[FFmpeg-devel] [PATCH v4] vvcdec: add thread executor
James Almer
jamrial at gmail.com
Fri Aug 18 18:54:33 EEST 2023
On 8/16/2023 1:42 PM, Rémi Denis-Courmont wrote:
> Le tiistaina 15. elokuuta 2023, 17.50.13 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. ---
>> 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
>
> Err, this should probably return an error value, e.g. ENOSYS or ENOTSUP.
pthread_create() is used below even if !HAVE_THREADS, so it should not fail.
>
>> +#define pthread_join(t, r) do {} while(0)
>
> ...and this should be an unreachable(), assert(0), abort() or something along
> those lines.
This is also used below. It being a no-op should be ok.
>
>> +
>> +#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)
>> +#endif
>> +
>> +typedef struct ThreadInfo {
>> + AVExecutor *e;
>> + pthread_t thread;
>
> Does this even work if !HAVE_THREAD ?
>
>> +} ThreadInfo;
>> +
>> +struct AVExecutor {
>> + AVTaskCallbacks cb;
>> + int thread_count;
>> +
>> + ThreadInfo *threads;
>> + uint8_t *local_contexts;
>> +
>> + pthread_mutex_t lock;
>> + pthread_cond_t cond;
>> + 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));
>> + 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
>
>
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