| 1 | /* -*- mode: c++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */ |
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| 2 | |
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| 3 | /* |
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| 4 | Copyright (C) 2004, 2005, 2007 StatPro Italia srl |
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| 5 | |
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| 6 | This file is part of QuantLib, a free-software/open-source library |
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| 7 | for financial quantitative analysts and developers - http://quantlib.org/ |
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| 8 | |
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| 9 | QuantLib is free software: you can redistribute it and/or modify it |
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| 10 | under the terms of the QuantLib license. You should have received a |
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| 11 | copy of the license along with this program; if not, please email |
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| 12 | <quantlib-dev@lists.sf.net>. The license is also available online at |
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| 13 | <http://quantlib.org/license.shtml>. |
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| 14 | |
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| 15 | This program is distributed in the hope that it will be useful, but WITHOUT |
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| 16 | ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS |
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| 17 | FOR A PARTICULAR PURPOSE. See the license for more details. |
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| 18 | */ |
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| 19 | |
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| 20 | /*! \file singleton.hpp |
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| 21 | \brief basic support for the singleton pattern |
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| 22 | */ |
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| 23 | |
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| 24 | #ifndef quantlib_singleton_hpp |
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| 25 | #define quantlib_singleton_hpp |
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| 26 | |
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| 27 | #include <ql/types.hpp> |
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| 28 | #include <type_traits> |
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| 29 | |
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| 30 | namespace QuantLib { |
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| 31 | |
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| 32 | //! Basic support for the singleton pattern. |
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| 33 | /*! The typical use of this class is: |
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| 34 | |
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| 35 | \code |
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| 36 | class Foo : public Singleton<Foo> { |
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| 37 | friend class Singleton<Foo>; |
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| 38 | private: |
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| 39 | Foo() {} |
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| 40 | public: |
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| 41 | ... |
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| 42 | }; |
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| 43 | \endcode |
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| 44 | |
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| 45 | which, albeit sub-optimal, frees one from the concerns of creating and managing the unique instance |
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| 46 | and can serve later as a single implemementation point should synchronization features be added. |
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| 47 | |
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| 48 | Global can be used to distinguish Singletons that are local to a session (Global = false) or that are global |
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| 49 | across all sessions (B = true). This is only relevant if QL_ENABLE_SESSIONS is enabled. |
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| 50 | |
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| 51 | Notice that the creation and retrieval of (local or global) singleton instances through instance() is thread |
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| 52 | safe, but obviously subsequent operations on the singleton have to be synchronized within the singleton |
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| 53 | implementation itself. |
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| 54 | |
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| 55 | \ingroup patterns |
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| 56 | */ |
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| 57 | template <class T, class Global = std::integral_constant<bool, false> > |
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| 58 | class Singleton { |
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| 59 | public: |
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| 60 | // disable copy/move |
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| 61 | Singleton(const Singleton&) = delete; |
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| 62 | Singleton(Singleton&&) = delete; |
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| 63 | Singleton& operator=(const Singleton&) = delete; |
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| 64 | Singleton& operator=(Singleton&&) = delete; |
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| 65 | ~Singleton() = default; |
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| 66 | |
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| 67 | //! access to the unique instance |
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| 68 | static T& instance(); |
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| 69 | |
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| 70 | protected: |
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| 71 | Singleton() = default; |
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| 72 | }; |
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| 73 | |
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| 74 | // template definitions |
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| 75 | |
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| 76 | #ifdef QL_ENABLE_SESSIONS |
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| 77 | |
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| 78 | #if (defined(__GNUC__) && !defined(__clang__)) && (((__GNUC__ == 8) && (__GNUC_MINOR__ < 4)) || (__GNUC__ < 8)) |
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| 79 | #pragma message("Singleton::instance() is always compiled with `-O0` for versions of GCC below 8.4 when sessions are enabled.") |
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| 80 | #pragma message("This is to work around the following compiler bug: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91757") |
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| 81 | #pragma message("If possible, please update your compiler to a more recent version.") |
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| 82 | #pragma GCC push_options |
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| 83 | #pragma GCC optimize("-O0") |
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| 84 | #endif |
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| 85 | |
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| 86 | template <class T, class Global> |
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| 87 | T& Singleton<T, Global>::instance() { |
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| 88 | if(Global()) { |
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| 89 | static T global_instance; |
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| 90 | return global_instance; |
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| 91 | } else { |
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| 92 | thread_local static T local_instance; |
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| 93 | return local_instance; |
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| 94 | } |
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| 95 | } |
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| 96 | |
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| 97 | #if (defined(__GNUC__) && !defined(__clang__)) && (((__GNUC__ == 8) && (__GNUC_MINOR__ < 4)) || (__GNUC__ < 8)) |
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| 98 | #pragma GCC pop_options |
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| 99 | #endif |
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| 100 | |
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| 101 | #else |
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| 102 | |
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| 103 | template <class T, class Global> |
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| 104 | T& Singleton<T, Global>::instance() { |
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| 105 | static T instance; |
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| 106 | return instance; |
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| 107 | } |
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| 108 | |
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| 109 | #endif |
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| 110 | |
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| 111 | // backwards compatibility |
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| 112 | |
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| 113 | #if defined(QL_THREAD_KEY) |
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| 114 | /*! \deprecated This typedef is obsolete. Do not use it. |
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| 115 | Deprecated in version 1.29. |
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| 116 | */ |
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| 117 | QL_DEPRECATED |
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| 118 | typedef QL_THREAD_KEY ThreadKey; |
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| 119 | #else |
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| 120 | /*! \deprecated This typedef is obsolete. Do not use it. |
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| 121 | Deprecated in version 1.29. |
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| 122 | */ |
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| 123 | QL_DEPRECATED |
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| 124 | typedef Integer ThreadKey; |
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| 125 | #endif |
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| 126 | |
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| 127 | } |
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| 128 | |
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| 129 | #endif |
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| 130 | |
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