import RT-Thread@9217865c without bsp, libcpu and components/net

components/libc/cplusplus/cpp11/gcc/mutex.cpp

@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 2006-2021, RT-Thread Development Team
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Change Logs:
+ * Date           Author       Notes
+ * 2021-04-27     flybreak     the first version.
+ */
+
+#include "mutex"
+
+namespace std
+{
+    // use a set of global and static objects
+    // a proxy function to pthread_once
+
+    function<void()> once_functor;
+
+    mutex& get_once_mutex()
+    {
+        static mutex once_mutex;
+        return once_mutex;
+    }
+
+    inline unique_lock<mutex>*& get_once_functor_lock_ptr()
+    {
+        static unique_lock<mutex>* once_functor_mutex_ptr = nullptr;
+        return once_functor_mutex_ptr;
+    }
+
+    void set_once_functor_lock_ptr(unique_lock<mutex>* m_ptr)
+    {
+        get_once_functor_lock_ptr() = m_ptr;
+    }
+
+    extern "C"
+    {
+        void once_proxy()
+        {
+            // need to first transfer the functor's ownership so as to call it
+            function<void()> once_call = std::move(once_functor);
+
+            // no need to hold the lock anymore
+            unique_lock<mutex>* lock_ptr = get_once_functor_lock_ptr();
+            get_once_functor_lock_ptr() = nullptr;
+            lock_ptr->unlock();
+
+            once_call();
+        }
+    }
+}