smart_ptr/detail/spinlock_std_atomic.hpp

0001 #ifndef BOOST_SMART_PTR_DETAIL_SPINLOCK_STD_ATOMIC_HPP_INCLUDED
0002 #define BOOST_SMART_PTR_DETAIL_SPINLOCK_STD_ATOMIC_HPP_INCLUDED
0003
0004 // MS compatible compilers support #pragma once
0005
0006 #if defined(_MSC_VER) && (_MSC_VER >= 1020)
0007 # pragma once
0008 #endif
0009
0010 //
0011 //  Copyright (c) 2014 Peter Dimov
0012 //
0013 //  Distributed under the Boost Software License, Version 1.0.
0014 //  See accompanying file LICENSE_1_0.txt or copy at
0015 //  http://www.boost.org/LICENSE_1_0.txt)
0016 //
0017
0018 #include <boost/smart_ptr/detail/yield_k.hpp>
0019 #include <boost/config.hpp>
0020 #include <atomic>
0021
0022 #if defined(BOOST_SP_REPORT_IMPLEMENTATION)
0023
0024 #include <boost/config/pragma_message.hpp>
0025 BOOST_PRAGMA_MESSAGE("Using std::atomic spinlock")
0026
0027 #endif
0028
0029 namespace boost
0030 {
0031
0032 namespace detail
0033 {
0034
0035 class spinlock
0036 {
0037 public:
0038
0039     std::atomic_flag v_;
0040
0041 public:
0042
0043     bool try_lock() BOOST_NOEXCEPT
0044     {
0045         return !v_.test_and_set( std::memory_order_acquire );
0046     }
0047
0048     void lock() BOOST_NOEXCEPT
0049     {
0050         for( unsigned k = 0; !try_lock(); ++k )
0051         {
0052             boost::detail::yield( k );
0053         }
0054     }
0055
0056     void unlock() BOOST_NOEXCEPT
0057     {
0058         v_ .clear( std::memory_order_release );
0059     }
0060
0061 public:
0062
0063     class scoped_lock
0064     {
0065     private:
0066
0067         spinlock & sp_;
0068
0069         scoped_lock( scoped_lock const & );
0070         scoped_lock & operator=( scoped_lock const & );
0071
0072     public:
0073
0074         explicit scoped_lock( spinlock & sp ) BOOST_NOEXCEPT: sp_( sp )
0075         {
0076             sp.lock();
0077         }
0078
0079         ~scoped_lock() /*BOOST_NOEXCEPT*/
0080         {
0081             sp_.unlock();
0082         }
0083     };
0084 };
0085
0086 } // namespace detail
0087 } // namespace boost
0088
0089 #define BOOST_DETAIL_SPINLOCK_INIT { ATOMIC_FLAG_INIT }
0090
0091 #endif // #ifndef BOOST_SMART_PTR_DETAIL_SPINLOCK_STD_ATOMIC_HPP_INCLUDED