2 * Copyright (C) 2011 Wim Taymans <wim.taymans@gmail.be>
4 * gstmemory.c: memory block handling
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., 59 Temple Place - Suite 330,
19 * Boston, MA 02111-1307, USA.
24 * @short_description: refcounted wrapper for memory blocks
25 * @see_also: #GstBuffer
27 * GstMemory is a lightweight refcounted object that wraps a region of memory.
28 * They are typically used to manage the data of a #GstBuffer.
30 * A GstMemory object has an allocated region of memory of maxsize. The maximum
31 * size does not change during the lifetime of the memory object. The memory
32 * also has an offset and size property that specifies the valid range of memory
33 * in the allocated region.
35 * Memory is usually created by allocators with a gst_allocator_alloc()
36 * method call. When NULL is used as the allocator, the default allocator will
39 * New allocators can be registered with gst_allocator_register().
40 * Allocators are identified by name and can be retrieved with
41 * gst_allocator_find().
43 * New memory can be created with gst_memory_new_wrapped() that wraps the memory
44 * allocated elsewhere.
46 * Refcounting of the memory block is performed with gst_memory_ref() and
49 * The size of the memory can be retrieved and changed with
50 * gst_memory_get_sizes() and gst_memory_resize() respectively.
52 * Getting access to the data of the memory is performed with gst_memory_map().
53 * The call will return a pointer to offset bytes into the region of memory.
54 * After the memory access is completed, gst_memory_unmap() should be called.
56 * Memory can be copied with gst_memory_copy(), which will return a writable
57 * copy. gst_memory_share() will create a new memory block that shares the
58 * memory with an existing memory block at a custom offset and with a custom
61 * Memory can be efficiently merged when gst_memory_is_span() returns TRUE.
63 * Last reviewed on 2011-06-08 (0.11.0)
70 #include "gst_private.h"
71 #include "gstmemory.h"
73 #ifndef GST_DISABLE_TRACE
75 static GstAllocTrace *_gst_memory_trace;
76 static GstAllocTrace *_gst_allocator_trace;
79 G_DEFINE_BOXED_TYPE (GstMemory, gst_memory, (GBoxedCopyFunc) gst_memory_ref,
80 (GBoxedFreeFunc) gst_memory_unref);
82 G_DEFINE_BOXED_TYPE (GstAllocator, gst_allocator,
83 (GBoxedCopyFunc) gst_allocator_ref, (GBoxedFreeFunc) gst_allocator_unref);
86 * gst_memory_alignment:
88 * The default memory alignment in bytes - 1
89 * an alignment of 7 would be the same as what malloc() guarantees.
91 #if defined(MEMORY_ALIGNMENT_MALLOC)
92 size_t gst_memory_alignment = 7;
93 #elif defined(MEMORY_ALIGNMENT_PAGESIZE)
94 /* we fill this in in the _init method */
95 size_t gst_memory_alignment = 0;
96 #elif defined(MEMORY_ALIGNMENT)
97 size_t gst_memory_alignment = MEMORY_ALIGNMENT - 1;
99 #error "No memory alignment configured"
100 size_t gst_memory_alignment = 0;
110 GDestroyNotify notify;
113 /* default memory implementation */
120 GDestroyNotify notify;
123 /* the default allocator */
124 static GstAllocator *_default_allocator;
126 /* our predefined allocators */
127 static GstAllocator *_default_mem_impl;
129 /* initialize the fields */
131 _default_mem_init (GstMemoryDefault * mem, GstMemoryFlags flags,
132 GstMemory * parent, gsize slice_size, gpointer data,
133 gsize maxsize, gsize offset, gsize size, gpointer user_data,
134 GDestroyNotify notify)
