mpv/video/mp_image_pool.c

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/*
* This file is part of mpv.
*
* mpv is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* mpv 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with mpv; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include <assert.h>
#include "talloc.h"
#include "core/mp_common.h"
#include "video/mp_image.h"
#include "mp_image_pool.h"
struct pool_trampoline {
struct mp_image_pool *pool;
int refcount;
};
static int image_pool_destructor(void *ptr)
{
struct mp_image_pool *pool = ptr;
mp_image_pool_clear(pool);
pool->trampoline->pool = NULL;
if (!pool->trampoline->refcount)
talloc_free(pool->trampoline);
return 0;
}
struct mp_image_pool *mp_image_pool_new(int max_count)
{
struct mp_image_pool *pool = talloc_ptrtype(NULL, pool);
talloc_set_destructor(pool, image_pool_destructor);
*pool = (struct mp_image_pool) {
.max_count = max_count,
.trampoline = talloc_struct(NULL, struct pool_trampoline, {
.pool = pool,
}),
};
return pool;
}
void mp_image_pool_clear(struct mp_image_pool *pool)
{
for (int n = 0; n < pool->num_images; n++) {
struct mp_image *img = pool->images[n];
if (img->priv) {
// Image data is being used - detach from the pool, and make it
// free itself when pool_free_image() is called
img->priv = talloc_struct(NULL, struct pool_trampoline, {
.refcount = 1,
});
} else {
talloc_free(img);
}
}
pool->num_images = 0;
pool->trampoline->refcount = 0;
}
static void pool_free_image(void *ptr)
{
struct mp_image *img = ptr;
struct pool_trampoline *trampoline = img->priv;
trampoline->refcount--;
img->priv = NULL;
if (!trampoline->pool) {
// pool was free'd while image reference was still held
if (trampoline->refcount == 0)
talloc_free(trampoline);
talloc_free(img);
}
}
// Return a new image of given format/size. The only difference to
// mp_image_alloc() is that there is a transparent mechanism to recycle image
// data allocations through this pool.
// The image can be free'd with talloc_free().
struct mp_image *mp_image_pool_get(struct mp_image_pool *pool, unsigned int fmt,
int w, int h)
{
struct mp_image *new = NULL;
for (int n = 0; n < pool->num_images; n++) {
struct mp_image *img = pool->images[n];
if (!img->priv && img->imgfmt == fmt && img->w == w && img->h == h) {
new = img;
break;
}
}
if (!new) {
if (pool->num_images >= pool->max_count)
mp_image_pool_clear(pool);
new = mp_image_alloc(fmt, w, h);
MP_TARRAY_APPEND(pool, pool->images, pool->num_images, new);
}
pool->trampoline->refcount++;
new->priv = pool->trampoline;
return mp_image_new_custom_ref(new, new, pool_free_image);
}
// Like mp_image_new_copy(), but allocate the image out of the pool.
struct mp_image *mp_image_pool_new_copy(struct mp_image_pool *pool,
struct mp_image *img)
{
struct mp_image *new = mp_image_pool_get(pool, img->imgfmt, img->w, img->h);
mp_image_copy(new, img);
mp_image_copy_attributes(new, img);
return new;
}
// Like mp_image_make_writeable(), but if a copy has to be made, allocate it
// out of the pool.
void mp_image_pool_make_writeable(struct mp_image_pool *pool,
struct mp_image *img)
{
if (mp_image_is_writeable(img))
return;
mp_image_steal_data(img, mp_image_pool_new_copy(pool, img));
assert(mp_image_is_writeable(img));
}