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/* -*- mode: c++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
Copyright (C) 2004, 2005, 2007 StatPro Italia srl
This file is part of QuantLib, a free-software/open-source library
for financial quantitative analysts and developers - http://quantlib.org/
QuantLib is free software: you can redistribute it and/or modify it
under the terms of the QuantLib license. You should have received a
copy of the license along with this program; if not, please email
<quantlib-dev@lists.sf.net>. The license is also available online at
<http://quantlib.org/license.shtml>.
This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the license for more details.
*/
/*! \file singleton.hpp
\brief basic support for the singleton pattern
*/
#ifndef quantlib_singleton_hpp
#define quantlib_singleton_hpp
#include <ql/qldefines.hpp>
#ifdef QL_ENABLE_SINGLETON_THREAD_SAFE_INIT
#if defined(QL_ENABLE_SESSIONS)
#ifdef BOOST_MSVC
#pragma message(\
"Thread-safe singleton initialization not supported " \
"when sessions are enabled.")
#else
#warning \
Thread-safe singleton initialization not supported \
when sessions are enabled.
#endif
#else
#include <boost/atomic.hpp>
#include <boost/thread/mutex.hpp>
#if !defined(BOOST_ATOMIC_ADDRESS_LOCK_FREE)
#ifdef BOOST_MSVC
#pragma message(\
"Thread-safe singleton initialization " \
"may degrade performances.")
#else
#warning \
Thread-safe singleton initialization \
may degrade performances.
#endif
#endif
#define QL_SINGLETON_THREAD_SAFE_INIT
#endif
#endif
#include <ql/types.hpp>
#include <ql/shared_ptr.hpp>
#if defined(QL_PATCH_MSVC)
#pragma managed(push, off)
#endif
#include <boost/noncopyable.hpp>
#if defined(QL_PATCH_MSVC)
#pragma managed(pop)
#endif
#include <map>
#if (_MANAGED == 1) || (_M_CEE == 1)
// One of the Visual C++ /clr modes. In this case, the global instance
// map must be declared as a static data member of the class.
#define QL_MANAGED 1
#else
// Every other configuration. The map can be declared as a static
// variable inside the creation method.
#define QL_MANAGED 0
#endif
namespace QuantLib {
// This allows to define a different type if needed, while keeping
// backwards compatibility with the current implementation.
// For instance, one might create a file threadkey.hpp with:
//
// #include <pthread.h>
// #define QL_THREAD_KEY pthread_t
//
// and then compile QuantLib with the option -DQL_INCLUDE_FIRST=threadkey.hpp
// to have that file included by qldefines.hpp and thus this one.
#if defined(QL_THREAD_KEY)
typedef QL_THREAD_KEY ThreadKey;
#else
typedef Integer ThreadKey;
#endif
#if defined(QL_ENABLE_SESSIONS)
// definition must be provided by the user
ThreadKey sessionId();
#endif
// this is required on VC++ when CLR support is enabled
#if defined(QL_PATCH_MSVC)
#pragma managed(push, off)
#endif
//! Basic support for the singleton pattern.
/*! The typical use of this class is:
\code
class Foo : public Singleton<Foo> {
friend class Singleton<Foo>;
private:
Foo() {}
public:
...
};
\endcode
which, albeit sub-optimal, frees one from the concerns of
creating and managing the unique instance and can serve later
as a single implemementation point should synchronization
features be added.
\ingroup patterns
*/
template <class T>
class Singleton : private boost::noncopyable {
#if (QL_MANAGED == 1) && !defined(QL_SINGLETON_THREAD_SAFE_INIT)
private:
static std::map<ThreadKey, ext::shared_ptr<T> > instances_;
#endif
#if defined(QL_SINGLETON_THREAD_SAFE_INIT)
private:
static boost::atomic<T*> instance_;
static boost::mutex mutex_;
#endif
public:
//! access to the unique instance
static T& instance();
protected:
Singleton() {}
};
// static member definitions
#if (QL_MANAGED == 1) && !defined(QL_SINGLETON_THREAD_SAFE_INIT)
template <class T>
std::map<ThreadKey, ext::shared_ptr<T> > Singleton<T>::instances_;
#endif
#if defined(QL_SINGLETON_THREAD_SAFE_INIT)
template <class T> boost::atomic<T*> Singleton<T>::instance_;
template <class T> boost::mutex Singleton<T>::mutex_;
#endif
// template definitions
template <class T>
T& Singleton<T>::instance() {
#if (QL_MANAGED == 0) && !defined(QL_SINGLETON_THREAD_SAFE_INIT)
static std::map<ThreadKey, ext::shared_ptr<T> > instances_;
#endif
// thread safe double checked locking pattern with atomic memory calls
#if defined(QL_SINGLETON_THREAD_SAFE_INIT)
T* instance = instance_.load(boost::memory_order_consume);
if (!instance) {
boost::mutex::scoped_lock guard(mutex_);
instance = instance_.load(boost::memory_order_consume);
if (!instance) {
instance = new T();
instance_.store(instance, boost::memory_order_release);
}
}
#else //this is not thread safe
#if defined(QL_ENABLE_SESSIONS)
ThreadKey id = sessionId();
#else
ThreadKey id = 0;
#endif
ext::shared_ptr<T>& instance = instances_[id];
if (!instance)
instance = ext::shared_ptr<T>(new T);
#endif
return *instance;
}
// reverts the change above
#if defined(QL_PATCH_MSVC)
#pragma managed(pop)
#endif
}
#undef QL_MANAGED
#endif
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