Re: [FFmpeg-devel] [PATCH 01/14] vvcdec: add thread executor

[Nuo Mi <nuomi2021@gmail.com>]

On Sun, May 21, 2023 at 9:15 PM Rémi Denis-Courmont <remi@remlab.net> wrote:

> Le sunnuntaina 21. toukokuuta 2023, 16.03.06 EEST Nuo Mi a écrit :
> > The executor design pattern was inroduced by java
> > <
> https://docs.oracle.com/en/java/javase/20/docs/api/java.base/java/util/conc
> > urrent/Executor.html> it also adapted by python
> > <https://docs.python.org/3/library/concurrent.futures.html>
> > Compared to handcrafted thread pool management, it greatly simplifies the
> > thread code. ---
> >  libavcodec/Makefile           |   1 +
> >  libavcodec/vvc/Makefile       |   4 +
> >  libavcodec/vvc/vvc_executor.c | 193 ++++++++++++++++++++++++++++++++++
> >  libavcodec/vvc/vvc_executor.h |  73 +++++++++++++
> >  4 files changed, 271 insertions(+)
> >  create mode 100644 libavcodec/vvc/Makefile
> >  create mode 100644 libavcodec/vvc/vvc_executor.c
> >  create mode 100644 libavcodec/vvc/vvc_executor.h
> >
> > diff --git a/libavcodec/Makefile b/libavcodec/Makefile
> > index dab09f483a..b1fcbf71b2 100644
> > --- a/libavcodec/Makefile
> > +++ b/libavcodec/Makefile
> > @@ -62,6 +62,7 @@ OBJS = ac3_parser.o
>
> >              \ xiph.o
>
> >     \
> >
> >  # subsystems
> > +include $(SRC_PATH)/libavcodec/vvc/Makefile
> >  OBJS-$(CONFIG_AANDCTTABLES)            += aandcttab.o
> >  OBJS-$(CONFIG_AC3DSP)                  += ac3dsp.o ac3.o ac3tab.o
> >  OBJS-$(CONFIG_ADTS_HEADER)             += adts_header.o
> > mpeg4audio_sample_rates.o diff --git a/libavcodec/vvc/Makefile
> > b/libavcodec/vvc/Makefile
> > new file mode 100644
> > index 0000000000..c4b93e0389
> > --- /dev/null
> > +++ b/libavcodec/vvc/Makefile
> > @@ -0,0 +1,4 @@
> > +clean::
> > +     $(RM) $(CLEANSUFFIXES:%=libavcodec/vvc/%)
> > +
> > +OBJS-$(CONFIG_VVC_DECODER)          +=  vvc/vvc_executor.o
> > diff --git a/libavcodec/vvc/vvc_executor.c
> b/libavcodec/vvc/vvc_executor.c
> > new file mode 100644
> > index 0000000000..f2afdf79ae
> > --- /dev/null
> > +++ b/libavcodec/vvc/vvc_executor.c
> > @@ -0,0 +1,193 @@
> > +/*
> > + * VVC video Decoder
> > + *
> > + * Copyright (C) 2022 Nuo Mi
> > + *
> > + * 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 "libavutil/avutil.h"
> > +#include "libavutil/thread.h"
> > +
> > +#include "vvc_executor.h"
>
> This does not seem specific to VVC in any way, so the naming (and choice
> of
> folder placement) is rather weird.
>
The utils can use as filter, encoder or any component.
Will move to libavcodec first. Somebody can promote it to libavutils if
they find it useful.

