Add options to test-ratelim.c to check its results

The new options let you specify a maximum deviation of bandwidth used
from expected bandwidth used, and make test-ratelim.c exit with a
nonzero status when those deviations are violated.

This patch also adds a test-ratelim.sh script to run test-ratelim with
a few sensible options for testing.

test/test-ratelim.c

@@ -54,11 +54,16 @@ static int cfg_connlimit = 0;
 static int cfg_grouplimit = 0;
 static int cfg_tick_msec = 1000;
 
+static int cfg_connlimit_tolerance = -1;
+static int cfg_grouplimit_tolerance = -1;
+static int cfg_stddev_tolerance = -1;
+
 static struct timeval cfg_tick = { 0, 500*1000 };
 
 static struct ev_token_bucket_cfg *conn_bucket_cfg = NULL;
 static struct ev_token_bucket_cfg *group_bucket_cfg = NULL;
 struct bufferevent_rate_limit_group *ratelim_group = NULL;
+static double seconds_per_tick = 0.0;
 
 struct client_state {
 	size_t queued;
@@ -131,7 +136,7 @@ echo_listenercb(struct evconnlistener *listener, evutil_socket_t newsock,
 	bufferevent_enable(bev, EV_READ|EV_WRITE);
 }
 
-static void
+static int
 test_ratelimiting(void)
 {
 	struct event_base *base;
@@ -151,6 +156,8 @@ test_ratelimiting(void)
 	ev_uint64_t total_received;
 	double total_sq_persec, total_persec;
 	double variance;
+	double expected_total_persec = -1.0, expected_avg_persec = -1.0;
+	int ok = 1;
 
 	memset(&sin, 0, sizeof(sin));
 	sin.sin_family = AF_INET;
@@ -166,7 +173,7 @@ test_ratelimiting(void)
 	if (getsockname(evconnlistener_get_fd(listener), (struct sockaddr *)&ss,
 		&slen) < 0) {
 		perror("getsockname");
-		return;
+		return 1;
 	}
 
 	if (cfg_connlimit > 0) {
@@ -184,7 +191,19 @@ test_ratelimiting(void)
 			&cfg_tick);
 		ratelim_group = bufferevent_rate_limit_group_new(
 			base, group_bucket_cfg);
-	};
+		expected_total_persec = cfg_grouplimit;
+		expected_avg_persec = cfg_grouplimit / cfg_n_connections;
+		if (cfg_connlimit > 0 && expected_avg_persec > cfg_connlimit)
+			expected_avg_persec = cfg_connlimit;
+	}
+
+	if (expected_avg_persec < 0 && cfg_connlimit > 0)
+		expected_avg_persec = cfg_connlimit;
+
+	if (expected_avg_persec > 0)
+		expected_avg_persec /= seconds_per_tick;
+	if (expected_total_persec > 0)
+		expected_total_persec /= seconds_per_tick;
 
 	bevs = calloc(cfg_n_connections, sizeof(struct bufferevent *));
 	states = calloc(cfg_n_connections, sizeof(struct client_state));
@@ -200,8 +219,8 @@ test_ratelimiting(void)
 		    slen);
 	}
 
-	tv.tv_sec = cfg_duration;
+	tv.tv_sec = cfg_duration - 1;
-	tv.tv_usec = 0;
+	tv.tv_usec = 995000;
 
 	event_base_loopexit(base, &tv);
 
@@ -216,16 +235,43 @@ test_ratelimiting(void)
 		total_received += states[i].received;
 		total_persec += persec;
 		total_sq_persec += persec*persec;
-		printf("%d: %f per second\n", i, persec);
+		printf("%d: %f per second\n", i+1, persec);
 	}
 	printf("   total: %f per second\n",
 	    ((double)total_received)/cfg_duration);
+	if (expected_total_persec > 0) {
+		double diff = expected_total_persec -
+		    ((double)total_received/cfg_duration);
+		printf("  [Off by %lf]\n", diff);
+		if (cfg_grouplimit_tolerance > 0 &&
+		    fabs(diff) > cfg_grouplimit_tolerance) {
+			fprintf(stderr, "Group bandwidth out of bounds\n");
+			ok = 0;
+		}
+	}
+
 	printf(" average: %f per second\n",
 	    (((double)total_received)/cfg_duration)/cfg_n_connections);
+	if (expected_avg_persec > 0) {
+		double diff = expected_avg_persec - (((double)total_received)/cfg_duration)/cfg_n_connections;
+		printf("  [Off by %lf]\n", diff);
+		if (cfg_connlimit_tolerance > 0 &&
+		    fabs(diff) > cfg_connlimit_tolerance) {
+			fprintf(stderr, "Connection bandwidth out of bounds\n");
+			ok = 0;
+		}
+	}
 