136 mem->mem.allocator = _default_mem_impl;
137 mem->mem.flags = flags;
138 mem->mem.refcount = 1;
139 mem->mem.parent = parent ? gst_memory_ref (parent) : NULL;
140 mem->mem.state = (flags & GST_MEMORY_FLAG_READONLY ? 0x1 : 0);
141 mem->mem.maxsize = maxsize;
142 mem->mem.offset = offset;
143 mem->mem.size = size;
144 mem->slice_size = slice_size;
146 mem->user_data = user_data;
147 mem->notify = notify;
149 GST_CAT_DEBUG (GST_CAT_MEMORY, "new memory %p", mem);
152 /* create a new memory block that manages the given memory */
153 static GstMemoryDefault *
154 _default_mem_new (GstMemoryFlags flags, GstMemory * parent, gpointer data,
155 gsize maxsize, gsize offset, gsize size, gpointer user_data,
156 GDestroyNotify notify)
158 GstMemoryDefault *mem;
161 slice_size = sizeof (GstMemoryDefault);
163 mem = g_slice_alloc (slice_size);
164 _default_mem_init (mem, flags, parent, slice_size,
165 data, maxsize, offset, size, user_data, notify);
170 /* allocate the memory and structure in one block */
171 static GstMemoryDefault *
172 _default_mem_new_block (GstMemoryFlags flags, gsize maxsize, gsize align,
173 gsize offset, gsize size)
175 GstMemoryDefault *mem;
176 gsize aoffset, slice_size, padding;
179 /* ensure configured alignment */
180 align |= gst_memory_alignment;
181 /* allocate more to compensate for alignment */
183 /* alloc header and data in one block */
184 slice_size = sizeof (GstMemoryDefault) + maxsize;
186 mem = g_slice_alloc (slice_size);
190 data = (guint8 *) mem + sizeof (GstMemoryDefault);
192 if ((aoffset = ((guintptr) data & align)))
193 data += (align + 1) - aoffset;
195 if (offset && (flags & GST_MEMORY_FLAG_ZERO_PREFIXED))
196 memset (data, 0, offset);
198 padding = maxsize - (offset + size);
199 if (padding && (flags & GST_MEMORY_FLAG_ZERO_PADDED))
200 memset (data + offset + size, 0, padding);
202 _default_mem_init (mem, flags, NULL, slice_size, data, maxsize,
203 offset, size, NULL, NULL);
209 _default_alloc_alloc (GstAllocator * allocator, GstMemoryFlags flags,
210 gsize maxsize, gsize offset, gsize size, gsize align, gpointer user_data)
212 return (GstMemory *) _default_mem_new_block (flags, maxsize, align, offset,
217 _default_mem_map (GstMemoryDefault * mem, GstMapFlags flags)
223 _default_mem_unmap (GstMemoryDefault * mem)
229 _default_mem_free (GstMemoryDefault * mem)
231 GST_CAT_DEBUG (GST_CAT_MEMORY, "free memory %p", mem);
234 gst_memory_unref (mem->mem.parent);
237 mem->notify (mem->user_data);
239 g_slice_free1 (mem->slice_size, mem);
242 static GstMemoryDefault *
243 _default_mem_copy (GstMemoryDefault * mem, gssize offset, gsize size)
245 GstMemoryDefault *copy;
248 size = mem->mem.size > offset ? mem->mem.size - offset : 0;
251 _default_mem_new_block (0, mem->mem.maxsize, 0, mem->mem.offset + offset,
253 memcpy (copy->data, mem->data, mem->mem.maxsize);
254 GST_CAT_DEBUG (GST_CAT_PERFORMANCE, "copy memory %p -> %p", mem, copy);
259 static GstMemoryDefault *
260 _default_mem_share (GstMemoryDefault * mem, gssize offset, gsize size)
262 GstMemoryDefault *sub;
265 /* find the real parent */
266 if ((parent = mem->mem.parent) == NULL)
267 parent = (GstMemory *) mem;
270 size = mem->mem.size - offset;
273 _default_mem_new (parent->flags, parent, mem->data,
274 mem->mem.maxsize, mem->mem.offset + offset, size, NULL, NULL);
280 _default_mem_is_span (GstMemoryDefault * mem1, GstMemoryDefault * mem2,
