avutil: add thread executor

The executor design pattern was introduced 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.

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

1 files changed, 67 insertions, 0 deletions

diff --git a/libavutil/executor.h b/libavutil/executor.h
new file mode 100644
index 0000000000..c602bcb613
--- /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 structure 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