GstMiniObject

GstMiniObject

gst_mini_object_add_parent

gst_mini_object_add_parent (GstMiniObject * object,
                            GstMiniObject * parent)

This adds parent as a parent for object. Having one ore more parents affects the writability of object: if a parent is not writable, object is also not writable, regardless of its refcount. object is only writable if all the parents are writable and its own refcount is exactly 1.

Note: This function does not take ownership of parent and also does not take an additional reference. It is the responsibility of the caller to remove the parent again at a later time.

Since : 1.16

gst_mini_object_copy

GstMiniObject *
gst_mini_object_copy (const GstMiniObject * mini_object)

Creates a copy of the mini-object.

MT safe

gst_mini_object_get_qdata

gpointer
gst_mini_object_get_qdata (GstMiniObject * object,
                           GQuark quark)

This function gets back user data pointers stored via gst_mini_object_set_qdata.

gst_mini_object_init

gst_mini_object_init (GstMiniObject * mini_object,
                      guint flags,
                      GType type,
                      GstMiniObjectCopyFunction copy_func,
                      GstMiniObjectDisposeFunction dispose_func,
                      GstMiniObjectFreeFunction free_func)

Initializes a mini-object with the desired type and copy/dispose/free functions.

gst_mini_object_is_writable

gboolean
gst_mini_object_is_writable (const GstMiniObject * mini_object)

If mini_object has the LOCKABLE flag set, check if the current EXCLUSIVE lock on object is the only one, this means that changes to the object will not be visible to any other object.

If the LOCKABLE flag is not set, check if the refcount of mini_object is exactly 1, meaning that no other reference exists to the object and that the object is therefore writable.

Modification of a mini-object should only be done after verifying that it is writable.

gst_mini_object_lock

gboolean
gst_mini_object_lock (GstMiniObject * object,
                      GstLockFlags flags)

Lock the mini-object with the specified access mode in flags.

gst_mini_object_make_writable

GstMiniObject *
gst_mini_object_make_writable (GstMiniObject * mini_object)

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

gst_mini_object_ref

GstMiniObject *
gst_mini_object_ref (GstMiniObject * mini_object)

Increase the reference count of the mini-object.

Note that the refcount affects the writability 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.

gst_mini_object_remove_parent

gst_mini_object_remove_parent (GstMiniObject * object,
                               GstMiniObject * parent)

This removes parent as a parent for object. See gst_mini_object_add_parent.

Since : 1.16

gst_mini_object_set_qdata

gst_mini_object_set_qdata (GstMiniObject * object,
                           GQuark quark,
                           gpointer data,
                           GDestroyNotify destroy)

This sets an opaque, named pointer on a miniobject. The name is specified through a GQuark (retrieved e.g. via g_quark_from_static_string), and the pointer can be gotten back from the object with gst_mini_object_get_qdata until the object is disposed. Setting a previously set user data pointer, overrides (frees) the old pointer set, using NULL as pointer essentially removes the data stored.

destroy may be specified which is called with data as argument when the object is disposed, or the data is being overwritten by a call to gst_mini_object_set_qdata with the same quark.

gst_mini_object_steal_qdata

gpointer
gst_mini_object_steal_qdata (GstMiniObject * object,
                             GQuark quark)

This function gets back user data pointers stored via gst_mini_object_set_qdata and removes the data from object without invoking its destroy() function (if any was set).

gst_mini_object_unlock

gst_mini_object_unlock (GstMiniObject * object,
                        GstLockFlags flags)

Unlock the mini-object with the specified access mode in flags.

gst_mini_object_unref

gst_mini_object_unref (GstMiniObject * mini_object)

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

gst_mini_object_weak_ref

gst_mini_object_weak_ref (GstMiniObject * object,
                          GstMiniObjectNotify notify,
                          gpointer data)

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).

gst_mini_object_weak_unref

gst_mini_object_weak_unref (GstMiniObject * object,
                            GstMiniObjectNotify notify,
                            gpointer data)

Removes a weak reference callback from a mini object.

gst_mini_object_replace

gboolean
gst_mini_object_replace (GstMiniObject ** olddata,
                         GstMiniObject * newdata)

Atomically modifies a pointer to point to a new mini-object. The reference count of olddata is decreased and the reference count of newdata is increased.

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

gst_mini_object_steal

GstMiniObject *
gst_mini_object_steal (GstMiniObject ** olddata)

Replace the current GstMiniObject pointer to by olddata with NULL and return the old value.

gst_mini_object_take

gboolean
gst_mini_object_take (GstMiniObject ** olddata,
                      GstMiniObject * newdata)

Modifies a pointer to point to a new mini-object. The modification is done atomically. This version is similar to gst_mini_object_replace except that it does not increase the refcount of newdata and thus takes ownership of newdata.

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

gst_clear_mini_object

gst_clear_mini_object (GstMiniObject ** object_ptr)

Clears a reference to a GstMiniObject.

object_ptr must not be NULL.

