tracer: simplify hook api

Instead of a single invoke() function and a 'mask', register to individual
hooks. This avoids one level of indirection and allows us to remove the
hook enums. The message enms are now renamed to hook enums.

8 files changed, 465 insertions, 529 deletions

diff --git a/gst/gsttracer.c b/gst/gsttracer.c
index fd95ba28c..0d783a003 100644
--- a/gst/gsttracer.c
+++ b/gst/gsttracer.c
@@ -45,7 +45,6 @@ enum
 {
   PROP_0,
   PROP_PARAMS,
-  PROP_MASK,
   PROP_LAST
 };
 
@@ -59,7 +58,6 @@ static void gst_tracer_get_property (GObject * object, guint prop_id,
 struct _GstTracerPrivate
 {
   const gchar *params;
-  GstTracerHook mask;
 };
 
 #define gst_tracer_parent_class parent_class
@@ -77,10 +75,6 @@ gst_tracer_class_init (GstTracerClass * klass)
       g_param_spec_string ("params", "Params", "Extra configuration parameters",
       NULL, G_PARAM_READWRITE | G_PARAM_CONSTRUCT | G_PARAM_STATIC_STRINGS);
 
-  properties[PROP_MASK] =
-      g_param_spec_flags ("mask", "Mask", "Event mask", GST_TYPE_TRACER_HOOK,
-      GST_TRACER_HOOK_NONE, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS);
-
   g_object_class_install_properties (gobject_class, PROP_LAST, properties);
   g_type_class_add_private (klass, sizeof (GstTracerPrivate));
 }
@@ -102,9 +96,6 @@ gst_tracer_set_property (GObject * object, guint prop_id,
     case PROP_PARAMS:
       self->priv->params = g_value_get_string (value);
       break;
-    case PROP_MASK:
-      self->priv->mask = g_value_get_flags (value);
-      break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
       break;
@@ -121,25 +112,12 @@ gst_tracer_get_property (GObject * object, guint prop_id,
     case PROP_PARAMS:
       g_value_set_string (value, self->priv->params);
       break;
-    case PROP_MASK:
-      g_value_set_flags (value, self->priv->mask);
-      break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
       break;
   }
 }
 
-void
-gst_tracer_invoke (GstTracer * self, GstTracerMessageId mid, va_list var_args)
-{
-  GstTracerClass *klass = GST_TRACER_GET_CLASS (self);
-
-  g_return_if_fail (klass->invoke);
-
-  klass->invoke (self, mid, var_args);
-}
-
 /* tracing modules */
 
 gboolean
diff --git a/gst/gsttracer.h b/gst/gsttracer.h
index 6c96a0fbe..3b5b5805e 100644
--- a/gst/gsttracer.h
+++ b/gst/gsttracer.h
@@ -53,24 +53,20 @@ struct _GstTracer {
   gpointer _gst_reserved[GST_PADDING];
 };
 
-typedef void (*GstTracerInvokeFunction) (GstTracer * self, 
-    GstTracerMessageId mid, va_list var_args);
+typedef void (*GstTracerHookFunction) (GstTracer * self, va_list var_args);
 
 struct _GstTracerClass {
   GstObjectClass parent_class;
-  
-  /* plugin vmethods */
-  GstTracerInvokeFunction invoke;
-  
+    
   /*< private >*/
   gpointer _gst_reserved[GST_PADDING];
 };
 
-void gst_tracer_invoke (GstTracer * self, GstTracerMessageId mid, 
-    va_list var_args);
-
 GType gst_tracer_get_type          (void);
 
+void gst_tracer_register_hook (GstTracer *tracer, GstTracerHookId id, 
+  GstTracerHookFunction func);
+
 G_END_DECLS
 
 #endif /* __GST_TRACER_H__ */
diff --git a/gst/gsttracerutils.c b/gst/gsttracerutils.c
index 33678c2d1..ecd6b038a 100644
--- a/gst/gsttracerutils.c
+++ b/gst/gsttracerutils.c
@@ -45,6 +45,12 @@ gboolean _priv_tracer_enabled = FALSE;
 /* TODO(ensonic): use array of GPtrArray* ? */
 GList *_priv_tracers[GST_TRACER_HOOK_ID_LAST] = { NULL, };
 
+typedef struct
+{
+  GstTracer *tracer;
+  GstTracerHookFunction func;
+} GstTracerHook;
+
 /* Initialize the tracing system */
 void
 _priv_gst_tracer_init (void)
@@ -55,10 +61,8 @@ _priv_gst_tracer_init (void)
     GstRegistry *registry = gst_registry_get ();
     GstPluginFeature *feature;
     GstTracerFactory *factory;
-    GstTracerHook mask;
-    GstObject *tracer;
     gchar **t = g_strsplit_set (env, ";", 0);
-    gint i = 0, j;
+    gint i = 0;
     gchar *params;
 
     GST_INFO ("enabling tracers: '%s'", env);
@@ -83,28 +87,9 @@ _priv_gst_tracer_init (void)
           GST_INFO_OBJECT (factory, "creating tracer: type-id=%u",
               (guint) factory->type);
 
-          tracer = g_object_new (factory->type, "params", params, NULL);
-          g_object_get (tracer, "mask", &mask, NULL);
-
-          if (mask) {
-            /* add to lists according to mask */
-            j = 0;
-            while (mask && (j < GST_TRACER_HOOK_ID_LAST)) {
-              if (mask & 1) {
-                _priv_tracers[j] = g_list_prepend (_priv_tracers[j],
-                    gst_object_ref (tracer));
-                GST_WARNING_OBJECT (tracer, "added tracer to hook %d", j);
-              }
-              mask >>= 1;
-              j++;
-            }
-
-            _priv_tracer_enabled = TRUE;
-          } else {
-            GST_WARNING_OBJECT (tracer,
-                "tracer with zero mask won't have any effect");
-          }
-          gst_object_unref (tracer);
+          /* tracers register them self to the hooks */
+          gst_object_unref (g_object_new (factory->type, "params", params,
+                  NULL));
         } else {
           GST_WARNING_OBJECT (feature,
               "loading plugin containing feature %s failed!", t[i]);
@@ -123,11 +108,14 @@ _priv_gst_tracer_deinit (void)
 {
   gint i;
   GList *node;
+  GstTracerHook *hook;
 
   /* shutdown tracers for final reports */
   for (i = 0; i < GST_TRACER_HOOK_ID_LAST; i++) {
     for (node = _priv_tracers[i]; node; node = g_list_next (node)) {
-      gst_object_unref (node->data);
+      hook = (GstTracerHook *) node->data;
+      gst_object_unref (hook->tracer);
+      g_slice_free (GstTracerHook, hook);
     }
     g_list_free (_priv_tracers[i]);
     _priv_tracers[i] = NULL;
@@ -136,14 +124,28 @@ _priv_gst_tracer_deinit (void)
 }
 
 void
-gst_tracer_dispatch (GstTracerHookId hid, GstTracerMessageId mid, ...)
+gst_tracer_register_hook (GstTracer * tracer, GstTracerHookId id,
+    GstTracerHookFunction func)
+{
+  GstTracerHook *hook = g_slice_new0 (GstTracerHook);
+  hook->tracer = gst_object_ref (tracer);
+  hook->func = func;
+  _priv_tracers[id] = g_list_prepend (_priv_tracers[id], hook);
+  GST_DEBUG_OBJECT (tracer, "added tracer to hook %d", id);
+  _priv_tracer_enabled = TRUE;
+}
+
+void
+gst_tracer_dispatch (GstTracerHookId id, ...)
 {
   va_list var_args;
   GList *node;
+  GstTracerHook *hook;
 
-  for (node = _priv_tracers[hid]; node; node = g_list_next (node)) {
-    va_start (var_args, mid);
-    gst_tracer_invoke (node->data, mid, var_args);
+  for (node = _priv_tracers[id]; node; node = g_list_next (node)) {
+    hook = (GstTracerHook *) node->data;
+    va_start (var_args, id);
+    hook->func (hook->tracer, var_args);
     va_end (var_args);
   }
 }
diff --git a/gst/gsttracerutils.h b/gst/gsttracerutils.h
index c3bd5f35a..77fa2ab41 100644
--- a/gst/gsttracerutils.h
+++ b/gst/gsttracerutils.h
@@ -32,52 +32,25 @@ G_BEGIN_DECLS
 
