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 #ifndef GST_DISABLE_TRACE
133 _gst_alloc_trace_new (_gst_mini_object_trace, mini_object);
138 * gst_mini_object_copy:
139 * @mini_object: the mini-object to copy
141 * Creates a copy of the mini-object.
145 * Returns: (transfer full): the new mini-object.
148 gst_mini_object_copy (const GstMiniObject * mini_object)
152 g_return_val_if_fail (mini_object != NULL, NULL);
154 if (mini_object->copy)
155 copy = mini_object->copy (mini_object);
163 * gst_mini_object_lock:
164 * @object: the mini-object to lock
165 * @flags: #GstLockFlags
167 * Lock the mini-object with the specified access mode in @flags.
169 * Returns: %TRUE if @object could be locked.
172 gst_mini_object_lock (GstMiniObject * object, GstLockFlags flags)
174 gint access_mode, state, newstate;
176 g_return_val_if_fail (object != NULL, FALSE);
177 g_return_val_if_fail (GST_MINI_OBJECT_IS_LOCKABLE (object), FALSE);
179 if (G_UNLIKELY (object->flags & GST_MINI_OBJECT_FLAG_LOCK_READONLY &&
180 flags & GST_LOCK_FLAG_WRITE))
184 access_mode = flags & FLAG_MASK;
185 newstate = state = g_atomic_int_get (&object->lockstate);
187 GST_CAT_TRACE (GST_CAT_LOCKING, "lock %p: state %08x, access_mode %d",
188 object, state, access_mode);
190 if (access_mode & GST_LOCK_FLAG_EXCLUSIVE) {
192 newstate += SHARE_ONE;
193 access_mode &= ~GST_LOCK_FLAG_EXCLUSIVE;
197 /* shared counter > 1 and write access is not allowed */
198 if (access_mode & GST_LOCK_FLAG_WRITE && IS_SHARED (state))
201 if ((state & LOCK_FLAG_MASK) == 0) {
202 /* nothing mapped, set access_mode */
203 newstate |= access_mode;
205 /* access_mode must match */
206 if ((state & access_mode) != access_mode)
209 /* increase refcount */
210 newstate += LOCK_ONE;
212 } while (!g_atomic_int_compare_and_exchange (&object->lockstate, state,
219 GST_CAT_DEBUG (GST_CAT_LOCKING,
220 "lock failed %p: state %08x, access_mode %d", object, state,
227 * gst_mini_object_unlock:
228 * @object: the mini-object to unlock
229 * @flags: #GstLockFlags
231 * Unlock the mini-object with the specified access mode in @flags.
234 gst_mini_object_unlock (GstMiniObject * object, GstLockFlags flags)
236 gint access_mode, state, newstate;
238 g_return_if_fail (object != NULL);
239 g_return_if_fail (GST_MINI_OBJECT_IS_LOCKABLE (object));
242 access_mode = flags & FLAG_MASK;
243 newstate = state = g_atomic_int_get (&object->lockstate);
245 GST_CAT_TRACE (GST_CAT_LOCKING, "unlock %p: state %08x, access_mode %d",
246 object, state, access_mode);
248 if (access_mode & GST_LOCK_FLAG_EXCLUSIVE) {
250 g_return_if_fail (state >= SHARE_ONE);
251 newstate -= SHARE_ONE;
252 access_mode &= ~GST_LOCK_FLAG_EXCLUSIVE;
256 g_return_if_fail ((state & access_mode) == access_mode);
257 /* decrease the refcount */
258 newstate -= LOCK_ONE;
259 /* last refcount, unset access_mode */
260 if ((newstate & LOCK_FLAG_MASK) == access_mode)
261 newstate &= ~LOCK_FLAG_MASK;
263 } while (!g_atomic_int_compare_and_exchange (&object->lockstate, state,
268 * gst_mini_object_is_writable:
269 * @mini_object: the mini-object to check
271 * If @mini_object has the LOCKABLE flag set, check if the current EXCLUSIVE
272 * lock on @object is the only one, this means that changes to the object will
273 * not be visible to any other object.
275 * If the LOCKABLE flag is not set, check if the refcount of @mini_object is
276 * exactly 1, meaning that no other reference exists to the object and that the
277 * object is therefore writable.
279 * Modification of a mini-object should only be done after verifying that it
282 * Returns: %TRUE if the object is writable.
