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lavc/pthread_frame: add support for thread-safe hwaccels

This commit is contained in:
Anton Khirnov 2023-04-28 13:37:28 +02:00 committed by Lynne
parent 3d2e1aa324
commit 8b23644408
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GPG Key ID: A2FEA5F03F034464
3 changed files with 89 additions and 19 deletions
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6
libavcodec/avcodec.h
View File

@ -2253,6 +2253,12 @@ typedef struct AVHWAccel {
* that avctx->hwaccel_priv_data is invalid.
*/
int (*frame_params)(AVCodecContext *avctx, AVBufferRef *hw_frames_ctx);
/**
* Copy necessary context variables from a previous thread context to the current one.
* For thread-safe hwaccels only.
*/
int (*update_thread_context)(AVCodecContext *dst, const AVCodecContext *src);
} AVHWAccel;
/**

1
libavcodec/hwconfig.h
View File

@ -24,6 +24,7 @@
#define HWACCEL_CAP_ASYNC_SAFE (1 << 0)
#define HWACCEL_CAP_THREAD_SAFE (1 << 1)
typedef struct AVCodecHWConfigInternal {

89
libavcodec/pthread_frame.c
View File

@ -104,6 +104,12 @@ typedef struct PerThreadContext {
int hwaccel_serializing;
int async_serializing;
// set to 1 in ff_thread_finish_setup() when a threadsafe hwaccel is used;
// cannot check hwaccel caps directly, because
// worked threads clear hwaccel state for thread-unsafe hwaccels
// after each decode call
int hwaccel_threadsafe;
atomic_int debug_threads; ///< Set if the FF_DEBUG_THREADS option is set.
} PerThreadContext;
@ -117,8 +123,8 @@ typedef struct FrameThreadContext {
unsigned pthread_init_cnt; ///< Number of successfully initialized mutexes/conditions
pthread_mutex_t buffer_mutex; ///< Mutex used to protect get/release_buffer().
/**
* This lock is used for ensuring threads run in serial when hwaccel
* is used.
* This lock is used for ensuring threads run in serial when thread-unsafe
* hwaccel is used.
*/
pthread_mutex_t hwaccel_mutex;
pthread_mutex_t async_mutex;
@ -133,13 +139,19 @@ typedef struct FrameThreadContext {
* While it is set, ff_thread_en/decode_frame won't return any results.
*/
/* hwaccel state is temporarily stored here in order to transfer its ownership
* to the next decoding thread without the need for extra synchronization */
/* hwaccel state for thread-unsafe hwaccels is temporarily stored here in
* order to transfer its ownership to the next decoding thread without the
* need for extra synchronization */
const AVHWAccel *stash_hwaccel;
void *stash_hwaccel_context;
void *stash_hwaccel_priv;
} FrameThreadContext;
static int hwaccel_serial(const AVCodecContext *avctx)
{
return avctx->hwaccel && !(avctx->hwaccel->caps_internal & HWACCEL_CAP_THREAD_SAFE);
}
static void async_lock(FrameThreadContext *fctx)
{
pthread_mutex_lock(&fctx->async_mutex);
@ -202,9 +214,9 @@ static attribute_align_arg void *frame_worker_thread(void *arg)
* cannot be true here. */
av_assert0(!p->hwaccel_serializing);
/* if the previous thread uses hwaccel then we take the lock to ensure
* the threads don't run concurrently */
if (avctx->hwaccel) {
/* if the previous thread uses thread-unsafe hwaccel then we take the
* lock to ensure the threads don't run concurrently */
if (hwaccel_serial(avctx)) {
pthread_mutex_lock(&p->parent->hwaccel_mutex);
p->hwaccel_serializing = 1;
}
@ -220,7 +232,8 @@ static attribute_align_arg void *frame_worker_thread(void *arg)
ff_thread_finish_setup(avctx);
if (p->hwaccel_serializing) {
/* wipe hwaccel state to avoid stale pointers lying around;
/* wipe hwaccel state for thread-unsafe hwaccels to avoid stale
