[FFmpeg-devel] [PATCH v3] vvcdec: add thread executor
Nuo Mi
nuomi2021 at gmail.com
Wed Jul 19 16:13:00 EEST 2023
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 bd9c6f9e32..b40aacdd06 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 \
@@ -126,6 +127,7 @@ 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..9823fc3d5d
--- /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)
+#endif
+
+typedef struct ThreadInfo {
+ AVExecutor *e;
+ pthread_t 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* avpriv_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 avpriv_executor_free(AVExecutor **executor)
+{
+ if (!executor || !*executor)
+ return;
+ executor_free(*executor, 1, 1);
+ *executor = NULL;
+}
+
+void avpriv_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..48c7d47c7d
--- /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* avpriv_executor_alloc(const AVTaskCallbacks *callbacks, int thread_count);
+
+/**
+ * Free executor
+ * @param e pointer to executor
+ */
+void avpriv_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 avpriv_executor_execute(AVExecutor *e, AVTask *t);
+
+#endif //AVUTIL_EXECUTOR_H
--
2.25.1
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