gst: debug: Add information about active tracers in dot files

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/8820>

subprojects/gstreamer/gst/gstdebugutils.c

@@ -60,6 +60,7 @@
 #include "gstobject.h"
 #include "gstghostpad.h"
 #include "gstpad.h"
+#include "gsttracer.h"
 #include "gstutils.h"
 #include "gstvalue.h"
 #include "gstidstr-private.h"
@@ -109,7 +110,8 @@ debug_dump_get_element_state (GstElement * element)
 
 static gchar *
 debug_dump_get_object_params (GObject * object,
-    GstDebugGraphDetails details, const char *const *ignored_propnames)
+    GstDebugGraphDetails details, const char *const *ignored_propnames,
+    const gchar * prop_separator)
 {
   gchar *param_name = NULL;
   GParamSpec **properties, *property;
@@ -215,12 +217,13 @@ debug_dump_get_object_params (GObject * object,
           tmp = (char *) "";
 
         if (details & GST_DEBUG_GRAPH_SHOW_FULL_PARAMS) {
-          param_name = g_strdup_printf ("%s\\n%s=%s", tmp, property->name,
+          param_name =
+              g_strdup_printf ("%s%s%s=%s", tmp, prop_separator, property->name,
               value_str);
         } else {
-          param_name = g_strdup_printf ("%s\\n%s=%."
+          param_name = g_strdup_printf ("%s%s%s=%."
-              G_STRINGIFY (PARAM_MAX_LENGTH) "s%s", tmp, property->name,
+              G_STRINGIFY (PARAM_MAX_LENGTH) "s%s", tmp, prop_separator,
-              value_str, ellipses);
+              property->name, value_str, ellipses);
         }
 
         if (tmp[0] != '\0')
@@ -264,7 +267,8 @@ debug_dump_pad (GstPad * pad, const gchar * color_name,
   }
 
   param_name =
-      debug_dump_get_object_params (G_OBJECT (pad), details, ignore_propnames);
+      debug_dump_get_object_params (G_OBJECT (pad), details, ignore_propnames,
+      "\n");
   if (details & GST_DEBUG_GRAPH_SHOW_STATES) {
     gchar pad_flags[5];
     const gchar *activation_mode = "-><";
@@ -643,7 +647,7 @@ debug_dump_element (GstBin * bin, GstDebugGraphDetails details,
         }
         if (details & GST_DEBUG_GRAPH_SHOW_NON_DEFAULT_PARAMS) {
           param_name = debug_dump_get_object_params (G_OBJECT (element),
-              details, ignore_propnames);
+              details, ignore_propnames, "\n");
         }
         /* elements */
         g_string_append_printf (str, "%ssubgraph cluster_%s {\n", spc,
@@ -759,17 +763,53 @@ debug_dump_element (GstBin * bin, GstDebugGraphDetails details,
   gst_iterator_free (element_iter);
 }
 
+static gchar *
+debug_dump_get_tracers_info (GstDebugGraphDetails details)
+{
+  GList *tracers, *tmp;
+
+  tracers = gst_tracing_get_active_tracers ();
+  if (!tracers)
+    return NULL;
+
+  GString *str = g_string_new ("Active Tracers:");
+  for (tmp = tracers; tmp; tmp = tmp->next) {
+    GObject *tracer = G_OBJECT (tmp->data);
+    gchar *props = NULL;
+
+    g_string_append_printf (str, "\\l    - %s", G_OBJECT_TYPE_NAME (tracer));
+    if (details & GST_DEBUG_GRAPH_SHOW_NON_DEFAULT_PARAMS) {
+      props =
+          debug_dump_get_object_params (tracer, details, NULL, "\\l        * ");
+      if (props) {
+        g_string_append_c (str, ':');
+        g_string_append_printf (str, "    %s", props);
+      }
+      g_free (props);
+    }
+
+    /* Make sure each tracer line ends with \l even if it has no properties */
+    g_string_append (str, "\\l");
+
+  }
+
+  g_list_free (tracers);
+  return g_string_free (str, FALSE);
+}
+
 static void
 debug_dump_header (GstBin * bin, GstDebugGraphDetails details, GString * str)
 {
   gchar *state_name = NULL;
   gchar *param_name = NULL;
+  gchar *tracers_info = NULL;
 
   if (details & GST_DEBUG_GRAPH_SHOW_STATES) {
     state_name = debug_dump_get_element_state (GST_ELEMENT (bin));
   }
   if (details & GST_DEBUG_GRAPH_SHOW_NON_DEFAULT_PARAMS) {
-    param_name = debug_dump_get_object_params (G_OBJECT (bin), details, NULL);
+    param_name =
+        debug_dump_get_object_params (G_OBJECT (bin), details, NULL, "\n");
   }
 
   /* write header */
@@ -795,10 +835,23 @@ debug_dump_header (GstBin * bin, GstDebugGraphDetails details, GString * str)
       (state_name ? state_name : ""), (param_name ? param_name : "")
       );
 
+  tracers_info = debug_dump_get_tracers_info (details);
+  if (tracers_info) {           /* More than just "Active Tracers:\l" */
+    g_string_append_printf (str,
+        "  tracers [\n"
+        "    pos=\"0,0!\",\n"
+        "    margin=\"0.05,0.05\",\n"
+        "    style=\"filled\",\n"
+        "    fillcolor=\"#e0e0ff\",\n"
+        "    label=\"%s\",\n" "  ];\n" "\n", tracers_info);
+  }
+
   if (state_name)
     g_free (state_name);
   if (param_name)
     g_free (param_name);
+  if (tracers_info)
+    g_free (tracers_info);
 }
 
 static void