ceph/src/boost/libs/serialization/include/boost/serialization/singleton.hpp

   1 #ifndef BOOST_SERIALIZATION_SINGLETON_HPP
   2 #define BOOST_SERIALIZATION_SINGLETON_HPP
   3
   4 /////////1/////////2///////// 3/////////4/////////5/////////6/////////7/////////8
   5 //  singleton.hpp
   6 //
   7 // Copyright David Abrahams 2006. Original version
   8 //
   9 // Copyright Robert Ramey 2007.  Changes made to permit
  10 // application throughout the serialization library.
  11 //
  12 // Distributed under the Boost
  13 // Software License, Version 1.0. (See accompanying
  14 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
  15 //
  16 // The intention here is to define a template which will convert
  17 // any class into a singleton with the following features:
  18 //
  19 // a) initialized before first use.
  20 // b) thread-safe for const access to the class
  21 // c) non-locking
  22 //
  23 // In order to do this,
  24 // a) Initialize dynamically when used.
  25 // b) Require that all singletons be initialized before main
  26 // is called or any entry point into the shared library is invoked.
  27 // This guarentees no race condition for initialization.
  28 // In debug mode, we assert that no non-const functions are called
  29 // after main is invoked.
  30 //
  31
  32 // MS compatible compilers support #pragma once
  33 #if defined(_MSC_VER)
  34 # pragma once
  35 #endif
  36
  37 #include <boost/assert.hpp>
  38 #include <boost/config.hpp>
  39 #include <boost/noncopyable.hpp>
  40 #include <boost/serialization/force_include.hpp>
  41
  42 #include <boost/archive/detail/auto_link_archive.hpp>
  43 #include <boost/serialization/config.hpp>
  44 #include <boost/archive/detail/abi_prefix.hpp> // must be the last header
  45
  46 #ifdef BOOST_MSVC
  47 #  pragma warning(push)
  48 #  pragma warning(disable : 4511 4512)
  49 #endif
  50
  51 namespace boost {
  52 namespace serialization {
  53
  54 //////////////////////////////////////////////////////////////////////
  55 // Provides a dynamically-initialized (singleton) instance of T in a
  56 // way that avoids LNK1179 on vc6.  See http://tinyurl.com/ljdp8 or
  57 // http://lists.boost.org/Archives/boost/2006/05/105286.php for
  58 // details.
  59 //
  60
  61 // singletons created by this code are guarenteed to be unique
  62 // within the executable or shared library which creates them.
  63 // This is sufficient and in fact ideal for the serialization library.
  64 // The singleton is created when the module is loaded and destroyed
  65 // when the module is unloaded.
  66
  67 // This base class has two functions.
  68
  69 // First it provides a module handle for each singleton indicating
  70 // the executable or shared library in which it was created. This
  71 // turns out to be necessary and sufficient to implement the tables
  72 // used by serialization library.
  73
  74 // Second, it provides a mechanism to detect when a non-const function
  75 // is called after initialization.
  76
  77 // make a singleton to lock/unlock all singletons for alteration.
  78 // The intent is that all singletons created/used by this code
  79 // are to be initialized before main is called. A test program
  80 // can lock all the singletons when main is entereed.  This any
  81 // attempt to retieve a mutable instances while locked will
  82 // generate a assertion if compiled for debug.
  83
  84 class BOOST_SYMBOL_VISIBLE singleton_module :
  85     public boost::noncopyable
  86 {
  87 private:
  88     static bool & get_lock();
  89 public:
  90     BOOST_SERIALIZATION_DECL static void lock();
  91     BOOST_SERIALIZATION_DECL static void unlock();
  92     BOOST_SERIALIZATION_DECL static bool is_locked();
  93 };
  94
  95 #include <boost/archive/detail/abi_suffix.hpp> // pops abi_suffix.hpp pragmas
  96
  97 namespace detail {
  98
  99 template<class T>
 100 class singleton_wrapper : public T
 101 {
 102 public:
 103     static bool m_is_destroyed;
 104     ~singleton_wrapper(){
 105         m_is_destroyed = true;
 106     }
 107 };
 108
 109 template<class T>
 110 bool detail::singleton_wrapper< T >::m_is_destroyed = false;
 111
 112 } // detail
 113
 114 template <class T>
 115 class singleton : public singleton_module
 116 {
 117 private:
 118     BOOST_DLLEXPORT static T & instance;
 119     // include this to provoke instantiation at pre-execution time
 120     static void use(T const *) {}
 121     BOOST_DLLEXPORT static T & get_instance() {
 122         static detail::singleton_wrapper< T > t;
 123         // refer to instance, causing it to be instantiated (and
 124         // initialized at startup on working compilers)
 125         BOOST_ASSERT(! detail::singleton_wrapper< T >::m_is_destroyed);
 126         use(& instance);
 127         return static_cast<T &>(t);
 128     }
 129 public:
 130     BOOST_DLLEXPORT static T & get_mutable_instance(){
 131         BOOST_ASSERT(! is_locked());
 132         return get_instance();
 133     }
 134     BOOST_DLLEXPORT static const T & get_const_instance(){
 135         return get_instance();
 136     }
 137     BOOST_DLLEXPORT static bool is_destroyed(){
 138         return detail::singleton_wrapper< T >::m_is_destroyed;
 139     }
 140 };
 141
 142 template<class T>
 143 BOOST_DLLEXPORT T & singleton< T >::instance = singleton< T >::get_instance();
 144
 145 } // namespace serialization
 146 } // namespace boost
 147
 148 #ifdef BOOST_MSVC
 149 #pragma warning(pop)
 150 #endif
 151
 152 #endif // BOOST_SERIALIZATION_SINGLETON_HPP