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 * @title: GstMiniObject
24 * @short_description: Lightweight base class for the GStreamer object hierarchy
26 * #GstMiniObject is a simple structure that can be used to implement refcounted
29 * Subclasses will include #GstMiniObject as the first member in their structure
30 * and then call gst_mini_object_init() to initialize the #GstMiniObject fields.
32 * gst_mini_object_ref() and gst_mini_object_unref() increment and decrement the
33 * refcount respectively. When the refcount of a mini-object reaches 0, the
34 * dispose function is called first and when this returns %TRUE, the free
35 * function of the miniobject is called.
37 * A copy can be made with gst_mini_object_copy().
39 * gst_mini_object_is_writable() will return %TRUE when the refcount of the
40 * object is exactly 1, meaning the current caller has the only reference to the
41 * object. gst_mini_object_make_writable() will return a writable version of the
42 * object, which might be a new copy when the refcount was not 1.
44 * Opaque data can be associated with a #GstMiniObject with
45 * gst_mini_object_set_qdata() and gst_mini_object_get_qdata(). The data is
46 * meant to be specific to the particular object and is not automatically copied
47 * with gst_mini_object_copy() or similar methods.
49 * A weak reference can be added and remove with gst_mini_object_weak_ref()
50 * and gst_mini_object_weak_unref() respectively.
56 #include "gst/gst_private.h"
57 #include "gst/gstminiobject.h"
58 #include "gst/gstinfo.h"
59 #include <gobject/gvaluecollector.h>
61 /* Mutex used for weak referencing */
62 G_LOCK_DEFINE_STATIC (qdata_mutex);
63 static GQuark weak_ref_quark;
65 #define SHARE_ONE (1 << 16)
66 #define SHARE_TWO (2 << 16)
67 #define SHARE_MASK (~(SHARE_ONE - 1))
68 #define IS_SHARED(state) (state >= SHARE_TWO)
69 #define LOCK_ONE (GST_LOCK_FLAG_LAST)
70 #define FLAG_MASK (GST_LOCK_FLAG_LAST - 1)
71 #define LOCK_MASK ((SHARE_ONE - 1) - FLAG_MASK)
72 #define LOCK_FLAG_MASK (SHARE_ONE - 1)
77 GstMiniObjectNotify notify;
79 GDestroyNotify destroy;
82 #define QDATA(o,i) ((GstQData *)(o)->qdata)[(i)]
83 #define QDATA_QUARK(o,i) (QDATA(o,i).quark)
84 #define QDATA_NOTIFY(o,i) (QDATA(o,i).notify)
85 #define QDATA_DATA(o,i) (QDATA(o,i).data)
86 #define QDATA_DESTROY(o,i) (QDATA(o,i).destroy)
89 _priv_gst_mini_object_initialize (void)
91 weak_ref_quark = g_quark_from_static_string ("GstMiniObjectWeakRefQuark");
95 * gst_mini_object_init: (skip)
96 * @mini_object: a #GstMiniObject
97 * @flags: initial #GstMiniObjectFlags
98 * @type: the #GType of the mini-object to create
99 * @copy_func: (allow-none): the copy function, or %NULL
100 * @dispose_func: (allow-none): the dispose function, or %NULL
101 * @free_func: (allow-none): the free function or %NULL
103 * Initializes a mini-object with the desired type and copy/dispose/free
107 gst_mini_object_init (GstMiniObject * mini_object, guint flags, GType type,
108 GstMiniObjectCopyFunction copy_func,
109 GstMiniObjectDisposeFunction dispose_func,
110 GstMiniObjectFreeFunction free_func)
112 mini_object->type = type;
113 mini_object->refcount = 1;
114 mini_object->lockstate = 0;
115 mini_object->flags = flags;
117 mini_object->copy = copy_func;
118 mini_object->dispose = dispose_func;
119 mini_object->free = free_func;
121 mini_object->n_qdata = 0;
122 mini_object->qdata = NULL;
124 GST_TRACER_MINI_OBJECT_CREATED (mini_object);
128 * gst_mini_object_copy: (skip)
129 * @mini_object: the mini-object to copy
131 * Creates a copy of the mini-object.
135 * Returns: (transfer full): the new mini-object.
138 gst_mini_object_copy (const GstMiniObject * mini_object)
142 g_return_val_if_fail (mini_object != NULL, NULL);
144 if (mini_object->copy)
145 copy = mini_object->copy (mini_object);
153 * gst_mini_object_lock:
154 * @object: the mini-object to lock
155 * @flags: #GstLockFlags
157 * Lock the mini-object with the specified access mode in @flags.