285 gst_mini_object_is_writable (const GstMiniObject * mini_object)
289 g_return_val_if_fail (mini_object != NULL, FALSE);
291 if (GST_MINI_OBJECT_IS_LOCKABLE (mini_object)) {
292 result = !IS_SHARED (g_atomic_int_get (&mini_object->lockstate));
294 result = (GST_MINI_OBJECT_REFCOUNT_VALUE (mini_object) == 1);
300 * gst_mini_object_make_writable:
301 * @mini_object: (transfer full): the mini-object to make writable
303 * Checks if a mini-object is writable. If not, a writable copy is made and
304 * returned. This gives away the reference to the original mini object,
305 * and returns a reference to the new object.
309 * Returns: (transfer full): a mini-object (possibly the same pointer) that
313 gst_mini_object_make_writable (GstMiniObject * mini_object)
317 g_return_val_if_fail (mini_object != NULL, NULL);
319 if (gst_mini_object_is_writable (mini_object)) {
322 ret = gst_mini_object_copy (mini_object);
323 GST_CAT_DEBUG (GST_CAT_PERFORMANCE, "copy %s miniobject %p -> %p",
324 g_type_name (GST_MINI_OBJECT_TYPE (mini_object)), mini_object, ret);
325 gst_mini_object_unref (mini_object);
332 * gst_mini_object_ref:
333 * @mini_object: the mini-object
335 * Increase the reference count of the mini-object.
337 * Note that the refcount affects the writability
338 * of @mini-object, see gst_mini_object_is_writable(). It is
339 * important to note that keeping additional references to
340 * GstMiniObject instances can potentially increase the number
341 * of memcpy operations in a pipeline, especially if the miniobject
344 * Returns: (transfer full): the mini-object.
347 gst_mini_object_ref (GstMiniObject * mini_object)
349 g_return_val_if_fail (mini_object != NULL, NULL);
350 /* we can't assert that the refcount > 0 since the _free functions
351 * increments the refcount from 0 to 1 again to allow resurecting
353 g_return_val_if_fail (mini_object->refcount > 0, NULL);
356 GST_CAT_TRACE (GST_CAT_REFCOUNTING, "%p ref %d->%d", mini_object,
357 GST_MINI_OBJECT_REFCOUNT_VALUE (mini_object),
358 GST_MINI_OBJECT_REFCOUNT_VALUE (mini_object) + 1);
360 g_atomic_int_inc (&mini_object->refcount);
366 find_notify (GstMiniObject * object, GQuark quark, gboolean match_notify,
367 GstMiniObjectNotify notify, gpointer data)
371 for (i = 0; i < object->n_qdata; i++) {
372 if (QDATA_QUARK (object, i) == quark) {
373 /* check if we need to match the callback too */
374 if (!match_notify || (QDATA_NOTIFY (object, i) == notify &&
375 QDATA_DATA (object, i) == data))
383 remove_notify (GstMiniObject * object, gint index)
386 if (--object->n_qdata == 0) {
387 /* we don't shrink but free when everything is gone */
388 g_free (object->qdata);
389 object->qdata = NULL;
390 } else if (index != object->n_qdata)
391 QDATA (object, index) = QDATA (object, object->n_qdata);
395 set_notify (GstMiniObject * object, gint index, GQuark quark,
396 GstMiniObjectNotify notify, gpointer data, GDestroyNotify destroy)
400 index = object->n_qdata++;
402 g_realloc (object->qdata, sizeof (GstQData) * object->n_qdata);
404 QDATA_QUARK (object, index) = quark;
405 QDATA_NOTIFY (object, index) = notify;
406 QDATA_DATA (object, index) = data;
407 QDATA_DESTROY (object, index) = destroy;
411 call_finalize_notify (GstMiniObject * obj)
415 for (i = 0; i < obj->n_qdata; i++) {
416 if (QDATA_QUARK (obj, i) == weak_ref_quark)
417 QDATA_NOTIFY (obj, i) (QDATA_DATA (obj, i), obj);
418 if (QDATA_DESTROY (obj, i))
419 QDATA_DESTROY (obj, i) (QDATA_DATA (obj, i));
424 * gst_mini_object_unref:
425 * @mini_object: the mini-object
427 * Decreases the reference count of the mini-object, possibly freeing
431 gst_mini_object_unref (GstMiniObject * mini_object)
433 g_return_if_fail (mini_object != NULL);
435 GST_CAT_TRACE (GST_CAT_REFCOUNTING, "%p unref %d->%d",
437 GST_MINI_OBJECT_REFCOUNT_VALUE (mini_object),
438 GST_MINI_OBJECT_REFCOUNT_VALUE (mini_object) - 1);
440 g_return_if_fail (mini_object->refcount > 0);
442 if (G_UNLIKELY (g_atomic_int_dec_and_test (&mini_object->refcount))) {
445 if (mini_object->dispose)
446 do_free = mini_object->dispose (mini_object);
450 /* if the subclass recycled the object (and returned FALSE) we don't
451 * want to free the instance anymore */
452 if (G_LIKELY (do_free)) {
453 /* there should be no outstanding locks */
454 g_return_if_fail ((g_atomic_int_get (&mini_object->lockstate) & LOCK_MASK)
457 if (mini_object->n_qdata) {
458 call_finalize_notify (mini_object);
459 g_free (mini_object->qdata);
461 #ifndef GST_DISABLE_TRACE
462 _gst_alloc_trace_free (_gst_mini_object_trace, mini_object);
464 if (mini_object->free)
465 mini_object->free (mini_object);
471 * gst_mini_object_replace:
472 * @olddata: (inout) (transfer full): pointer to a pointer to a mini-object to
474 * @newdata: pointer to new mini-object
476 * Atomically modifies a pointer to point to a new mini-object.
