/* GStreamer

 * Copyright (C) 2005 David Schleef <ds@schleef.org>

 *

 * gstminiobject.h: Header for GstMiniObject

 *

 * 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., 59 Temple Place - Suite 330,

 * Boston, MA 02111-1307, USA.

 */

/**

 * SECTION:gstminiobject

 * @short_description: Lightweight base class for the GStreamer object hierarchy

 *

 * #GstMiniObject is a baseclass like #GObject, but has been stripped down of 

 * features to be fast and small.

 * It offers sub-classing and ref-counting in the same way as #GObject does.

 * It has no properties and no signal-support though.

 *

 * Last reviewed on 2005-11-23 (0.9.5)

 */

#ifdef HAVE_CONFIG_H

#include "config.h"

#endif

#include "gst/gst_private.h"

#include "gst/gstminiobject.h"

#include "gst/gstinfo.h"

#include <gobject/gvaluecollector.h>

#ifndef GST_DISABLE_TRACE

#include "gsttrace.h"

static GstAllocTrace *_gst_mini_object_trace;

#endif

#define DEBUG_REFCOUNT

#if 0

static void gst_mini_object_base_init (gpointer g_class);

static void gst_mini_object_base_finalize (gpointer g_class);

#endif

static void gst_mini_object_class_init (gpointer g_class, gpointer class_data);

static void gst_mini_object_init (GTypeInstance * instance, gpointer klass);

static void gst_value_mini_object_init (GValue * value);

static void gst_value_mini_object_free (GValue * value);

static void gst_value_mini_object_copy (const GValue * src_value,

    GValue * dest_value);

static gpointer gst_value_mini_object_peek_pointer (const GValue * value);

static gchar *gst_value_mini_object_collect (GValue * value,

    guint n_collect_values, GTypeCValue * collect_values, guint collect_flags);

static gchar *gst_value_mini_object_lcopy (const GValue * value,

    guint n_collect_values, GTypeCValue * collect_values, guint collect_flags);

static GstMiniObject *gst_mini_object_copy_default (const GstMiniObject * obj);

static void gst_mini_object_finalize (GstMiniObject * obj);

#ifdef __SYMBIAN32__

EXPORT_C

#endif

GType

gst_mini_object_get_type (void)

{

  static GType _gst_mini_object_type = 0;

  if (G_UNLIKELY (_gst_mini_object_type == 0)) {

    GTypeValueTable value_table = {

      gst_value_mini_object_init,

      gst_value_mini_object_free,

      gst_value_mini_object_copy,

      gst_value_mini_object_peek_pointer,

      "p",

      gst_value_mini_object_collect,

      "p",

      gst_value_mini_object_lcopy

    };

    GTypeInfo mini_object_info = {

      sizeof (GstMiniObjectClass),

#if 0

      gst_mini_object_base_init,

      gst_mini_object_base_finalize,

#else

      NULL, NULL,

#endif

      gst_mini_object_class_init,

      NULL,

      NULL,

      sizeof (GstMiniObject),

      0,

      (GInstanceInitFunc) gst_mini_object_init,

      NULL

    };

    static const GTypeFundamentalInfo mini_object_fundamental_info = {

      (G_TYPE_FLAG_CLASSED | G_TYPE_FLAG_INSTANTIATABLE |

          G_TYPE_FLAG_DERIVABLE | G_TYPE_FLAG_DEEP_DERIVABLE)

    };

    mini_object_info.value_table = &value_table;

    _gst_mini_object_type = g_type_fundamental_next ();

    g_type_register_fundamental (_gst_mini_object_type, "GstMiniObject",

        &mini_object_info, &mini_object_fundamental_info, G_TYPE_FLAG_ABSTRACT);

#ifndef GST_DISABLE_TRACE

    _gst_mini_object_trace =

        gst_alloc_trace_register (g_type_name (_gst_mini_object_type));

#endif

  }

  return _gst_mini_object_type;