 #ifndef GST_DISABLE_GST_DEBUG
 
-/* hook flags and ids */
+/* tracer hook message ids */
 
 typedef enum
 {
-  GST_TRACER_HOOK_NONE      = 0,
-  GST_TRACER_HOOK_BUFFERS   = (1 << 0),
-  GST_TRACER_HOOK_EVENTS    = (1 << 1),
-  GST_TRACER_HOOK_MESSAGES  = (1 << 2),
-  GST_TRACER_HOOK_QUERIES   = (1 << 3),
-  GST_TRACER_HOOK_TOPOLOGY  = (1 << 4),
-  /*
-  GST_TRACER_HOOK_TIMER
-  */
-  GST_TRACER_HOOK_ALL       = (1 << 5) - 1
-} GstTracerHook;
-
-typedef enum
-{
-  GST_TRACER_HOOK_ID_BUFFERS = 0,
-  GST_TRACER_HOOK_ID_EVENTS,
-  GST_TRACER_HOOK_ID_MESSAGES,
-  GST_TRACER_HOOK_ID_QUERIES,
-  GST_TRACER_HOOK_ID_TOPLOGY,
-  /*
-  GST_TRACER_HOOK_ID_TIMER
-  */
+  GST_TRACER_HOOK_ID_PAD_PUSH_PRE = 0,
+  GST_TRACER_HOOK_ID_PAD_PUSH_POST,
+  GST_TRACER_HOOK_ID_PAD_PUSH_LIST_PRE,
+  GST_TRACER_HOOK_ID_PAD_PUSH_LIST_POST,
+  GST_TRACER_HOOK_ID_PAD_PULL_RANGE_PRE,
+  GST_TRACER_HOOK_ID_PAD_PULL_RANGE_POST,
+  GST_TRACER_HOOK_ID_PAD_PUSH_EVENT_PRE,
+  GST_TRACER_HOOK_ID_PAD_PUSH_EVENT_POST,
+  GST_TRACER_HOOK_ID_ELEMENT_POST_MESSAGE_PRE,
+  GST_TRACER_HOOK_ID_ELEMENT_POST_MESSAGE_POST,
+  GST_TRACER_HOOK_ID_ELEMENT_QUERY_PRE,
+  GST_TRACER_HOOK_ID_ELEMENT_QUERY_POST,
   GST_TRACER_HOOK_ID_LAST
 } GstTracerHookId;
 
-typedef enum
-{
-  GST_TRACER_MESSAGE_ID_PAD_PUSH_PRE = 0,
-  GST_TRACER_MESSAGE_ID_PAD_PUSH_POST,
-  GST_TRACER_MESSAGE_ID_PAD_PUSH_LIST_PRE,
-  GST_TRACER_MESSAGE_ID_PAD_PUSH_LIST_POST,
-  GST_TRACER_MESSAGE_ID_PAD_PULL_RANGE_PRE,
-  GST_TRACER_MESSAGE_ID_PAD_PULL_RANGE_POST,
-  GST_TRACER_MESSAGE_ID_PAD_PUSH_EVENT_PRE,
-  GST_TRACER_MESSAGE_ID_PAD_PUSH_EVENT_POST,
-  GST_TRACER_MESSAGE_ID_ELEMENT_POST_MESSAGE_PRE,
-  GST_TRACER_MESSAGE_ID_ELEMENT_POST_MESSAGE_POST,
-  GST_TRACER_MESSAGE_ID_ELEMENT_QUERY_PRE,
-  GST_TRACER_MESSAGE_ID_ELEMENT_QUERY_POST,
-  GST_TRACER_MESSAGE_ID_LAST
-} GstTracerMessageId;
-
 /* tracing hooks */
 
 void _priv_gst_tracer_init (void);
@@ -89,7 +62,7 @@ gboolean gst_tracer_register (GstPlugin * plugin, const gchar * name, GType type
 
 /* tracing helpers */
 
-void gst_tracer_dispatch (GstTracerHookId hid, GstTracerMessageId mid, ...);
+void gst_tracer_dispatch (GstTracerHookId id, ...);
 
 /* tracing module helpers */
 
@@ -107,97 +80,97 @@ extern GList *_priv_tracers[GST_TRACER_HOOK_ID_LAST];
 /* tracing hooks */
 
 #define GST_TRACER_PAD_PUSH_PRE(pad, buffer) G_STMT_START{ \
-  if (GST_TRACER_IS_ENABLED(GST_TRACER_HOOK_ID_BUFFERS)) { \
-    gst_tracer_dispatch (GST_TRACER_HOOK_ID_BUFFERS, \
-        GST_TRACER_MESSAGE_ID_PAD_PUSH_PRE, GST_TRACER_TS, \
+  if (GST_TRACER_IS_ENABLED(GST_TRACER_HOOK_ID_PAD_PUSH_PRE)) { \
+    gst_tracer_dispatch (GST_TRACER_HOOK_ID_PAD_PUSH_PRE, \
+        GST_TRACER_TS, \
         pad, buffer); \
   } \
 }G_STMT_END
 
 #define GST_TRACER_PAD_PUSH_POST(pad, res) G_STMT_START{ \
-  if (GST_TRACER_IS_ENABLED(GST_TRACER_HOOK_ID_BUFFERS)) { \
-    gst_tracer_dispatch (GST_TRACER_HOOK_ID_BUFFERS, \
-        GST_TRACER_MESSAGE_ID_PAD_PUSH_POST, GST_TRACER_TS, \
+  if (GST_TRACER_IS_ENABLED(GST_TRACER_HOOK_ID_PAD_PUSH_POST)) { \
+    gst_tracer_dispatch (GST_TRACER_HOOK_ID_PAD_PUSH_POST, \
+        GST_TRACER_TS, \
         pad, res); \
   } \
 }G_STMT_END
 
 #define GST_TRACER_PAD_PUSH_LIST_PRE(pad, list) G_STMT_START{ \
-  if (GST_TRACER_IS_ENABLED(GST_TRACER_HOOK_ID_BUFFERS)) { \
-    gst_tracer_dispatch (GST_TRACER_HOOK_ID_BUFFERS, \
-        GST_TRACER_MESSAGE_ID_PAD_PUSH_LIST_PRE, GST_TRACER_TS, \
+  if (GST_TRACER_IS_ENABLED(GST_TRACER_HOOK_ID_PAD_PUSH_LIST_PRE)) { \
+    gst_tracer_dispatch (GST_TRACER_HOOK_ID_PAD_PUSH_LIST_PRE, \
+        GST_TRACER_TS, \
         pad, list); \
   } \
 }G_STMT_END
 
 #define GST_TRACER_PAD_PUSH_LIST_POST(pad, res) G_STMT_START{ \
-  if (GST_TRACER_IS_ENABLED(GST_TRACER_HOOK_ID_BUFFERS)) { \
-    gst_tracer_dispatch (GST_TRACER_HOOK_ID_BUFFERS, \
-        GST_TRACER_MESSAGE_ID_PAD_PUSH_LIST_POST, GST_TRACER_TS, \
+  if (GST_TRACER_IS_ENABLED(GST_TRACER_HOOK_ID_PAD_PUSH_LIST_POST)) { \
+    gst_tracer_dispatch (GST_TRACER_HOOK_ID_PAD_PUSH_LIST_POST, \
+        GST_TRACER_TS, \
         pad, res); \
   } \
 }G_STMT_END
 
 #define GST_TRACER_PAD_PULL_RANGE_PRE(pad, offset, size) G_STMT_START{ \
-  if (GST_TRACER_IS_ENABLED(GST_TRACER_HOOK_ID_BUFFERS)) { \
-    gst_tracer_dispatch (GST_TRACER_HOOK_ID_BUFFERS, \
-        GST_TRACER_MESSAGE_ID_PAD_PULL_RANGE_PRE, GST_TRACER_TS, \
+  if (GST_TRACER_IS_ENABLED(GST_TRACER_HOOK_ID_PAD_PULL_RANGE_PRE)) { \
+    gst_tracer_dispatch (GST_TRACER_HOOK_ID_PAD_PULL_RANGE_PRE, \
+        GST_TRACER_TS, \
         pad, offset, size); \
   } \
 }G_STMT_END
 
 #define GST_TRACER_PAD_PULL_RANGE_POST(pad, buffer, res) G_STMT_START{ \
-  if (GST_TRACER_IS_ENABLED(GST_TRACER_HOOK_ID_BUFFERS)) { \
-    gst_tracer_dispatch (GST_TRACER_HOOK_ID_BUFFERS, \
-        GST_TRACER_MESSAGE_ID_PAD_PULL_RANGE_POST, GST_TRACER_TS, \
+  if (GST_TRACER_IS_ENABLED(GST_TRACER_HOOK_ID_PAD_PULL_RANGE_POST)) { \
+    gst_tracer_dispatch (GST_TRACER_HOOK_ID_PAD_PULL_RANGE_POST, \
+        GST_TRACER_TS, \
         pad, buffer, res); \
   } \
 }G_STMT_END
 