159 * Returns: %TRUE if @object could be locked.
162 gst_mini_object_lock (GstMiniObject * object, GstLockFlags flags)
164 gint access_mode, state, newstate;
166 g_return_val_if_fail (object != NULL, FALSE);
167 g_return_val_if_fail (GST_MINI_OBJECT_IS_LOCKABLE (object), FALSE);
169 if (G_UNLIKELY (object->flags & GST_MINI_OBJECT_FLAG_LOCK_READONLY &&
170 flags & GST_LOCK_FLAG_WRITE))
174 access_mode = flags & FLAG_MASK;
175 newstate = state = g_atomic_int_get (&object->lockstate);
177 GST_CAT_TRACE (GST_CAT_LOCKING, "lock %p: state %08x, access_mode %d",
178 object, state, access_mode);
180 if (access_mode & GST_LOCK_FLAG_EXCLUSIVE) {
182 newstate += SHARE_ONE;
183 access_mode &= ~GST_LOCK_FLAG_EXCLUSIVE;
186 /* shared counter > 1 and write access is not allowed */
187 if (((state & GST_LOCK_FLAG_WRITE) != 0
188 || (access_mode & GST_LOCK_FLAG_WRITE) != 0)
189 && IS_SHARED (newstate))
193 if ((state & LOCK_FLAG_MASK) == 0) {
194 /* nothing mapped, set access_mode */
195 newstate |= access_mode;
197 /* access_mode must match */
198 if ((state & access_mode) != access_mode)
201 /* increase refcount */
202 newstate += LOCK_ONE;
204 } while (!g_atomic_int_compare_and_exchange (&object->lockstate, state,
211 GST_CAT_DEBUG (GST_CAT_LOCKING,
212 "lock failed %p: state %08x, access_mode %d", object, state,
219 * gst_mini_object_unlock:
220 * @object: the mini-object to unlock
221 * @flags: #GstLockFlags
223 * Unlock the mini-object with the specified access mode in @flags.
226 gst_mini_object_unlock (GstMiniObject * object, GstLockFlags flags)
228 gint access_mode, state, newstate;
230 g_return_if_fail (object != NULL);
231 g_return_if_fail (GST_MINI_OBJECT_IS_LOCKABLE (object));
234 access_mode = flags & FLAG_MASK;
235 newstate = state = g_atomic_int_get (&object->lockstate);
237 GST_CAT_TRACE (GST_CAT_LOCKING, "unlock %p: state %08x, access_mode %d",
238 object, state, access_mode);
240 if (access_mode & GST_LOCK_FLAG_EXCLUSIVE) {
242 g_return_if_fail (state >= SHARE_ONE);
243 newstate -= SHARE_ONE;
244 access_mode &= ~GST_LOCK_FLAG_EXCLUSIVE;
248 g_return_if_fail ((state & access_mode) == access_mode);
249 /* decrease the refcount */
250 newstate -= LOCK_ONE;
251 /* last refcount, unset access_mode */
252 if ((newstate & LOCK_FLAG_MASK) == access_mode)
253 newstate &= ~LOCK_FLAG_MASK;
255 } while (!g_atomic_int_compare_and_exchange (&object->lockstate, state,
260 * gst_mini_object_is_writable:
261 * @mini_object: the mini-object to check
263 * If @mini_object has the LOCKABLE flag set, check if the current EXCLUSIVE
264 * lock on @object is the only one, this means that changes to the object will
265 * not be visible to any other object.
267 * If the LOCKABLE flag is not set, check if the refcount of @mini_object is
268 * exactly 1, meaning that no other reference exists to the object and that the
269 * object is therefore writable.
271 * Modification of a mini-object should only be done after verifying that it
274 * Returns: %TRUE if the object is writable.
277 gst_mini_object_is_writable (const GstMiniObject * mini_object)
281 g_return_val_if_fail (mini_object != NULL, FALSE);
283 if (GST_MINI_OBJECT_IS_LOCKABLE (mini_object)) {
284 result = !IS_SHARED (g_atomic_int_get (&mini_object->lockstate));
286 result = (GST_MINI_OBJECT_REFCOUNT_VALUE (mini_object) == 1);
292 * gst_mini_object_make_writable: (skip)
293 * @mini_object: (transfer full): the mini-object to make writable
295 * Checks if a mini-object is writable. If not, a writable copy is made and
296 * returned. This gives away the reference to the original mini object,
297 * and returns a reference to the new object.