}

#if 0

static void

gst_mini_object_base_init (gpointer g_class)

{

  /* do nothing */

}

static void

gst_mini_object_base_finalize (gpointer g_class)

{

  /* do nothing */

}

#endif

static void

gst_mini_object_class_init (gpointer g_class, gpointer class_data)

{

  GstMiniObjectClass *mo_class = GST_MINI_OBJECT_CLASS (g_class);

  mo_class->copy = gst_mini_object_copy_default;

  mo_class->finalize = gst_mini_object_finalize;

}

static void

gst_mini_object_init (GTypeInstance * instance, gpointer klass)

{

  GstMiniObject *mini_object = GST_MINI_OBJECT_CAST (instance);

  mini_object->refcount = 1;

}

static GstMiniObject *

gst_mini_object_copy_default (const GstMiniObject * obj)

{

  g_warning ("GstMiniObject classes must implement GstMiniObject::copy");

  return NULL;

}

static void

gst_mini_object_finalize (GstMiniObject * obj)

{

  /* do nothing */

}

/**

 * gst_mini_object_new:

 * @type: the #GType of the mini-object to create

 *

 * Creates a new mini-object of the desired type.

 *

 * MT safe

 *

 * Returns: the new mini-object.

 */

#ifdef __SYMBIAN32__

EXPORT_C

#endif

GstMiniObject *

gst_mini_object_new (GType type)

{

  GstMiniObject *mini_object;

  /* we don't support dynamic types because they really aren't useful,

   * and could cause refcount problems */

  mini_object = (GstMiniObject *) g_type_create_instance (type);

#ifndef GST_DISABLE_TRACE

  gst_alloc_trace_new (_gst_mini_object_trace, mini_object);

#endif

  return mini_object;

}

/* FIXME 0.11: Current way of doing the copy makes it impossible

 * to currectly chain to the parent classes and do a copy in a

 * subclass without knowing all internals of the parent classes.

 *

 * For 0.11 we should do something like the following:

 *  - The GstMiniObjectClass::copy() implementation of GstMiniObject

 *    should call g_type_create_instance() with the type of the source

 *    object.

 *  - All GstMiniObjectClass::copy() implementations should as first

 *    thing chain up to the parent class and then do whatever they need

 *    to do to copy their type specific data. Note that this way the

 *    instance_init() functions are called!

 */

/**

 * gst_mini_object_copy:

 * @mini_object: the mini-object to copy

 *

 * Creates a copy of the mini-object.

 *

 * MT safe

 *

 * Returns: the new mini-object.

 */

#ifdef __SYMBIAN32__

EXPORT_C

#endif

GstMiniObject *

gst_mini_object_copy (const GstMiniObject * mini_object)

{

  GstMiniObjectClass *mo_class;

  g_return_val_if_fail (mini_object != NULL, NULL);

  mo_class = GST_MINI_OBJECT_GET_CLASS (mini_object);

  return mo_class->copy (mini_object);

}

/**

 * gst_mini_object_is_writable:

 * @mini_object: the mini-object to check

 *

 * Checks if a mini-object is writable.  A mini-object is writable

 * if the reference count is one and the #GST_MINI_OBJECT_FLAG_READONLY

 * flag is not set.  Modification of a mini-object should only be

 * done after verifying that it is writable.

 *

 * MT safe

 *

 * Returns: TRUE if the object is writable.

 */

#ifdef __SYMBIAN32__

EXPORT_C

#endif

gboolean

gst_mini_object_is_writable (const GstMiniObject * mini_object)

{

  g_return_val_if_fail (mini_object != NULL, FALSE);

  return (GST_MINI_OBJECT_REFCOUNT_VALUE (mini_object) == 1) &&

      ((mini_object->flags & GST_MINI_OBJECT_FLAG_READONLY) == 0);

}

/**

 * gst_mini_object_make_writable:

 * @mini_object: the mini-object to make writable

 *

 * Checks if a mini-object is writable.  If not, a writable copy is made and

 * returned.  This gives away the reference to the original mini object,

 * and returns a reference to the new object.