 #define GST_TRACER_PAD_PUSH_EVENT_PRE(pad, event) G_STMT_START{ \
-  if (GST_TRACER_IS_ENABLED(GST_TRACER_HOOK_ID_EVENTS)) { \
-    gst_tracer_dispatch (GST_TRACER_HOOK_ID_EVENTS, \
-        GST_TRACER_MESSAGE_ID_PAD_PUSH_EVENT_PRE, GST_TRACER_TS, \
+  if (GST_TRACER_IS_ENABLED(GST_TRACER_HOOK_ID_PAD_PUSH_EVENT_PRE)) { \
+    gst_tracer_dispatch (GST_TRACER_HOOK_ID_PAD_PUSH_EVENT_PRE, \
+        GST_TRACER_TS, \
         pad, event); \
   } \
 }G_STMT_END
 
 #define GST_TRACER_PAD_PUSH_EVENT_POST(pad, res) G_STMT_START{ \
-  if (GST_TRACER_IS_ENABLED(GST_TRACER_HOOK_ID_EVENTS)) { \
-    gst_tracer_dispatch (GST_TRACER_HOOK_ID_EVENTS, \
-        GST_TRACER_MESSAGE_ID_PAD_PUSH_EVENT_POST, GST_TRACER_TS, \
+  if (GST_TRACER_IS_ENABLED(GST_TRACER_HOOK_ID_PAD_PUSH_EVENT_POST)) { \
+    gst_tracer_dispatch (GST_TRACER_HOOK_ID_PAD_PUSH_EVENT_POST, \
+        GST_TRACER_TS, \
         pad, res); \
   } \
 }G_STMT_END
 
 #define GST_TRACER_ELEMENT_POST_MESSAGE_PRE(element, message) G_STMT_START{ \
-  if (GST_TRACER_IS_ENABLED(GST_TRACER_HOOK_ID_MESSAGES)) { \
-    gst_tracer_dispatch (GST_TRACER_HOOK_ID_MESSAGES, \
-        GST_TRACER_MESSAGE_ID_ELEMENT_POST_MESSAGE_PRE, GST_TRACER_TS, \
+  if (GST_TRACER_IS_ENABLED(GST_TRACER_HOOK_ID_ELEMENT_POST_MESSAGE_PRE)) { \
+    gst_tracer_dispatch (GST_TRACER_HOOK_ID_ELEMENT_POST_MESSAGE_PRE, \
+        GST_TRACER_TS, \
         element, message); \
   } \
 }G_STMT_END
 
 #define GST_TRACER_ELEMENT_POST_MESSAGE_POST(element, res) G_STMT_START{ \
-  if (GST_TRACER_IS_ENABLED(GST_TRACER_HOOK_ID_MESSAGES)) { \
-    gst_tracer_dispatch (GST_TRACER_HOOK_ID_MESSAGES, \
-        GST_TRACER_MESSAGE_ID_ELEMENT_POST_MESSAGE_POST, GST_TRACER_TS, \
+  if (GST_TRACER_IS_ENABLED(GST_TRACER_HOOK_ID_ELEMENT_POST_MESSAGE_POST)) { \
+    gst_tracer_dispatch (GST_TRACER_HOOK_ID_ELEMENT_POST_MESSAGE_POST, \
+        GST_TRACER_TS, \
         element, res); \
   } \
 }G_STMT_END
 
 #define GST_TRACER_ELEMENT_QUERY_PRE(element, query) G_STMT_START{ \
-  if (GST_TRACER_IS_ENABLED(GST_TRACER_HOOK_ID_QUERIES)) { \
-    gst_tracer_dispatch (GST_TRACER_HOOK_ID_QUERIES, \
-        GST_TRACER_MESSAGE_ID_ELEMENT_QUERY_PRE, GST_TRACER_TS, \
+  if (GST_TRACER_IS_ENABLED(GST_TRACER_HOOK_ID_ELEMENT_QUERY_PRE)) { \
+    gst_tracer_dispatch (GST_TRACER_HOOK_ID_ELEMENT_QUERY_PRE, \
+        GST_TRACER_TS, \
         element, query); \
   } \
 }G_STMT_END
 
 #define GST_TRACER_ELEMENT_QUERY_POST(element, res) G_STMT_START{ \
-  if (GST_TRACER_IS_ENABLED(GST_TRACER_HOOK_ID_QUERIES)) { \
-    gst_tracer_dispatch (GST_TRACER_HOOK_ID_QUERIES, \
-        GST_TRACER_MESSAGE_ID_ELEMENT_QUERY_POST, GST_TRACER_TS, \
+  if (GST_TRACER_IS_ENABLED(GST_TRACER_HOOK_ID_ELEMENT_QUERY_POST)) { \
+    gst_tracer_dispatch (GST_TRACER_HOOK_ID_ELEMENT_QUERY_POST, \
+        GST_TRACER_TS, \
         element, res); \
   } \
 }G_STMT_END
diff --git a/plugins/tracers/gstlatency.c b/plugins/tracers/gstlatency.c
index aa1dfa600..715fc0790 100644
--- a/plugins/tracers/gstlatency.c
+++ b/plugins/tracers/gstlatency.c
@@ -87,50 +87,6 @@ get_real_pad_parent (GstPad * pad)
   return GST_ELEMENT_CAST (parent);
 }
 
-/* tracer class */
-
-static void gst_latency_tracer_invoke (GstTracer * obj, GstTracerMessageId mid,
-    va_list var_args);
-
-static void
-gst_latency_tracer_class_init (GstLatencyTracerClass * klass)
-{
-  GstTracerClass *gst_tracer_class = GST_TRACER_CLASS (klass);
-
-  gst_tracer_class->invoke = gst_latency_tracer_invoke;
-
-  latency_probe_id = g_quark_from_static_string ("latency_probe.id");
-  latency_probe_pad = g_quark_from_static_string ("latency_probe.pad");
-  latency_probe_ts = g_quark_from_static_string ("latency_probe.ts");
-
-  /* announce trace formats */
-  /* *INDENT-OFF* */
-  gst_tracer_log_trace (gst_structure_new ("latency.class",
-      "src", GST_TYPE_STRUCTURE, gst_structure_new ("scope",
-          "related-to", G_TYPE_STRING, "pad",  /* TODO: use genum */
-          NULL),
-      "sink", GST_TYPE_STRUCTURE, gst_structure_new ("scope",
-          "related-to", G_TYPE_STRING, "pad",  /* TODO: use genum */
-          NULL),
-      "time", GST_TYPE_STRUCTURE, gst_structure_new ("value",
-          "type", G_TYPE_GTYPE, G_TYPE_UINT64,
-          "description", G_TYPE_STRING,
-              "time it took for the buffer to go from src to sink ns",
-          "flags", G_TYPE_STRING, "aggregated",  /* TODO: use gflags */ 
-          "min", G_TYPE_UINT64, G_GUINT64_CONSTANT (0),
-          "max", G_TYPE_UINT64, G_MAXUINT64,
-          NULL),
-      NULL));
-  /* *INDENT-ON* */
-}
-
-static void
-gst_latency_tracer_init (GstLatencyTracer * self)
-{
-  g_object_set (self, "mask", GST_TRACER_HOOK_BUFFERS | GST_TRACER_HOOK_EVENTS,
-      NULL);
-}
-
 /* hooks */
 
 static void
@@ -172,24 +128,24 @@ send_latency_probe (GstLatencyTracer * self, GstElement * parent, GstPad * pad,
 }
 
 static void
-do_push_buffer_pre (GstLatencyTracer * self, va_list var_args)
+do_push_buffer_pre (GstTracer * self, va_list var_args)
 {
   guint64 ts = va_arg (var_args, guint64);
   GstPad *pad = va_arg (var_args, GstPad *);
   GstElement *parent = get_real_pad_parent (pad);
 
-  send_latency_probe (self, parent, pad, ts);
+  send_latency_probe ((GstLatencyTracer *) self, parent, pad, ts);
 }
 
 static void
-do_pull_buffer_pre (GstLatencyTracer * self, va_list var_args)
+do_pull_range_pre (GstTracer * self, va_list var_args)
 {
   guint64 ts = va_arg (var_args, guint64);
   GstPad *pad = va_arg (var_args, GstPad *);
   GstPad *peer_pad = GST_PAD_PEER (pad);
   GstElement *parent = get_real_pad_parent (peer_pad);
 
