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libavcodec/utils.c: simplify avcodec locking with atomics

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Also makes it more robust than using volatiles.

Signed-off-by: Rostislav Pehlivanov <atomnuker@gmail.com>
This commit is contained in:
Rostislav Pehlivanov 2017-11-25 16:55:44 +00:00
parent 3154f4417a
commit 590136e78d
2 changed files with 6 additions and 7 deletions
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1
libavcodec/internal.h
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@ -246,7 +246,6 @@ int ff_init_buffer_info(AVCodecContext *s, AVFrame *frame);
void ff_color_frame(AVFrame *frame, const int color[4]);
extern volatile int ff_avcodec_locked;
int ff_lock_avcodec(AVCodecContext *log_ctx, const AVCodec *codec);
int ff_unlock_avcodec(const AVCodec *codec);

12
libavcodec/utils.c
View File

@ -114,7 +114,7 @@ static int (*lockmgr_cb)(void **mutex, enum AVLockOp op) = NULL;
#endif
volatile int ff_avcodec_locked;
static atomic_bool ff_avcodec_locked;
static atomic_int entangled_thread_counter = ATOMIC_VAR_INIT(0);
static void *codec_mutex;
static void *avformat_mutex;
@ -1937,6 +1937,7 @@ int av_lockmgr_register(int (*cb)(void **mutex, enum AVLockOp op))
int ff_lock_avcodec(AVCodecContext *log_ctx, const AVCodec *codec)
{
_Bool exp = 0;
if (codec->caps_internal & FF_CODEC_CAP_INIT_THREADSAFE || !codec->init)
return 0;
@ -1952,22 +1953,21 @@ int ff_lock_avcodec(AVCodecContext *log_ctx, const AVCodec *codec)
atomic_load(&entangled_thread_counter));
if (!lockmgr_cb)
av_log(log_ctx, AV_LOG_ERROR, "No lock manager is set, please see av_lockmgr_register()\n");
ff_avcodec_locked = 1;
atomic_store(&ff_avcodec_locked, 1);
ff_unlock_avcodec(codec);
return AVERROR(EINVAL);
}
av_assert0(!ff_avcodec_locked);
ff_avcodec_locked = 1;
av_assert0(atomic_compare_exchange_strong(&ff_avcodec_locked, &exp, 1));
return 0;
}
int ff_unlock_avcodec(const AVCodec *codec)
{
_Bool exp = 1;
if (codec->caps_internal & FF_CODEC_CAP_INIT_THREADSAFE || !codec->init)
return 0;
av_assert0(ff_avcodec_locked);
ff_avcodec_locked = 0;
av_assert0(atomic_compare_exchange_strong(&ff_avcodec_locked, &exp, 0));
atomic_fetch_add(&entangled_thread_counter, -1);
if (lockmgr_cb) {
if ((*lockmgr_cb)(&codec_mutex, AV_LOCK_RELEASE))