gstreamer/gst/gstbufferlist.c
Mathieu Duponchelle 85763437c7 docs: standardize GstBufferList documentation
* Don't repeat what annotations are stating with respect to ownership
  transfer, nullability

* Misc cleanup / typo fixes / addition of links

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/752>
2021-02-08 14:31:09 +01:00

665 lines
18 KiB
C

/* GStreamer
* Copyright (C) 2009 Axis Communications <dev-gstreamer at axis dot com>
* @author Jonas Holmberg <jonas dot holmberg at axis dot com>
* Copyright (C) 2014 Tim-Philipp Müller <tim at centricular dot com>
*
* gstbufferlist.c: Buffer list
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
* Boston, MA 02110-1301, USA.
*/
/**
* SECTION:gstbufferlist
* @title: GstBufferList
* @short_description: Lists of buffers for data-passing
* @see_also: #GstPad, #GstMiniObject
*
* Buffer lists are an object containing a list of buffers.
*
* Buffer lists are created with gst_buffer_list_new() and filled with data
* using gst_buffer_list_insert().
*
* Buffer lists can be pushed on a srcpad with gst_pad_push_list(). This is
* interesting when multiple buffers need to be pushed in one go because it
* can reduce the amount of overhead for pushing each buffer individually.
*/
#define GST_DISABLE_MINIOBJECT_INLINE_FUNCTIONS
#include "gst_private.h"
#include "gstbuffer.h"
#include "gstbufferlist.h"
#include "gstutils.h"
#define GST_CAT_DEFAULT GST_CAT_BUFFER_LIST
#define GST_BUFFER_LIST_IS_USING_DYNAMIC_ARRAY(list) \
((list)->buffers != &(list)->arr[0])
/**
* GstBufferList:
*
* Opaque list of grouped buffers.
*/
struct _GstBufferList
{
GstMiniObject mini_object;
GstBuffer **buffers;
guint n_buffers;
guint n_allocated;
gsize slice_size;
/* one-item array, in reality more items are pre-allocated
* as part of the GstBufferList structure, and that
* pre-allocated array extends beyond the declared struct */
GstBuffer *arr[1];
};
GType _gst_buffer_list_type = 0;
GST_DEFINE_MINI_OBJECT_TYPE (GstBufferList, gst_buffer_list);
void
_priv_gst_buffer_list_initialize (void)
{
_gst_buffer_list_type = gst_buffer_list_get_type ();
}
static GstBufferList *
_gst_buffer_list_copy (GstBufferList * list)
{
GstBufferList *copy;
guint i, len;
len = list->n_buffers;
copy = gst_buffer_list_new_sized (list->n_allocated);
/* add and ref all buffers in the array */
for (i = 0; i < len; i++) {
copy->buffers[i] = gst_buffer_ref (list->buffers[i]);
gst_mini_object_add_parent (GST_MINI_OBJECT_CAST (copy->buffers[i]),
GST_MINI_OBJECT_CAST (copy));
}
copy->n_buffers = len;
return copy;
}
static void
_gst_buffer_list_free (GstBufferList * list)
{
guint i, len;
gsize slice_size;
GST_LOG ("free %p", list);
/* unrefs all buffers too */
len = list->n_buffers;
for (i = 0; i < len; i++) {
gst_mini_object_remove_parent (GST_MINI_OBJECT_CAST (list->buffers[i]),
GST_MINI_OBJECT_CAST (list));
gst_buffer_unref (list->buffers[i]);
}
if (GST_BUFFER_LIST_IS_USING_DYNAMIC_ARRAY (list))
g_free (list->buffers);
slice_size = list->slice_size;
#ifdef USE_POISONING
memset (list, 0xff, slice_size);
#endif
g_slice_free1 (slice_size, list);
}
static void
gst_buffer_list_init (GstBufferList * list, guint n_allocated, gsize slice_size)
{
gst_mini_object_init (GST_MINI_OBJECT_CAST (list), 0, _gst_buffer_list_type,
(GstMiniObjectCopyFunction) _gst_buffer_list_copy, NULL,
(GstMiniObjectFreeFunction) _gst_buffer_list_free);
list->buffers = &list->arr[0];
list->n_buffers = 0;
list->n_allocated = n_allocated;
list->slice_size = slice_size;
GST_LOG ("init %p", list);
}
/**
* gst_buffer_list_new_sized:
* @size: an initial reserved size
*
* Creates a new, empty #GstBufferList. The list will have @size space
* preallocated so that memory reallocations can be avoided.