285 GstMemoryDefault *parent;
287 parent = (GstMemoryDefault *) mem1->mem.parent;
289 *offset = mem1->mem.offset - parent->mem.offset;
292 /* and memory is contiguous */
293 return mem1->data + mem1->mem.offset + mem1->mem.size ==
294 mem2->data + mem2->mem.offset;
298 _fallback_mem_copy (GstMemory * mem, gssize offset, gssize size)
301 GstMapInfo sinfo, dinfo;
303 if (!gst_memory_map (mem, &sinfo, GST_MAP_READ))
307 size = sinfo.size > offset ? sinfo.size - offset : 0;
309 /* use the same allocator as the memory we copy */
310 copy = gst_allocator_alloc (mem->allocator, 0, size, 0, size, mem->align);
311 if (!gst_memory_map (copy, &dinfo, GST_MAP_WRITE)) {
312 GST_CAT_WARNING (GST_CAT_MEMORY, "could not write map memory %p", copy);
313 gst_memory_unmap (mem, &sinfo);
317 memcpy (dinfo.data, sinfo.data + offset, size);
318 GST_CAT_DEBUG (GST_CAT_PERFORMANCE, "copy memory %p -> %p", mem, copy);
319 gst_memory_unmap (copy, &dinfo);
320 gst_memory_unmap (mem, &sinfo);
326 _fallback_mem_is_span (GstMemory * mem1, GstMemory * mem2, gsize * offset)
332 static GHashTable *allocators;
335 _priv_sysmem_notify (gpointer user_data)
337 g_warning ("The default memory allocator was freed!");
341 _priv_gst_memory_initialize (void)
343 static const GstMemoryInfo _mem_info = {
344 GST_ALLOCATOR_SYSMEM,
345 (GstAllocatorAllocFunction) _default_alloc_alloc,
346 (GstMemoryMapFunction) _default_mem_map,
347 (GstMemoryUnmapFunction) _default_mem_unmap,
348 (GstMemoryFreeFunction) _default_mem_free,
349 (GstMemoryCopyFunction) _default_mem_copy,
350 (GstMemoryShareFunction) _default_mem_share,
351 (GstMemoryIsSpanFunction) _default_mem_is_span,
354 #ifndef GST_DISABLE_TRACE
355 _gst_memory_trace = _gst_alloc_trace_register ("GstMemory", -1);
356 _gst_allocator_trace = _gst_alloc_trace_register ("GstAllocator", -1);
359 g_rw_lock_init (&lock);
360 allocators = g_hash_table_new (g_str_hash, g_str_equal);
362 #ifdef HAVE_GETPAGESIZE
363 #ifdef MEMORY_ALIGNMENT_PAGESIZE
364 gst_memory_alignment = getpagesize () - 1;
368 GST_CAT_DEBUG (GST_CAT_MEMORY, "memory alignment: %" G_GSIZE_FORMAT,
369 gst_memory_alignment);
371 _default_mem_impl = gst_allocator_new (&_mem_info, NULL, _priv_sysmem_notify);
373 _default_allocator = gst_allocator_ref (_default_mem_impl);
374 gst_allocator_register (GST_ALLOCATOR_SYSMEM,
375 gst_allocator_ref (_default_mem_impl));
379 * gst_memory_new_wrapped:
380 * @flags: #GstMemoryFlags
381 * @data: data to wrap
382 * @maxsize: allocated size of @data
383 * @offset: offset in @data
384 * @size: size of valid data
385 * @user_data: user_data
386 * @notify: called with @user_data when the memory is freed
388 * Allocate a new memory block that wraps the given @data.
390 * The prefix/padding must be filled with 0 if @flags contains
391 * #GST_MEMORY_FLAG_ZERO_PREFIXED and #GST_MEMORY_FLAG_ZERO_PADDED respectively.
393 * Returns: a new #GstMemory.
396 gst_memory_new_wrapped (GstMemoryFlags flags, gpointer data,
397 gsize maxsize, gsize offset, gsize size, gpointer user_data,
398 GDestroyNotify notify)
400 GstMemoryDefault *mem;
402 g_return_val_if_fail (data != NULL, NULL);
403 g_return_val_if_fail (offset + size <= maxsize, NULL);
406 _default_mem_new (flags, NULL, data, maxsize, offset, size, user_data,
409 #ifndef GST_DISABLE_TRACE
410 _gst_alloc_trace_new (_gst_memory_trace, mem);
413 return (GstMemory *) mem;
420 * Increases the refcount of @mem.