 	variance = total_sq_persec/cfg_n_connections - total_persec*total_persec/(cfg_n_connections*cfg_n_connections);
 
 	printf("  stddev: %f per second\n", sqrt(variance));
+	if (cfg_stddev_tolerance > 0 &&
+	    sqrt(variance) > cfg_stddev_tolerance) {
+		fprintf(stderr, "Connection variance out of bounds\n");
+		ok = 0;
+	}
+
+	return ok ? 0 : 1;
 }
 
 static struct option {
@@ -238,6 +284,9 @@ static struct option {
 	{ "-c", &cfg_connlimit, 0, 0 },
 	{ "-g", &cfg_grouplimit, 0, 0 },
 	{ "-t", &cfg_tick_msec, 10, 0 },
+	{ "--check-connlimit", &cfg_connlimit_tolerance, 0, 0 },
+	{ "--check-grouplimit", &cfg_grouplimit_tolerance, 0, 0 },
+	{ "--check-stddev", &cfg_stddev_tolerance, 0, 0 },
 	{ NULL, NULL, -1, 0 },
 };
 
@@ -324,7 +373,7 @@ main(int argc, char **argv)
 	cfg_tick.tv_sec = cfg_tick_msec / 1000;
 	cfg_tick.tv_usec = (cfg_tick_msec % 1000)*1000;
 
-	ratio = cfg_tick_msec / 1000.0;
+	seconds_per_tick = ratio = cfg_tick_msec / 1000.0;
 
 	cfg_connlimit *= ratio;
 	cfg_grouplimit *= ratio;
@@ -343,7 +392,5 @@ main(int argc, char **argv)
 	evthread_enable_lock_debuging();
 #endif
 
-	test_ratelimiting();
+	return test_ratelimiting();
-
-	return 0;
 }

test/test-ratelim.sh

@@ -0,0 +1,68 @@
+#!/bin/sh
+
+if test "x$TEST_OUTPUT_FILE" = "x"
+then
+	TEST_OUTPUT_FILE=/dev/null
+fi
+
+# /bin/echo is a little more likely to support -n than sh's builtin echo.
+if test -x /bin/echo
+then
+	ECHO=/bin/echo
+else
+	ECHO=echo
+fi
+
+if test "$TEST_OUTPUT_FILE" != "/dev/null"
+then
+	touch "$TEST_OUTPUT_FILE" || exit 1
+fi
+
+TEST_DIR=.
+
+T=`echo "$0" | sed -e 's/test-ratelim.sh$//'`
+if test -x "$T/test-ratelim"
+then
+	TEST_DIR="$T"
+fi
+
+announce () {
+	echo $@
+	echo $@ >>"$TEST_OUTPUT_FILE"
+}
+
+announce_n () {
+	$ECHO -n $@
+	echo $@ >>"$TEST_OUTPUT_FILE"
+}
+
+
+run_tests () {
+	announce_n "  Group limits, no connection limit:"
+	if $TEST_DIR/test-ratelim -g 30000 -n 30 -t 100 --check-grouplimit 1000 --check-stddev 100 >>"$TEST_OUTPUT_FILE"
+	then
+		announce OKAY
+	else
+		announce FAILED
+	fi
+
+	announce_n "  Connection limit, no group limit:"
+	if $TEST_DIR/test-ratelim -c 1000 -n 30 -t 100 --check-connlimit 50 --check-stddev 50 >>"$TEST_OUTPUT_FILE"
+	then
+		announce OKAY ;
+	else
+		announce FAILED ;
+	fi
+
+	announce_n "  Connection limit and group limit:"
+	if $TEST_DIR/test-ratelim -c 1000 -g 30000 -n 30 -t 100 --check-grouplimit 1000 --check-connlimit 50 --check-stddev 50 >>"$TEST_OUTPUT_FILE"
+	then
+		announce OKAY ;
+	else
+		announce FAILED ;
+	fi
+}
+
+announce "Running rate-limiting tests:"
+
+run_tests