[FFmpeg-devel] [PATCH v4] vvcdec: add thread executor
James Almer
jamrial at gmail.com
Fri Aug 18 19:17:11 EEST 2023
On 8/15/2023 11:50 AM, Nuo Mi wrote:
> The executor design pattern was inroduced by java
> <https://docs.oracle.com/en/java/javase/20/docs/api/java.base/java/util/concurrent/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.
> ---
> libavutil/Makefile | 2 +
> libavutil/executor.c | 201 +++++++++++++++++++++++++++++++++++++++++++
> libavutil/executor.h | 67 +++++++++++++++
> 3 files changed, 270 insertions(+)
> create mode 100644 libavutil/executor.c
> create mode 100644 libavutil/executor.h
>
> diff --git a/libavutil/Makefile b/libavutil/Makefile
> index 7828c94dc5..4711f8cde8 100644
> --- a/libavutil/Makefile
> +++ b/libavutil/Makefile
> @@ -31,6 +31,7 @@ HEADERS = adler32.h \
> encryption_info.h \
> error.h \
> eval.h \
> + executor.h \
> fifo.h \
> file.h \
> frame.h \
> @@ -127,6 +128,7 @@ OBJS = adler32.o \
> encryption_info.o \
> error.o \
> eval.o \
> + executor.o \
> fifo.o \
> file.o \
> file_open.o \
> diff --git a/libavutil/executor.c b/libavutil/executor.c
> new file mode 100644
> index 0000000000..6b47ba0bf2
> --- /dev/null
> +++ b/libavutil/executor.c
> @@ -0,0 +1,201 @@
> +/*
> + * Copyright (C) 2023 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 "internal.h"
> +#include "mem.h"
> +#include "thread.h"
> +
> +#include "executor.h"
> +
> +#if !HAVE_THREADS
> +#define pthread_create(t, a, s, ar) 0
> +#define pthread_join(t, r) do {} while(0)
> +
> +#define pthread_cond_init(c, a) 0
> +#define pthread_cond_broadcast(c) do {} while(0)
> +#define pthread_cond_signal(c) do {} while(0)
> +#define pthread_cond_wait(c, m) do {} while(0)
> +#define pthread_cond_destroy(c) do {} while(0)
> +
> +#define pthread_mutex_init(m, a) 0
> +#define pthread_mutex_lock(l) do {} while(0)
> +#define pthread_mutex_unlock(l) do {} while(0)
> +#define pthread_mutex_destroy(l) do {} while(0)
You have ff_mutex_* and AVMutex for this. I sent a patch adding
ff_cond_* and AVCond, as well as ff_thread_create/join and AVThread to
thread.h to simplify things.
> +#endif
> +
> +typedef struct ThreadInfo {
> + AVExecutor *e;
> + pthread_t thread;
You will need to use AVThread, else this will not be defined when
!HAVE_THREADS.
> +} ThreadInfo;
> +
> +struct AVExecutor {
> + AVTaskCallbacks cb;
> + int thread_count;
> +
> + ThreadInfo *threads;
> + uint8_t *local_contexts;
> +
> + pthread_mutex_t lock;
> + pthread_cond_t cond;
Same here. AVMutex and AVCond.
