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

[Nuo Mi <nuomi2021@gmail.com>]

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.
---
 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"
+
+typedef struct ThreadInfo {
+    int idx;
+    VVCExecutor *e;
+    pthread_t thread;
+} ThreadInfo;
+
+struct VVCExecutor {
+    VVCTaskCallbacks cb;
+    ThreadInfo *threads;
+    uint8_t *local_contexts;
+    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);
+}
diff --git a/libavcodec/vvc/vvc_executor.h b/libavcodec/vvc/vvc_executor.h
new file mode 100644
index 0000000000..79c00d58ca
--- /dev/null
+++ b/libavcodec/vvc/vvc_executor.h
@@ -0,0 +1,73 @@
+/*
+ * 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
+ */
+
+#ifndef AVCODEC_VVC_EXECUTOR_H
+#define AVCODEC_VVC_EXECUTOR_H
+
+typedef struct VVCExecutor VVCExecutor;
+typedef struct VVCTasklet VVCTasklet;
+
+struct VVCTasklet {
+    VVCTasklet *next;
+};
+
+typedef struct VVCTaskCallbacks {
+    void *user_data;
+
+    int local_context_size;
+
+    // return 1 if a's priority > b's priority
+    int (*priority_higher)(const VVCTasklet *a, const VVCTasklet *b);
+
+    // task is ready for run
+    int (*ready)(const VVCTasklet *t, void *user_data);
+
+    // run the task
+    int (*run)(VVCTasklet *t, void *local_context, void *user_data);
+} VVCTaskCallbacks;
+
+/**
+ * Alloc executor
+ * @param callbacks callback strucutre for executor
+ * @param thread_count worker thread number
+ * @return return the executor
+ */
+VVCExecutor* ff_vvc_executor_alloc(const VVCTaskCallbacks *callbacks, int thread_count);
+
+/**
+ * Free executor
+ * @param e  pointer to executor
+ */
+void ff_vvc_executor_free(VVCExecutor **e);
+
+/**
+ * Add task to executor
+ * @param e pointer to executor
+ * @param t pointer to task
+ */
+void ff_vvc_executor_execute(VVCExecutor *e, VVCTasklet *t);
+
+/**
+ * Wakeup all threads
+ * @param e pointer to executor
+ */
+void ff_vvc_executor_wakeup(VVCExecutor *e);
+
+#endif //AVCODEC_VVC_EXECUTOR_H
-- 
2.25.1

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