/*
* 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 "config.h"
#include <stddef.h>
#include <stdbool.h>
#include <pthread.h>
#include <assert.h>
#include "talloc.h"
#include "common/common.h"
#include "video/mp_image.h"
#include "mp_image_pool.h"
static pthread_mutex_t pool_mutex = PTHREAD_MUTEX_INITIALIZER;
#define pool_lock() pthread_mutex_lock(&pool_mutex)
#define pool_unlock() pthread_mutex_unlock(&pool_mutex)
// Thread-safety: the pool itself is not thread-safe, but pool-allocated images
// can be referenced and unreferenced from other threads. (As long as the image
// destructors are thread-safe.)
struct mp_image_pool {
int max_count;
struct mp_image **images;
int num_images;
mp_image_allocator allocator;
void *allocator_ctx;
bool use_lru;
unsigned int lru_counter;
};
// Used to gracefully handle the case when the pool is freed while image
// references allocated from the image pool are still held by someone.
struct image_flags {
// If both of these are false, the image must be freed.
bool referenced; // outside mp_image reference exists
bool pool_alive; // the mp_image_pool references this
unsigned int order; // for LRU allocation (basically a timestamp)
};
static void image_pool_destructor(void *ptr)
{
struct mp_image_pool *pool = ptr;
mp_image_pool_clear(pool);
}
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,
};
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];
struct image_flags *it = img->priv;
bool referenced;
pool_lock();
assert(it->pool_alive);
it->pool_alive = false;
referenced = it->referenced;
pool_unlock();
if (!referenced)
talloc_free(img);
}
pool->num_images = 0;
}
// This is the only function that is allowed to run in a different thread.
// (Consider passing an image to another thread, which frees it.)
static void unref_image(void *ptr)
{
struct mp_image *img = ptr;
struct image_flags *it = img->priv;
bool alive;
pool_lock();
assert(it->referenced);
it->referenced = false;
alive = it->pool_alive;
pool_unlock();
if (!alive)
talloc_free(img);
}
// Return a new image of given format/size. Unlike mp_image_pool_get(), this
// returns NULL if there is no free image of this format/size.
struct mp_image *mp_image_pool_get_no_alloc(struct mp_image_pool *pool, int fmt,
int w, int h)
{
struct mp_image *new = NULL;
pool_lock();
for (int n = 0; n < pool->num_images; n++) {
struct mp_image *img = pool->images[n];
struct image_flags *img_it = img->priv;
assert(img_it->pool_alive);
if (!img_it->referenced) {
if (img->imgfmt == fmt && img->w == w && img->h == h) {
if (pool->use_lru) {
struct image_flags *new_it = new ? new->priv : NULL;
if (!new_it || new_it->order > img_it->order)
new = img;
} else {
new = img;
break;
}
}
}
}
pool_unlock();
if (!new)
return NULL;
struct image_flags *it = new->priv;
assert(!it->referenced && it->pool_alive);
it->referenced = true;
it->order = ++pool->lru_counter;
return mp_image_new_custom_ref(new, new, unref_image);
}
// 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().
// Returns NULL on OOM.
struct mp_image *mp_image_pool_get(struct mp_image_pool *pool, int fmt,
int w, int h)
{
struct mp_image *new = mp_image_pool_get_no_alloc(pool, fmt, w, h);
if (!new) {
if (pool->num_images >= pool->max_count)
mp_image_pool_clear(pool);
if (pool->allocator) {
new = pool->allocator(pool->allocator_ctx, fmt, w, h);
} else {
new = mp_image_alloc(fmt, w, h);
}
if (!new)
return NULL;
struct image_flags *it = talloc_ptrtype(new, it);
*it = (struct image_flags) { .pool_alive = true };
new->priv = it;
MP_TARRAY_APPEND(pool, pool->images, pool->num_images, new);
new = mp_image_pool_get_no_alloc(pool, fmt, w, h);
}
return new;
}
// Like mp_image_new_copy(), but allocate the image out of the pool.
// Returns NULL on OOM.
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);
if (new) {
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.
// If pool==NULL, mp_image_make_writeable() is called (for convenience).
// Returns false on failure (see mp_image_make_writeable()).
bool mp_image_pool_make_writeable(struct mp_image_pool *pool,
struct mp_image *img)
{
if (mp_image_is_writeable(img))
return true;
if (!pool)
return mp_image_make_writeable(img);
struct mp_image *new = mp_image_pool_new_copy(pool, img);
if (!new)
return false;
mp_image_steal_data(img, new);
assert(mp_image_is_writeable(img));
return true;
}
void mp_image_pool_set_allocator(struct mp_image_pool *pool,
mp_image_allocator cb, void *cb_data)
{
pool->allocator = cb;
pool->allocator_ctx = cb_data;
}
// Put into LRU mode. (Likely better for hwaccel surfaces, but worse for memory.)
void mp_image_pool_set_lru(struct mp_image_pool *pool)
{
pool->use_lru = true;
}