301 * Returns: (transfer full): a mini-object (possibly the same pointer) that
305 gst_mini_object_make_writable (GstMiniObject * mini_object)
309 g_return_val_if_fail (mini_object != NULL, NULL);
311 if (gst_mini_object_is_writable (mini_object)) {
314 ret = gst_mini_object_copy (mini_object);
315 GST_CAT_DEBUG (GST_CAT_PERFORMANCE, "copy %s miniobject %p -> %p",
316 g_type_name (GST_MINI_OBJECT_TYPE (mini_object)), mini_object, ret);
317 gst_mini_object_unref (mini_object);
324 * gst_mini_object_ref: (skip)
325 * @mini_object: the mini-object
327 * Increase the reference count of the mini-object.
329 * Note that the refcount affects the writability
330 * of @mini-object, see gst_mini_object_is_writable(). It is
331 * important to note that keeping additional references to
332 * GstMiniObject instances can potentially increase the number
333 * of memcpy operations in a pipeline, especially if the miniobject
336 * Returns: (transfer full): the mini-object.
339 gst_mini_object_ref (GstMiniObject * mini_object)
341 g_return_val_if_fail (mini_object != NULL, NULL);
342 /* we can't assert that the refcount > 0 since the _free functions
343 * increments the refcount from 0 to 1 again to allow resurecting
345 g_return_val_if_fail (mini_object->refcount > 0, NULL);
348 GST_TRACER_MINI_OBJECT_REFFED (mini_object, mini_object->refcount + 1);
349 GST_CAT_TRACE (GST_CAT_REFCOUNTING, "%p ref %d->%d", mini_object,
350 GST_MINI_OBJECT_REFCOUNT_VALUE (mini_object),
351 GST_MINI_OBJECT_REFCOUNT_VALUE (mini_object) + 1);
353 g_atomic_int_inc (&mini_object->refcount);
359 find_notify (GstMiniObject * object, GQuark quark, gboolean match_notify,
360 GstMiniObjectNotify notify, gpointer data)
364 for (i = 0; i < object->n_qdata; i++) {
365 if (QDATA_QUARK (object, i) == quark) {
366 /* check if we need to match the callback too */
367 if (!match_notify || (QDATA_NOTIFY (object, i) == notify &&
368 QDATA_DATA (object, i) == data))
376 remove_notify (GstMiniObject * object, gint index)
379 if (--object->n_qdata == 0) {
380 /* we don't shrink but free when everything is gone */
381 g_free (object->qdata);
382 object->qdata = NULL;
383 } else if (index != object->n_qdata)
384 QDATA (object, index) = QDATA (object, object->n_qdata);
388 set_notify (GstMiniObject * object, gint index, GQuark quark,
389 GstMiniObjectNotify notify, gpointer data, GDestroyNotify destroy)
393 index = object->n_qdata++;
395 g_realloc (object->qdata, sizeof (GstQData) * object->n_qdata);
397 QDATA_QUARK (object, index) = quark;
398 QDATA_NOTIFY (object, index) = notify;
399 QDATA_DATA (object, index) = data;
400 QDATA_DESTROY (object, index) = destroy;
404 call_finalize_notify (GstMiniObject * obj)
408 for (i = 0; i < obj->n_qdata; i++) {
409 if (QDATA_QUARK (obj, i) == weak_ref_quark)
410 QDATA_NOTIFY (obj, i) (QDATA_DATA (obj, i), obj);
411 if (QDATA_DESTROY (obj, i))
412 QDATA_DESTROY (obj, i) (QDATA_DATA (obj, i));
417 * gst_mini_object_unref: (skip)
418 * @mini_object: the mini-object
420 * Decreases the reference count of the mini-object, possibly freeing
424 gst_mini_object_unref (GstMiniObject * mini_object)
426 g_return_if_fail (mini_object != NULL);
428 GST_CAT_TRACE (GST_CAT_REFCOUNTING, "%p unref %d->%d",
430 GST_MINI_OBJECT_REFCOUNT_VALUE (mini_object),
431 GST_MINI_OBJECT_REFCOUNT_VALUE (mini_object) - 1);
433 g_return_if_fail (mini_object->refcount > 0);
435 if (G_UNLIKELY (g_atomic_int_dec_and_test (&mini_object->refcount))) {
438 GST_TRACER_MINI_OBJECT_UNREFFED (mini_object, mini_object->refcount);
439 if (mini_object->dispose)
440 do_free = mini_object->dispose (mini_object);
444 /* if the subclass recycled the object (and returned FALSE) we don't
445 * want to free the instance anymore */
446 if (G_LIKELY (do_free)) {
447 /* there should be no outstanding locks */
448 g_return_if_fail ((g_atomic_int_get (&mini_object->lockstate) & LOCK_MASK)
451 if (mini_object->n_qdata) {
452 call_finalize_notify (mini_object);
453 g_free (mini_object->qdata);
455 GST_TRACER_MINI_OBJECT_DESTROYED (mini_object);
456 if (mini_object->free)
457 mini_object->free (mini_object);
460 GST_TRACER_MINI_OBJECT_UNREFFED (mini_object, mini_object->refcount);
465 * gst_mini_object_replace:
466 * @olddata: (inout) (transfer full) (nullable): pointer to a pointer to a
467 * mini-object to be replaced
468 * @newdata: (allow-none): pointer to new mini-object
470 * Atomically modifies a pointer to point to a new mini-object.