477 * The reference count of @olddata is decreased and the reference count of
478 * @newdata is increased.
480 * Either @newdata and the value pointed to by @olddata may be %NULL.
482 * Returns: %TRUE if @newdata was different from @olddata
485 gst_mini_object_replace (GstMiniObject ** olddata, GstMiniObject * newdata)
487 GstMiniObject *olddata_val;
489 g_return_val_if_fail (olddata != NULL, FALSE);
491 GST_CAT_TRACE (GST_CAT_REFCOUNTING, "replace %p (%d) with %p (%d)",
492 *olddata, *olddata ? (*olddata)->refcount : 0,
493 newdata, newdata ? newdata->refcount : 0);
495 olddata_val = g_atomic_pointer_get ((gpointer *) olddata);
497 if (G_UNLIKELY (olddata_val == newdata))
501 gst_mini_object_ref (newdata);
503 while (G_UNLIKELY (!g_atomic_pointer_compare_and_exchange ((gpointer *)
504 olddata, olddata_val, newdata))) {
505 olddata_val = g_atomic_pointer_get ((gpointer *) olddata);
506 if (G_UNLIKELY (olddata_val == newdata))
511 gst_mini_object_unref (olddata_val);
513 return olddata_val != newdata;
517 * gst_mini_object_steal:
518 * @olddata: (inout) (transfer full): pointer to a pointer to a mini-object to
521 * Replace the current #GstMiniObject pointer to by @olddata with %NULL and
522 * return the old value.
524 * Returns: the #GstMiniObject at @oldata
527 gst_mini_object_steal (GstMiniObject ** olddata)
529 GstMiniObject *olddata_val;
531 g_return_val_if_fail (olddata != NULL, NULL);
533 GST_CAT_TRACE (GST_CAT_REFCOUNTING, "steal %p (%d)",
534 *olddata, *olddata ? (*olddata)->refcount : 0);
537 olddata_val = g_atomic_pointer_get ((gpointer *) olddata);
538 if (olddata_val == NULL)
540 } while (G_UNLIKELY (!g_atomic_pointer_compare_and_exchange ((gpointer *)
541 olddata, olddata_val, NULL)));
547 * gst_mini_object_take:
548 * @olddata: (inout) (transfer full): pointer to a pointer to a mini-object to
550 * @newdata: pointer to new mini-object
552 * Modifies a pointer to point to a new mini-object. The modification
553 * is done atomically. This version is similar to gst_mini_object_replace()
554 * except that it does not increase the refcount of @newdata and thus
555 * takes ownership of @newdata.
557 * Either @newdata and the value pointed to by @olddata may be %NULL.
559 * Returns: %TRUE if @newdata was different from @olddata
562 gst_mini_object_take (GstMiniObject ** olddata, GstMiniObject * newdata)
564 GstMiniObject *olddata_val;
566 g_return_val_if_fail (olddata != NULL, FALSE);
568 GST_CAT_TRACE (GST_CAT_REFCOUNTING, "take %p (%d) with %p (%d)",
569 *olddata, *olddata ? (*olddata)->refcount : 0,
570 newdata, newdata ? newdata->refcount : 0);
573 olddata_val = g_atomic_pointer_get ((gpointer *) olddata);
574 if (G_UNLIKELY (olddata_val == newdata))
576 } while (G_UNLIKELY (!g_atomic_pointer_compare_and_exchange ((gpointer *)
577 olddata, olddata_val, newdata)));
580 gst_mini_object_unref (olddata_val);
582 return olddata_val != newdata;
586 * gst_mini_object_weak_ref: (skip)
587 * @object: #GstMiniObject to reference weakly
588 * @notify: callback to invoke before the mini object is freed
589 * @data: extra data to pass to notify
591 * Adds a weak reference callback to a mini object. Weak references are
592 * used for notification when a mini object is finalized. They are called
593 * "weak references" because they allow you to safely hold a pointer
594 * to the mini object without calling gst_mini_object_ref()
595 * (gst_mini_object_ref() adds a strong reference, that is, forces the object
599 gst_mini_object_weak_ref (GstMiniObject * object,
600 GstMiniObjectNotify notify, gpointer data)
602 g_return_if_fail (object != NULL);
603 g_return_if_fail (notify != NULL);
604 g_return_if_fail (GST_MINI_OBJECT_REFCOUNT_VALUE (object) >= 1);
606 G_LOCK (qdata_mutex);
607 set_notify (object, -1, weak_ref_quark, notify, data, NULL);
608 G_UNLOCK (qdata_mutex);
612 * gst_mini_object_weak_unref: (skip)
613 * @object: #GstMiniObject to remove a weak reference from
614 * @notify: callback to search for
615 * @data: data to search for
617 * Removes a weak reference callback from a mini object.