-  send_latency_probe (self, parent, peer_pad, ts);
+  send_latency_probe ((GstLatencyTracer *) self, parent, peer_pad, ts);
 }
 
 static void
@@ -206,28 +162,28 @@ calculate_latency (GstLatencyTracer * self, GstElement * parent, GstPad * pad,
 }
 
 static void
-do_push_buffer_post (GstLatencyTracer * self, va_list var_args)
+do_push_buffer_post (GstTracer * self, va_list var_args)
 {
   guint64 ts = va_arg (var_args, guint64);
   GstPad *pad = va_arg (var_args, GstPad *);
   GstPad *peer_pad = GST_PAD_PEER (pad);
   GstElement *parent = get_real_pad_parent (peer_pad);
 
-  calculate_latency (self, parent, peer_pad, ts);
+  calculate_latency ((GstLatencyTracer *) self, parent, peer_pad, ts);
 }
 
 static void
-do_pull_range_post (GstLatencyTracer * self, va_list var_args)
+do_pull_range_post (GstTracer * self, va_list var_args)
 {
   guint64 ts = va_arg (var_args, guint64);
   GstPad *pad = va_arg (var_args, GstPad *);
   GstElement *parent = get_real_pad_parent (pad);
 
-  calculate_latency (self, parent, pad, ts);
+  calculate_latency ((GstLatencyTracer *) self, parent, pad, ts);
 }
 
 static void
-do_push_event_pre (GstLatencyTracer * self, va_list var_args)
+do_push_event_pre (GstTracer * self, va_list var_args)
 {
   G_GNUC_UNUSED guint64 ts = va_arg (var_args, guint64);
   GstPad *pad = va_arg (var_args, GstPad *);
@@ -250,31 +206,59 @@ do_push_event_pre (GstLatencyTracer * self, va_list var_args)
   }
 }
 
+/* tracer class */
+
 static void
-gst_latency_tracer_invoke (GstTracer * obj, GstTracerMessageId mid,
-    va_list var_args)
+gst_latency_tracer_class_init (GstLatencyTracerClass * klass)
 {
-  GstLatencyTracer *self = GST_LATENCY_TRACER_CAST (obj);
-
-  switch (mid) {
-    case GST_TRACER_MESSAGE_ID_PAD_PUSH_PRE:
-    case GST_TRACER_MESSAGE_ID_PAD_PUSH_LIST_PRE:
-      do_push_buffer_pre (self, var_args);
-      break;
-    case GST_TRACER_MESSAGE_ID_PAD_PUSH_POST:
-    case GST_TRACER_MESSAGE_ID_PAD_PUSH_LIST_POST:
-      do_push_buffer_post (self, var_args);
-      break;
-    case GST_TRACER_MESSAGE_ID_PAD_PULL_RANGE_PRE:
-      do_pull_buffer_pre (self, var_args);
-      break;
-    case GST_TRACER_MESSAGE_ID_PAD_PULL_RANGE_POST:
-      do_pull_range_post (self, var_args);
-      break;
-    case GST_TRACER_MESSAGE_ID_PAD_PUSH_EVENT_PRE:
-      do_push_event_pre (self, var_args);
-      break;
-    default:
-      break;
-  }
+  latency_probe_id = g_quark_from_static_string ("latency_probe.id");
+  latency_probe_pad = g_quark_from_static_string ("latency_probe.pad");
+  latency_probe_ts = g_quark_from_static_string ("latency_probe.ts");
+
+  /* announce trace formats */
+  /* *INDENT-OFF* */
+  gst_tracer_log_trace (gst_structure_new ("latency.class",
+      "src", GST_TYPE_STRUCTURE, gst_structure_new ("scope",
+          "related-to", G_TYPE_STRING, "pad",  /* TODO: use genum */
+          NULL),
+      "sink", GST_TYPE_STRUCTURE, gst_structure_new ("scope",
+          "related-to", G_TYPE_STRING, "pad",  /* TODO: use genum */
+          NULL),
+      "time", GST_TYPE_STRUCTURE, gst_structure_new ("value",
+          "type", G_TYPE_GTYPE, G_TYPE_UINT64,
+          "description", G_TYPE_STRING,
+              "time it took for the buffer to go from src to sink ns",
+          "flags", G_TYPE_STRING, "aggregated",  /* TODO: use gflags */ 
+          "min", G_TYPE_UINT64, G_GUINT64_CONSTANT (0),
+          "max", G_TYPE_UINT64, G_MAXUINT64,
+          NULL),
+      NULL));
+  /* *INDENT-ON* */
+}
+
+static void
+gst_latency_tracer_init (GstLatencyTracer * self)
+{
+  GstTracer *tracer = GST_TRACER (self);
+  gst_tracer_register_hook (tracer, GST_TRACER_HOOK_ID_PAD_PUSH_PRE,
+      do_push_buffer_pre);
+  gst_tracer_register_hook (tracer, GST_TRACER_HOOK_ID_PAD_PUSH_LIST_PRE,
+      do_push_buffer_pre);
+  gst_tracer_register_hook (tracer, GST_TRACER_HOOK_ID_PAD_PUSH_POST,
+      do_push_buffer_post);
+  gst_tracer_register_hook (tracer, GST_TRACER_HOOK_ID_PAD_PUSH_LIST_POST,
+      do_push_buffer_post);
+  gst_tracer_register_hook (tracer, GST_TRACER_HOOK_ID_PAD_PULL_RANGE_PRE,
+      do_pull_range_pre);
+  gst_tracer_register_hook (tracer, GST_TRACER_HOOK_ID_PAD_PULL_RANGE_POST,
+      do_pull_range_post);
+  gst_tracer_register_hook (tracer, GST_TRACER_HOOK_ID_PAD_PUSH_EVENT_PRE,
+      do_push_event_pre);
+  /*
+     - we should also replace GstTracerHookId with a 'detail' string like in
+     signals
+     - then we can attach to *all* hooks with 'null' as detail
+     gst_tracer_register_hook (self, gchar *detail, func);
+     gst_tracer_register_hook_id (self, GQuark detail, func);
+   */
 }
diff --git a/plugins/tracers/gstlog.c b/plugins/tracers/gstlog.c
index 200e76670..75e1c4b8b 100644
--- a/plugins/tracers/gstlog.c
+++ b/plugins/tracers/gstlog.c
@@ -52,95 +52,138 @@ GST_DEBUG_CATEGORY_STATIC (GST_CAT_QUERY);
 G_DEFINE_TYPE_WITH_CODE (GstLogTracer, gst_log_tracer, GST_TYPE_TRACER,
     _do_init);
 
-static void gst_log_tracer_invoke (GstTracer * self, GstTracerMessageId mid,
-    va_list var_args);
+static void
+do_log (GstDebugCategory * cat, const char *format, va_list var_args)
+{
+  gst_debug_log_valist (cat, GST_LEVEL_TRACE, "", "", 0, NULL,
+      format, var_args);
+}
 
 static void
-gst_log_tracer_class_init (GstLogTracerClass * klass)
+do_push_buffer_pre (GstTracer * self, va_list var_args)
+{
+  do_log (GST_CAT_BUFFER,
+      "%" GST_TIME_FORMAT ", pad=%" GST_PTR_FORMAT ", buffer=%" GST_PTR_FORMAT,
+      var_args);
+}
+
+static void
+do_push_buffer_post (GstTracer * self, va_list var_args)
 {
-  GstTracerClass *gst_tracer_class = GST_TRACER_CLASS (klass);
+  do_log (GST_CAT_BUFFER,
+      "%" GST_TIME_FORMAT ", pad=%" GST_PTR_FORMAT ", res=%d", var_args);
+}
 
