From: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Date: Sat, 9 Dec 2017 17:51:46 +0000 (-0500)
Subject: Tests: race between consumer pause and trace start/stop
X-Git-Tag: v2.11.0-rc1~414
X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=commitdiff_plain;h=ff2b03c86766eba10a9fdee2ebeedf801efe83a3

Tests: race between consumer pause and trace start/stop

This fixes two problems with the current test.

1. Starting the tracing before pausing the consumption can result
in an arbitrary number of buffer usage conditions being sent to
the client as the buffers can be filled and emptied a number of
times.

2. Resuming the consumption before stopping tracing can, in a
similar way as '1', result in an arbitrary number of notifications
being sent to the client.

Note that the non-blocking stop is used since the blocking
variant would wait for pending data to be flushed forever since
the consumption is paused. Hence, we stop the tracing, resume
the consumption, and wait for the buffers to be flushed explicitly
using the lttng_data_pending() call. No sleeps are performed in
that loop since those could hide races triggered by this test.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---

diff --git a/tests/regression/tools/notification/notification.c b/tests/regression/tools/notification/notification.c
index 6c52bed01..de8734603 100644
--- a/tests/regression/tools/notification/notification.c
+++ b/tests/regression/tools/notification/notification.c
@@ -374,6 +374,17 @@ end:
 	lttng_action_destroy(action);
 }
 
+static
+void wait_data_pending(const char *session_name)
+{
+	int ret;
+
+	do {
+		ret = lttng_data_pending(session_name);
+		assert(ret >= 0);
+	} while (ret != 0);
+}
+
 void test_notification_channel(const char *session_name, const char *channel_name, const enum lttng_domain_type domain_type, const char **argv)
 {
 	int ret = 0;
@@ -575,8 +586,8 @@ void test_notification_channel(const char *session_name, const char *channel_nam
 	ok(nc_status == LTTNG_NOTIFICATION_CHANNEL_STATUS_ALREADY_SUBSCRIBED, "Subscribe to a condition for which subscription was already done");
 
 	/* Wait for notification to happen */
-	lttng_start_tracing(session_name);
 	stop_consumer(argv);
+	lttng_start_tracing(session_name);
 
 	/* Wait for high notification */
 	nc_status = lttng_notification_channel_get_next_notification(notification_channel, &notification);
@@ -588,8 +599,9 @@ void test_notification_channel(const char *session_name, const char *channel_nam
 	notification = NULL;
 
 	suspend_application();
+	lttng_stop_tracing_no_wait(session_name);
 	resume_consumer(argv);
-	lttng_stop_tracing(session_name);
+	wait_data_pending(session_name);
 
 	/*
 	 * Test that communication still work even if there is notification
@@ -611,9 +623,9 @@ void test_notification_channel(const char *session_name, const char *channel_nam
 	notification = NULL;
 
 	/* Stop consumer to force a high notification */
+	stop_consumer(argv);
 	resume_application();
 	lttng_start_tracing(session_name);
-	stop_consumer(argv);
 
 	nc_status = lttng_notification_channel_get_next_notification(notification_channel, &notification);
 	ok(nc_status == LTTNG_NOTIFICATION_CHANNEL_STATUS_OK && notification &&
@@ -623,9 +635,9 @@ void test_notification_channel(const char *session_name, const char *channel_nam
 	notification = NULL;
 
 	suspend_application();
-	/* Resume consumer to allow event consumption */
+	lttng_stop_tracing_no_wait(session_name);
 	resume_consumer(argv);
-	lttng_stop_tracing(session_name);
+	wait_data_pending(session_name);
 
 	nc_status = lttng_notification_channel_get_next_notification(notification_channel, &notification);
 	ok(nc_status == LTTNG_NOTIFICATION_CHANNEL_STATUS_OK && notification &&
@@ -634,10 +646,10 @@ void test_notification_channel(const char *session_name, const char *channel_nam
 	lttng_notification_destroy(notification);
 	notification = NULL;
 
+	stop_consumer(argv);
 	resume_application();
 	/* Stop consumer to force a high notification */
 	lttng_start_tracing(session_name);
-	stop_consumer(argv);
 
 	nc_status = lttng_notification_channel_get_next_notification(notification_channel, &notification);
 	ok(nc_status == LTTNG_NOTIFICATION_CHANNEL_STATUS_OK && notification &&
@@ -647,8 +659,10 @@ void test_notification_channel(const char *session_name, const char *channel_nam
 	notification = NULL;
 
 	/* Resume consumer to allow event consumption */
+	suspend_application();
+	lttng_stop_tracing_no_wait(session_name);
 	resume_consumer(argv);
-	lttng_stop_tracing(session_name);
+	wait_data_pending(session_name);
 
 	nc_status = lttng_notification_channel_unsubscribe(notification_channel, low_condition);
 	ok(nc_status == LTTNG_NOTIFICATION_CHANNEL_STATUS_OK, "Unsubscribe low condition with pending notification");