*
* Returns: (transfer full): the new #GstBufferList.
*/
GstBufferList *
gst_buffer_list_new_sized (guint size)
{
GstBufferList *list;
gsize slice_size;
guint n_allocated;
if (size == 0)
size = 1;
n_allocated = GST_ROUND_UP_16 (size);
slice_size = sizeof (GstBufferList) + (n_allocated - 1) * sizeof (gpointer);
list = g_slice_alloc0 (slice_size);
GST_LOG ("new %p", list);
gst_buffer_list_init (list, n_allocated, slice_size);
return list;
}
/**
* gst_buffer_list_new:
*
* Creates a new, empty #GstBufferList.
*
* Returns: (transfer full): the new #GstBufferList.
*/
GstBufferList *
gst_buffer_list_new (void)
{
return gst_buffer_list_new_sized (8);
}
/**
* gst_buffer_list_length:
* @list: a #GstBufferList
*
* Returns the number of buffers in @list.
*
* Returns: the number of buffers in the buffer list
*/
guint
gst_buffer_list_length (GstBufferList * list)
{
g_return_val_if_fail (GST_IS_BUFFER_LIST (list), 0);
return list->n_buffers;
}
static inline void
gst_buffer_list_remove_range_internal (GstBufferList * list, guint idx,
guint length, gboolean unref_old)
{
guint i;
if (unref_old) {
for (i = idx; i < idx + length; ++i) {
gst_mini_object_remove_parent (GST_MINI_OBJECT_CAST (list->buffers[i]),
GST_MINI_OBJECT_CAST (list));
gst_buffer_unref (list->buffers[i]);
}
}
if (idx + length != list->n_buffers) {
memmove (&list->buffers[idx], &list->buffers[idx + length],
(list->n_buffers - (idx + length)) * sizeof (void *));
}
list->n_buffers -= length;
}
/**
* gst_buffer_list_foreach:
* @list: a #GstBufferList
* @func: (scope call): a #GstBufferListFunc to call
* @user_data: (closure): user data passed to @func
*
* Calls @func with @data for each buffer in @list.
*
* @func can modify the passed buffer pointer or its contents. The return value
* of @func defines if this function returns or if the remaining buffers in
* the list should be skipped.
*
* Returns: %TRUE when @func returned %TRUE for each buffer in @list or when
* @list is empty.
*/
gboolean
gst_buffer_list_foreach (GstBufferList * list, GstBufferListFunc func,
gpointer user_data)
{
guint i, len;
gboolean ret = TRUE;
gboolean list_was_writable, first_warning = TRUE;
g_return_val_if_fail (GST_IS_BUFFER_LIST (list), FALSE);
g_return_val_if_fail (func != NULL, FALSE);
list_was_writable = gst_buffer_list_is_writable (list);
len = list->n_buffers;
for (i = 0; i < len;) {
GstBuffer *buf, *buf_ret;
gboolean was_writable;
buf = buf_ret = list->buffers[i];
/* If the buffer is writable, we remove us as parent for now to
* allow the callback to destroy the buffer. If we get the buffer
* back, we add ourselves as parent again.
*
* Non-writable buffers just get another reference as they were not
* writable to begin with, and they would possibly become writable
* by removing ourselves as parent
*/
was_writable = list_was_writable && gst_buffer_is_writable (buf);
if (was_writable)
gst_mini_object_remove_parent (GST_MINI_OBJECT_CAST (buf),
GST_MINI_OBJECT_CAST (list));
else
gst_buffer_ref (buf);
ret = func (&buf_ret, i, user_data);
/* Check if the function changed the buffer */
if (buf != buf_ret) {
/* If the list was not writable but the callback was actually changing
* our buffer, then it wouldn't have been allowed to do so.
