2 * Copyright (C) 2005 David Schleef <ds@schleef.org>
4 * gstminiobject.h: Header for GstMiniObject
6 * This library is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Library General Public
8 * License as published by the Free Software Foundation; either
9 * version 2 of the License, or (at your option) any later version.
11 * This library is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Library General Public License for more details.
16 * You should have received a copy of the GNU Library General Public
17 * License along with this library; if not, write to the
18 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
19 * Boston, MA 02110-1301, USA.
22 * SECTION:gstminiobject
23 * @short_description: Lightweight base class for the GStreamer object hierarchy
25 * #GstMiniObject is a simple structure that can be used to implement refcounted
28 * Subclasses will include #GstMiniObject as the first member in their structure
29 * and then call gst_mini_object_init() to initialize the #GstMiniObject fields.
31 * gst_mini_object_ref() and gst_mini_object_unref() increment and decrement the
32 * refcount respectively. When the refcount of a mini-object reaches 0, the
33 * dispose function is called first and when this returns %TRUE, the free
34 * function of the miniobject is called.
36 * A copy can be made with gst_mini_object_copy().
38 * gst_mini_object_is_writable() will return %TRUE when the refcount of the
39 * object is exactly 1, meaning the current caller has the only reference to the
40 * object. gst_mini_object_make_writable() will return a writable version of the
41 * object, which might be a new copy when the refcount was not 1.
43 * Opaque data can be associated with a #GstMiniObject with
44 * gst_mini_object_set_qdata() and gst_mini_object_get_qdata(). The data is
45 * meant to be specific to the particular object and is not automatically copied
46 * with gst_mini_object_copy() or similar methods.
48 * A weak reference can be added and remove with gst_mini_object_weak_ref()
49 * and gst_mini_object_weak_unref() respectively.
55 #include "gst/gst_private.h"
56 #include "gst/gstminiobject.h"
57 #include "gst/gstinfo.h"
58 #include <gobject/gvaluecollector.h>
60 #ifndef GST_DISABLE_TRACE
62 static GstAllocTrace *_gst_mini_object_trace;
65 /* Mutex used for weak referencing */
66 G_LOCK_DEFINE_STATIC (qdata_mutex);
67 static GQuark weak_ref_quark;
69 #define SHARE_ONE (1 << 16)
70 #define SHARE_TWO (2 << 16)
71 #define SHARE_MASK (~(SHARE_ONE - 1))
72 #define IS_SHARED(state) (state >= SHARE_TWO)
73 #define LOCK_ONE (GST_LOCK_FLAG_LAST)
74 #define FLAG_MASK (GST_LOCK_FLAG_LAST - 1)
75 #define LOCK_MASK ((SHARE_ONE - 1) - FLAG_MASK)
76 #define LOCK_FLAG_MASK (SHARE_ONE - 1)
81 GstMiniObjectNotify notify;
83 GDestroyNotify destroy;
86 #define QDATA(o,i) ((GstQData *)(o)->qdata)[(i)]
87 #define QDATA_QUARK(o,i) (QDATA(o,i).quark)
88 #define QDATA_NOTIFY(o,i) (QDATA(o,i).notify)
89 #define QDATA_DATA(o,i) (QDATA(o,i).data)
90 #define QDATA_DESTROY(o,i) (QDATA(o,i).destroy)
93 _priv_gst_mini_object_initialize (void)
95 weak_ref_quark = g_quark_from_static_string ("GstMiniObjectWeakRefQuark");
97 #ifndef GST_DISABLE_TRACE
98 _gst_mini_object_trace = _gst_alloc_trace_register ("GstMiniObject", 0);
103 * gst_mini_object_init: (skip)
104 * @mini_object: a #GstMiniObject
105 * @flags: initial #GstMiniObjectFlags
106 * @type: the #GType of the mini-object to create
107 * @copy_func: (allow-none): the copy function, or %NULL
108 * @dispose_func: (allow-none): the dispose function, or %NULL
109 * @free_func: (allow-none): the free function or %NULL
111 * Initializes a mini-object with the desired type and copy/dispose/free
115 gst_mini_object_init (GstMiniObject * mini_object, guint flags, GType type,
116 GstMiniObjectCopyFunction copy_func,
117 GstMiniObjectDisposeFunction dispose_func,
118 GstMiniObjectFreeFunction free_func)
120 mini_object->type = type;
121 mini_object->refcount = 1;
122 mini_object->lockstate = 0;
123 mini_object->flags = flags;
125 mini_object->copy = copy_func;
126 mini_object->dispose = dispose_func;
127 mini_object->free = free_func;
129 mini_object->n_qdata = 0;
130 mini_object->qdata = NULL;
132 GST_TRACER_MINI_OBJECT_CREATED (mini_object);
133 #ifndef GST_DISABLE_TRACE
134 _gst_alloc_trace_new (_gst_mini_object_trace, mini_object);
139 * gst_mini_object_copy: (skip)
140 * @mini_object: the mini-object to copy
142 * Creates a copy of the mini-object.