471 * The reference count of @olddata is decreased and the reference count of
472 * @newdata is increased.
474 * Either @newdata and the value pointed to by @olddata may be %NULL.
476 * Returns: %TRUE if @newdata was different from @olddata
479 gst_mini_object_replace (GstMiniObject ** olddata, GstMiniObject * newdata)
481 GstMiniObject *olddata_val;
483 g_return_val_if_fail (olddata != NULL, FALSE);
485 GST_CAT_TRACE (GST_CAT_REFCOUNTING, "replace %p (%d) with %p (%d)",
486 *olddata, *olddata ? (*olddata)->refcount : 0,
487 newdata, newdata ? newdata->refcount : 0);
489 olddata_val = g_atomic_pointer_get ((gpointer *) olddata);
491 if (G_UNLIKELY (olddata_val == newdata))
495 gst_mini_object_ref (newdata);
497 while (G_UNLIKELY (!g_atomic_pointer_compare_and_exchange ((gpointer *)
498 olddata, olddata_val, newdata))) {
499 olddata_val = g_atomic_pointer_get ((gpointer *) olddata);
500 if (G_UNLIKELY (olddata_val == newdata))
505 gst_mini_object_unref (olddata_val);
507 return olddata_val != newdata;
511 * gst_mini_object_steal: (skip)
512 * @olddata: (inout) (transfer full): pointer to a pointer to a mini-object to
515 * Replace the current #GstMiniObject pointer to by @olddata with %NULL and
516 * return the old value.
518 * Returns: the #GstMiniObject at @oldata
521 gst_mini_object_steal (GstMiniObject ** olddata)
523 GstMiniObject *olddata_val;
525 g_return_val_if_fail (olddata != NULL, NULL);
527 GST_CAT_TRACE (GST_CAT_REFCOUNTING, "steal %p (%d)",
528 *olddata, *olddata ? (*olddata)->refcount : 0);
531 olddata_val = g_atomic_pointer_get ((gpointer *) olddata);
532 if (olddata_val == NULL)
534 } while (G_UNLIKELY (!g_atomic_pointer_compare_and_exchange ((gpointer *)
535 olddata, olddata_val, NULL)));
541 * gst_mini_object_take:
542 * @olddata: (inout) (transfer full): pointer to a pointer to a mini-object to
544 * @newdata: pointer to new mini-object
546 * Modifies a pointer to point to a new mini-object. The modification
547 * is done atomically. This version is similar to gst_mini_object_replace()
548 * except that it does not increase the refcount of @newdata and thus
549 * takes ownership of @newdata.
551 * Either @newdata and the value pointed to by @olddata may be %NULL.
553 * Returns: %TRUE if @newdata was different from @olddata
556 gst_mini_object_take (GstMiniObject ** olddata, GstMiniObject * newdata)
558 GstMiniObject *olddata_val;
560 g_return_val_if_fail (olddata != NULL, FALSE);
562 GST_CAT_TRACE (GST_CAT_REFCOUNTING, "take %p (%d) with %p (%d)",
563 *olddata, *olddata ? (*olddata)->refcount : 0,
564 newdata, newdata ? newdata->refcount : 0);
567 olddata_val = g_atomic_pointer_get ((gpointer *) olddata);
568 if (G_UNLIKELY (olddata_val == newdata))
570 } while (G_UNLIKELY (!g_atomic_pointer_compare_and_exchange ((gpointer *)
571 olddata, olddata_val, newdata)));
574 gst_mini_object_unref (olddata_val);
576 return olddata_val != newdata;
580 * gst_mini_object_weak_ref: (skip)
581 * @object: #GstMiniObject to reference weakly
582 * @notify: callback to invoke before the mini object is freed
583 * @data: extra data to pass to notify
585 * Adds a weak reference callback to a mini object. Weak references are
586 * used for notification when a mini object is finalized. They are called
587 * "weak references" because they allow you to safely hold a pointer
588 * to the mini object without calling gst_mini_object_ref()
589 * (gst_mini_object_ref() adds a strong reference, that is, forces the object
593 gst_mini_object_weak_ref (GstMiniObject * object,
594 GstMiniObjectNotify notify, gpointer data)
596 g_return_if_fail (object != NULL);
597 g_return_if_fail (notify != NULL);
598 g_return_if_fail (GST_MINI_OBJECT_REFCOUNT_VALUE (object) >= 1);
600 G_LOCK (qdata_mutex);
601 set_notify (object, -1, weak_ref_quark, notify, data, NULL);
602 G_UNLOCK (qdata_mutex);
606 * gst_mini_object_weak_unref: (skip)
607 * @object: #GstMiniObject to remove a weak reference from
608 * @notify: callback to search for
609 * @data: data to search for
611 * Removes a weak reference callback from a mini object.
