1 /* 2 * Copyright Andrey Semashev 2007 - 2015. 3 * Distributed under the Boost Software License, Version 1.0. 4 * (See accompanying file LICENSE_1_0.txt or copy at 5 * http://www.boost.org/LICENSE_1_0.txt) 6 */ 7 /*! 8 * \file thread_specific.hpp 9 * \author Andrey Semashev 10 * \date 01.03.2008 11 * 12 * \brief This header is the Boost.Log library implementation, see the library documentation 13 * at http://www.boost.org/doc/libs/release/libs/log/doc/html/index.html. 14 */ 15 16 #ifndef BOOST_LOG_DETAIL_THREAD_SPECIFIC_HPP_INCLUDED_ 17 #define BOOST_LOG_DETAIL_THREAD_SPECIFIC_HPP_INCLUDED_ 18 19 #include <boost/static_assert.hpp> 20 #include <boost/type_traits/is_pod.hpp> 21 #include <boost/log/detail/config.hpp> 22 23 #ifdef BOOST_HAS_PRAGMA_ONCE 24 #pragma once 25 #endif 26 27 #if !defined(BOOST_LOG_NO_THREADS) 28 29 #include <boost/log/detail/header.hpp> 30 31 namespace boost { 32 33 BOOST_LOG_OPEN_NAMESPACE 34 35 namespace aux { 36 37 //! Base class for TLS to hide platform-specific storage management 38 class thread_specific_base 39 { 40 private: 41 #if defined(BOOST_THREAD_PLATFORM_WIN32) 42 typedef unsigned long key_storage; 43 #else 44 typedef void* key_storage; 45 #endif 46 47 key_storage m_Key; 48 49 protected: 50 BOOST_LOG_API thread_specific_base(); 51 BOOST_LOG_API ~thread_specific_base(); 52 BOOST_LOG_API void* get_content() const; 53 BOOST_LOG_API void set_content(void* value) const; 54 55 // Copying prohibited 56 BOOST_DELETED_FUNCTION(thread_specific_base(thread_specific_base const&)) 57 BOOST_DELETED_FUNCTION(thread_specific_base& operator= (thread_specific_base const&)) 58 }; 59 60 //! A TLS wrapper for small POD types with least possible overhead 61 template< typename T > 62 class thread_specific : 63 public thread_specific_base 64 { 65 BOOST_STATIC_ASSERT_MSG(sizeof(T) <= sizeof(void*) && is_pod< T >::value, "Boost.Log: Thread-specific values must be PODs and must not exceed the size of a pointer"); 66 67 //! Union to perform type casting 68 union value_storage 69 { 70 void* as_pointer; 71 T as_value; 72 }; 73 74 public: 75 //! Default constructor thread_specific()76 BOOST_DEFAULTED_FUNCTION(thread_specific(), {}) 77 //! Initializing constructor 78 thread_specific(T const& value) 79 { 80 set(value); 81 } 82 //! Assignment operator =(T const & value)83 thread_specific& operator= (T const& value) 84 { 85 set(value); 86 return *this; 87 } 88 89 //! Accessor get() const90 T get() const 91 { 92 value_storage cast = {}; 93 cast.as_pointer = thread_specific_base::get_content(); 94 return cast.as_value; 95 } 96 97 //! Setter set(T const & value)98 void set(T const& value) 99 { 100 value_storage cast = {}; 101 cast.as_value = value; 102 thread_specific_base::set_content(cast.as_pointer); 103 } 104 }; 105 106 } // namespace aux 107 108 BOOST_LOG_CLOSE_NAMESPACE // namespace log 109 110 } // namespace boost 111 112 #include <boost/log/detail/footer.hpp> 113 114 #endif // !defined(BOOST_LOG_NO_THREADS) 115 116 #endif // BOOST_LOG_DETAIL_THREAD_SPECIFIC_HPP_INCLUDED_ 117