-  gst_tracer_class->invoke = gst_log_tracer_invoke;
+static void
+do_push_buffer_list_pre (GstTracer * self, va_list var_args)
+{
+  do_log (GST_CAT_BUFFER_LIST,
+      "%" GST_TIME_FORMAT ", pad=%" GST_PTR_FORMAT ", list=%p", var_args);
 }
 
 static void
-gst_log_tracer_init (GstLogTracer * self)
+do_push_buffer_list_post (GstTracer * self, va_list var_args)
 {
-  g_object_set (self, "mask", GST_TRACER_HOOK_ALL, NULL);
+  do_log (GST_CAT_BUFFER_LIST,
+      "%" GST_TIME_FORMAT ", pad=%" GST_PTR_FORMAT ", res=%d", var_args);
 }
 
 static void
-gst_log_tracer_invoke (GstTracer * self, GstTracerMessageId mid,
-    va_list var_args)
+do_pull_range_pre (GstTracer * self, va_list var_args)
 {
-  const gchar *fmt = NULL;
-  GstDebugCategory *cat = GST_CAT_DEFAULT;
-  guint64 ts = va_arg (var_args, guint64);
-
-  /* TODO(ensonic): log to different categories depending on 'mid'
-   * GST_TRACER_HOOK_ID_QUERIES  -> (static category)
-   * GST_TRACER_HOOK_ID_TOPLOGY  -> ?
-   */
-  switch (mid) {
-    case GST_TRACER_MESSAGE_ID_PAD_PUSH_PRE:
-      cat = GST_CAT_BUFFER;
-      fmt = "pad=%" GST_PTR_FORMAT ", buffer=%" GST_PTR_FORMAT;
-      break;
-    case GST_TRACER_MESSAGE_ID_PAD_PUSH_POST:
-      cat = GST_CAT_BUFFER;
-      fmt = "pad=%" GST_PTR_FORMAT ", res=%d";
-      break;
-    case GST_TRACER_MESSAGE_ID_PAD_PUSH_LIST_PRE:
-      cat = GST_CAT_BUFFER_LIST;
-      fmt = "pad=%" GST_PTR_FORMAT ", list=%p";
-      break;
-    case GST_TRACER_MESSAGE_ID_PAD_PUSH_LIST_POST:
-      cat = GST_CAT_BUFFER_LIST;
-      fmt = "pad=%" GST_PTR_FORMAT ", res=%d";
-      break;
-    case GST_TRACER_MESSAGE_ID_PAD_PULL_RANGE_PRE:
-      cat = GST_CAT_BUFFER;
-      fmt = "pad=%" GST_PTR_FORMAT ", offset=%" G_GUINT64_FORMAT ", size=%u";
-      break;
-    case GST_TRACER_MESSAGE_ID_PAD_PULL_RANGE_POST:
-      cat = GST_CAT_BUFFER;
-      fmt = "pad=%" GST_PTR_FORMAT ", buffer=%" GST_PTR_FORMAT ", res=%d";
-      break;
-    case GST_TRACER_MESSAGE_ID_PAD_PUSH_EVENT_PRE:
-      cat = GST_CAT_EVENT;
-      fmt = "pad=%" GST_PTR_FORMAT ", event=%" GST_PTR_FORMAT;
-      break;
-    case GST_TRACER_MESSAGE_ID_PAD_PUSH_EVENT_POST:
-      cat = GST_CAT_EVENT;
-      fmt = "pad=%" GST_PTR_FORMAT ", res=%d";
-      break;
-    case GST_TRACER_MESSAGE_ID_ELEMENT_POST_MESSAGE_PRE:
-      cat = GST_CAT_MESSAGE;
-      fmt = "element=%" GST_PTR_FORMAT ", message=%" GST_PTR_FORMAT;
-      break;
-    case GST_TRACER_MESSAGE_ID_ELEMENT_POST_MESSAGE_POST:
-      cat = GST_CAT_MESSAGE;
-      fmt = "element=%" GST_PTR_FORMAT ", res=%d";
-      break;
-    case GST_TRACER_MESSAGE_ID_ELEMENT_QUERY_PRE:
-      cat = GST_CAT_QUERY;
-      fmt = "element=%" GST_PTR_FORMAT ", query=%" GST_PTR_FORMAT;
-      break;
-    case GST_TRACER_MESSAGE_ID_ELEMENT_QUERY_POST:
-      cat = GST_CAT_QUERY;
-      fmt = "element=%" GST_PTR_FORMAT ", res=%d";
-      break;
-    default:
-      break;
-  }
-  if (fmt) {
-    gchar *str;
-
-    __gst_vasprintf (&str, fmt, var_args);
-    GST_CAT_TRACE (cat, "[%d] %" GST_TIME_FORMAT ", %s",
-        mid, GST_TIME_ARGS (ts), str);
-    g_free (str);
-  } else {
-    GST_CAT_TRACE (cat, "[%d] %" GST_TIME_FORMAT, mid, GST_TIME_ARGS (ts));
-  }
+  do_log (GST_CAT_BUFFER,
+      "%" GST_TIME_FORMAT ", pad=%" GST_PTR_FORMAT ", offset=%" G_GUINT64_FORMAT
+      ", size=%u", var_args);
+}
+
+static void
+do_pull_range_post (GstTracer * self, va_list var_args)
+{
+  do_log (GST_CAT_BUFFER,
+      "%" GST_TIME_FORMAT ", pad=%" GST_PTR_FORMAT ", buffer=%" GST_PTR_FORMAT
+      ", res=%d", var_args);
+}
+
+static void
+do_push_event_pre (GstTracer * self, va_list var_args)
+{
+  do_log (GST_CAT_EVENT,
+      "%" GST_TIME_FORMAT ", pad=%" GST_PTR_FORMAT ", event=%" GST_PTR_FORMAT,
+      var_args);
+}
+
+static void
+do_push_event_post (GstTracer * self, va_list var_args)
+{
+  do_log (GST_CAT_EVENT,
+      "%" GST_TIME_FORMAT ", pad=%" GST_PTR_FORMAT ", res=%d", var_args);
+}
+
+static void
+do_post_message_pre (GstTracer * self, va_list var_args)
+{
+  do_log (GST_CAT_EVENT,
+      "%" GST_TIME_FORMAT ", element=%" GST_PTR_FORMAT ", message=%"
+      GST_PTR_FORMAT, var_args);
+}
+
+static void
+do_post_message_post (GstTracer * self, va_list var_args)
+{
+  do_log (GST_CAT_EVENT,
+      "%" GST_TIME_FORMAT ", element=%" GST_PTR_FORMAT ", res=%d", var_args);
+}
+
+static void
+do_query_pre (GstTracer * self, va_list var_args)
+{
+  do_log (GST_CAT_QUERY,
+      "%" GST_TIME_FORMAT ", element=%" GST_PTR_FORMAT ", query=%"
+      GST_PTR_FORMAT, var_args);
+}
+
+static void
+do_query_post (GstTracer * self, va_list var_args)
+{
+  do_log (GST_CAT_QUERY,
+      "%" GST_TIME_FORMAT ", element=%" GST_PTR_FORMAT ", res=%d", var_args);
+}
+
+
+/* tracer class */
+
+static void
+gst_log_tracer_class_init (GstLogTracerClass * klass)
+{
+}
+
+static void
+gst_log_tracer_init (GstLogTracer * self)
+{
+  GstTracer *tracer = GST_TRACER (self);
+
+  gst_tracer_register_hook (tracer, GST_TRACER_HOOK_ID_PAD_PUSH_PRE,
+      do_push_buffer_pre);
+  gst_tracer_register_hook (tracer, GST_TRACER_HOOK_ID_PAD_PUSH_POST,
+      do_push_buffer_post);
+  gst_tracer_register_hook (tracer, GST_TRACER_HOOK_ID_PAD_PUSH_LIST_PRE,
+      do_push_buffer_list_pre);
+  gst_tracer_register_hook (tracer, GST_TRACER_HOOK_ID_PAD_PUSH_LIST_POST,
+      do_push_buffer_list_post);
+  gst_tracer_register_hook (tracer, GST_TRACER_HOOK_ID_PAD_PULL_RANGE_PRE,
+      do_pull_range_pre);
+  gst_tracer_register_hook (tracer, GST_TRACER_HOOK_ID_PAD_PULL_RANGE_POST,
+      do_pull_range_post);
+  gst_tracer_register_hook (tracer, GST_TRACER_HOOK_ID_PAD_PUSH_EVENT_PRE,
+      do_push_event_pre);
+  gst_tracer_register_hook (tracer, GST_TRACER_HOOK_ID_PAD_PUSH_EVENT_POST,
+      do_push_event_post);
+  gst_tracer_register_hook (tracer, GST_TRACER_HOOK_ID_ELEMENT_POST_MESSAGE_PRE,
+      do_post_message_pre);
+  gst_tracer_register_hook (tracer,
+      GST_TRACER_HOOK_ID_ELEMENT_POST_MESSAGE_POST, do_post_message_post);
+  gst_tracer_register_hook (tracer, GST_TRACER_HOOK_ID_ELEMENT_QUERY_PRE,
+      do_query_pre);
+  gst_tracer_register_hook (tracer, GST_TRACER_HOOK_ID_ELEMENT_QUERY_POST,
+      do_query_post);
 }
diff --git a/plugins/tracers/gstrusage.c b/plugins/tracers/gstrusage.c
index 721af78e7..1764ef3ae 100644
--- a/plugins/tracers/gstrusage.c
+++ b/plugins/tracers/gstrusage.c
@@ -78,9 +78,6 @@ typedef struct
 
 static GstTraceValues *tvs_proc;
 