422 * Returns: @mem with increased refcount
425 gst_memory_ref (GstMemory * mem)
427 g_return_val_if_fail (mem != NULL, NULL);
429 GST_CAT_TRACE (GST_CAT_MEMORY, "memory %p, %d->%d", mem, mem->refcount,
432 g_atomic_int_inc (&mem->refcount);
441 * Decreases the refcount of @mem. When the refcount reaches 0, the free
442 * function of @mem will be called.
445 gst_memory_unref (GstMemory * mem)
447 g_return_if_fail (mem != NULL);
448 g_return_if_fail (mem->allocator != NULL);
450 GST_CAT_TRACE (GST_CAT_MEMORY, "memory %p, %d->%d", mem, mem->refcount,
453 if (g_atomic_int_dec_and_test (&mem->refcount)) {
454 /* there should be no outstanding mappings */
455 g_return_if_fail (g_atomic_int_get (&mem->state) < 4);
456 #ifndef GST_DISABLE_TRACE
457 _gst_alloc_trace_free (_gst_memory_trace, mem);
459 mem->allocator->info.mem_free (mem);
464 * gst_memory_is_exclusive:
467 * Check if the current ref to @mem is exclusive, this means that no other
468 * references exist other than @mem.
471 gst_memory_is_exclusive (GstMemory * mem)
473 g_return_val_if_fail (mem != NULL, FALSE);
475 return (g_atomic_int_get (&mem->refcount) == 1);
479 * gst_memory_get_sizes:
481 * @offset: pointer to offset
482 * @maxsize: pointer to maxsize
484 * Get the current @size, @offset and @maxsize of @mem.
486 * Returns: the current sizes of @mem
489 gst_memory_get_sizes (GstMemory * mem, gsize * offset, gsize * maxsize)
491 g_return_val_if_fail (mem != NULL, 0);
494 *offset = mem->offset;
496 *maxsize = mem->maxsize;
504 * @offset: a new offset
507 * Resize the memory region. @mem should be writable and offset + size should be
508 * less than the maxsize of @mem.
510 * #GST_MEMORY_FLAG_ZERO_PREFIXED and #GST_MEMORY_FLAG_ZERO_PADDED will be
511 * cleared when offset or padding is increased respectively.
514 gst_memory_resize (GstMemory * mem, gssize offset, gsize size)
516 g_return_if_fail (mem != NULL);
517 g_return_if_fail (offset >= 0 || mem->offset >= -offset);
518 g_return_if_fail (size + mem->offset + offset <= mem->maxsize);
520 /* if we increase the prefix, we can't guarantee it is still 0 filled */
521 if ((offset > 0) && GST_MEMORY_IS_ZERO_PREFIXED (mem))
522 GST_MEMORY_FLAG_UNSET (mem, GST_MEMORY_FLAG_ZERO_PREFIXED);
524 /* if we increase the padding, we can't guarantee it is still 0 filled */
525 if ((offset + size < mem->size) && GST_MEMORY_IS_ZERO_PADDED (mem))
526 GST_MEMORY_FLAG_UNSET (mem, GST_MEMORY_FLAG_ZERO_PADDED);
528 mem->offset += offset;
533 gst_memory_lock (GstMemory * mem, GstMapFlags flags)
535 gint access_mode, state, newstate;
537 access_mode = flags & 3;
540 state = g_atomic_int_get (&mem->state);
542 /* nothing mapped, set access_mode and refcount */
543 newstate = 4 | access_mode;
545 /* access_mode must match */
546 if ((state & access_mode) != access_mode)
548 /* increase refcount */
549 newstate = state + 4;
551 } while (!g_atomic_int_compare_and_exchange (&mem->state, state, newstate));
557 GST_CAT_DEBUG (GST_CAT_MEMORY, "lock failed %p: state %d, access_mode %d",
558 mem, state, access_mode);
564 gst_memory_unlock (GstMemory * mem)
566 gint state, newstate;
569 state = g_atomic_int_get (&mem->state);
570 /* decrease the refcount */
571 newstate = state - 4;
572 /* last refcount, unset access_mode */
575 } while (!g_atomic_int_compare_and_exchange (&mem->state, state, newstate));
580 * gst_memory_make_mapped:
581 * @mem: (transfer full): a #GstMemory
582 * @info: (out): pointer for info
583 * @flags: mapping flags
585 * Create a #GstMemory object that is mapped with @flags. If @mem is mappable
586 * with @flags, this function returns the mapped @mem directly. Otherwise a
587 * mapped copy of @mem is returned.