 *

 * MT safe

 *

 * Returns: a mini-object (possibly the same pointer) that is writable.

 */

#ifdef __SYMBIAN32__

EXPORT_C

#endif

GstMiniObject *

gst_mini_object_make_writable (GstMiniObject * mini_object)

{

  GstMiniObject *ret;

  g_return_val_if_fail (mini_object != NULL, NULL);

  if (gst_mini_object_is_writable (mini_object)) {

    ret = (GstMiniObject *) mini_object;

  } else {

    ret = gst_mini_object_copy (mini_object);

    gst_mini_object_unref ((GstMiniObject *) mini_object);

  }

  return ret;

}

/**

 * gst_mini_object_ref:

 * @mini_object: the mini-object

 *

 * Increase the reference count of the mini-object.

 *

 * Note that the refcount affects the writeability

 * of @mini-object, see gst_mini_object_is_writable(). It is 

 * important to note that keeping additional references to

 * GstMiniObject instances can potentially increase the number

 * of memcpy operations in a pipeline, especially if the miniobject

 * is a #GstBuffer.

 *

 * Returns: the mini-object.

 */

#ifdef __SYMBIAN32__

EXPORT_C

#endif

GstMiniObject *

gst_mini_object_ref (GstMiniObject * mini_object)

{

  g_return_val_if_fail (mini_object != NULL, NULL);

  /* we cannot assert that the refcount > 0 since a bufferalloc

   * function might resurrect an object

   g_return_val_if_fail (mini_object->refcount > 0, NULL);

   */

#ifdef DEBUG_REFCOUNT

  g_return_val_if_fail (GST_IS_MINI_OBJECT (mini_object), NULL);

  GST_CAT_LOG (GST_CAT_REFCOUNTING, "%p ref %d->%d",

      mini_object,

      GST_MINI_OBJECT_REFCOUNT_VALUE (mini_object),

      GST_MINI_OBJECT_REFCOUNT_VALUE (mini_object) + 1);

#endif

  g_atomic_int_inc (&mini_object->refcount);

  return mini_object;

}

static void

gst_mini_object_free (GstMiniObject * mini_object)

{

  GstMiniObjectClass *mo_class;

  mo_class = GST_MINI_OBJECT_GET_CLASS (mini_object);

  mo_class->finalize (mini_object);

  /* if the refcount is still 0 we can really free the

   * object, else the finalize method recycled the object */

  if (g_atomic_int_get (&mini_object->refcount) == 0) {

#ifndef GST_DISABLE_TRACE

    gst_alloc_trace_free (_gst_mini_object_trace, mini_object);

#endif

    g_type_free_instance ((GTypeInstance *) mini_object);

  }

}

/**

 * gst_mini_object_unref:

 * @mini_object: the mini-object

 *

 * Decreases the reference count of the mini-object, possibly freeing

 * the mini-object.

 */

#ifdef __SYMBIAN32__

EXPORT_C

#endif

void

gst_mini_object_unref (GstMiniObject * mini_object)

{

  g_return_if_fail (mini_object != NULL);

  g_return_if_fail (mini_object->refcount > 0);

#ifdef DEBUG_REFCOUNT

  g_return_if_fail (GST_IS_MINI_OBJECT (mini_object));

  GST_CAT_LOG (GST_CAT_REFCOUNTING, "%p unref %d->%d",

      mini_object,

      GST_MINI_OBJECT_REFCOUNT_VALUE (mini_object),

      GST_MINI_OBJECT_REFCOUNT_VALUE (mini_object) - 1);

#endif

  if (G_UNLIKELY (g_atomic_int_dec_and_test (&mini_object->refcount))) {

    gst_mini_object_free (mini_object);

  }

}

/**

 * gst_mini_object_replace:

 * @olddata: pointer to a pointer to a mini-object to be replaced

 * @newdata: pointer to new mini-object

 *

 * Modifies a pointer to point to a new mini-object.  The modification

 * is done atomically, and the reference counts are updated correctly.