-static void gst_rusage_tracer_invoke (GstTracer * self, GstTracerMessageId mid,
-    va_list var_args);
-
 /* data helper */
 
 static void
@@ -166,91 +163,7 @@ free_thread_stats (gpointer data)
 }
 
 static void
-gst_rusage_tracer_class_init (GstRUsageTracerClass * klass)
-{
-  GstTracerClass *gst_tracer_class = GST_TRACER_CLASS (klass);
-
-  gst_tracer_class->invoke = gst_rusage_tracer_invoke;
-}
-
-static void
-gst_rusage_tracer_init (GstRUsageTracer * self)
-{
-  g_object_set (self, "mask", GST_TRACER_HOOK_ALL, NULL);
-  self->threads = g_hash_table_new_full (NULL, NULL, NULL, free_thread_stats);
-
-  main_thread_id = g_thread_self ();
-  tvs_proc = make_trace_values (GST_SECOND);
-  if ((num_cpus = sysconf (_SC_NPROCESSORS_ONLN)) == -1) {
-    GST_WARNING_OBJECT (self, "failed to get number of cpus online");
-    if ((num_cpus = sysconf (_SC_NPROCESSORS_CONF)) == -1) {
-      GST_WARNING_OBJECT (self, "failed to get number of cpus, assuming 1");
-      num_cpus = 1;
-    }
-  }
-
-  GST_DEBUG ("rusage: main thread=%p, num_cpus=%ld", main_thread_id, num_cpus);
-
-  /* announce trace formats */
-  /* *INDENT-OFF* */
-  gst_tracer_log_trace (gst_structure_new ("thread-rusage.class",
-      "thread-id", GST_TYPE_STRUCTURE, gst_structure_new ("scope",
-          "related-to", G_TYPE_STRING, "thread",  /* TODO: use genum */
-          NULL),
-      "average-cpuload", GST_TYPE_STRUCTURE, gst_structure_new ("value",
-          "type", G_TYPE_GTYPE, G_TYPE_UINT,
-          "description", G_TYPE_STRING, "average cpu usage per thread in ‰",
-          "flags", G_TYPE_STRING, "aggregated",  /* TODO: use gflags */ 
-          "min", G_TYPE_UINT, 0, 
-          "max", G_TYPE_UINT, 1000,
-          NULL),
-      "current-cpuload", GST_TYPE_STRUCTURE, gst_structure_new ("value",
-          "type", G_TYPE_GTYPE, G_TYPE_UINT,
-          "description", G_TYPE_STRING, "current cpu usage per thread in ‰",
-          "flags", G_TYPE_STRING, "windowed",  /* TODO: use gflags */ 
-          "min", G_TYPE_UINT, 0, 
-          "max", G_TYPE_UINT, 1000,
-          NULL),
-      "time", GST_TYPE_STRUCTURE, gst_structure_new ("value",
-          "type", G_TYPE_GTYPE, G_TYPE_UINT64,
-          "description", G_TYPE_STRING, "time spent in thread in ns",
-          "flags", G_TYPE_STRING, "aggregated",  /* TODO: use gflags */ 
-          "min", G_TYPE_UINT64, G_GUINT64_CONSTANT (0),
-          "max", G_TYPE_UINT64, G_MAXUINT64,
-          NULL),
-      NULL));
-  gst_tracer_log_trace (gst_structure_new ("proc-rusage.class",
-      "thread-id", GST_TYPE_STRUCTURE, gst_structure_new ("scope",
-          "related-to", G_TYPE_STRING, "process",  /* TODO: use genum */
-          NULL),
-      "average-cpuload", GST_TYPE_STRUCTURE, gst_structure_new ("value",
-          "type", G_TYPE_GTYPE, G_TYPE_UINT,
-          "description", G_TYPE_STRING, "average cpu usage per process in ‰",
-          "flags", G_TYPE_STRING, "aggregated",  /* TODO: use gflags */ 
-          "min", G_TYPE_UINT, 0, 
-          "max", G_TYPE_UINT, 1000,
-          NULL),
-      "current-cpuload", GST_TYPE_STRUCTURE, gst_structure_new ("value",
-          "type", G_TYPE_GTYPE, G_TYPE_UINT,
-          "description", G_TYPE_STRING, "current cpu usage per process in ‰",
-          "flags", G_TYPE_STRING, "windowed",  /* TODO: use gflags */ 
-          "min", G_TYPE_UINT, 0, 
-          "max", G_TYPE_UINT, 1000,
-          NULL),
-      "time", GST_TYPE_STRUCTURE, gst_structure_new ("value",
-          "type", G_TYPE_GTYPE, G_TYPE_UINT64,
-          "description", G_TYPE_STRING, "time spent in process in ns",
-          "flags", G_TYPE_STRING, "aggregated",  /* TODO: use gflags */ 
-          "min", G_TYPE_UINT64, G_GUINT64_CONSTANT (0),
-          "max", G_TYPE_UINT64, G_MAXUINT64,
-          NULL),
-      NULL));
-  /* *INDENT-ON* */
-}
-
-static void
-gst_rusage_tracer_invoke (GstTracer * obj, GstTracerMessageId mid,
-    va_list var_args)
+do_stats (GstTracer * obj, va_list var_args)
 {
   GstRUsageTracer *self = GST_RUSAGE_TRACER_CAST (obj);
   guint64 ts = va_arg (var_args, guint64);
@@ -360,3 +273,89 @@ gst_rusage_tracer_invoke (GstTracer * obj, GstTracerMessageId mid,
       NULL));
   /* *INDENT-ON* */
 }
+
+/* tracer class */
+
+static void
+gst_rusage_tracer_class_init (GstRUsageTracerClass * klass)
+{
+  /* announce trace formats */
+  /* *INDENT-OFF* */
+  gst_tracer_log_trace (gst_structure_new ("thread-rusage.class",
+      "thread-id", GST_TYPE_STRUCTURE, gst_structure_new ("scope",
+          "related-to", G_TYPE_STRING, "thread",  /* TODO: use genum */
+          NULL),
+      "average-cpuload", GST_TYPE_STRUCTURE, gst_structure_new ("value",
+          "type", G_TYPE_GTYPE, G_TYPE_UINT,
+          "description", G_TYPE_STRING, "average cpu usage per thread in ‰",
+          "flags", G_TYPE_STRING, "aggregated",  /* TODO: use gflags */ 
+          "min", G_TYPE_UINT, 0, 
+          "max", G_TYPE_UINT, 1000,
+          NULL),
+      "current-cpuload", GST_TYPE_STRUCTURE, gst_structure_new ("value",
+          "type", G_TYPE_GTYPE, G_TYPE_UINT,
+          "description", G_TYPE_STRING, "current cpu usage per thread in ‰",
+          "flags", G_TYPE_STRING, "windowed",  /* TODO: use gflags */ 
+          "min", G_TYPE_UINT, 0, 
+          "max", G_TYPE_UINT, 1000,
+          NULL),
+      "time", GST_TYPE_STRUCTURE, gst_structure_new ("value",
+          "type", G_TYPE_GTYPE, G_TYPE_UINT64,
+          "description", G_TYPE_STRING, "time spent in thread in ns",
+          "flags", G_TYPE_STRING, "aggregated",  /* TODO: use gflags */ 
+          "min", G_TYPE_UINT64, G_GUINT64_CONSTANT (0),
+          "max", G_TYPE_UINT64, G_MAXUINT64,
+          NULL),
+      NULL));
+  gst_tracer_log_trace (gst_structure_new ("proc-rusage.class",
+      "thread-id", GST_TYPE_STRUCTURE, gst_structure_new ("scope",
+          "related-to", G_TYPE_STRING, "process",  /* TODO: use genum */
+          NULL),
+      "average-cpuload", GST_TYPE_STRUCTURE, gst_structure_new ("value",
+          "type", G_TYPE_GTYPE, G_TYPE_UINT,
+          "description", G_TYPE_STRING, "average cpu usage per process in ‰",
+          "flags", G_TYPE_STRING, "aggregated",  /* TODO: use gflags */ 
+          "min", G_TYPE_UINT, 0, 
+          "max", G_TYPE_UINT, 1000,
+          NULL),
+      "current-cpuload", GST_TYPE_STRUCTURE, gst_structure_new ("value",
+          "type", G_TYPE_GTYPE, G_TYPE_UINT,
+          "description", G_TYPE_STRING, "current cpu usage per process in ‰",
+          "flags", G_TYPE_STRING, "windowed",  /* TODO: use gflags */ 
+          "min", G_TYPE_UINT, 0, 
+          "max", G_TYPE_UINT, 1000,
+          NULL),
+      "time", GST_TYPE_STRUCTURE, gst_structure_new ("value",
+          "type", G_TYPE_GTYPE, G_TYPE_UINT64,
+          "description", G_TYPE_STRING, "time spent in process in ns",
+          "flags", G_TYPE_STRING, "aggregated",  /* TODO: use gflags */ 
+          "min", G_TYPE_UINT64, G_GUINT64_CONSTANT (0),
+          "max", G_TYPE_UINT64, G_MAXUINT64,
+          NULL),
+      NULL));
+  /* *INDENT-ON* */
+}
+
+static void
+gst_rusage_tracer_init (GstRUsageTracer * self)
+{
+  GstTracer *tracer = GST_TRACER (self);
+  gint i;
+
+  for (i = 0; i < GST_TRACER_HOOK_ID_LAST; i++) {
+    gst_tracer_register_hook (tracer, i, do_stats);
+  }
+
+  self->threads = g_hash_table_new_full (NULL, NULL, NULL, free_thread_stats);
+
+  main_thread_id = g_thread_self ();
+  tvs_proc = make_trace_values (GST_SECOND);
+  if ((num_cpus = sysconf (_SC_NPROCESSORS_ONLN)) == -1) {
+    GST_WARNING_OBJECT (self, "failed to get number of cpus online");
+    if ((num_cpus = sysconf (_SC_NPROCESSORS_CONF)) == -1) {
+      GST_WARNING_OBJECT (self, "failed to get number of cpus, assuming 1");
+      num_cpus = 1;
+    }
+  }
+  GST_DEBUG ("rusage: main thread=%p, num_cpus=%ld", main_thread_id, num_cpus);
+}
diff --git a/plugins/tracers/gststats.c b/plugins/tracers/gststats.c
index 972a352d8..8172057b3 100644
--- a/plugins/tracers/gststats.c
+++ b/plugins/tracers/gststats.c
@@ -336,106 +336,6 @@ do_element_stats (GstStatsTracer * self, GstPad * pad, GstClockTime elapsed1,
 #endif
 }
 