*
* Fortunately we still have a reference to the old buffer in that case
* and just not modify the list, unref the new buffer (if any) and warn
* about this */
if (!list_was_writable) {
if (first_warning) {
g_critical
("gst_buffer_list_foreach: non-writable list %p was changed from callback",
list);
first_warning = FALSE;
}
if (buf_ret)
gst_buffer_unref (buf_ret);
} else if (buf_ret == NULL) {
gst_buffer_list_remove_range_internal (list, i, 1, !was_writable);
--len;
} else {
if (!was_writable) {
gst_mini_object_remove_parent (GST_MINI_OBJECT_CAST (buf),
GST_MINI_OBJECT_CAST (list));
gst_buffer_unref (buf);
}
list->buffers[i] = buf_ret;
gst_mini_object_add_parent (GST_MINI_OBJECT_CAST (buf_ret),
GST_MINI_OBJECT_CAST (list));
}
} else {
if (was_writable)
gst_mini_object_add_parent (GST_MINI_OBJECT_CAST (buf),
GST_MINI_OBJECT_CAST (list));
else
gst_buffer_unref (buf);
}
if (!ret)
break;
/* If the buffer was not removed by func go to the next buffer */
if (buf_ret != NULL)
i++;
}
return ret;
}
/**
* gst_buffer_list_get:
* @list: a #GstBufferList
* @idx: the index
*
* Gets the buffer at @idx.
*
* You must make sure that @idx does not exceed the number of
* buffers available.
*
* Returns: (transfer none) (nullable): the buffer at @idx in @group
* or %NULL when there is no buffer. The buffer remains valid as
* long as @list is valid and buffer is not removed from the list.
*/
GstBuffer *
gst_buffer_list_get (GstBufferList * list, guint idx)
{
g_return_val_if_fail (GST_IS_BUFFER_LIST (list), NULL);
g_return_val_if_fail (idx < list->n_buffers, NULL);
return list->buffers[idx];
}
/**
* gst_buffer_list_get_writable:
* @list: a (writable) #GstBufferList
* @idx: the index
*
* Gets the buffer at @idx, ensuring it is a writable buffer.
*
* You must make sure that @idx does not exceed the number of
* buffers available.
*
* Returns: (transfer none) (nullable): the buffer at @idx in @group.
* The returned buffer remains valid as long as @list is valid and
* the buffer is not removed from the list.
*
* Since: 1.14
*/
GstBuffer *
gst_buffer_list_get_writable (GstBufferList * list, guint idx)
{
GstBuffer *new_buf;
g_return_val_if_fail (GST_IS_BUFFER_LIST (list), NULL);
g_return_val_if_fail (gst_buffer_list_is_writable (list), NULL);
g_return_val_if_fail (idx < list->n_buffers, NULL);
/* We have to implement this manually here to correctly add/remove the
* parent */
if (gst_buffer_is_writable (list->buffers[idx]))
return list->buffers[idx];
gst_mini_object_remove_parent (GST_MINI_OBJECT_CAST (list->buffers[idx]),
GST_MINI_OBJECT_CAST (list));
new_buf = gst_buffer_copy (list->buffers[idx]);
gst_mini_object_add_parent (GST_MINI_OBJECT_CAST (new_buf),
GST_MINI_OBJECT_CAST (list));
gst_buffer_unref (list->buffers[idx]);
list->buffers[idx] = new_buf;
return new_buf;
}
/**
* gst_buffer_list_add:
* @l: a #GstBufferList
* @b: a #GstBuffer
*
* Append @b at the end of @l.
*/
/**
* gst_buffer_list_insert:
* @list: a #GstBufferList
* @idx: the index
* @buffer: (transfer full): a #GstBuffer
*
* Inserts @buffer at @idx in @list. Other buffers are moved to make room for
* this new buffer.
