tracer: latency: Add parameter to select latency type

This sets back the default to trace only pipeline latency, and add flags
to enabled element tracing. It is now possible to only trace element
latency, only trace pipeline latency, trace both or none.

plugins/tracers/gstlatency.c

@@ -23,7 +23,14 @@
  * @short_description: log processing latency stats
  *
  * A tracing module that determines src-to-sink latencies by injecting custom
- * events at sources and process them at sinks.
+ * events at sources and process them at sinks. This elements supports tracing
+ * the entire pipeline latency and per element latency. By default, only
+ * pipeline latency is traced. The 'flags' parameter can be used to enabled
+ * element tracing.
+ *
+ * ```
+ * GST_TRACERS="latency(flags=pipeline+element)" GST_DEBUG=GST_TRACER:7 ./...
+ * ```
  */
 /* TODO(ensonic): if there are two sources feeding into a mixer/muxer and later
  * we fan-out with tee and have two sinks, each sink would get all two events,
@@ -135,7 +142,8 @@ log_element_latency (const GstStructure * data, GstElement * element,
 }
 
 static void
-send_latency_probe (GstElement * parent, GstPad * pad, guint64 ts)
+send_latency_probe (GstLatencyTracer * self, GstElement * parent, GstPad * pad,
+    guint64 ts)
 {
   GstPad *peer_pad = GST_PAD_PEER (pad);
 
@@ -145,7 +153,8 @@ send_latency_probe (GstElement * parent, GstPad * pad, guint64 ts)
     gchar *pad_name;
     GstEvent *latency_probe;
 
-    if (GST_OBJECT_FLAG_IS_SET (parent, GST_ELEMENT_FLAG_SOURCE)) {
+    if (self->flags & GST_LATENCY_TRACER_FLAG_PIPELINE &&
+        GST_OBJECT_FLAG_IS_SET (parent, GST_ELEMENT_FLAG_SOURCE)) {
       pad_name = g_strdup_printf ("%s_%s", GST_DEBUG_PAD_NAME (pad));
 
       GST_DEBUG ("%s: Sending latency event", pad_name);
@@ -158,6 +167,7 @@ send_latency_probe (GstElement * parent, GstPad * pad, guint64 ts)
       gst_pad_push_event (pad, latency_probe);
     }
 
+    if (self->flags & GST_LATENCY_TRACER_FLAG_ELEMENT) {
       GST_DEBUG ("%s_%s: Sending sub-latency event", GST_DEBUG_PAD_NAME (pad));
 
       pad_name = g_strdup_printf ("%s_%s", GST_DEBUG_PAD_NAME (peer_pad));
@@ -168,6 +178,7 @@ send_latency_probe (GstElement * parent, GstPad * pad, guint64 ts)
       gst_pad_push_event (pad, latency_probe);
       g_free (pad_name);
     }
+  }
 }
 
 static void
@@ -202,21 +213,23 @@ calculate_latency (GstElement * parent, GstPad * pad, guint64 ts)
 }
 
 static void
-do_push_buffer_pre (GstTracer * self, guint64 ts, GstPad * pad)
+do_push_buffer_pre (GstTracer * tracer, guint64 ts, GstPad * pad)
 {
+  GstLatencyTracer *self = (GstLatencyTracer *) tracer;
   GstElement *parent = get_real_pad_parent (pad);
 
-  send_latency_probe (parent, pad, ts);
+  send_latency_probe (self, parent, pad, ts);
   calculate_latency (parent, pad, ts);
 }
 
 static void
-do_pull_range_pre (GstTracer * self, guint64 ts, GstPad * pad)
+do_pull_range_pre (GstTracer * tracer, guint64 ts, GstPad * pad)
 {
+  GstLatencyTracer *self = (GstLatencyTracer *) tracer;
   GstPad *peer_pad = GST_PAD_PEER (pad);
   GstElement *parent = get_real_pad_parent (peer_pad);
 
-  send_latency_probe (parent, peer_pad, ts);
+  send_latency_probe (self, parent, peer_pad, ts);
 }
 
 static void
@@ -312,9 +325,55 @@ do_push_event_pre (GstTracer * self, guint64 ts, GstPad * pad, GstEvent * ev)
 
 /* tracer class */
 
+static void
+gst_latency_tracer_constructed (GObject * object)
+{
+  GstLatencyTracer *self = GST_LATENCY_TRACER (object);
+  gchar *params, *tmp;
+  GstStructure *params_struct = NULL;
+
+  g_object_get (self, "params", &params, NULL);
+
+  if (!params)
+    return;
+
+  tmp = g_strdup_printf ("latency,%s", params);
+  params_struct = gst_structure_from_string (tmp, NULL);
+  g_free (tmp);
+
+  /* Read the flags if available */
+  if (params_struct) {
+    const gchar *flags = gst_structure_get_string (params_struct, "flags");
+
+    self->flags = 0;
+
+    if (flags) {
+      GStrv split = g_strsplit (flags, "+", -1);
+      gint i;
+
+      for (i = 0; split[i]; i++) {
+        if (g_str_equal (split[i], "pipeline"))
+          self->flags |= GST_LATENCY_TRACER_FLAG_PIPELINE;
+        else if (g_str_equal (split[i], "element"))
+          self->flags |= GST_LATENCY_TRACER_FLAG_ELEMENT;
+        else
+          GST_WARNING ("Invalid latency tracer flags %s", split[i]);
+      }
+
+      g_strfreev (split);
+    }
+  }
+
+  g_free (params);
+}
+
 static void
 gst_latency_tracer_class_init (GstLatencyTracerClass * klass)
 {
+  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
+
+  gobject_class->constructed = gst_latency_tracer_constructed;
+
   latency_probe_id = g_quark_from_static_string ("latency_probe.id");
   sub_latency_probe_id = g_quark_from_static_string ("sub_latency_probe.id");
   latency_probe_pad = g_quark_from_static_string ("latency_probe.pad");
@@ -375,6 +434,9 @@ gst_latency_tracer_init (GstLatencyTracer * self)
 {
   GstTracer *tracer = GST_TRACER (self);
 
+  /* only trace pipeline latency by default */
+  self->flags = GST_LATENCY_TRACER_FLAG_PIPELINE;
+
   /* in push mode, pre/post will be called before/after the peer chain
    * function has been called. For this reaosn, we only use -pre to avoid
    * accounting for the processing time of the peer element (the sink) */

plugins/tracers/gstlatency.h

@@ -42,6 +42,12 @@ G_BEGIN_DECLS
 typedef struct _GstLatencyTracer GstLatencyTracer;
 typedef struct _GstLatencyTracerClass GstLatencyTracerClass;
 
+typedef enum
+{
+  GST_LATENCY_TRACER_FLAG_PIPELINE = 1 << 0,
+  GST_LATENCY_TRACER_FLAG_ELEMENT = 1 << 1,
+} GstLatencyTracerFlags;
+
 /**
  * GstLatencyTracer:
  *
@@ -51,6 +57,7 @@ struct _GstLatencyTracer {
   GstTracer 	 parent;
 
   /*< private >*/
+  GstLatencyTracerFlags flags;
 };
 
 struct _GstLatencyTracerClass {