146 * Returns: (transfer full): the new mini-object.
149 gst_mini_object_copy (const GstMiniObject * mini_object)
153 g_return_val_if_fail (mini_object != NULL, NULL);
155 if (mini_object->copy)
156 copy = mini_object->copy (mini_object);
164 * gst_mini_object_lock:
165 * @object: the mini-object to lock
166 * @flags: #GstLockFlags
168 * Lock the mini-object with the specified access mode in @flags.
170 * Returns: %TRUE if @object could be locked.
173 gst_mini_object_lock (GstMiniObject * object, GstLockFlags flags)
175 gint access_mode, state, newstate;
177 g_return_val_if_fail (object != NULL, FALSE);
178 g_return_val_if_fail (GST_MINI_OBJECT_IS_LOCKABLE (object), FALSE);
180 if (G_UNLIKELY (object->flags & GST_MINI_OBJECT_FLAG_LOCK_READONLY &&
181 flags & GST_LOCK_FLAG_WRITE))
185 access_mode = flags & FLAG_MASK;
186 newstate = state = g_atomic_int_get (&object->lockstate);
188 GST_CAT_TRACE (GST_CAT_LOCKING, "lock %p: state %08x, access_mode %d",
189 object, state, access_mode);
191 if (access_mode & GST_LOCK_FLAG_EXCLUSIVE) {
193 newstate += SHARE_ONE;
194 access_mode &= ~GST_LOCK_FLAG_EXCLUSIVE;
197 /* shared counter > 1 and write access is not allowed */
198 if (((state & GST_LOCK_FLAG_WRITE) != 0
199 || (access_mode & GST_LOCK_FLAG_WRITE) != 0)
200 && IS_SHARED (newstate))
204 if ((state & LOCK_FLAG_MASK) == 0) {
205 /* nothing mapped, set access_mode */
206 newstate |= access_mode;
208 /* access_mode must match */
209 if ((state & access_mode) != access_mode)
212 /* increase refcount */
213 newstate += LOCK_ONE;
215 } while (!g_atomic_int_compare_and_exchange (&object->lockstate, state,
222 GST_CAT_DEBUG (GST_CAT_LOCKING,
223 "lock failed %p: state %08x, access_mode %d", object, state,
230 * gst_mini_object_unlock:
231 * @object: the mini-object to unlock
232 * @flags: #GstLockFlags
234 * Unlock the mini-object with the specified access mode in @flags.
