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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>
This commit is contained in:
Andreas Rheinhardt 2021-09-14 11:29:23 +02:00
parent 6556146aa0
commit 4e0da7d311
2 changed files with 41 additions and 14 deletions
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44
libavutil/buffer.c
View File

@ -26,16 +26,11 @@
#include "mem.h"
#include "thread.h"
AVBufferRef *av_buffer_create(uint8_t *data, size_t size,
void (*free)(void *opaque, uint8_t *data),
void *opaque, int flags)
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;
AVBuffer *buf = NULL;
buf = av_mallocz(sizeof(*buf));
if (!buf)
return NULL;
buf->data = data;
buf->size = size;
@ -47,10 +42,8 @@ AVBufferRef *av_buffer_create(uint8_t *data, size_t size,
buf->flags = flags;
ref = av_mallocz(sizeof(*ref));
if (!ref) {
av_freep(&buf);
if (!ref)
return NULL;
}
ref->buffer = buf;
ref->data = data;
@ -59,6 +52,23 @@ AVBufferRef *av_buffer_create(uint8_t *data, size_t 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);
@ -117,8 +127,12 @@ static void buffer_replace(AVBufferRef **dst, AVBufferRef **src)
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);
av_freep(&b);
if (free_avbuffer)
av_free(b);
}
}
@ -378,11 +392,13 @@ AVBufferRef *av_buffer_pool_get(AVBufferPool *pool)
ff_mutex_lock(&pool->mutex);
buf = pool->pool;
if (buf) {
ret = av_buffer_create(buf->data, pool->size, pool_release_buffer,
buf, 0);
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);

11
libavutil/buffer_internal.h
View File

@ -30,6 +30,11 @@
* The buffer was av_realloc()ed, so it is reallocatable.
*/
#define BUFFER_FLAG_REALLOCATABLE (1 << 0)
/**
* The AVBuffer structure is part of a larger structure
* and should not be freed.
*/
#define BUFFER_FLAG_NO_FREE (1 << 1)
struct AVBuffer {
uint8_t *data; /**< data described by this buffer */
@ -73,6 +78,12 @@ typedef struct BufferPoolEntry {
AVBufferPool *pool;
struct BufferPoolEntry *next;
/*
* An AVBuffer structure to (re)use as AVBuffer for subsequent uses
* of this BufferPoolEntry.
*/
AVBuffer buffer;
} BufferPoolEntry;
struct AVBufferPool {