Tests: add snapshot with low bandwidth data socket testcase

This commit adds a testcase that simulates a snapshot on a relayd with a
data socket with very low bandwidth. This configuration can trigger a
race where the trace is unreadable because the snapshot is reported as
completed even though data is still in flight.

As of right now, this testcase fails because the trace is unreadable.

Babeltrace outputs the following error:
[error] Packet size (4194304 bits) is larger than remaining file size
(175104 bits) in trace with UUID "d9e6182e6469405094f839a08f438c3b", at
path:
"/tmp/tmp.sY3M2G54Oy/raton/snapshot-1-20181203-100618-0/ust/uid/0/64-bit",
within stream id 0, at relative path: "chan1_1".

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>

tests/regression/tools/streaming/test_high_throughput_limits

@@ -24,6 +24,7 @@ TESTAPP_PATH="$TESTDIR/utils/testapp"
 TESTAPP_NAME="gen-ust-events"
 TESTAPP_BIN="$TESTAPP_PATH/$TESTAPP_NAME/$TESTAPP_NAME"
 SESSION_NAME="high-throughput"
+CHANNEL_NAME="chan1"
 EVENT_NAME="tp:tptest"
 NETWORK_URI="net://localhost"
 SESSIOND_CTRL_PORT=5342
@@ -32,7 +33,7 @@ DEFAULT_IF="lo"
 APPS_PID=
 
 
-NUM_TESTS=104
+NUM_TESTS=119
 
 source $TESTDIR/utils/utils.sh
 
@@ -204,6 +205,38 @@ function test_low_bandwidth_link
 	done
 }
 
+function test_low_data_socket_bandwidth_snapshot
+{
+	bw_limit=1000
+	bw_dataportlimit=1
+	bw_ctrlportlimit=$((${bw_limit}-${bw_dataportlimit}))
+
+	TRACE_PATH=$(mktemp -d)
+	diag "Test data port with bandwidth limit set to ${bw_dataportlimit}kbps"
+
+	set_bw_limit_per_relayd_port $bw_limit $bw_ctrlportlimit $bw_dataportlimit
+
+	start_lttng_sessiond
+	start_lttng_relayd "-o $TRACE_PATH"
+	create_lttng_session_no_output $SESSION_NAME
+	enable_lttng_mmap_overwrite_ust_channel $SESSION_NAME $CHANNEL_NAME
+	enable_ust_lttng_event_ok $SESSION_NAME $EVENT_NAME $CHANNEL_NAME
+	start_lttng_tracing_ok $SESSION_NAME
+	run_apps 1 10000
+	lttng_snapshot_add_output_ok $SESSION_NAME $NETWORK_URI
+	lttng_snapshot_record $SESSION_NAME
+
+	# Validate that the trace is readable
+	validate_trace $EVENT_NAME $TRACE_PATH/$HOSTNAME/snapshot-1*
+	stop_lttng_tracing_ok $SESSION_NAME
+	destroy_lttng_session_ok $SESSION_NAME
+	stop_test_apps
+	stop_lttng_relayd
+	stop_lttng_sessiond
+	reset_bw_limit
+	rm -rf "$TRACE_PATH"
+}
+
 plan_tests $NUM_TESTS
 
 print_test_banner "$TEST_DESC"
@@ -220,5 +253,6 @@ skip $isroot "Root access is needed to set bandwith limits. Skipping all tests."
 	trap interrupt_cleanup SIGTERM
 	trap interrupt_cleanup SIGINT
 
+	test_low_data_socket_bandwidth_snapshot
 	test_low_bandwidth_link
 }