589 * This function takes ownership of old @mem and returns a reference to a new
592 * Returns: (transfer full): a #GstMemory object mapped with @flags or NULL when
593 * a mapping is not possible.
596 gst_memory_make_mapped (GstMemory * mem, GstMapInfo * info, GstMapFlags flags)
600 if (gst_memory_map (mem, info, flags)) {
603 result = gst_memory_copy (mem, 0, -1);
604 gst_memory_unref (mem);
609 if (!gst_memory_map (result, info, flags))
617 GST_CAT_DEBUG (GST_CAT_MEMORY, "cannot copy memory %p", mem);
622 GST_CAT_DEBUG (GST_CAT_MEMORY, "cannot map memory %p with flags %d", mem,
624 gst_memory_unref (result);
632 * @info: (out): pointer for info
633 * @flags: mapping flags
635 * Fill @info with the pointer and sizes of the memory in @mem that can be
636 * accessed according to @flags.
638 * This function can return %FALSE for various reasons:
639 * - the memory backed by @mem is not accessible with the given @flags.
640 * - the memory was already mapped with a different mapping.
642 * @info and its contents remain valid for as long as @mem is valid and
643 * until gst_memory_unmap() is called.
645 * For each gst_memory_map() call, a corresponding gst_memory_unmap() call
648 * Returns: %TRUE if the map operation was successful.
651 gst_memory_map (GstMemory * mem, GstMapInfo * info, GstMapFlags flags)
653 g_return_val_if_fail (mem != NULL, FALSE);
654 g_return_val_if_fail (info != NULL, FALSE);
656 if (!gst_memory_lock (mem, flags))
659 info->data = mem->allocator->info.mem_map (mem, mem->maxsize, flags);
661 if (G_UNLIKELY (info->data == NULL))
666 info->size = mem->size;
667 info->maxsize = mem->maxsize - mem->offset;
668 info->data = info->data + mem->offset;
675 GST_CAT_DEBUG (GST_CAT_MEMORY, "mem %p: lock %d failed", mem, flags);
680 /* something went wrong, restore the orginal state again */
681 GST_CAT_ERROR (GST_CAT_MEMORY, "mem %p: map failed", mem);
682 gst_memory_unlock (mem);
690 * @info: a #GstMapInfo
692 * Release the memory obtained with gst_memory_map()
695 gst_memory_unmap (GstMemory * mem, GstMapInfo * info)
697 g_return_if_fail (mem != NULL);
698 g_return_if_fail (info != NULL);
699 g_return_if_fail (info->memory == mem);
700 /* there must be a ref */
701 g_return_if_fail (g_atomic_int_get (&mem->state) >= 4);
703 mem->allocator->info.mem_unmap (mem);
704 gst_memory_unlock (mem);
710 * @offset: an offset to copy
711 * @size: size to copy or -1 to copy all bytes from offset
713 * Return a copy of @size bytes from @mem starting from @offset. This copy is
714 * guaranteed to be writable. @size can be set to -1 to return a copy all bytes
717 * Returns: a new #GstMemory.
720 gst_memory_copy (GstMemory * mem, gssize offset, gssize size)
724 g_return_val_if_fail (mem != NULL, NULL);
726 copy = mem->allocator->info.mem_copy (mem, offset, size);
728 #ifndef GST_DISABLE_TRACE
729 _gst_alloc_trace_new (_gst_memory_trace, copy);
738 * @offset: an offset to share
739 * @size: size to share or -1 to share bytes from offset
741 * Return a shared copy of @size bytes from @mem starting from @offset. No
742 * memory copy is performed and the memory region is simply shared. The result
743 * is guaranteed to be not-writable. @size can be set to -1 to return a share
744 * all bytes from @offset.
746 * Returns: a new #GstMemory.