-/* tracer class */
-
-static void gst_stats_tracer_finalize (GObject * obj);
-static void gst_stats_tracer_invoke (GstTracer * obj, GstTracerMessageId mid,
-    va_list var_args);
-
-static void
-gst_stats_tracer_class_init (GstStatsTracerClass * klass)
-{
-  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
-  GstTracerClass *gst_tracer_class = GST_TRACER_CLASS (klass);
-
-  gobject_class->finalize = gst_stats_tracer_finalize;
-
-  gst_tracer_class->invoke = gst_stats_tracer_invoke;
-}
-
-static void
-gst_stats_tracer_init (GstStatsTracer * self)
-{
-  g_object_set (self, "mask",
-      GST_TRACER_HOOK_BUFFERS | GST_TRACER_HOOK_EVENTS |
-      GST_TRACER_HOOK_MESSAGES | GST_TRACER_HOOK_QUERIES, NULL);
-  self->elements = g_ptr_array_new_with_free_func (free_element_stats);
-  self->pads = g_ptr_array_new_with_free_func (free_pad_stats);
-
-  /* announce trace formats */
-  /* *INDENT-OFF* */
-  gst_tracer_log_trace (gst_structure_new ("buffer.class",
-      "pad-ix", GST_TYPE_STRUCTURE, gst_structure_new ("scope",
-          "related-to", G_TYPE_STRING, "pad",  /* TODO: use genum */
-          NULL),
-      "element-ix", GST_TYPE_STRUCTURE, gst_structure_new ("scope",
-          "related-to", G_TYPE_STRING, "element",  /* TODO: use genum */
-          NULL),
-      "peer-pad-ix", GST_TYPE_STRUCTURE, gst_structure_new ("scope",
-          "related-to", G_TYPE_STRING, "pad",  /* TODO: use genum */
-          NULL),
-      "peer-element-ix", GST_TYPE_STRUCTURE, gst_structure_new ("scope",
-          "related-to", G_TYPE_STRING, "element",  /* TODO: use genum */
-          NULL),
-      "buffer-size", GST_TYPE_STRUCTURE, gst_structure_new ("value",
-          "type", G_TYPE_GTYPE, G_TYPE_UINT,
-          "description", G_TYPE_STRING, "size of buffer in bytes",
-          "flags", G_TYPE_STRING, "",  /* TODO: use gflags */ 
-          "min", G_TYPE_UINT, 0, 
-          "max", G_TYPE_UINT, G_MAXUINT,
-          NULL),
-      "buffer-ts", GST_TYPE_STRUCTURE, gst_structure_new ("value",
-          "type", G_TYPE_GTYPE, G_TYPE_UINT64,
-          "description", G_TYPE_STRING, "timestamp of the buffer in ns",
-          "flags", G_TYPE_STRING, "",  /* TODO: use gflags */ 
-          "min", G_TYPE_UINT64, G_GUINT64_CONSTANT (0),
-          "max", G_TYPE_UINT64, G_MAXUINT64,
-          NULL),
-      "buffer-duration", GST_TYPE_STRUCTURE, gst_structure_new ("value",
-          "type", G_TYPE_GTYPE, G_TYPE_UINT64,
-          "description", G_TYPE_STRING, "duration of the buffer in ns",
-          "flags", G_TYPE_STRING, "",  /* TODO: use gflags */ 
-          "min", G_TYPE_UINT64, G_GUINT64_CONSTANT (0),
-          "max", G_TYPE_UINT64, G_MAXUINT64,
-          NULL),
-      /* TODO(ensonic): "buffer-flags" */
-      NULL));
-  gst_tracer_log_trace (gst_structure_new ("event.class",
-      "pad-ix", GST_TYPE_STRUCTURE, gst_structure_new ("scope",
-          "related-to", G_TYPE_STRING, "pad",  /* TODO: use genum */
-          NULL),
-      "element-ix", GST_TYPE_STRUCTURE, gst_structure_new ("scope",
-          "related-to", G_TYPE_STRING, "element",  /* TODO: use genum */
-          NULL),
-      "name", GST_TYPE_STRUCTURE, gst_structure_new ("value",
-          "type", G_TYPE_GTYPE, G_TYPE_STRING,
-          "description", G_TYPE_STRING, "name of the event",
-          "flags", G_TYPE_STRING, "",  /* TODO: use gflags */ 
-          NULL),
-      NULL));
-  gst_tracer_log_trace (gst_structure_new ("message.class",
-      "element-ix", GST_TYPE_STRUCTURE, gst_structure_new ("scope",
-          "related-to", G_TYPE_STRING, "element",  /* TODO: use genum */
-          NULL),
-      "name", GST_TYPE_STRUCTURE, gst_structure_new ("value",
-          "type", G_TYPE_GTYPE, G_TYPE_STRING,
-          "description", G_TYPE_STRING, "name of the message",
-          "flags", G_TYPE_STRING, "",  /* TODO: use gflags */ 
-          NULL),
-      NULL));
-  gst_tracer_log_trace (gst_structure_new ("query.class",
-      "element-ix", GST_TYPE_STRUCTURE, gst_structure_new ("scope",
-          "related-to", G_TYPE_STRING, "element",  /* TODO: use genum */
-          NULL),
-      "name", GST_TYPE_STRUCTURE, gst_structure_new ("value",
-          "type", G_TYPE_GTYPE, G_TYPE_STRING,
-          "description", G_TYPE_STRING, "name of the query",
-          "flags", G_TYPE_STRING, "",  /* TODO: use gflags */ 
-          NULL),
-      NULL));
-  /* *INDENT-ON* */
-}
-
 /* hooks */
 
 static void
@@ -610,56 +510,117 @@ do_query_post (GstStatsTracer * self, va_list var_args)
 #endif
 }
 
