gstreamer/gst/gsttracerrecord.c

/* GStreamer
 * Copyright (C) 2016 Stefan Sauer <ensonic@users.sf.net>
 *
 * gsttracerrecord.c: tracer log record class
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 */

/**
 * SECTION:gsttracerrecord
 * @short_description: Trace log entry class
 *
 * Tracing modules will create instances of this class to announce the data they
 * will log and create a log formatter.
 *
 * Since: 1.8
 */

#include "gst_private.h"
#include "gstinfo.h"
#include "gststructure.h"
#include "gsttracerrecord.h"
#include "gstvalue.h"

GST_DEBUG_CATEGORY_EXTERN (tracer_debug);
#define GST_CAT_DEFAULT tracer_debug


enum
{
  PROP_0,
  PROP_SPEC,
  PROP_LAST
};

static GParamSpec *properties[PROP_LAST];

struct _GstTracerRecord
{
  GstObject parent;

  GstStructure *spec;
  gchar *format;
};

struct _GstTracerRecordClass
{
  GstObjectClass parent_class;
};

#define gst_tracer_record_parent_class parent_class
G_DEFINE_TYPE (GstTracerRecord, gst_tracer_record, GST_TYPE_OBJECT);

static gboolean
build_field_template (GQuark field_id, const GValue * value, gpointer user_data)
{
  GString *s = (GString *) user_data;
  const GstStructure *sub;
  GValue template_value = { 0, };
  GType type;
  gboolean res;

  g_return_val_if_fail (G_VALUE_TYPE (value) == GST_TYPE_STRUCTURE, FALSE);

  sub = gst_value_get_structure (value);
  type = g_value_get_gtype (gst_structure_get_value (sub, "type"));
  g_value_init (&template_value, type);

  res = priv__gst_structure_append_template_to_gstring (field_id,
      &template_value, s);
  g_value_unset (&template_value);
  return res;
}

static void
gst_tracer_record_build_format (GstTracerRecord * self)
{
  GstStructure *structure = self->spec;
  GString *s;
  gchar *name = (gchar *) g_quark_to_string (structure->name);
  gchar *p;

  g_return_if_fail (g_str_has_suffix (name, ".class"));

  GST_TRACE ("%" GST_PTR_FORMAT, structure);

  /* cut off '.class' suffix */
  name = g_strdup (name);
  p = strrchr (name, '.');
  *p = '\0';

  s = g_string_sized_new (STRUCTURE_ESTIMATED_STRING_LEN (structure));
  g_string_append (s, name);
  gst_structure_foreach (structure, build_field_template, s);
  g_string_append_c (s, ';');

  self->format = g_string_free (s, FALSE);
  GST_INFO ("new format string: %s", self->format);
  g_free (name);
}

static void
gst_tracer_record_dispose (GObject * object)
{
  GstTracerRecord *self = GST_TRACER_RECORD (object);

  gst_structure_free (self->spec);
  g_free (self->format);
}

static void
gst_tracer_record_set_property (GObject * object, guint prop_id,
    const GValue * value, GParamSpec * pspec)
{
  GstTracerRecord *self = GST_TRACER_RECORD_CAST (object);

  switch (prop_id) {
    case PROP_SPEC:
      self->spec = g_value_get_boxed (value);
      gst_tracer_record_build_format (self);
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
  }
}

static void
gst_tracer_record_get_property (GObject * object, guint prop_id,
    GValue * value, GParamSpec * pspec)
{
  GstTracerRecord *self = GST_TRACER_RECORD_CAST (object);

  switch (prop_id) {
    case PROP_SPEC:
      // TODO(ensonic): copy?
      g_value_set_boxed (value, self->spec);
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
  }
}

static void
gst_tracer_record_class_init (GstTracerRecordClass * klass)
{
  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);

  gobject_class->set_property = gst_tracer_record_set_property;
  gobject_class->get_property = gst_tracer_record_get_property;
  gobject_class->dispose = gst_tracer_record_dispose;

  properties[PROP_SPEC] =
      g_param_spec_boxed ("spec", "Spec", "Log record specification",
      GST_TYPE_STRUCTURE,
      G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY | G_PARAM_STATIC_STRINGS);

  g_object_class_install_properties (gobject_class, PROP_LAST, properties);
}

static void
gst_tracer_record_init (GstTracerRecord * self)
{
}

/**
 * gst_tracer_record_new:
 * @spec: the record specification
 *
 * Create a new tracer record. The record instance can be used to efficiently
 * log entries using gst_tracer_record_log().
 *
 * The name of the @spec #GstStructure must end on '.class'. This name without
 * the suffix will be used for the log records. The @spec must have a field for
 * each value that gets logged where the field name is the value name. The field
 * must be a nested structure describing the value. The sub structure must
 * contain a field called 'type' of %G_TYPE_GTYPE that contains the GType of the
 * value.
 *
 * The way to deal with optional values is to log an additional boolean before
 * the optional field, that if %TRUE signals that the optional field is valid
 * and %FALSE signals that the optional field should be ignored. One must still
 * log a placeholder value for the optional field though. Please also note, that
 * pointer type values must not be NULL - the underlying serialisation can not
 * handle that right now.
 *
 * <note><para>
 *   Please note that this is still under discussion and subject to change.
 * </para></note>
 *
 * Returns: a new #GstTracerRecord
 */
GstTracerRecord *
gst_tracer_record_new (GstStructure * spec)
{
  return g_object_new (GST_TYPE_TRACER_RECORD, "spec", spec, NULL);
}

/**
 * gst_tracer_record_log:
 * @self: the tracer-record
 * @...: the args as described in the spec-
 *
 * Serialzes the trace event into the log.
 *
 * Right now this is using the gstreamer debug log with the level TRACE (7) and
 * the category "GST_TRACER".
 * <note><para>
 *   Please note that this is still under discussion and subject to change.
 * </para></note>
 */
void
gst_tracer_record_log (GstTracerRecord * self, ...)
{
  va_list var_args;

  /*
   * does it make sense to use the {file, line, func} from the tracer hook?
   * a)
   * - we'd need to pass them in the macros to gst_tracer_dispatch()
   * - and each tracer needs to grab them from the va_list and pass them here
   * b)
   * - we create a context in dispatch, pass that to the tracer
   * - and the tracer will pass that here
   * ideally we also use *our* ts instead of the one that
   * gst_debug_log_default() will pick
   */

  va_start (var_args, self);
  if (G_LIKELY (GST_LEVEL_TRACE <= _gst_debug_min)) {
    gst_debug_log_valist (GST_CAT_DEFAULT, GST_LEVEL_TRACE, "", "", 0, NULL,
        self->format, var_args);
  }
  va_end (var_args);
}