mosquitto_rr: Add --latency option

Author: ralight

ChangeLog.txt

@@ -194,6 +194,8 @@ Clients:
 - mosquitto_sub payload hex output can now be split by fixed field length.
 - Add `--message-rate` option to mosquitto_sub, for printing the count of
   messages received each second.
+- Add `--latency` option to mosquitto_rr, for printing the request/response
+  latency.
 - Remove support for TLS v1.1.
 
 DB Dump:

client/CMakeLists.txt

@@ -54,7 +54,7 @@ endif()
 
 target_link_libraries(mosquitto_pub PRIVATE client-common)
 target_link_libraries(mosquitto_sub PRIVATE client-common)
-target_link_libraries(mosquitto_rr PRIVATE client-common)
+target_link_libraries(mosquitto_rr PRIVATE client-common libmosquitto_common)
 
 install(TARGETS mosquitto_pub RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}")
 install(TARGETS mosquitto_sub RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}")

client/Makefile

@@ -10,8 +10,8 @@ endif
 LOCAL_CFLAGS+=
 LOCAL_CPPFLAGS+=
 LOCAL_LDFLAGS+=
-LOCAL_LDADD+=-lcjson ${SHARED_DEP}
-STATIC_LDADD+=-lcjson
+LOCAL_LDADD+=-lcjson ${SHARED_DEP} ${LIBMOSQ_COMMON}
+STATIC_LDADD+=-lcjson ${LIBMOSQ_COMMON}
 
 ifeq ($(WITH_SOCKS),yes)
 	LOCAL_CPPFLAGS+=-DWITH_SOCKS

client/client_shared.c

@@ -831,6 +831,12 @@ int client_config_line_proc(struct mosq_config *cfg, int pub_or_sub, int argc, c
 			}else{
 				cfg->pub_mode = MSGMODE_STDIN_LINE;
 			}
+		}else if(!strcmp(argv[i], "--latency")){
+			if(pub_or_sub != CLIENT_RR){
+				goto unknown_option;
+			}
+			cfg->measure_latency = true;
+			cfg->tcp_nodelay = true; /* Remove influence of nagle */
 		}else if(!strcmp(argv[i], "-m") || !strcmp(argv[i], "--message")){
 			if(pub_or_sub == CLIENT_SUB){
 				goto unknown_option;

client/client_shared.h

@@ -143,6 +143,7 @@ struct mosq_config {
 	bool tcp_nodelay;
 	bool no_tls;
 	bool message_rate; /* sub */
+	bool measure_latency; /* rr */
 };
 
 extern const char hexseplist[32];

client/rr_client.c

@@ -53,6 +53,8 @@ int msg_count = 0;
 struct mosquitto *g_mosq = NULL;
 static bool timed_out = false;
 static int connack_result = 0;
+static struct timespec publish_send_time;
+static struct timespec publish_recv_time;
 
 #ifndef WIN32
 static void my_signal_handler(int signum)
@@ -68,6 +70,8 @@ static void my_signal_handler(int signum)
 
 int my_publish(struct mosquitto *mosq, int *mid, const char *topic, int payloadlen, void *payload, int qos, bool retain)
 {
+	mosquitto_time_ns(&publish_send_time.tv_sec, &publish_send_time.tv_nsec);
+
 	if(cfg.protocol_version < MQTT_PROTOCOL_V5){
 		return mosquitto_publish_v5(mosq, mid, topic, payloadlen, payload, qos, retain, NULL);
 	}else{
@@ -85,6 +89,8 @@ static void my_message_callback(struct mosquitto *mosq, void *obj, const struct
 	if(process_messages == false) return;
 	if(message->retain && cfg.no_retain) return;
 
+	mosquitto_time_ns(&publish_recv_time.tv_sec, &publish_recv_time.tv_nsec);
+
 	print_message(&cfg, message, properties);
 
 	switch(cfg.pub_mode){
@@ -267,6 +273,33 @@ static void print_usage(void)
 	printf("\nSee https://mosquitto.org/ for more information.\n\n");
 }
 
+static void report_latency(void)
+{
+	if(cfg.measure_latency){
+		time_t s = publish_recv_time.tv_sec - publish_send_time.tv_sec;
+		long ns = publish_recv_time.tv_nsec - publish_send_time.tv_nsec;
+
+		if(s < 0){
+			if(ns < 0){
+				s++;
+				ns -= 1000000000;
+			}
+		}
+
+		if(s > 0){
+			printf("Latency: %ld.%09ld\n", s, ns);
+		}else{
+			if(ns < 1000){
+				printf("Latency: %ldns\n", ns);
+			}else if(ns < 1000000){
+				printf("Latency: %fµs\n", ((double)ns)/1000.0);
+			}else{
+				printf("Latency: %fms\n", ((double)ns)/1000000.0);
+			}
+		}
+	}
+}
+
 int main(int argc, char *argv[])
 {
 	int rc;
@@ -385,6 +418,8 @@ int main(int argc, char *argv[])
 		}
 	}while(rc == MOSQ_ERR_SUCCESS && client_state != rr_s_disconnect);
 
+	report_latency();
+
 	mosquitto_destroy(g_mosq);
 	mosquitto_lib_cleanup();
 

man/mosquitto_rr.1.xml

@@ -63,6 +63,7 @@
 		<cmdsynopsis>
 			<command>misc-options:</command>
 			<sbr/>
+			<arg><option>--latency</option></arg>
 			<arg><option>-W</option> <replaceable>message-processing-timeout</replaceable></arg>
 		</cmdsynopsis>
 		<cmdsynopsis>
@@ -424,6 +425,28 @@
 					</para>
 				</listitem>
 			</varlistentry>
+			<varlistentry>
+				<term><option>--latency</option></term>
+				<listitem>
+					<para>
+						If this option is specified, mosquitto_rr will print out
+						the latency between it starting to publish a request and
+						the response arriving. This number includes both the
+						broker and client processing times, as well as any
+						inherent network latency.
+					</para>
+
+					<para>
+						This can be used to measure message delivery latency
+						very simply by specifying an identical request and
+						response topic.
+					</para>
+					<para>
+						The <option>--nodelay</option> option will be automatically
+						used when <option>--latency</option> is in use.
+					</para>
+				</listitem>
+			</varlistentry>
 			<varlistentry>
 				<term><option>-m</option></term>
 				<term><option>--message</option></term>