+/* tracer class */
+
 static void
-gst_stats_tracer_invoke (GstTracer * obj, GstTracerMessageId mid,
-    va_list var_args)
+gst_stats_tracer_class_init (GstStatsTracerClass * klass)
 {
-  GstStatsTracer *self = GST_STATS_TRACER_CAST (obj);
-
-  switch (mid) {
-    case GST_TRACER_MESSAGE_ID_PAD_PUSH_PRE:
-      do_push_buffer_pre (self, var_args);
-      break;
-    case GST_TRACER_MESSAGE_ID_PAD_PUSH_POST:
-      do_push_buffer_post (self, var_args);
-      break;
-    case GST_TRACER_MESSAGE_ID_PAD_PUSH_LIST_PRE:
-      do_push_buffer_list_pre (self, var_args);
-      break;
-    case GST_TRACER_MESSAGE_ID_PAD_PUSH_LIST_POST:
-      do_push_buffer_list_post (self, var_args);
-      break;
-    case GST_TRACER_MESSAGE_ID_PAD_PULL_RANGE_PRE:
-      do_pull_range_pre (self, var_args);
-      break;
-    case GST_TRACER_MESSAGE_ID_PAD_PULL_RANGE_POST:
-      do_pull_range_post (self, var_args);
-      break;
-    case GST_TRACER_MESSAGE_ID_PAD_PUSH_EVENT_PRE:
-      do_push_event_pre (self, var_args);
-      break;
-    case GST_TRACER_MESSAGE_ID_PAD_PUSH_EVENT_POST:
-      do_push_event_post (self, var_args);
-      break;
-    case GST_TRACER_MESSAGE_ID_ELEMENT_POST_MESSAGE_PRE:
-      do_post_message_pre (self, var_args);
-      break;
-    case GST_TRACER_MESSAGE_ID_ELEMENT_POST_MESSAGE_POST:
-      do_post_message_post (self, var_args);
-      break;
-    case GST_TRACER_MESSAGE_ID_ELEMENT_QUERY_PRE:
-      do_query_pre (self, var_args);
-      break;
-    case GST_TRACER_MESSAGE_ID_ELEMENT_QUERY_POST:
-      do_query_post (self, var_args);
-      break;
-    default:
-      break;
-  }
+  /* announce trace formats */
+  /* *INDENT-OFF* */
+  gst_tracer_log_trace (gst_structure_new ("buffer.class",
+      "pad-ix", GST_TYPE_STRUCTURE, gst_structure_new ("scope",
+          "related-to", G_TYPE_STRING, "pad",  /* TODO: use genum */
+          NULL),
+      "element-ix", GST_TYPE_STRUCTURE, gst_structure_new ("scope",
+          "related-to", G_TYPE_STRING, "element",  /* TODO: use genum */
+          NULL),
+      "peer-pad-ix", GST_TYPE_STRUCTURE, gst_structure_new ("scope",
+          "related-to", G_TYPE_STRING, "pad",  /* TODO: use genum */
+          NULL),
+      "peer-element-ix", GST_TYPE_STRUCTURE, gst_structure_new ("scope",
+          "related-to", G_TYPE_STRING, "element",  /* TODO: use genum */
+          NULL),
+      "buffer-size", GST_TYPE_STRUCTURE, gst_structure_new ("value",
+          "type", G_TYPE_GTYPE, G_TYPE_UINT,
+          "description", G_TYPE_STRING, "size of buffer in bytes",
+          "flags", G_TYPE_STRING, "",  /* TODO: use gflags */ 
+          "min", G_TYPE_UINT, 0, 
+          "max", G_TYPE_UINT, G_MAXUINT,
+          NULL),
+      "buffer-ts", GST_TYPE_STRUCTURE, gst_structure_new ("value",
+          "type", G_TYPE_GTYPE, G_TYPE_UINT64,
+          "description", G_TYPE_STRING, "timestamp of the buffer in ns",
+          "flags", G_TYPE_STRING, "",  /* TODO: use gflags */ 
+          "min", G_TYPE_UINT64, G_GUINT64_CONSTANT (0),
+          "max", G_TYPE_UINT64, G_MAXUINT64,
+          NULL),
+      "buffer-duration", GST_TYPE_STRUCTURE, gst_structure_new ("value",
+          "type", G_TYPE_GTYPE, G_TYPE_UINT64,
+          "description", G_TYPE_STRING, "duration of the buffer in ns",
+          "flags", G_TYPE_STRING, "",  /* TODO: use gflags */ 
+          "min", G_TYPE_UINT64, G_GUINT64_CONSTANT (0),
+          "max", G_TYPE_UINT64, G_MAXUINT64,
+          NULL),
+      /* TODO(ensonic): "buffer-flags" */
+      NULL));
+  gst_tracer_log_trace (gst_structure_new ("event.class",
+      "pad-ix", GST_TYPE_STRUCTURE, gst_structure_new ("scope",
+          "related-to", G_TYPE_STRING, "pad",  /* TODO: use genum */
+          NULL),
+      "element-ix", GST_TYPE_STRUCTURE, gst_structure_new ("scope",
+          "related-to", G_TYPE_STRING, "element",  /* TODO: use genum */
+          NULL),
+      "name", GST_TYPE_STRUCTURE, gst_structure_new ("value",
+          "type", G_TYPE_GTYPE, G_TYPE_STRING,
+          "description", G_TYPE_STRING, "name of the event",
+          "flags", G_TYPE_STRING, "",  /* TODO: use gflags */ 
+          NULL),
+      NULL));
+  gst_tracer_log_trace (gst_structure_new ("message.class",
+      "element-ix", GST_TYPE_STRUCTURE, gst_structure_new ("scope",
+          "related-to", G_TYPE_STRING, "element",  /* TODO: use genum */
+          NULL),
+      "name", GST_TYPE_STRUCTURE, gst_structure_new ("value",
+          "type", G_TYPE_GTYPE, G_TYPE_STRING,
+          "description", G_TYPE_STRING, "name of the message",
+          "flags", G_TYPE_STRING, "",  /* TODO: use gflags */ 
+          NULL),
+      NULL));
+  gst_tracer_log_trace (gst_structure_new ("query.class",
+      "element-ix", GST_TYPE_STRUCTURE, gst_structure_new ("scope",
+          "related-to", G_TYPE_STRING, "element",  /* TODO: use genum */
+          NULL),
+      "name", GST_TYPE_STRUCTURE, gst_structure_new ("value",
+          "type", G_TYPE_GTYPE, G_TYPE_STRING,
+          "description", G_TYPE_STRING, "name of the query",
+          "flags", G_TYPE_STRING, "",  /* TODO: use gflags */ 
+          NULL),
+      NULL));
+  /* *INDENT-ON* */
 }
 
 static void
-gst_stats_tracer_finalize (GObject * obj)
+gst_stats_tracer_init (GstStatsTracer * self)
 {
-  G_OBJECT_CLASS (parent_class)->finalize (obj);
+  GstTracer *tracer = GST_TRACER (self);
+
+  gst_tracer_register_hook (tracer, GST_TRACER_HOOK_ID_PAD_PUSH_PRE,
+      (GstTracerHookFunction) do_push_buffer_pre);
+  gst_tracer_register_hook (tracer, GST_TRACER_HOOK_ID_PAD_PUSH_POST,
+      (GstTracerHookFunction) do_push_buffer_post);
+  gst_tracer_register_hook (tracer, GST_TRACER_HOOK_ID_PAD_PUSH_LIST_PRE,
+      (GstTracerHookFunction) do_push_buffer_list_pre);
+  gst_tracer_register_hook (tracer, GST_TRACER_HOOK_ID_PAD_PUSH_LIST_POST,
+      (GstTracerHookFunction) do_push_buffer_list_post);
+  gst_tracer_register_hook (tracer, GST_TRACER_HOOK_ID_PAD_PULL_RANGE_PRE,
+      (GstTracerHookFunction) do_pull_range_pre);
+  gst_tracer_register_hook (tracer, GST_TRACER_HOOK_ID_PAD_PULL_RANGE_POST,
+      (GstTracerHookFunction) do_pull_range_post);
+  gst_tracer_register_hook (tracer, GST_TRACER_HOOK_ID_PAD_PUSH_EVENT_PRE,
+      (GstTracerHookFunction) do_push_event_pre);
+  gst_tracer_register_hook (tracer, GST_TRACER_HOOK_ID_PAD_PUSH_EVENT_POST,
+      (GstTracerHookFunction) do_push_event_post);
+  gst_tracer_register_hook (tracer, GST_TRACER_HOOK_ID_ELEMENT_POST_MESSAGE_PRE,
+      (GstTracerHookFunction) do_post_message_pre);
+  gst_tracer_register_hook (tracer,
+      GST_TRACER_HOOK_ID_ELEMENT_POST_MESSAGE_POST,
+      (GstTracerHookFunction) do_post_message_post);
+  gst_tracer_register_hook (tracer, GST_TRACER_HOOK_ID_ELEMENT_QUERY_PRE,
+      (GstTracerHookFunction) do_query_pre);
+  gst_tracer_register_hook (tracer, GST_TRACER_HOOK_ID_ELEMENT_QUERY_POST,
+      (GstTracerHookFunction) do_query_post);
+
+
+  self->elements = g_ptr_array_new_with_free_func (free_element_stats);
+  self->pads = g_ptr_array_new_with_free_func (free_pad_stats);
 }