/EchoClient.cpp

@@ -50,12 +50,22 @@ const size_t SERVER_BACKLOG = 1024;
 std::string host = HOST;
 std::string port = PORT;
 size_t iterations = ITERATIONS;
+size_t execution_seconds = 0;
 size_t clients = CLIENTS;
 size_t size = SIZE;
 size_t server_backlog = SERVER_BACKLOG;
 
+std::atomic<bool> terminate = false;
+
 std::atomic<size_t> client_ids = 0;
-uint64_t* client_avgs;
+
+struct ClientResult {
+	size_t iterations;
+	size_t avg_ns;
+};
+using ClientResult = struct ClientResult;
+
+struct ClientResult* clientResults;
 
 struct addrinfo* server;
 
@@ -89,7 +99,8 @@ static void clientFunc(uint64_t client_id, Semaphore& readySem, Semaphore& start
 	readySem.release();
 	startSem.acquire();
 
-	for (size_t i = 0; i < iterations; ++i) {
+	size_t i = 0;
+	while (i < iterations && !terminate.load(std::memory_order_relaxed)) {
 		char* outBuf = buf[i % 2];
 		char* inBuf = buf[(i + 1) % 2];
 
@@ -134,6 +145,8 @@ static void clientFunc(uint64_t client_id, Semaphore& readySem, Semaphore& start
 			avg_ns += ns;
 			avg_ns /= 2;
 		}
+
+		i++;
 	}
 
 	// Shutdown and close the client socket;
@@ -149,7 +162,8 @@ static void clientFunc(uint64_t client_id, Semaphore& readySem, Semaphore& start
 
 	cf.wait();
 
-	client_avgs[client_id] = avg_ns;
+	clientResults[client_id].avg_ns = avg_ns;
+	clientResults[client_id].iterations = i;
 }
 
 auto getOption(int argc, char** argv, const std::string& option) -> char* {
@@ -170,8 +184,8 @@ static auto existsOption(int argc, char** argv, const std::string& option) -> bo
 
 static void printUsage(char* name) {
 	std::cerr << "Usage: " << name
-						<< "[-h] [-p <port>] [-c <clients>] [-i <iterations>] [-a <address>] [-s <size>] [-b "
-							 "<server backlog>] [-f <output-file>]"
+						<< "[-h] [-p <port>] [-c <clients>] [-a <address>] [-s <size>] [-b <server backlog>]"
+							 " [-f <output-file>]  [-i <iterations> | -t <execution time in sec>]"
 						<< std::endl;
 }
 
@@ -201,6 +215,16 @@ auto main(int argc, char* argv[]) -> int {
 		iterations = strtol(iterations_s, nullptr, DECIMAL);
 	}
 
+	char* time_s = getOption(argc, argv, "-t");
+	if (time_s) {
+		if (iterations_s) {
+			std::cerr << "-t and -i are mutual exclusive" << std::endl;
+			printUsage(argv[0]);
+			exit(EXIT_FAILURE);
+		}
+		execution_seconds = strtol(time_s, nullptr, DECIMAL);
+	}
+
 	char* size_s = getOption(argc, argv, "-s");
 	if (size_s) {
 		size = strtol(size_s, nullptr, DECIMAL);
@@ -227,7 +251,7 @@ auto main(int argc, char* argv[]) -> int {
 	Runtime runtime;
 
 	Fiber* alphaFiber = Fiber::from([&] {
-		client_avgs = new uint64_t[clients];
+		clientResults = new ClientResult[clients];
 		CPS cps;
 		Semaphore readySemaphore;
 		Semaphore startSemaphore;
@@ -250,6 +274,14 @@ auto main(int argc, char* argv[]) -> int {
 			readySemaphore.acquire();
 		}
 
+		if (execution_seconds) {
+			iterations = SIZE_MAX;
+			async([] {
+				sleep(execution_seconds);
+				terminate.store(true, std::memory_order_relaxed);
+			});
+		}
+
 		auto echo_start = std::chrono::high_resolution_clock::now();
 
 		// start the clients
@@ -262,10 +294,14 @@ auto main(int argc, char* argv[]) -> int {
 
 		auto echo_end = std::chrono::high_resolution_clock::now();
 
-		uint64_t avg_ns = client_avgs[0];
+		uint64_t avg_ns = clientResults[0].avg_ns;
+		uint64_t avg_iterations = clientResults[0].iterations;
 		for (size_t i = 1; i < clients; ++i) {
-			avg_ns += client_avgs[i];
+			avg_ns += clientResults[i].avg_ns;
 			avg_ns /= 2;
+
+			avg_iterations += clientResults[i].iterations;
+			avg_iterations /= 2;
 		}
 
 		auto connect_duration = duration_cast<nanoseconds>(echo_start - connect_start).count();
@@ -293,8 +329,8 @@ auto main(int argc, char* argv[]) -> int {
 		if (!exists) {
 			sst << "clients,iterations,size,avg_ns,connect,echo,total" << std::endl;
 		}
-		sst << clients << "," << iterations << "," << size << "," << avg_ns << "," << connect_duration
-				<< "," << echo_duration << "," << total_duration << std::endl;
+		sst << clients << "," << avg_iterations << "," << size << "," << avg_ns << ","
+				<< connect_duration << "," << echo_duration << "," << total_duration << std::endl;
 
 		auto output = sst.str();
 		if (emper::io::writeFileAndWait(out_fd, output.c_str(), output.size()) < 0) {
@@ -305,7 +341,7 @@ auto main(int argc, char* argv[]) -> int {
 			emper::io::closeAndForget(out_fd);
 		}
 
-		delete[] client_avgs;
+		delete[] clientResults;
 
 		exit(EXIT_SUCCESS);
 	});