620 gst_mini_object_weak_unref (GstMiniObject * object,
621 GstMiniObjectNotify notify, gpointer data)
625 g_return_if_fail (object != NULL);
626 g_return_if_fail (notify != NULL);
628 G_LOCK (qdata_mutex);
629 if ((i = find_notify (object, weak_ref_quark, TRUE, notify, data)) != -1) {
630 remove_notify (object, i);
632 g_warning ("%s: couldn't find weak ref %p(%p)", G_STRFUNC, notify, data);
634 G_UNLOCK (qdata_mutex);
638 * gst_mini_object_set_qdata:
639 * @object: a #GstMiniObject
640 * @quark: A #GQuark, naming the user data pointer
641 * @data: An opaque user data pointer
642 * @destroy: Function to invoke with @data as argument, when @data
645 * This sets an opaque, named pointer on a miniobject.
646 * The name is specified through a #GQuark (retrieved e.g. via
647 * g_quark_from_static_string()), and the pointer
648 * can be gotten back from the @object with gst_mini_object_get_qdata()
649 * until the @object is disposed.
650 * Setting a previously set user data pointer, overrides (frees)
651 * the old pointer set, using %NULL as pointer essentially
652 * removes the data stored.
654 * @destroy may be specified which is called with @data as argument
655 * when the @object is disposed, or the data is being overwritten by
656 * a call to gst_mini_object_set_qdata() with the same @quark.
659 gst_mini_object_set_qdata (GstMiniObject * object, GQuark quark,
660 gpointer data, GDestroyNotify destroy)
663 gpointer old_data = NULL;
664 GDestroyNotify old_notify = NULL;
666 g_return_if_fail (object != NULL);
667 g_return_if_fail (quark > 0);
669 G_LOCK (qdata_mutex);
670 if ((i = find_notify (object, quark, FALSE, NULL, NULL)) != -1) {
672 old_data = QDATA_DATA (object, i);
673 old_notify = QDATA_DESTROY (object, i);
676 remove_notify (object, i);
679 set_notify (object, i, quark, NULL, data, destroy);
680 G_UNLOCK (qdata_mutex);
683 old_notify (old_data);
687 * gst_mini_object_get_qdata:
688 * @object: The GstMiniObject to get a stored user data pointer from
689 * @quark: A #GQuark, naming the user data pointer
691 * This function gets back user data pointers stored via
692 * gst_mini_object_set_qdata().
694 * Returns: (transfer none) (nullable): The user data pointer set, or
698 gst_mini_object_get_qdata (GstMiniObject * object, GQuark quark)
703 g_return_val_if_fail (object != NULL, NULL);
704 g_return_val_if_fail (quark > 0, NULL);
706 G_LOCK (qdata_mutex);
707 if ((i = find_notify (object, quark, FALSE, NULL, NULL)) != -1)
708 result = QDATA_DATA (object, i);
711 G_UNLOCK (qdata_mutex);
717 * gst_mini_object_steal_qdata:
718 * @object: The GstMiniObject to get a stored user data pointer from
719 * @quark: A #GQuark, naming the user data pointer
721 * This function gets back user data pointers stored via gst_mini_object_set_qdata()
722 * and removes the data from @object without invoking its destroy() function (if
725 * Returns: (transfer full) (nullable): The user data pointer set, or
729 gst_mini_object_steal_qdata (GstMiniObject * object, GQuark quark)
734 g_return_val_if_fail (object != NULL, NULL);
735 g_return_val_if_fail (quark > 0, NULL);
737 G_LOCK (qdata_mutex);
738 if ((i = find_notify (object, quark, FALSE, NULL, NULL)) != -1) {
739 result = QDATA_DATA (object, i);
740 remove_notify (object, i);
744 G_UNLOCK (qdata_mutex);