ffmpeg/libavutil/buffer.c
Andreas Rheinhardt 4e0da7d311 avutil/buffer: Avoid allocation of AVBuffer when using buffer pool
Do this by putting an AVBuffer structure into BufferPoolEntry and
reuse it for all subsequent uses of said BufferPoolEntry.

Reviewed-by: James Almer <jamrial@gmail.com>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
2021-09-18 23:16:49 +02:00

420 lines
9.8 KiB
C

/*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <stdatomic.h>
#include <stdint.h>
#include <string.h>
#include "avassert.h"
#include "buffer_internal.h"
#include "common.h"
#include "mem.h"
#include "thread.h"
static AVBufferRef *buffer_create(AVBuffer *buf, uint8_t *data, size_t size,
void (*free)(void *opaque, uint8_t *data),
void *opaque, int flags)
{
AVBufferRef *ref = NULL;
buf->data = data;
buf->size = size;
buf->free = free ? free : av_buffer_default_free;
buf->opaque = opaque;
atomic_init(&buf->refcount, 1);
buf->flags = flags;
ref = av_mallocz(sizeof(*ref));
if (!ref)
return NULL;
ref->buffer = buf;
ref->data = data;
ref->size = size;
return ref;
}
AVBufferRef *av_buffer_create(uint8_t *data, size_t size,
void (*free)(void *opaque, uint8_t *data),
void *opaque, int flags)
{
AVBufferRef *ret;
AVBuffer *buf = av_mallocz(sizeof(*buf));
if (!buf)
return NULL;
ret = buffer_create(buf, data, size, free, opaque, flags);
if (!ret) {
av_free(buf);
return NULL;
}
return ret;
}
void av_buffer_default_free(void *opaque, uint8_t *data)
{
av_free(data);
}
AVBufferRef *av_buffer_alloc(size_t size)
{
AVBufferRef *ret = NULL;
uint8_t *data = NULL;
data = av_malloc(size);
if (!data)
return NULL;
ret = av_buffer_create(data, size, av_buffer_default_free, NULL, 0);
if (!ret)
av_freep(&data);
return ret;
}
AVBufferRef *av_buffer_allocz(size_t size)
{
AVBufferRef *ret = av_buffer_alloc(size);
if (!ret)
return NULL;
memset(ret->data, 0, size);
return ret;
}
AVBufferRef *av_buffer_ref(const AVBufferRef *buf)
{
AVBufferRef *ret = av_mallocz(sizeof(*ret));
if (!ret)
return NULL;
*ret = *buf;
atomic_fetch_add_explicit(&buf->buffer->refcount, 1, memory_order_relaxed);
return ret;
}
static void buffer_replace(AVBufferRef **dst, AVBufferRef **src)
{
AVBuffer *b;
b = (*dst)->buffer;
if (src) {
**dst = **src;
av_freep(src);
} else
av_freep(dst);
if (atomic_fetch_sub_explicit(&b->refcount, 1, memory_order_acq_rel) == 1) {
/* b->free below might already free the structure containing *b,
* so we have to read the flag now to avoid use-after-free. */
int free_avbuffer = !(b->flags_internal & BUFFER_FLAG_NO_FREE);
b->free(b->opaque, b->data);
if (free_avbuffer)
av_free(b);
}
}
void av_buffer_unref(AVBufferRef **buf)
{
if (!buf || !*buf)
return;
buffer_replace(buf, NULL);
}
int av_buffer_is_writable(const AVBufferRef *buf)
{
if (buf->buffer->flags & AV_BUFFER_FLAG_READONLY)
return 0;
return atomic_load(&buf->buffer->refcount) == 1;
}
void *av_buffer_get_opaque(const AVBufferRef *buf)
{
return buf->buffer->opaque;
}
int av_buffer_get_ref_count(const AVBufferRef *buf)
{
return atomic_load(&buf->buffer->refcount);
}
int av_buffer_make_writable(AVBufferRef **pbuf)
{
AVBufferRef *newbuf, *buf = *pbuf;
if (av_buffer_is_writable(buf))
return 0;
newbuf = av_buffer_alloc(buf->size);
if (!newbuf)
return AVERROR(ENOMEM);
memcpy(newbuf->data, buf->data, buf->size);
buffer_replace(pbuf, &newbuf);
return 0;
}
int av_buffer_realloc(AVBufferRef **pbuf, size_t size)
{
AVBufferRef *buf = *pbuf;
uint8_t *tmp;
int ret;
if (!buf) {
/* allocate a new buffer with av_realloc(), so it will be reallocatable
* later */
uint8_t *data = av_realloc(NULL, size);
if (!data)
return AVERROR(ENOMEM);
buf = av_buffer_create(data, size, av_buffer_default_free, NULL, 0);
if (!buf) {
av_freep(&data);
return AVERROR(ENOMEM);
}
buf->buffer->flags_internal |= BUFFER_FLAG_REALLOCATABLE;
*pbuf = buf;
return 0;
} else if (buf->size == size)
return 0;
if (!(buf->buffer->flags_internal & BUFFER_FLAG_REALLOCATABLE) ||
!av_buffer_is_writable(buf) || buf->data != buf->buffer->data) {
/* cannot realloc, allocate a new reallocable buffer and copy data */