749 gst_memory_share (GstMemory * mem, gssize offset, gssize size)
753 g_return_val_if_fail (mem != NULL, NULL);
754 g_return_val_if_fail (!GST_MEMORY_FLAG_IS_SET (mem, GST_MEMORY_FLAG_NO_SHARE),
757 shared = mem->allocator->info.mem_share (mem, offset, size);
759 #ifndef GST_DISABLE_TRACE
760 _gst_alloc_trace_new (_gst_memory_trace, shared);
767 * gst_memory_is_span:
768 * @mem1: a #GstMemory
769 * @mem2: a #GstMemory
770 * @offset: a pointer to a result offset
772 * Check if @mem1 and mem2 share the memory with a common parent memory object
773 * and that the memory is contiguous.
775 * If this is the case, the memory of @mem1 and @mem2 can be merged
776 * efficiently by performing gst_memory_share() on the parent object from
777 * the returned @offset.
779 * Returns: %TRUE if the memory is contiguous and of a common parent.
782 gst_memory_is_span (GstMemory * mem1, GstMemory * mem2, gsize * offset)
784 g_return_val_if_fail (mem1 != NULL, FALSE);
785 g_return_val_if_fail (mem2 != NULL, FALSE);
787 /* need to have the same allocators */
788 if (mem1->allocator != mem2->allocator)
791 /* need to have the same parent */
792 if (mem1->parent == NULL || mem1->parent != mem2->parent)
795 /* and memory is contiguous */
796 if (!mem1->allocator->info.mem_is_span (mem1, mem2, offset))
803 * gst_allocator_register:
804 * @info: a #GstMemoryInfo
805 * @user_data: user data
806 * @notify: a #GDestroyNotify for @user_data
808 * Create a new memory allocator with @info and @user_data.
810 * All functions in @info are mandatory exept the copy and is_span
811 * functions, which will have a default implementation when left NULL.
813 * The @user_data will be passed to all calls of the alloc function. @notify
814 * will be called with @user_data when the allocator is freed.
816 * Returns: a new #GstAllocator.
819 gst_allocator_new (const GstMemoryInfo * info, gpointer user_data,
820 GDestroyNotify notify)
822 GstAllocator *allocator;
824 #define INSTALL_FALLBACK(_t) \
825 if (allocator->info._t == NULL) allocator->info._t = _fallback_ ##_t;
827 g_return_val_if_fail (info != NULL, NULL);
828 g_return_val_if_fail (info->alloc != NULL, NULL);
829 g_return_val_if_fail (info->mem_map != NULL, NULL);
830 g_return_val_if_fail (info->mem_unmap != NULL, NULL);
831 g_return_val_if_fail (info->mem_free != NULL, NULL);
832 g_return_val_if_fail (info->mem_share != NULL, NULL);
834 allocator = g_slice_new (GstAllocator);
835 allocator->refcount = 1;
836 allocator->info = *info;
837 allocator->user_data = user_data;
838 allocator->notify = notify;
839 INSTALL_FALLBACK (mem_copy);
840 INSTALL_FALLBACK (mem_is_span);
841 #undef INSTALL_FALLBACK
843 GST_CAT_DEBUG (GST_CAT_MEMORY, "new allocator %p", allocator);
845 #ifndef GST_DISABLE_TRACE
846 _gst_alloc_trace_new (_gst_allocator_trace, allocator);
853 * gst_alocator_get_memory_type:
854 * @allocator: a #GstAllocator
856 * Get the memory type allocated by this allocator
858 * Returns: the memory type provided by @allocator
861 gst_allocator_get_memory_type (GstAllocator * allocator)
863 g_return_val_if_fail (allocator != NULL, NULL);
865 return allocator->info.mem_type;
870 * @allocator: a #GstAllocator
872 * Increases the refcount of @allocator.
874 * Returns: @allocator with increased refcount
877 gst_allocator_ref (GstAllocator * allocator)
879 g_return_val_if_fail (allocator != NULL, NULL);
881 GST_CAT_TRACE (GST_CAT_MEMORY, "alocator %p, %d->%d", allocator,
882 allocator->refcount, allocator->refcount + 1);
884 g_atomic_int_inc (&allocator->refcount);
890 * gst_allocator_unref:
891 * @allocator: a #GstAllocator
893 * Decreases the refcount of @allocator. When the refcount reaches 0, the notify
894 * function of @allocator will be called and the allocator will be freed.
