compositor: Allow disabling default flight recorders

Add a command line option to disable the default flight recorders
so we can save a little bit of CPU and memory on systems where
this isn't necessary.

Signed-off-by: Derek Foreman <derek.foreman@collabora.com>
Signed-off-by: Marius Vlad <marius.vlad@collabora.com>

compositor/main.c

@@ -69,6 +69,7 @@
 #define WINDOW_TITLE "Weston Compositor"
 /* flight recorder size (in bytes) */
 #define DEFAULT_FLIGHT_REC_SIZE (5 * 1024 * 1024)
+#define DEFAULT_FLIGHT_REC_SCOPES "log,drm-backend"
 
 struct wet_output_config {
 	int width;
@@ -3197,18 +3198,13 @@ weston_log_subscribe_to_scopes(struct weston_log_context *log_ctx,
 			       const char *log_scopes,
 			       const char *flight_rec_scopes)
 {
-	if (log_scopes)
+	if (logger && log_scopes)
 		weston_log_setup_scopes(log_ctx, logger, log_scopes);
 	else
 		weston_log_subscribe(log_ctx, logger, "log");
 
-	if (flight_rec_scopes) {
+	if (flight_rec && flight_rec_scopes)
 		weston_log_setup_scopes(log_ctx, flight_rec, flight_rec_scopes);
-	} else {
-		/* by default subscribe to 'log', and 'drm-backend' */
-		weston_log_subscribe(log_ctx, flight_rec, "log");
-		weston_log_subscribe(log_ctx, flight_rec, "drm-backend");
-	}
 }
 
 WL_EXPORT int
@@ -3305,6 +3301,11 @@ wet_main(int argc, char *argv[], const struct weston_testsuite_data *test_data)
 	weston_log_set_handler(vlog, vlog_continue);
 
 	logger = weston_log_subscriber_create_log(weston_logfile);
+
+	if (!flight_rec_scopes)
+		flight_rec_scopes = DEFAULT_FLIGHT_REC_SCOPES;
+
+	if (flight_rec_scopes && strlen(flight_rec_scopes) > 0)
 		flight_rec = weston_log_subscriber_create_flight_rec(DEFAULT_FLIGHT_REC_SIZE);
 
 	weston_log_subscribe_to_scopes(log_ctx, logger, flight_rec,
@@ -3320,6 +3321,7 @@ wet_main(int argc, char *argv[], const struct weston_testsuite_data *test_data)
 	free(cmdline);
 	log_uname();
 
+	weston_log("Flight recorder: %s\n", flight_rec ? "enabled" : "disabled");
 	verify_xdg_runtime_dir();
 
 	display = wl_display_create();
@@ -3393,6 +3395,7 @@ wet_main(int argc, char *argv[], const struct weston_testsuite_data *test_data)
 	if (debug_protocol)
 		weston_compositor_enable_debug_protocol(wet.compositor);
 
+	if (flight_rec)
 		weston_compositor_add_debug_binding(wet.compositor, KEY_D,
 						    flight_rec_key_binding_handler,
 						    flight_rec);
@@ -3534,6 +3537,7 @@ out_display:
 	weston_log_scope_destroy(log_scope);
 	log_scope = NULL;
 	weston_log_subscriber_destroy(logger);
+	if (flight_rec)
 		weston_log_subscriber_destroy(flight_rec);
 	weston_log_ctx_destroy(log_ctx);
 	weston_log_file_close();

man/weston.man

@@ -157,7 +157,8 @@ start-up code.
 Specify to which scopes should subscribe to. Useful to control which streams to
 write data into the flight recorder. Flight recorder has limited space, once
 the flight recorder is full new data will overwrite the old data. Without any
-scopes specified, it subscribes to 'log' and 'drm-backend' scopes.
+scopes specified, it subscribes to 'log' and 'drm-backend' scopes. Passing
+an empty value would disable the flight recorder entirely.
 .TP
 .BR \-\-version
 Print the program version.