 * Either @newdata and the value pointed to by @olddata may be NULL.

 */

#ifdef __SYMBIAN32__

EXPORT_C

#endif

void

gst_mini_object_replace (GstMiniObject ** olddata, GstMiniObject * newdata)

{

  GstMiniObject *olddata_val;

  g_return_if_fail (olddata != NULL);

#ifdef DEBUG_REFCOUNT

  GST_CAT_LOG (GST_CAT_REFCOUNTING, "replace %p (%d) with %p (%d)",

      *olddata, *olddata ? (*olddata)->refcount : 0,

      newdata, newdata ? newdata->refcount : 0);

#endif

  olddata_val = g_atomic_pointer_get ((gpointer *) olddata);

  if (olddata_val == newdata)

    return;

  if (newdata)

    gst_mini_object_ref (newdata);

  while (!g_atomic_pointer_compare_and_exchange ((gpointer *) olddata,

          olddata_val, newdata)) {

    olddata_val = g_atomic_pointer_get ((gpointer *) olddata);

  }

  if (olddata_val)

    gst_mini_object_unref (olddata_val);

}

static void

gst_value_mini_object_init (GValue * value)

{

  value->data[0].v_pointer = NULL;

}

static void

gst_value_mini_object_free (GValue * value)

{

  if (value->data[0].v_pointer) {

    gst_mini_object_unref (GST_MINI_OBJECT_CAST (value->data[0].v_pointer));

  }

}

static void

gst_value_mini_object_copy (const GValue * src_value, GValue * dest_value)

{

  if (src_value->data[0].v_pointer) {

    dest_value->data[0].v_pointer =

  } else {

    dest_value->data[0].v_pointer = NULL;

  }

}

static gpointer

gst_value_mini_object_peek_pointer (const GValue * value)

{

  return value->data[0].v_pointer;

}

static gchar *

gst_value_mini_object_collect (GValue * value, guint n_collect_values,

    GTypeCValue * collect_values, guint collect_flags)

{

  gst_value_set_mini_object (value, collect_values[0].v_pointer);

  return NULL;

}

static gchar *

gst_value_mini_object_lcopy (const GValue * value, guint n_collect_values,

    GTypeCValue * collect_values, guint collect_flags)

{

  gpointer *mini_object_p = collect_values[0].v_pointer;

  if (!mini_object_p) {

    return g_strdup_printf ("value location for '%s' passed as NULL",

        G_VALUE_TYPE_NAME (value));

  }

  if (!value->data[0].v_pointer)

    *mini_object_p = NULL;

  else if (collect_flags & G_VALUE_NOCOPY_CONTENTS)

    *mini_object_p = value->data[0].v_pointer;

  else

    *mini_object_p = gst_mini_object_ref (value->data[0].v_pointer);

  return NULL;

}

/**

 * gst_value_set_mini_object:

 * @value:       a valid #GValue of %GST_TYPE_MINI_OBJECT derived type

 * @mini_object: mini object value to set

 *

 * Set the contents of a %GST_TYPE_MINI_OBJECT derived #GValue to

 * @mini_object.

 * The caller retains ownership of the reference.

 */

#ifdef __SYMBIAN32__

EXPORT_C

#endif

void

gst_value_set_mini_object (GValue * value, GstMiniObject * mini_object)

{

  gpointer *pointer_p;

  g_return_if_fail (GST_VALUE_HOLDS_MINI_OBJECT (value));

  g_return_if_fail (mini_object == NULL || GST_IS_MINI_OBJECT (mini_object));

  pointer_p = &value->data[0].v_pointer;

  gst_mini_object_replace ((GstMiniObject **) pointer_p, mini_object);

}