237 gst_mini_object_unlock (GstMiniObject * object, GstLockFlags flags)
239 gint access_mode, state, newstate;
241 g_return_if_fail (object != NULL);
242 g_return_if_fail (GST_MINI_OBJECT_IS_LOCKABLE (object));
245 access_mode = flags & FLAG_MASK;
246 newstate = state = g_atomic_int_get (&object->lockstate);
248 GST_CAT_TRACE (GST_CAT_LOCKING, "unlock %p: state %08x, access_mode %d",
249 object, state, access_mode);
251 if (access_mode & GST_LOCK_FLAG_EXCLUSIVE) {
253 g_return_if_fail (state >= SHARE_ONE);
254 newstate -= SHARE_ONE;
255 access_mode &= ~GST_LOCK_FLAG_EXCLUSIVE;
259 g_return_if_fail ((state & access_mode) == access_mode);
260 /* decrease the refcount */
261 newstate -= LOCK_ONE;
262 /* last refcount, unset access_mode */
263 if ((newstate & LOCK_FLAG_MASK) == access_mode)
264 newstate &= ~LOCK_FLAG_MASK;
266 } while (!g_atomic_int_compare_and_exchange (&object->lockstate, state,
271 * gst_mini_object_is_writable:
272 * @mini_object: the mini-object to check
274 * If @mini_object has the LOCKABLE flag set, check if the current EXCLUSIVE
275 * lock on @object is the only one, this means that changes to the object will
276 * not be visible to any other object.
278 * If the LOCKABLE flag is not set, check if the refcount of @mini_object is
279 * exactly 1, meaning that no other reference exists to the object and that the
280 * object is therefore writable.
282 * Modification of a mini-object should only be done after verifying that it
285 * Returns: %TRUE if the object is writable.
288 gst_mini_object_is_writable (const GstMiniObject * mini_object)
292 g_return_val_if_fail (mini_object != NULL, FALSE);
294 if (GST_MINI_OBJECT_IS_LOCKABLE (mini_object)) {
295 result = !IS_SHARED (g_atomic_int_get (&mini_object->lockstate));
297 result = (GST_MINI_OBJECT_REFCOUNT_VALUE (mini_object) == 1);
303 * gst_mini_object_make_writable: (skip)
304 * @mini_object: (transfer full): the mini-object to make writable
306 * Checks if a mini-object is writable. If not, a writable copy is made and
307 * returned. This gives away the reference to the original mini object,
308 * and returns a reference to the new object.
312 * Returns: (transfer full): a mini-object (possibly the same pointer) that
316 gst_mini_object_make_writable (GstMiniObject * mini_object)
320 g_return_val_if_fail (mini_object != NULL, NULL);
322 if (gst_mini_object_is_writable (mini_object)) {
325 ret = gst_mini_object_copy (mini_object);
326 GST_CAT_DEBUG (GST_CAT_PERFORMANCE, "copy %s miniobject %p -> %p",
327 g_type_name (GST_MINI_OBJECT_TYPE (mini_object)), mini_object, ret);
328 gst_mini_object_unref (mini_object);
335 * gst_mini_object_ref: (skip)
336 * @mini_object: the mini-object
338 * Increase the reference count of the mini-object.
340 * Note that the refcount affects the writability
341 * of @mini-object, see gst_mini_object_is_writable(). It is
342 * important to note that keeping additional references to
343 * GstMiniObject instances can potentially increase the number
344 * of memcpy operations in a pipeline, especially if the miniobject
347 * Returns: (transfer full): the mini-object.
