整理

include/boost/smart_ptr/detail/spinlock_std_atomic.hpp

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+#ifndef BOOST_SMART_PTR_DETAIL_SPINLOCK_STD_ATOMIC_HPP_INCLUDED
+#define BOOST_SMART_PTR_DETAIL_SPINLOCK_STD_ATOMIC_HPP_INCLUDED
+
+// MS compatible compilers support #pragma once
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1020)
+# pragma once
+#endif
+
+//
+//  Copyright (c) 2014 Peter Dimov
+//
+//  Distributed under the Boost Software License, Version 1.0.
+//  See accompanying file LICENSE_1_0.txt or copy at
+//  http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <boost/smart_ptr/detail/yield_k.hpp>
+#include <atomic>
+
+#if defined(BOOST_SP_REPORT_IMPLEMENTATION)
+
+#include <boost/config/pragma_message.hpp>
+BOOST_PRAGMA_MESSAGE("Using std::atomic spinlock")
+
+#endif
+
+namespace boost
+{
+
+namespace detail
+{
+
+class spinlock
+{
+public:
+
+    std::atomic_flag v_;
+
+public:
+
+    bool try_lock() noexcept
+    {
+        return !v_.test_and_set( std::memory_order_acquire );
+    }
+
+    void lock() noexcept
+    {
+        for( unsigned k = 0; !try_lock(); ++k )
+        {
+            boost::detail::yield( k );
+        }
+    }
+
+    void unlock() noexcept
+    {
+        v_ .clear( std::memory_order_release );
+    }
+
+public:
+
+    class scoped_lock
+    {
+    private:
+
+        spinlock & sp_;
+
+        scoped_lock( scoped_lock const & );
+        scoped_lock & operator=( scoped_lock const & );
+
+    public:
+
+        explicit scoped_lock( spinlock & sp ) noexcept: sp_( sp )
+        {
+            sp.lock();
+        }
+
+        ~scoped_lock() /*noexcept*/
+        {
+            sp_.unlock();
+        }
+    };
+};
+
+} // namespace detail
+} // namespace boost
+
+#define BOOST_DETAIL_SPINLOCK_INIT { ATOMIC_FLAG_INIT }
+
+#endif // #ifndef BOOST_SMART_PTR_DETAIL_SPINLOCK_STD_ATOMIC_HPP_INCLUDED