/* GStreamer * Copyright (C) 2005 David Schleef * * 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 #ifndef GST_DISABLE_TRACE #include "gsttrace.h" static GstAllocTrace *_gst_mini_object_trace; #endif #define GST_MINI_OBJECT_GET_CLASS_UNCHECKED(obj) \ ((GstMiniObjectClass *) (((GTypeInstance*)(obj))->g_class)) /* Structure used for storing weak references */ typedef struct { GstMiniObject *object; guint n_weak_refs; struct { GstMiniObjectWeakNotify notify; gpointer data; } weak_refs[1]; /* flexible array */ } WeakRefStack; /* Structure for storing a mini object's private data */ struct _GstMiniObjectPrivate { WeakRefStack *wstack; }; #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 weak_refs_notify (WeakRefStack * data); 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); /* Mutex used for weak referencing */ G_LOCK_DEFINE_STATIC (weak_refs_mutex); GType gst_mini_object_get_type (void) { static volatile GType _gst_mini_object_type = 0; if (g_once_init_enter (&_gst_mini_object_type)) { GType _type; static const GTypeValueTable value_table = { gst_value_mini_object_init, gst_value_mini_object_free, gst_value_mini_object_copy, gst_value_mini_object_peek_pointer, (char *) "p", gst_value_mini_object_collect, (char *) "p", gst_value_mini_object_lcopy }; static const 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, &value_table }; static const GTypeFundamentalInfo mini_object_fundamental_info = { (G_TYPE_FLAG_CLASSED | G_TYPE_FLAG_INSTANTIATABLE | G_TYPE_FLAG_DERIVABLE | G_TYPE_FLAG_DEEP_DERIVABLE) }; _type = g_type_fundamental_next (); g_type_register_fundamental (_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 (_type)); #endif g_once_init_leave (&_gst_mini_object_type, _type); } 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; /* Set the instance data type */ g_type_class_add_private (g_class, sizeof (GstMiniObjectPrivate)); } static void gst_mini_object_init (GTypeInstance * instance, gpointer klass) { GstMiniObject *mini_object = GST_MINI_OBJECT_CAST (instance); mini_object->refcount = 1; /* we delay initialising the mini object's private data until it's actually * needed for now (mini_object->priv automatically inited to NULL) */ } 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 */ /* WARNING: if anything is ever put in this method, make sure that the * following sub-classes' finalize method chains up to this one: * gstbuffer * gstevent * gstmessage * gstquery */ } /** * 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: (transfer full): the new mini-object. */ 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: (transfer full): the new mini-object. */ 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. */ 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: (transfer full): 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: (transfer full): a mini-object (possibly the same pointer) that * is writable. */ 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 = mini_object; } else { GST_CAT_DEBUG (GST_CAT_PERFORMANCE, "copy %s miniobject", g_type_name (G_TYPE_FROM_INSTANCE (mini_object))); ret = gst_mini_object_copy (mini_object); gst_mini_object_unref (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: (transfer full): the mini-object. */ GstMiniObject * gst_mini_object_ref (GstMiniObject * mini_object) { g_return_val_if_fail (mini_object != NULL, NULL); /* we can't assert that the refcount > 0 since the _free functions * increments the refcount from 0 to 1 again to allow resurecting * the object g_return_val_if_fail (mini_object->refcount > 0, NULL); */ g_return_val_if_fail (GST_IS_MINI_OBJECT (mini_object), NULL); GST_CAT_TRACE (GST_CAT_REFCOUNTING, "%p ref %d->%d", mini_object, GST_MINI_OBJECT_REFCOUNT_VALUE (mini_object), GST_MINI_OBJECT_REFCOUNT_VALUE (mini_object) + 1); g_atomic_int_inc (&mini_object->refcount); return mini_object; } static void weak_refs_notify (WeakRefStack * wstack) { guint i; for (i = 0; i < wstack->n_weak_refs; i++) wstack->weak_refs[i].notify (wstack->weak_refs[i].data, wstack->object); g_free (wstack); } static void gst_mini_object_free (GstMiniObject * mini_object) { GstMiniObjectClass *mo_class; /* At this point, the refcount of the object is 0. We increase the refcount * here because if a subclass recycles the object and gives out a new * reference we don't want to free the instance anymore. */ GST_CAT_TRACE (GST_CAT_REFCOUNTING, "%p ref %d->%d", mini_object, GST_MINI_OBJECT_REFCOUNT_VALUE (mini_object), GST_MINI_OBJECT_REFCOUNT_VALUE (mini_object) + 1); g_atomic_int_inc (&mini_object->refcount); mo_class = GST_MINI_OBJECT_GET_CLASS_UNCHECKED (mini_object); mo_class->finalize (mini_object); /* decrement the refcount again, if the subclass recycled the object we don't * want to free the instance anymore */ if (G_LIKELY (g_atomic_int_dec_and_test (&mini_object->refcount))) { /* The weak reference stack is freed in the notification function */ if (mini_object->priv != NULL && mini_object->priv->wstack != NULL) weak_refs_notify (mini_object->priv->wstack); #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. */ void gst_mini_object_unref (GstMiniObject * mini_object) { g_return_if_fail (GST_IS_MINI_OBJECT (mini_object)); g_return_if_fail (mini_object->refcount > 0); GST_CAT_TRACE (GST_CAT_REFCOUNTING, "%p unref %d->%d", mini_object, GST_MINI_OBJECT_REFCOUNT_VALUE (mini_object), GST_MINI_OBJECT_REFCOUNT_VALUE (mini_object) - 1); if (G_UNLIKELY (g_atomic_int_dec_and_test (&mini_object->refcount))) { gst_mini_object_free (mini_object); } } /** * gst_mini_object_weak_ref: (skip) * @object: #GstMiniObject to reference weakly * @notify: callback to invoke before the mini object is freed * @data: extra data to pass to notify * * Adds a weak reference callback to a mini object. Weak references are * used for notification when a mini object is finalized. They are called * "weak references" because they allow you to safely hold a pointer * to the mini object without calling gst_mini_object_ref() * (gst_mini_object_ref() adds a strong reference, that is, forces the object * to stay alive). * * Since: 0.10.36 */ void gst_mini_object_weak_ref (GstMiniObject * object, GstMiniObjectWeakNotify notify, gpointer data) { guint i; g_return_if_fail (GST_IS_MINI_OBJECT (object)); g_return_if_fail (notify != NULL); g_return_if_fail (GST_MINI_OBJECT_REFCOUNT_VALUE (object) >= 1); G_LOCK (weak_refs_mutex); if (object->priv == NULL) { object->priv = G_TYPE_INSTANCE_GET_PRIVATE (object, GST_TYPE_MINI_OBJECT, GstMiniObjectPrivate); /* object->priv->wstack will have been inited to NULL automatically */ } if (object->priv->wstack) { /* Don't add the weak reference if it already exists. */ for (i = 0; i < object->priv->wstack->n_weak_refs; i++) { if (object->priv->wstack->weak_refs[i].notify == notify && object->priv->wstack->weak_refs[i].data == data) { g_warning ("%s: Attempt to re-add existing weak ref %p(%p) failed.", G_STRFUNC, notify, data); goto found; } } i = object->priv->wstack->n_weak_refs++; object->priv->wstack = g_realloc (object->priv->wstack, sizeof (*(object->priv->wstack)) + sizeof (object->priv->wstack->weak_refs[0]) * i); } else { object->priv->wstack = g_renew (WeakRefStack, NULL, 1); object->priv->wstack->object = object; object->priv->wstack->n_weak_refs = 1; i = 0; } object->priv->wstack->weak_refs[i].notify = notify; object->priv->wstack->weak_refs[i].data = data; found: G_UNLOCK (weak_refs_mutex); } /** * gst_mini_object_weak_unref: (skip) * @object: #GstMiniObject to remove a weak reference from * @notify: callback to search for * @data: data to search for * * Removes a weak reference callback to a mini object. * * Since: 0.10.36 */ void gst_mini_object_weak_unref (GstMiniObject * object, GstMiniObjectWeakNotify notify, gpointer data) { gboolean found_one = FALSE; g_return_if_fail (GST_IS_MINI_OBJECT (object)); g_return_if_fail (notify != NULL); G_LOCK (weak_refs_mutex); if (object->priv != NULL && object->priv->wstack != NULL) { guint i; for (i = 0; i < object->priv->wstack->n_weak_refs; i++) if (object->priv->wstack->weak_refs[i].notify == notify && object->priv->wstack->weak_refs[i].data == data) { found_one = TRUE; object->priv->wstack->n_weak_refs -= 1; if (i != object->priv->wstack->n_weak_refs) object->priv->wstack->weak_refs[i] = object->priv->wstack->weak_refs[object->priv->wstack-> n_weak_refs]; break; } } G_UNLOCK (weak_refs_mutex); if (!found_one) g_warning ("%s: couldn't find weak ref %p(%p)", G_STRFUNC, notify, data); } /** * gst_mini_object_replace: * @olddata: (inout) (transfer full): 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. */ void gst_mini_object_replace (GstMiniObject ** olddata, GstMiniObject * newdata) { GstMiniObject *olddata_val; g_return_if_fail (olddata != NULL); GST_CAT_TRACE (GST_CAT_REFCOUNTING, "replace %p (%d) with %p (%d)", *olddata, *olddata ? (*olddata)->refcount : 0, newdata, newdata ? newdata->refcount : 0); 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 = gst_mini_object_ref (GST_MINI_OBJECT_CAST (src_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) { if (collect_values[0].v_pointer) { value->data[0].v_pointer = gst_mini_object_ref (collect_values[0].v_pointer); } else { value->data[0].v_pointer = NULL; } 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: (transfer none): 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. */ 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); } /** * gst_value_take_mini_object: * @value: a valid #GValue of %GST_TYPE_MINI_OBJECT derived type * @mini_object: (transfer full): mini object value to take * * Set the contents of a %GST_TYPE_MINI_OBJECT derived #GValue to * @mini_object. * Takes over the ownership of the caller's reference to @mini_object; * the caller doesn't have to unref it any more. */ void gst_value_take_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; /* takes additional refcount */ gst_mini_object_replace ((GstMiniObject **) pointer_p, mini_object); /* remove additional refcount */ if (mini_object) gst_mini_object_unref (mini_object); } /** * gst_value_get_mini_object: * @value: a valid #GValue of %GST_TYPE_MINI_OBJECT derived type * * Get the contents of a %GST_TYPE_MINI_OBJECT derived #GValue. * Does not increase the refcount of the returned object. * * Returns: (transfer none): mini object contents of @value */ GstMiniObject * gst_value_get_mini_object (const GValue * value) { g_return_val_if_fail (GST_VALUE_HOLDS_MINI_OBJECT (value), NULL); return value->data[0].v_pointer; } /** * gst_value_dup_mini_object: * @value: a valid #GValue of %GST_TYPE_MINI_OBJECT derived type * * Get the contents of a %GST_TYPE_MINI_OBJECT derived #GValue, * increasing its reference count. If the contents of the #GValue * are %NULL, %NULL will be returned. * * Returns: (transfer full): mini object contents of @value * * Since: 0.10.20 */ GstMiniObject * gst_value_dup_mini_object (const GValue * value) { g_return_val_if_fail (GST_VALUE_HOLDS_MINI_OBJECT (value), NULL); return value->data[0].v_pointer ? gst_mini_object_ref (value-> data[0].v_pointer) : NULL; } /* param spec */ static void param_mini_object_init (GParamSpec * pspec) { /* GParamSpecMiniObject *ospec = G_PARAM_SPEC_MINI_OBJECT (pspec); */ } static void param_mini_object_set_default (GParamSpec * pspec, GValue * value) { value->data[0].v_pointer = NULL; } static gboolean param_mini_object_validate (GParamSpec * pspec, GValue * value) { GstMiniObject *mini_object = value->data[0].v_pointer; gboolean changed = FALSE; if (mini_object && !g_value_type_compatible (G_OBJECT_TYPE (mini_object), pspec->value_type)) { gst_mini_object_unref (mini_object); value->data[0].v_pointer = NULL; changed = TRUE; } return changed; } static gint param_mini_object_values_cmp (GParamSpec * pspec, const GValue * value1, const GValue * value2) { guint8 *p1 = value1->data[0].v_pointer; guint8 *p2 = value2->data[0].v_pointer; /* not much to compare here, try to at least provide stable lesser/greater result */ return p1 < p2 ? -1 : p1 > p2; } GType gst_param_spec_mini_object_get_type (void) { static GType type; if (G_UNLIKELY (type) == 0) { static const GParamSpecTypeInfo pspec_info = { sizeof (GstParamSpecMiniObject), /* instance_size */ 16, /* n_preallocs */ param_mini_object_init, /* instance_init */ G_TYPE_OBJECT, /* value_type */ NULL, /* finalize */ param_mini_object_set_default, /* value_set_default */ param_mini_object_validate, /* value_validate */ param_mini_object_values_cmp, /* values_cmp */ }; /* FIXME 0.11: Should really be GstParamSpecMiniObject */ type = g_param_type_register_static ("GParamSpecMiniObject", &pspec_info); } return type; } /** * gst_param_spec_mini_object: * @name: the canonical name of the property * @nick: the nickname of the property * @blurb: a short description of the property * @object_type: the #GstMiniObject #GType for the property * @flags: a combination of #GParamFlags * * Creates a new #GParamSpec instance that hold #GstMiniObject references. * * Returns: (transfer full): a newly allocated #GParamSpec instance */ GParamSpec * gst_param_spec_mini_object (const char *name, const char *nick, const char *blurb, GType object_type, GParamFlags flags) { GstParamSpecMiniObject *ospec; g_return_val_if_fail (g_type_is_a (object_type, GST_TYPE_MINI_OBJECT), NULL); ospec = g_param_spec_internal (GST_TYPE_PARAM_MINI_OBJECT, name, nick, blurb, flags); G_PARAM_SPEC (ospec)->value_type = object_type; return G_PARAM_SPEC (ospec); }