On Tue, Sep 19, 2023 at 09:57:09PM +0200, Andreas Rheinhardt wrote:
> Very similar to the AVBufferPool API, but with some differences:
> 1. Reusing an already existing entry does not incur an allocation
> at all any more (the AVBufferPool API needs to allocate an AVBufferRef).
> 2. The tasks done while holding the lock are smaller; e.g.
> allocating new entries is now performed without holding the lock.
> The same goes for freeing.
> 3. The entries are freed as soon as possible (the AVBufferPool API
> frees them in two batches: The first in av_buffer_pool_uninit() and
> the second immediately before the pool is freed when the last
> outstanding entry is returned to the pool).
> 4. The API is designed for objects and not naked buffers and
> therefore has a reset callback. This is called whenever an object
> is returned to the pool.
> 5. Just like with the RefStruct API, custom allocators are not
> supported.
> 
> (If desired, the FFRefStructPool struct itself could be made
> reference counted via the RefStruct API; an FFRefStructPool
> would then be freed via ff_refstruct_unref().)
> 
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
> ---
>  libavcodec/refstruct.c | 194 ++++++++++++++++++++++++++++++++++++++++-
>  libavcodec/refstruct.h | 128 +++++++++++++++++++++++++++
>  2 files changed, 321 insertions(+), 1 deletion(-)

seems to break building on ppc (--disable-pthreads)

CC	libavcodec/refstruct.o
src/libavcodec/refstruct.c: In function ‘pool_free’:
src/libavcodec/refstruct.c:187:5: error: implicit declaration of function ‘pthread_mutex_destroy’; did you mean ‘ff_mutex_destroy’? [-Werror=implicit-function-declaration]
     pthread_mutex_destroy(&pool->mutex);
     ^~~~~~~~~~~~~~~~~~~~~
     ff_mutex_destroy
src/libavcodec/refstruct.c: In function ‘pool_return_entry’:
src/libavcodec/refstruct.c:205:5: error: implicit declaration of function ‘pthread_mutex_lock’; did you mean ‘ff_mutex_lock’? [-Werror=implicit-function-declaration]
     pthread_mutex_lock(&pool->mutex);
     ^~~~~~~~~~~~~~~~~~
     ff_mutex_lock
src/libavcodec/refstruct.c:211:5: error: implicit declaration of function ‘pthread_mutex_unlock’; did you mean ‘ff_mutex_unlock’? [-Werror=implicit-function-declaration]
     pthread_mutex_unlock(&pool->mutex);
     ^~~~~~~~~~~~~~~~~~~~
     ff_mutex_unlock
src/libavcodec/refstruct.c: In function ‘ff_refstruct_pool_alloc_ext_c’:
src/libavcodec/refstruct.c:339:11: error: implicit declaration of function ‘pthread_mutex_init’; did you mean ‘ff_mutex_init’? [-Werror=implicit-function-declaration]
     err = pthread_mutex_init(&pool->mutex, NULL);
           ^~~~~~~~~~~~~~~~~~
           ff_mutex_init
cc1: some warnings being treated as errors
/home/michael/ffmpeg-git/ffmpeg/ffbuild/common.mak:81: recipe for target 'libavcodec/refstruct.o' failed
make: *** [libavcodec/refstruct.o] Error 1
make: Target 'all' not remade because of errors.


[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

During times of universal deceit, telling the truth becomes a
revolutionary act. -- George Orwell