*
* A -1 value for @idx will append the buffer at the end.
*/
void
gst_buffer_list_insert (GstBufferList * list, gint idx, GstBuffer * buffer)
{
guint want_alloc;
g_return_if_fail (GST_IS_BUFFER_LIST (list));
g_return_if_fail (buffer != NULL);
g_return_if_fail (gst_buffer_list_is_writable (list));
if (idx == -1 && list->n_buffers < list->n_allocated) {
gst_mini_object_add_parent (GST_MINI_OBJECT_CAST (buffer),
GST_MINI_OBJECT_CAST (list));
list->buffers[list->n_buffers++] = buffer;
return;
}
if (idx == -1 || idx > list->n_buffers)
idx = list->n_buffers;
want_alloc = list->n_buffers + 1;
if (want_alloc > list->n_allocated) {
if (G_UNLIKELY (list->n_allocated > (G_MAXUINT / 2)))
g_error ("Growing GstBufferList would result in overflow");
want_alloc = MAX (GST_ROUND_UP_16 (want_alloc), list->n_allocated * 2);
if (GST_BUFFER_LIST_IS_USING_DYNAMIC_ARRAY (list)) {
list->buffers = g_renew (GstBuffer *, list->buffers, want_alloc);
} else {
list->buffers = g_new0 (GstBuffer *, want_alloc);
memcpy (list->buffers, &list->arr[0], list->n_buffers * sizeof (void *));
GST_CAT_LOG (GST_CAT_PERFORMANCE, "exceeding pre-alloced array");
}
list->n_allocated = want_alloc;
}
if (idx < list->n_buffers) {
memmove (&list->buffers[idx + 1], &list->buffers[idx],
(list->n_buffers - idx) * sizeof (void *));
}
++list->n_buffers;
list->buffers[idx] = buffer;
gst_mini_object_add_parent (GST_MINI_OBJECT_CAST (buffer),
GST_MINI_OBJECT_CAST (list));
}
/**
* gst_buffer_list_remove:
* @list: a #GstBufferList
* @idx: the index
* @length: the amount to remove
*
* Removes @length buffers starting from @idx in @list. The following buffers
* are moved to close the gap.
*/
void
gst_buffer_list_remove (GstBufferList * list, guint idx, guint length)
{
g_return_if_fail (GST_IS_BUFFER_LIST (list));
g_return_if_fail (idx < list->n_buffers);
g_return_if_fail (idx + length <= list->n_buffers);
g_return_if_fail (gst_buffer_list_is_writable (list));
gst_buffer_list_remove_range_internal (list, idx, length, TRUE);
}
/**
* gst_buffer_list_copy_deep:
* @list: a #GstBufferList
*
* Creates a copy of the given buffer list. This will make a newly allocated
* copy of the buffers that the source buffer list contains.
*
* Returns: (transfer full): a new copy of @list.
*
* Since: 1.6
*/
GstBufferList *
gst_buffer_list_copy_deep (const GstBufferList * list)
{
guint i, len;
GstBufferList *result = NULL;
g_return_val_if_fail (GST_IS_BUFFER_LIST (list), NULL);
result = gst_buffer_list_new ();
len = list->n_buffers;
for (i = 0; i < len; i++) {
GstBuffer *old = list->buffers[i];
GstBuffer *new = gst_buffer_copy_deep (old);
if (G_LIKELY (new)) {
gst_buffer_list_insert (result, i, new);
} else {
g_warning
("Failed to deep copy buffer %p while deep "
"copying buffer list %p. Buffer list copy "
"will be incomplete", old, list);
}
}
return result;
}
/**
* gst_buffer_list_calculate_size:
* @list: a #GstBufferList
*
* Calculates the size of the data contained in @list by adding the
* size of all buffers.
*
* Returns: the size of the data contained in @list in bytes.