>
> > +
> > +typedef struct ThreadInfo {
> > +    int idx;
> > +    VVCExecutor *e;
> > +    pthread_t thread;
> > +} ThreadInfo;
> > +
> > +struct VVCExecutor {
> > +    VVCTaskCallbacks cb;
> > +    ThreadInfo *threads;
> > +    uint8_t *local_contexts;
>
> It seems odd and needless complex to separate this from the thread info.
> It
> looks like you could simply append a pointer or a flexible array to
> ThreadInfo
> instead.
>
> > +    int thread_count;
> > +
> > +    pthread_mutex_t lock;
> > +    pthread_cond_t cond;
> > +    int die;
> > +    VVCTasklet *tasks;
> > +};
> > +
> > +static void remove_task(VVCTasklet **prev, VVCTasklet *t)
> > +{
> > +    *prev  = t->next;
> > +    t->next = NULL;
> > +}
> > +
> > +static void add_task(VVCTasklet **prev, VVCTasklet *t)
> > +{
> > +    t->next = *prev;
> > +    *prev   = t;
> > +}
> > +
> > +static void *executor_worker_task(void *data)
> > +{
> > +    ThreadInfo *ti = (ThreadInfo*)data;
> > +    VVCExecutor *e = ti->e;
> > +    void *lc       = e->local_contexts + ti->idx *
> > e->cb.local_context_size;
> > +    VVCTasklet **prev;
> > +    VVCTaskCallbacks *cb = &e->cb;
> > +
> > +    pthread_mutex_lock(&e->lock);
> > +    while (1) {
> > +        VVCTasklet* t = NULL;
> > +        if (e->die) break;
> > +
> > +        for (prev = &e->tasks; *prev; prev = &(*prev)->next) {
> > +            if (cb->ready(*prev, cb->user_data)) {
> > +                t = *prev;
> > +                break;
> > +            }
> > +        }
> > +        if (t) {
> > +            //found one task
> > +            remove_task(prev, t);
> > +            pthread_mutex_unlock(&e->lock);
> > +            cb->run(t, lc, cb->user_data);
> > +            pthread_mutex_lock(&e->lock);
> > +        } else {
> > +            //no task in one loop
> > +            pthread_cond_wait(&e->cond, &e->lock);
> > +        }
> > +    }
> > +    pthread_mutex_unlock(&e->lock);
> > +    return NULL;
> > +}
> > +
> > +VVCExecutor* ff_vvc_executor_alloc(const VVCTaskCallbacks *cb, int
> > thread_count) +{
> > +    VVCExecutor *e;
> > +    int i, j, ret;
> > +    if (!cb || !cb->user_data || !cb->ready || !cb->run ||
> > !cb->priority_higher) +        return NULL;
> > +    e = av_calloc(1, sizeof(*e));
> > +    if (!e)
> > +        return NULL;
> > +    e->cb = *cb;
> > +
> > +    e->local_contexts = av_malloc(thread_count *
> e->cb.local_context_size);
> > +    if (!e->local_contexts)
> > +        goto free_executor;
> > +
> > +    e->threads = av_calloc(thread_count, sizeof(*e->threads));
> > +    if (!e->threads)
> > +        goto free_contexts;
> > +    for (i = 0; i < thread_count; i++) {
> > +        ThreadInfo *ti = e->threads + i;
> > +        ti->e = e;
> > +        ti->idx = i;
> > +    }
> > +
> > +    ret = pthread_mutex_init(&e->lock, NULL);
> > +    if (ret)
> > +        goto free_threads;
> > +
> > +    ret = pthread_cond_init(&e->cond, NULL);
> > +    if (ret)
> > +        goto destroy_lock;
> > +
> > +    for (i = 0; i < thread_count; i++) {
> > +        ThreadInfo *ti = e->threads + i;
> > +        ret = pthread_create(&ti->thread, NULL, executor_worker_task,
> ti);
> > +        if (ret)
> > +            goto join_threads;
> > +    }
> > +    e->thread_count = thread_count;
> > +    return e;
> > +
> > +join_threads:
> > +    pthread_mutex_lock(&e->lock);
> > +    e->die = 1;
> > +    pthread_cond_broadcast(&e->cond);
> > +    pthread_mutex_unlock(&e->lock);
> > +    for (j = 0; j < i; j++)
> > +        pthread_join(e->threads[j].thread, NULL);
> > +    pthread_cond_destroy(&e->cond);
> > +destroy_lock:
> > +    pthread_mutex_destroy(&e->lock);
> > +free_threads:
> > +    av_free(e->threads);
> > +free_contexts:
> > +    av_free(e->local_contexts);
> > +free_executor:
> > +    free(e);
> > +    return NULL;
> > +}
> > +
> > +void ff_vvc_executor_free(VVCExecutor **executor)
> > +{
> > +    VVCExecutor *e;
> > +    if (!executor || !*executor)
> > +        return;
> > +    e = *executor;
> > +
> > +    //singal die
> > +    pthread_mutex_lock(&e->lock);
> > +    e->die = 1;
> > +    pthread_cond_broadcast(&e->cond);
> > +    pthread_mutex_unlock(&e->lock);
> > +
> > +    for (int i = 0; i < e->thread_count; i++)
> > +        pthread_join(e->threads[i].thread, NULL);
> > +    pthread_cond_destroy(&e->cond);
> > +    pthread_mutex_destroy(&e->lock);
> > +
> > +    av_free(e->threads);
> > +    av_free(e->local_contexts);
> > +
> > +    av_freep(executor);
> > +}
> > +
> > +void ff_vvc_executor_execute(VVCExecutor *e, VVCTasklet *t)
> > +{
> > +    VVCTaskCallbacks *cb = &e->cb;
> > +    VVCTasklet **prev;
> > +
> > +    pthread_mutex_lock(&e->lock);
> > +    for (prev = &e->tasks; *prev && cb->priority_higher(*prev, t); prev
> =
> > &(*prev)->next) +        /* nothing */;
> > +    add_task(prev, t);
> > +    pthread_cond_signal(&e->cond);
> > +    pthread_mutex_unlock(&e->lock);
> > +}
> > +
> > +void ff_vvc_executor_wakeup(VVCExecutor *e)
> > +{
> > +    pthread_mutex_lock(&e->lock);
> > +    pthread_cond_broadcast(&e->cond);
> > +    pthread_mutex_unlock(&e->lock);
>
> Signaling a condition variable without changing any state makes no sense.
>
> > +}
>
> --
> Rémi Denis-Courmont
> http://www.remlab.net/
>
>
>
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