* pointers lying around;
* the state was transferred to FrameThreadContext in
* ff_thread_finish_setup(), so nothing is leaked */
avctx->hwaccel = NULL;
@ -230,7 +243,8 @@ static attribute_align_arg void *frame_worker_thread(void *arg)
p->hwaccel_serializing = 0;
pthread_mutex_unlock(&p->parent->hwaccel_mutex);
}
av_assert0(!avctx->hwaccel);
av_assert0(!avctx->hwaccel ||
(avctx->hwaccel->caps_internal & HWACCEL_CAP_THREAD_SAFE));
if (p->async_serializing) {
p->async_serializing = 0;
@ -332,8 +346,49 @@ FF_ENABLE_DEPRECATION_WARNINGS
if (codec->update_thread_context_for_user)
err = codec->update_thread_context_for_user(dst, src);
} else {
if (codec->update_thread_context)
const PerThreadContext *p_src = src->internal->thread_ctx;
PerThreadContext *p_dst = dst->internal->thread_ctx;
if (codec->update_thread_context) {
err = codec->update_thread_context(dst, src);
if (err < 0)
return err;
}
// reset dst hwaccel state if needed
av_assert0(p_dst->hwaccel_threadsafe ||
(!dst->hwaccel && !dst->internal->hwaccel_priv_data));
if (p_dst->hwaccel_threadsafe &&
(!p_src->hwaccel_threadsafe || dst->hwaccel != src->hwaccel)) {
ff_hwaccel_uninit(dst);
p_dst->hwaccel_threadsafe = 0;
}
// propagate hwaccel state for threadsafe hwaccels
if (p_src->hwaccel_threadsafe) {
if (!dst->hwaccel) {
if (src->hwaccel->priv_data_size) {
av_assert0(src->hwaccel->update_thread_context);
dst->internal->hwaccel_priv_data =
av_mallocz(src->hwaccel->priv_data_size);
if (!dst->internal->hwaccel_priv_data)
return AVERROR(ENOMEM);
}
dst->hwaccel = src->hwaccel;
}
av_assert0(dst->hwaccel == src->hwaccel);
if (src->hwaccel->update_thread_context) {
err = src->hwaccel->update_thread_context(dst, src);
if (err < 0) {
av_log(dst, AV_LOG_ERROR, "Error propagating hwaccel state\n");
ff_hwaccel_uninit(dst);
return err;
}
}
p_dst->hwaccel_threadsafe = 1;
}
}
return err;
@ -441,10 +496,12 @@ static int submit_packet(PerThreadContext *p, AVCodecContext *user_avctx,
}
/* transfer the stashed hwaccel state, if any */
av_assert0(!p->avctx->hwaccel);
av_assert0(!p->avctx->hwaccel || p->hwaccel_threadsafe);
if (!p->hwaccel_threadsafe) {
FFSWAP(const AVHWAccel*, p->avctx->hwaccel, fctx->stash_hwaccel);
FFSWAP(void*, p->avctx->hwaccel_context, fctx->stash_hwaccel_context);
FFSWAP(void*, p->avctx->internal->hwaccel_priv_data, fctx->stash_hwaccel_priv);
}
av_packet_unref(p->avpkt);
ret = av_packet_ref(p->avpkt, avpkt);
@ -598,7 +655,10 @@ void ff_thread_finish_setup(AVCodecContext *avctx) {
if (!(avctx->active_thread_type&FF_THREAD_FRAME)) return;
if (avctx->hwaccel && !p->hwaccel_serializing) {
p->hwaccel_threadsafe = avctx->hwaccel &&
(avctx->hwaccel->caps_internal & HWACCEL_CAP_THREAD_SAFE);
if (hwaccel_serial(avctx) && !p->hwaccel_serializing) {
pthread_mutex_lock(&p->parent->hwaccel_mutex);
p->hwaccel_serializing = 1;
}
@ -611,13 +671,16 @@ void ff_thread_finish_setup(AVCodecContext *avctx) {
async_lock(p->parent);
}
/* save hwaccel state for passing to the next thread;
/* thread-unsafe hwaccels share a single private data instance, so we
* save hwaccel state for passing to the next thread;
* this is done here so that this worker thread can wipe its own hwaccel
* state after decoding, without requiring synchronization */
av_assert0(!p->parent->stash_hwaccel);
if (hwaccel_serial(avctx)) {
p->parent->stash_hwaccel = avctx->hwaccel;
p->parent->stash_hwaccel_context = avctx->hwaccel_context;
p->parent->stash_hwaccel_priv = avctx->internal->hwaccel_priv_data;
}
pthread_mutex_lock(&p->progress_mutex);
if(atomic_load(&p->state) == STATE_SETUP_FINISHED){