350 gst_mini_object_ref (GstMiniObject * mini_object)
352 g_return_val_if_fail (mini_object != NULL, NULL);
353 /* we can't assert that the refcount > 0 since the _free functions
354 * increments the refcount from 0 to 1 again to allow resurecting
356 g_return_val_if_fail (mini_object->refcount > 0, NULL);
359 GST_CAT_TRACE (GST_CAT_REFCOUNTING, "%p ref %d->%d", mini_object,
360 GST_MINI_OBJECT_REFCOUNT_VALUE (mini_object),
361 GST_MINI_OBJECT_REFCOUNT_VALUE (mini_object) + 1);
363 g_atomic_int_inc (&mini_object->refcount);
369 find_notify (GstMiniObject * object, GQuark quark, gboolean match_notify,
370 GstMiniObjectNotify notify, gpointer data)
374 for (i = 0; i < object->n_qdata; i++) {
375 if (QDATA_QUARK (object, i) == quark) {
376 /* check if we need to match the callback too */
377 if (!match_notify || (QDATA_NOTIFY (object, i) == notify &&
378 QDATA_DATA (object, i) == data))
386 remove_notify (GstMiniObject * object, gint index)
389 if (--object->n_qdata == 0) {
390 /* we don't shrink but free when everything is gone */
391 g_free (object->qdata);
392 object->qdata = NULL;
393 } else if (index != object->n_qdata)
394 QDATA (object, index) = QDATA (object, object->n_qdata);
398 set_notify (GstMiniObject * object, gint index, GQuark quark,
399 GstMiniObjectNotify notify, gpointer data, GDestroyNotify destroy)
403 index = object->n_qdata++;
405 g_realloc (object->qdata, sizeof (GstQData) * object->n_qdata);
407 QDATA_QUARK (object, index) = quark;
408 QDATA_NOTIFY (object, index) = notify;
409 QDATA_DATA (object, index) = data;
410 QDATA_DESTROY (object, index) = destroy;
414 call_finalize_notify (GstMiniObject * obj)
418 for (i = 0; i < obj->n_qdata; i++) {
419 if (QDATA_QUARK (obj, i) == weak_ref_quark)
420 QDATA_NOTIFY (obj, i) (QDATA_DATA (obj, i), obj);
421 if (QDATA_DESTROY (obj, i))
422 QDATA_DESTROY (obj, i) (QDATA_DATA (obj, i));
427 * gst_mini_object_unref: (skip)
428 * @mini_object: the mini-object
430 * Decreases the reference count of the mini-object, possibly freeing
434 gst_mini_object_unref (GstMiniObject * mini_object)
436 g_return_if_fail (mini_object != NULL);
438 GST_CAT_TRACE (GST_CAT_REFCOUNTING, "%p unref %d->%d",
440 GST_MINI_OBJECT_REFCOUNT_VALUE (mini_object),
441 GST_MINI_OBJECT_REFCOUNT_VALUE (mini_object) - 1);
443 g_return_if_fail (mini_object->refcount > 0);
445 if (G_UNLIKELY (g_atomic_int_dec_and_test (&mini_object->refcount))) {
448 if (mini_object->dispose)
449 do_free = mini_object->dispose (mini_object);
453 /* if the subclass recycled the object (and returned FALSE) we don't
454 * want to free the instance anymore */
455 if (G_LIKELY (do_free)) {
456 /* there should be no outstanding locks */
457 g_return_if_fail ((g_atomic_int_get (&mini_object->lockstate) & LOCK_MASK)
460 if (mini_object->n_qdata) {
461 call_finalize_notify (mini_object);
462 g_free (mini_object->qdata);
464 GST_TRACER_MINI_OBJECT_DESTROYED (mini_object);
465 #ifndef GST_DISABLE_TRACE
466 _gst_alloc_trace_free (_gst_mini_object_trace, mini_object);
468 if (mini_object->free)
469 mini_object->free (mini_object);
475 * gst_mini_object_replace:
476 * @olddata: (inout) (transfer full) (nullable): pointer to a pointer to a
477 * mini-object to be replaced
478 * @newdata: (allow-none): pointer to new mini-object
480 * Atomically modifies a pointer to point to a new mini-object.
481 * The reference count of @olddata is decreased and the reference count of
482 * @newdata is increased.
484 * Either @newdata and the value pointed to by @olddata may be %NULL.