*
* Since: 1.14
*/
gsize
gst_buffer_list_calculate_size (GstBufferList * list)
{
GstBuffer **buffers;
gsize size = 0;
guint i, n;
g_return_val_if_fail (GST_IS_BUFFER_LIST (list), 0);
n = list->n_buffers;
buffers = list->buffers;
for (i = 0; i < n; ++i)
size += gst_buffer_get_size (buffers[i]);
return size;
}
/**
* gst_buffer_list_ref: (skip)
* @list: a #GstBufferList
*
* Increases the refcount of the given buffer list by one.
*
* Note that the refcount affects the writability of @list and its data, see
* gst_buffer_list_make_writable(). It is important to note that keeping
* additional references to GstBufferList instances can potentially increase
* the number of memcpy operations in a pipeline.
*
* Returns: (transfer full): @list
*/
GstBufferList *
gst_buffer_list_ref (GstBufferList * list)
{
return
GST_BUFFER_LIST_CAST (gst_mini_object_ref (GST_MINI_OBJECT_CAST (list)));
}
/**
* gst_buffer_list_unref: (skip)
* @list: (transfer full): a #GstBufferList
*
* Decreases the refcount of the buffer list. If the refcount reaches 0, the
* buffer list will be freed.
*/
void
gst_buffer_list_unref (GstBufferList * list)
{
gst_mini_object_unref (GST_MINI_OBJECT_CAST (list));
}
/**
* gst_clear_buffer_list: (skip)
* @list_ptr: a pointer to a #GstBufferList reference
*
* Clears a reference to a #GstBufferList.
*
* @list_ptr must not be %NULL.
*
* If the reference is %NULL then this function does nothing. Otherwise, the
* reference count of the list is decreased and the pointer is set to %NULL.
*
* Since: 1.16
*/
void
gst_clear_buffer_list (GstBufferList ** list_ptr)
{
gst_clear_mini_object ((GstMiniObject **) list_ptr);
}
/**
* gst_buffer_list_copy: (skip)
* @list: a #GstBufferList
*
* Creates a shallow copy of the given buffer list. This will make a newly
* allocated copy of the source list with copies of buffer pointers. The
* refcount of buffers pointed to will be increased by one.
*
* Returns: (transfer full): a new copy of @list.
*/
GstBufferList *
gst_buffer_list_copy (const GstBufferList * list)
{
return
GST_BUFFER_LIST_CAST (gst_mini_object_copy (GST_MINI_OBJECT_CONST_CAST
(list)));
}
/**
* gst_buffer_list_replace:
* @old_list: (inout) (transfer full) (nullable): pointer to a pointer to a
* #GstBufferList to be replaced.
* @new_list: (transfer none) (allow-none): pointer to a #GstBufferList that
* will replace the buffer list pointed to by @old_list.
*
* Modifies a pointer to a #GstBufferList to point to a different
* #GstBufferList. The modification is done atomically (so this is useful for
* ensuring thread safety in some cases), and the reference counts are updated
* appropriately (the old buffer list is unreffed, the new is reffed).
*
* Either @new_list or the #GstBufferList pointed to by @old_list may be %NULL.
*
* Returns: %TRUE if @new_list was different from @old_list
*
* Since: 1.16
*/
gboolean
gst_buffer_list_replace (GstBufferList ** old_list, GstBufferList * new_list)
{
return gst_mini_object_replace ((GstMiniObject **) old_list,
(GstMiniObject *) new_list);
}
/**
* gst_buffer_list_take:
* @old_list: (inout) (transfer full): pointer to a pointer to a #GstBufferList
* to be replaced.
* @new_list: (transfer full) (allow-none): pointer to a #GstBufferList
* that will replace the bufferlist pointed to by @old_list.
*
* Modifies a pointer to a #GstBufferList to point to a different
* #GstBufferList. This function is similar to gst_buffer_list_replace() except
* that it takes ownership of @new_list.
*
* Returns: %TRUE if @new_list was different from @old_list
*
* Since: 1.16
*/
gboolean
gst_buffer_list_take (GstBufferList ** old_list, GstBufferList * new_list)
{
return gst_mini_object_take ((GstMiniObject **) old_list,
(GstMiniObject *) new_list);
}