> + int die;
> +
> + AVTask *tasks;
> +};
> +
> +static AVTask* remove_task(AVTask **prev, AVTask *t)
> +{
> + *prev = t->next;
> + t->next = NULL;
> + return t;
> +}
> +
> +static void add_task(AVTask **prev, AVTask *t)
> +{
> + t->next = *prev;
> + *prev = t;
> +}
> +
> +static int run_one_task(AVExecutor *e, void *lc)
> +{
> + AVTaskCallbacks *cb = &e->cb;
> + AVTask **prev;
> +
> + for (prev = &e->tasks; *prev && !cb->ready(*prev, cb->user_data); prev = &(*prev)->next)
> + /* nothing */;
> + if (*prev) {
> + AVTask *t = remove_task(prev, *prev);
> + pthread_mutex_unlock(&e->lock);
> + cb->run(t, lc, cb->user_data);
> + pthread_mutex_lock(&e->lock);
> + return 1;
> + }
> + return 0;
> +}
> +
> +#if HAVE_THREADS
> +static void *executor_worker_task(void *data)
> +{
> + ThreadInfo *ti = (ThreadInfo*)data;
> + AVExecutor *e = ti->e;
> + void *lc = e->local_contexts + (ti - e->threads) * e->cb.local_context_size;
> +
> + pthread_mutex_lock(&e->lock);
> + while (1) {
> + if (e->die) break;
> +
> + if (!run_one_task(e, lc)) {
> + //no task in one loop
> + pthread_cond_wait(&e->cond, &e->lock);
> + }
> + }
> + pthread_mutex_unlock(&e->lock);
> + return NULL;
> +}
> +#endif
> +
> +static void executor_free(AVExecutor *e, const int has_lock, const int has_cond)
> +{
> + if (e->thread_count) {
> + //signal 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);
> + }
> + if (has_cond)
> + pthread_cond_destroy(&e->cond);
> + if (has_lock)
> + pthread_mutex_destroy(&e->lock);
> +
> + av_free(e->threads);
> + av_free(e->local_contexts);
> +
> + av_free(e);
> +}
> +
> +AVExecutor* av_executor_alloc(const AVTaskCallbacks *cb, int thread_count)
> +{
> + AVExecutor *e;
> + int has_lock = 0, has_cond = 0;
> + if (!cb || !cb->user_data || !cb->ready || !cb->run || !cb->priority_higher)
> + return NULL;
> +
> + e = av_calloc(1, sizeof(*e));
av_mallocz()
> + if (!e)
> + return NULL;
> + e->cb = *cb;
> +
> + e->local_contexts = av_calloc(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_executor;
> +
> + has_lock = !pthread_mutex_init(&e->lock, NULL);
> + has_cond = !pthread_cond_init(&e->cond, NULL);
> +
> + if (!has_lock || !has_cond)
> + goto free_executor;
> +
> + for (/* nothing */; e->thread_count < thread_count; e->thread_count++) {
> + ThreadInfo *ti = e->threads + e->thread_count;
> + ti->e = e;
> + if (pthread_create(&ti->thread, NULL, executor_worker_task, ti))
> + goto free_executor;
> + }
> + return e;
> +
> +free_executor:
> + executor_free(e, has_lock, has_cond);
> + return NULL;
> +}
> +
> +void av_executor_free(AVExecutor **executor)
> +{
> + if (!executor || !*executor)
> + return;
> + executor_free(*executor, 1, 1);
> + *executor = NULL;
> +}
> +
> +void av_executor_execute(AVExecutor *e, AVTask *t)
> +{
> + AVTaskCallbacks *cb = &e->cb;
> + AVTask **prev;
> +
> + pthread_mutex_lock(&e->lock);
> + if (t) {
> + 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);
> +
> +#if !HAVE_THREADS
> + // We are running in a single-threaded environment, so we must handle all tasks ourselves
> + while (run_one_task(e, e->local_contexts))
> + /* nothing */;
> +#endif
> +}
> diff --git a/libavutil/executor.h b/libavutil/executor.h
> new file mode 100644
> index 0000000000..c3fe44bd0e
> --- /dev/null
> +++ b/libavutil/executor.h
> @@ -0,0 +1,67 @@
> +/*
> + * Copyright (C) 2023 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
> + */
> +
> +#ifndef AVUTIL_EXECUTOR_H
> +#define AVUTIL_EXECUTOR_H
> +
> +typedef struct AVExecutor AVExecutor;
> +typedef struct AVTask AVTask;
> +
> +struct AVTask {
> + AVTask *next;
> +};
> +
> +typedef struct AVTaskCallbacks {
> + void *user_data;
> +
> + int local_context_size;
> +
> + // return 1 if a's priority > b's priority
> + int (*priority_higher)(const AVTask *a, const AVTask *b);
> +
> + // task is ready for run
> + int (*ready)(const AVTask *t, void *user_data);
> +
> + // run the task
> + int (*run)(AVTask *t, void *local_context, void *user_data);
> +} AVTaskCallbacks;
> +
> +/**
> + * Alloc executor
> + * @param callbacks callback strucutre for executor
> + * @param thread_count worker thread number
> + * @return return the executor
> + */
> +AVExecutor* av_executor_alloc(const AVTaskCallbacks *callbacks, int thread_count);
> +
> +/**
> + * Free executor
> + * @param e pointer to executor
> + */
> +void av_executor_free(AVExecutor **e);
> +
> +/**
> + * Add task to executor
> + * @param e pointer to executor
> + * @param t pointer to task. If NULL, it will wakeup one work thread
> + */
> +void av_executor_execute(AVExecutor *e, AVTask *t);
> +
> +#endif //AVUTIL_EXECUTOR_H
More information about the ffmpeg-devel
mailing list