486 * Returns: %TRUE if @newdata was different from @olddata
489 gst_mini_object_replace (GstMiniObject ** olddata, GstMiniObject * newdata)
491 GstMiniObject *olddata_val;
493 g_return_val_if_fail (olddata != NULL, FALSE);
495 GST_CAT_TRACE (GST_CAT_REFCOUNTING, "replace %p (%d) with %p (%d)",
496 *olddata, *olddata ? (*olddata)->refcount : 0,
497 newdata, newdata ? newdata->refcount : 0);
499 olddata_val = g_atomic_pointer_get ((gpointer *) olddata);
501 if (G_UNLIKELY (olddata_val == newdata))
505 gst_mini_object_ref (newdata);
507 while (G_UNLIKELY (!g_atomic_pointer_compare_and_exchange ((gpointer *)
508 olddata, olddata_val, newdata))) {
509 olddata_val = g_atomic_pointer_get ((gpointer *) olddata);
510 if (G_UNLIKELY (olddata_val == newdata))
515 gst_mini_object_unref (olddata_val);
517 return olddata_val != newdata;
521 * gst_mini_object_steal: (skip)
522 * @olddata: (inout) (transfer full): pointer to a pointer to a mini-object to
525 * Replace the current #GstMiniObject pointer to by @olddata with %NULL and
526 * return the old value.
528 * Returns: the #GstMiniObject at @oldata
531 gst_mini_object_steal (GstMiniObject ** olddata)
533 GstMiniObject *olddata_val;
535 g_return_val_if_fail (olddata != NULL, NULL);
537 GST_CAT_TRACE (GST_CAT_REFCOUNTING, "steal %p (%d)",
538 *olddata, *olddata ? (*olddata)->refcount : 0);
541 olddata_val = g_atomic_pointer_get ((gpointer *) olddata);
542 if (olddata_val == NULL)
544 } while (G_UNLIKELY (!g_atomic_pointer_compare_and_exchange ((gpointer *)
545 olddata, olddata_val, NULL)));
551 * gst_mini_object_take:
552 * @olddata: (inout) (transfer full): pointer to a pointer to a mini-object to
554 * @newdata: pointer to new mini-object
556 * Modifies a pointer to point to a new mini-object. The modification
557 * is done atomically. This version is similar to gst_mini_object_replace()
558 * except that it does not increase the refcount of @newdata and thus
559 * takes ownership of @newdata.
561 * Either @newdata and the value pointed to by @olddata may be %NULL.
563 * Returns: %TRUE if @newdata was different from @olddata
566 gst_mini_object_take (GstMiniObject ** olddata, GstMiniObject * newdata)
568 GstMiniObject *olddata_val;
570 g_return_val_if_fail (olddata != NULL, FALSE);
572 GST_CAT_TRACE (GST_CAT_REFCOUNTING, "take %p (%d) with %p (%d)",
573 *olddata, *olddata ? (*olddata)->refcount : 0,
574 newdata, newdata ? newdata->refcount : 0);
577 olddata_val = g_atomic_pointer_get ((gpointer *) olddata);
578 if (G_UNLIKELY (olddata_val == newdata))
580 } while (G_UNLIKELY (!g_atomic_pointer_compare_and_exchange ((gpointer *)
581 olddata, olddata_val, newdata)));
584 gst_mini_object_unref (olddata_val);
586 return olddata_val != newdata;
590 * gst_mini_object_weak_ref: (skip)
591 * @object: #GstMiniObject to reference weakly
592 * @notify: callback to invoke before the mini object is freed
593 * @data: extra data to pass to notify
595 * Adds a weak reference callback to a mini object. Weak references are
596 * used for notification when a mini object is finalized. They are called
597 * "weak references" because they allow you to safely hold a pointer
598 * to the mini object without calling gst_mini_object_ref()
599 * (gst_mini_object_ref() adds a strong reference, that is, forces the object
603 gst_mini_object_weak_ref (GstMiniObject * object,
604 GstMiniObjectNotify notify, gpointer data)
606 g_return_if_fail (object != NULL);
607 g_return_if_fail (notify != NULL);
608 g_return_if_fail (GST_MINI_OBJECT_REFCOUNT_VALUE (object) >= 1);
610 G_LOCK (qdata_mutex);
611 set_notify (object, -1, weak_ref_quark, notify, data, NULL);
612 G_UNLOCK (qdata_mutex);
616 * gst_mini_object_weak_unref: (skip)
617 * @object: #GstMiniObject to remove a weak reference from
618 * @notify: callback to search for
619 * @data: data to search for
621 * Removes a weak reference callback from a mini object.