AVBufferRef *new = NULL;
ret = av_buffer_realloc(&new, size);
if (ret < 0)
return ret;
memcpy(new->data, buf->data, FFMIN(size, buf->size));
buffer_replace(pbuf, &new);
return 0;
}
tmp = av_realloc(buf->buffer->data, size);
if (!tmp)
return AVERROR(ENOMEM);
buf->buffer->data = buf->data = tmp;
buf->buffer->size = buf->size = size;
return 0;
}
int av_buffer_replace(AVBufferRef **pdst, const AVBufferRef *src)
{
AVBufferRef *dst = *pdst;
AVBufferRef *tmp;
if (!src) {
av_buffer_unref(pdst);
return 0;
}
if (dst && dst->buffer == src->buffer) {
/* make sure the data pointers match */
dst->data = src->data;
dst->size = src->size;
return 0;
}
tmp = av_buffer_ref(src);
if (!tmp)
return AVERROR(ENOMEM);
av_buffer_unref(pdst);
*pdst = tmp;
return 0;
}
AVBufferPool *av_buffer_pool_init2(size_t size, void *opaque,
AVBufferRef* (*alloc)(void *opaque, size_t size),
void (*pool_free)(void *opaque))
{
AVBufferPool *pool = av_mallocz(sizeof(*pool));
if (!pool)
return NULL;
ff_mutex_init(&pool->mutex, NULL);
pool->size = size;
pool->opaque = opaque;
pool->alloc2 = alloc;
pool->alloc = av_buffer_alloc; // fallback
pool->pool_free = pool_free;
atomic_init(&pool->refcount, 1);
return pool;
}
AVBufferPool *av_buffer_pool_init(size_t size, AVBufferRef* (*alloc)(size_t size))
{
AVBufferPool *pool = av_mallocz(sizeof(*pool));
if (!pool)
return NULL;
ff_mutex_init(&pool->mutex, NULL);
pool->size = size;
pool->alloc = alloc ? alloc : av_buffer_alloc;
atomic_init(&pool->refcount, 1);
return pool;
}
static void buffer_pool_flush(AVBufferPool *pool)
{
while (pool->pool) {
BufferPoolEntry *buf = pool->pool;
pool->pool = buf->next;
buf->free(buf->opaque, buf->data);
av_freep(&buf);
}
}
/*
* This function gets called when the pool has been uninited and
* all the buffers returned to it.
*/
static void buffer_pool_free(AVBufferPool *pool)
{
buffer_pool_flush(pool);
ff_mutex_destroy(&pool->mutex);
if (pool->pool_free)
pool->pool_free(pool->opaque);
av_freep(&pool);
}
void av_buffer_pool_uninit(AVBufferPool **ppool)
{
AVBufferPool *pool;
if (!ppool || !*ppool)
return;
pool = *ppool;
*ppool = NULL;
ff_mutex_lock(&pool->mutex);
buffer_pool_flush(pool);
ff_mutex_unlock(&pool->mutex);
if (atomic_fetch_sub_explicit(&pool->refcount, 1, memory_order_acq_rel) == 1)
buffer_pool_free(pool);
}
static void pool_release_buffer(void *opaque, uint8_t *data)
{
BufferPoolEntry *buf = opaque;
AVBufferPool *pool = buf->pool;
if(CONFIG_MEMORY_POISONING)
memset(buf->data, FF_MEMORY_POISON, pool->size);
ff_mutex_lock(&pool->mutex);
buf->next = pool->pool;
pool->pool = buf;
ff_mutex_unlock(&pool->mutex);
if (atomic_fetch_sub_explicit(&pool->refcount, 1, memory_order_acq_rel) == 1)
buffer_pool_free(pool);
}
/* allocate a new buffer and override its free() callback so that
* it is returned to the pool on free */
static AVBufferRef *pool_alloc_buffer(AVBufferPool *pool)
{
BufferPoolEntry *buf;
AVBufferRef *ret;
av_assert0(pool->alloc || pool->alloc2);
ret = pool->alloc2 ? pool->alloc2(pool->opaque, pool->size) :
pool->alloc(pool->size);
if (!ret)
return NULL;
buf = av_mallocz(sizeof(*buf));
if (!buf) {
av_buffer_unref(&ret);
return NULL;
}
buf->data = ret->buffer->data;
buf->opaque = ret->buffer->opaque;
buf->free = ret->buffer->free;
buf->pool = pool;
ret->buffer->opaque = buf;
ret->buffer->free = pool_release_buffer;
return ret;
}
AVBufferRef *av_buffer_pool_get(AVBufferPool *pool)
{
AVBufferRef *ret;
BufferPoolEntry *buf;
ff_mutex_lock(&pool->mutex);
buf = pool->pool;
if (buf) {
memset(&buf->buffer, 0, sizeof(buf->buffer));
ret = buffer_create(&buf->buffer, buf->data, pool->size,
pool_release_buffer, buf, 0);
if (ret) {
pool->pool = buf->next;
buf->next = NULL;
buf->buffer.flags_internal |= BUFFER_FLAG_NO_FREE;
}
} else {
ret = pool_alloc_buffer(pool);
}
ff_mutex_unlock(&pool->mutex);
if (ret)
atomic_fetch_add_explicit(&pool->refcount, 1, memory_order_relaxed);
return ret;
}
void *av_buffer_pool_buffer_get_opaque(const AVBufferRef *ref)
{
BufferPoolEntry *buf = ref->buffer->opaque;
av_assert0(buf);
return buf->opaque;
}