ceph/src/boost/libs/log/include/boost/log/detail/thread_specific.hpp

   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
  76     BOOST_DEFAULTED_FUNCTION(thread_specific(), {})
  77     //! Initializing constructor
  78     thread_specific(T const& value)
  79     {
  80         set(value);
  81     }
  82     //! Assignment
  83     thread_specific& operator= (T const& value)
  84     {
  85         set(value);
  86         return *this;
  87     }
  88
  89     //! Accessor
  90     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
  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_