897 gst_allocator_unref (GstAllocator * allocator)
899 g_return_if_fail (allocator != NULL);
901 GST_CAT_TRACE (GST_CAT_MEMORY, "allocator %p, %d->%d", allocator,
902 allocator->refcount, allocator->refcount - 1);
904 if (g_atomic_int_dec_and_test (&allocator->refcount)) {
905 if (allocator->notify)
906 allocator->notify (allocator->user_data);
907 #ifndef GST_DISABLE_TRACE
908 _gst_alloc_trace_free (_gst_allocator_trace, allocator);
910 g_slice_free1 (sizeof (GstAllocator), allocator);
915 * gst_allocator_register:
916 * @name: the name of the allocator
917 * @allocator: (transfer full): #GstAllocator
919 * Registers the memory @allocator with @name. This function takes ownership of
923 gst_allocator_register (const gchar * name, GstAllocator * allocator)
925 g_return_if_fail (name != NULL);
926 g_return_if_fail (allocator != NULL);
928 GST_CAT_DEBUG (GST_CAT_MEMORY, "registering allocator %p with name \"%s\"",
931 g_rw_lock_writer_lock (&lock);
932 g_hash_table_insert (allocators, (gpointer) name, (gpointer) allocator);
933 g_rw_lock_writer_unlock (&lock);
937 * gst_allocator_find:
938 * @name: the name of the allocator
940 * Find a previously registered allocator with @name. When @name is NULL, the
941 * default allocator will be returned.
943 * Returns: (transfer full): a #GstAllocator or NULL when the allocator with @name was not
944 * registered. Use gst_allocator_unref() to release the allocator after usage.
947 gst_allocator_find (const gchar * name)
949 GstAllocator *allocator;
951 g_rw_lock_reader_lock (&lock);
953 allocator = g_hash_table_lookup (allocators, (gconstpointer) name);
955 allocator = _default_allocator;
958 gst_allocator_ref (allocator);
959 g_rw_lock_reader_unlock (&lock);
965 * gst_allocator_set_default:
966 * @allocator: (transfer full): a #GstAllocator
968 * Set the default allocator. This function takes ownership of @allocator.
971 gst_allocator_set_default (GstAllocator * allocator)
974 g_return_if_fail (allocator != NULL);
976 g_rw_lock_writer_lock (&lock);
977 old = _default_allocator;
978 _default_allocator = allocator;
979 g_rw_lock_writer_unlock (&lock);
982 gst_allocator_unref (old);
986 * gst_allocator_alloc:
987 * @allocator: (transfer none) (allow-none): a #GstAllocator to use
989 * @maxsize: allocated size of @data
990 * @offset: offset in allocated memory
991 * @size: size of visible
992 * @align: alignment for the data
994 * Use @allocator to allocate a new memory block with memory that is at least
995 * @maxsize big and has the given alignment.
997 * @offset and @size describe the start and size of the accessible memory.
999 * The prefix/padding will be filled with 0 if @flags contains
1000 * #GST_MEMORY_FLAG_ZERO_PREFIXED and #GST_MEMORY_FLAG_ZERO_PADDED respectively.
1002 * When @allocator is NULL, the default allocator will be used.
1004 * @align is given as a bitmask so that @align + 1 equals the amount of bytes to
1005 * align to. For example, to align to 8 bytes, use an alignment of 7.
1007 * Returns: (transfer full): a new #GstMemory.
1010 gst_allocator_alloc (GstAllocator * allocator, GstMemoryFlags flags,
1011 gsize maxsize, gsize offset, gsize size, gsize align)
1015 g_return_val_if_fail (((align + 1) & align) == 0, NULL);
1017 if (allocator == NULL)
1018 allocator = _default_allocator;
1020 mem = allocator->info.alloc (allocator, flags, maxsize, offset, size,
1021 align, allocator->user_data);
1022 #ifndef GST_DISABLE_TRACE
1023 _gst_alloc_trace_new (_gst_memory_trace, mem);