614 gst_mini_object_weak_unref (GstMiniObject * object,
615 GstMiniObjectNotify notify, gpointer data)
619 g_return_if_fail (object != NULL);
620 g_return_if_fail (notify != NULL);
622 G_LOCK (qdata_mutex);
623 if ((i = find_notify (object, weak_ref_quark, TRUE, notify, data)) != -1) {
624 remove_notify (object, i);
626 g_warning ("%s: couldn't find weak ref %p (object:%p data:%p)", G_STRFUNC,
627 notify, object, data);
629 G_UNLOCK (qdata_mutex);
633 * gst_mini_object_set_qdata:
634 * @object: a #GstMiniObject
635 * @quark: A #GQuark, naming the user data pointer
636 * @data: An opaque user data pointer
637 * @destroy: Function to invoke with @data as argument, when @data
640 * This sets an opaque, named pointer on a miniobject.
641 * The name is specified through a #GQuark (retrieved e.g. via
642 * g_quark_from_static_string()), and the pointer
643 * can be gotten back from the @object with gst_mini_object_get_qdata()
644 * until the @object is disposed.
645 * Setting a previously set user data pointer, overrides (frees)
646 * the old pointer set, using %NULL as pointer essentially
647 * removes the data stored.
649 * @destroy may be specified which is called with @data as argument
650 * when the @object is disposed, or the data is being overwritten by
651 * a call to gst_mini_object_set_qdata() with the same @quark.
654 gst_mini_object_set_qdata (GstMiniObject * object, GQuark quark,
655 gpointer data, GDestroyNotify destroy)
658 gpointer old_data = NULL;
659 GDestroyNotify old_notify = NULL;
661 g_return_if_fail (object != NULL);
662 g_return_if_fail (quark > 0);
664 G_LOCK (qdata_mutex);
665 if ((i = find_notify (object, quark, FALSE, NULL, NULL)) != -1) {
667 old_data = QDATA_DATA (object, i);
668 old_notify = QDATA_DESTROY (object, i);
671 remove_notify (object, i);
674 set_notify (object, i, quark, NULL, data, destroy);
675 G_UNLOCK (qdata_mutex);
678 old_notify (old_data);
682 * gst_mini_object_get_qdata:
683 * @object: The GstMiniObject to get a stored user data pointer from
684 * @quark: A #GQuark, naming the user data pointer
686 * This function gets back user data pointers stored via
687 * gst_mini_object_set_qdata().
689 * Returns: (transfer none) (nullable): The user data pointer set, or
693 gst_mini_object_get_qdata (GstMiniObject * object, GQuark quark)
698 g_return_val_if_fail (object != NULL, NULL);
699 g_return_val_if_fail (quark > 0, NULL);
701 G_LOCK (qdata_mutex);
702 if ((i = find_notify (object, quark, FALSE, NULL, NULL)) != -1)
703 result = QDATA_DATA (object, i);
706 G_UNLOCK (qdata_mutex);
712 * gst_mini_object_steal_qdata:
713 * @object: The GstMiniObject to get a stored user data pointer from
714 * @quark: A #GQuark, naming the user data pointer
716 * This function gets back user data pointers stored via gst_mini_object_set_qdata()
717 * and removes the data from @object without invoking its destroy() function (if
720 * Returns: (transfer full) (nullable): The user data pointer set, or
724 gst_mini_object_steal_qdata (GstMiniObject * object, GQuark quark)
729 g_return_val_if_fail (object != NULL, NULL);
730 g_return_val_if_fail (quark > 0, NULL);
732 G_LOCK (qdata_mutex);
733 if ((i = find_notify (object, quark, FALSE, NULL, NULL)) != -1) {
734 result = QDATA_DATA (object, i);
735 remove_notify (object, i);
739 G_UNLOCK (qdata_mutex);