If the reference is NULL then this function does nothing. Otherwise, the reference count of the object is decreased using gst_mini_object_unref and the pointer is set to NULL.

A macro is also included that allows this function to be used without pointer casts.

Since : 1.16

GST_DEFINE_MINI_OBJECT_TYPE

#define GST_DEFINE_MINI_OBJECT_TYPE(TypeName,type_name) \
   G_DEFINE_BOXED_TYPE(TypeName,type_name,              \
       (GBoxedCopyFunc) gst_mini_object_ref,            \
       (GBoxedFreeFunc) gst_mini_object_unref)

Define a new mini-object type with the given name

GST_IS_MINI_OBJECT_TYPE

#define GST_IS_MINI_OBJECT_TYPE(obj,type)  ((obj) && GST_MINI_OBJECT_TYPE(obj) == (type))

GST_MINI_OBJECT_CAST

#define GST_MINI_OBJECT_CAST(obj)          ((GstMiniObject*)(obj))

GST_MINI_OBJECT_CONST_CAST

#define GST_MINI_OBJECT_CONST_CAST(obj)    ((const GstMiniObject*)(obj))

GST_MINI_OBJECT_FLAGS

#define GST_MINI_OBJECT_FLAGS(obj)  (GST_MINI_OBJECT_CAST(obj)->flags)

This macro returns the entire set of flags for the mini-object.

GST_MINI_OBJECT_FLAG_IS_SET

#define GST_MINI_OBJECT_FLAG_IS_SET(obj,flag)        !!(GST_MINI_OBJECT_FLAGS (obj) & (flag))

This macro checks to see if the given flag is set.

GST_MINI_OBJECT_FLAG_SET

#define GST_MINI_OBJECT_FLAG_SET(obj,flag)           (GST_MINI_OBJECT_FLAGS (obj) |= (flag))

This macro sets the given bits.

GST_MINI_OBJECT_FLAG_UNSET

#define GST_MINI_OBJECT_FLAG_UNSET(obj,flag)         (GST_MINI_OBJECT_FLAGS (obj) &= ~(flag))

This macro unsets the given bits.

GST_MINI_OBJECT_IS_LOCKABLE

#define GST_MINI_OBJECT_IS_LOCKABLE(obj)  GST_MINI_OBJECT_FLAG_IS_SET(obj, GST_MINI_OBJECT_FLAG_LOCKABLE)

Check if obj is lockable. A lockable object can be locked and unlocked with gst_mini_object_lock and gst_mini_object_unlock.

GST_MINI_OBJECT_REFCOUNT

#define GST_MINI_OBJECT_REFCOUNT(obj)           ((GST_MINI_OBJECT_CAST(obj))->refcount)

Get access to the reference count field of the mini-object.

GST_MINI_OBJECT_REFCOUNT_VALUE

#define GST_MINI_OBJECT_REFCOUNT_VALUE(obj)     (g_atomic_int_get (&(GST_MINI_OBJECT_CAST(obj))->refcount))

Get the reference count value of the mini-object.

GST_MINI_OBJECT_TYPE

#define GST_MINI_OBJECT_TYPE(obj)  (GST_MINI_OBJECT_CAST(obj)->type)

This macro returns the type of the mini-object.

GstLockFlags

Flags used when locking miniobjects

GstMiniObjectFlags

Flags for the mini object

GST_LOCK_FLAG_READWRITE

#define GST_LOCK_FLAG_READWRITE  ((GstLockFlags) (GST_LOCK_FLAG_READ | GST_LOCK_FLAG_WRITE))

GstLockFlags value alias for GST_LOCK_FLAG_READ | GST_LOCK_FLAG_WRITE

GST_TYPE_MINI_OBJECT

#define GST_TYPE_MINI_OBJECT               (_gst_mini_object_type)

The GType associated with GstMiniObject.

Since : 1.20

GstMiniObjectCopyFunction

GstMiniObject *
(*GstMiniObjectCopyFunction) (const GstMiniObject * obj)

Function prototype for methods to create copies of instances.

GstMiniObjectDisposeFunction

gboolean
(*GstMiniObjectDisposeFunction) (GstMiniObject * obj)

Function prototype for when a miniobject has lost its last refcount. Implementation of the mini object are allowed to revive the passed object by doing a gst_mini_object_ref. If the object is not revived after the dispose function, the function should return TRUE and the memory associated with the object is freed.

GstMiniObjectFreeFunction

(*GstMiniObjectFreeFunction) (GstMiniObject * obj)

Virtual function prototype for methods to free resources used by mini-objects.

GstMiniObjectNotify

(*GstMiniObjectNotify) (gpointer user_data,
                        GstMiniObject * obj)

A GstMiniObjectNotify function can be added to a mini object as a callback that gets triggered when gst_mini_object_unref drops the last ref and obj is about to be freed.