624 gst_mini_object_weak_unref (GstMiniObject * object,
625 GstMiniObjectNotify notify, gpointer data)
629 g_return_if_fail (object != NULL);
630 g_return_if_fail (notify != NULL);
632 G_LOCK (qdata_mutex);
633 if ((i = find_notify (object, weak_ref_quark, TRUE, notify, data)) != -1) {
634 remove_notify (object, i);
636 g_warning ("%s: couldn't find weak ref %p(%p)", G_STRFUNC, notify, data);
638 G_UNLOCK (qdata_mutex);
642 * gst_mini_object_set_qdata:
643 * @object: a #GstMiniObject
644 * @quark: A #GQuark, naming the user data pointer
645 * @data: An opaque user data pointer
646 * @destroy: Function to invoke with @data as argument, when @data
649 * This sets an opaque, named pointer on a miniobject.
650 * The name is specified through a #GQuark (retrieved e.g. via
651 * g_quark_from_static_string()), and the pointer
652 * can be gotten back from the @object with gst_mini_object_get_qdata()
653 * until the @object is disposed.
654 * Setting a previously set user data pointer, overrides (frees)
655 * the old pointer set, using %NULL as pointer essentially
656 * removes the data stored.
658 * @destroy may be specified which is called with @data as argument
659 * when the @object is disposed, or the data is being overwritten by
660 * a call to gst_mini_object_set_qdata() with the same @quark.
663 gst_mini_object_set_qdata (GstMiniObject * object, GQuark quark,
664 gpointer data, GDestroyNotify destroy)
667 gpointer old_data = NULL;
668 GDestroyNotify old_notify = NULL;
670 g_return_if_fail (object != NULL);
671 g_return_if_fail (quark > 0);
673 G_LOCK (qdata_mutex);
674 if ((i = find_notify (object, quark, FALSE, NULL, NULL)) != -1) {
676 old_data = QDATA_DATA (object, i);
677 old_notify = QDATA_DESTROY (object, i);
680 remove_notify (object, i);
683 set_notify (object, i, quark, NULL, data, destroy);
684 G_UNLOCK (qdata_mutex);
687 old_notify (old_data);
691 * gst_mini_object_get_qdata:
692 * @object: The GstMiniObject to get a stored user data pointer from
693 * @quark: A #GQuark, naming the user data pointer
695 * This function gets back user data pointers stored via
696 * gst_mini_object_set_qdata().
698 * Returns: (transfer none) (nullable): The user data pointer set, or
702 gst_mini_object_get_qdata (GstMiniObject * object, GQuark quark)
707 g_return_val_if_fail (object != NULL, NULL);
708 g_return_val_if_fail (quark > 0, NULL);
710 G_LOCK (qdata_mutex);
711 if ((i = find_notify (object, quark, FALSE, NULL, NULL)) != -1)
712 result = QDATA_DATA (object, i);
715 G_UNLOCK (qdata_mutex);
721 * gst_mini_object_steal_qdata:
722 * @object: The GstMiniObject to get a stored user data pointer from
723 * @quark: A #GQuark, naming the user data pointer
725 * This function gets back user data pointers stored via gst_mini_object_set_qdata()
726 * and removes the data from @object without invoking its destroy() function (if
729 * Returns: (transfer full) (nullable): The user data pointer set, or
733 gst_mini_object_steal_qdata (GstMiniObject * object, GQuark quark)
738 g_return_val_if_fail (object != NULL, NULL);
739 g_return_val_if_fail (quark > 0, NULL);
741 G_LOCK (qdata_mutex);
742 if ((i = find_notify (object, quark, FALSE, NULL, NULL)) != -1) {
743 result = QDATA_DATA (object, i);
744 remove_notify (object, i);
748 G_UNLOCK (qdata_mutex);