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Diffstat (limited to 'salhelper/inc/salhelper/singletonref.hxx')
| -rw-r--r-- | salhelper/inc/salhelper/singletonref.hxx | 197 |
1 files changed, 0 insertions, 197 deletions
diff --git a/salhelper/inc/salhelper/singletonref.hxx b/salhelper/inc/salhelper/singletonref.hxx deleted file mode 100644 index a602e50cc4bf..000000000000 --- a/salhelper/inc/salhelper/singletonref.hxx +++ /dev/null @@ -1,197 +0,0 @@ -/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */ -/* - * This file is part of the LibreOffice project. - * - * This Source Code Form is subject to the terms of the Mozilla Public - * License, v. 2.0. If a copy of the MPL was not distributed with this - * file, You can obtain one at http://mozilla.org/MPL/2.0/. - * - * This file incorporates work covered by the following license notice: - * - * Licensed to the Apache Software Foundation (ASF) under one or more - * contributor license agreements. See the NOTICE file distributed - * with this work for additional information regarding copyright - * ownership. The ASF licenses this file to you under the Apache - * License, Version 2.0 (the "License"); you may not use this file - * except in compliance with the License. You may obtain a copy of - * the License at http://www.apache.org/licenses/LICENSE-2.0 . - */ - -#ifndef _SALHELPER_SINGLETONREF_HXX_ -#define _SALHELPER_SINGLETONREF_HXX_ - -#include <osl/mutex.hxx> -#include "rtl/instance.hxx" -#include "osl/diagnose.h" -#include "osl/getglobalmutex.hxx" - - -namespace salhelper{ - - -/** @short template for implementing singleton classes. - - Such classes can be instanciated everytimes they - are needed. But the internal wrapped object will - be created one times only. Of course its used - resources are referenced one times only too. - This template hold it alive till the last - reference is gone. Further all operations - on this reference are threadsafe. Only - calls directly to the internal object (which modify - its state) must be made threadsafe by the object itself - or from outside. - - @attention To prevent the code against race conditions, its not - allowed to start operations inside the ctor - of the internal wrapped object - especialy operations - which needs a reference to the same singleton too. - - The only chance to supress such strange constellations - is a lazy-init mechanism. - - <ul> - <li>a) The singleton class can provide a special init() - method, which must be called as first after creation.</li> - <li>b) The singleton class can call a special impl_init() - method implicit for every called interface method.</li> - </ul> - - Note further that this singleton pattern can work only, if - all user of such singleton are located inside the same library! - Because static values cant be exported - e.g. from windows libraries. - */ -template< class SingletonClass > -class SingletonRef -{ - //------------------------------------------- - // member - - private : - - /** @short pointer to the internal wrapped singleton. */ - static SingletonClass* m_pInstance; - - /** @short ref count, which regulate creation and removing of m_pInstance. */ - static sal_Int32 m_nRef; - - //------------------------------------------- - // interface - - public : - - //--------------------------------------- - - /** @short standard ctor. - - The internal wrapped object is created only, - if its ref count was 0. Otherwhise this method - does nothing ... except increasing of the internal - ref count! - */ - SingletonRef() - { - // GLOBAL SAFE -> - ::osl::MutexGuard aLock(SingletonRef::ownStaticLock()); - - // must be increased before(!) the check is done. - // Otherwhise this check can fail inside the same thread ... - ++m_nRef; - if (m_nRef == 1) - m_pInstance = new SingletonClass(); - - OSL_ENSURE(m_nRef>0 && m_pInstance, "Race? Ref count of singleton >0, but instance is NULL!"); - // <- GLOBAL SAFE - } - - //--------------------------------------- - - /** @short standard dtor. - - The internal wrapped object is removed only, - if its ref count wil be 0. Otherwhise this method - does nothing ... except decreasing of the internal - ref count! - */ - ~SingletonRef() - { - // GLOBAL SAFE -> - ::osl::MutexGuard aLock(SingletonRef::ownStaticLock()); - - // must be decreased before(!) the check is done. - // Otherwhise this check can fail inside the same thread ... - --m_nRef; - if (m_nRef == 0) - { - delete m_pInstance; - m_pInstance = 0; - } - // <- GLOBAL SAFE - } - - //--------------------------------------- - - /** @short Allows rSingle->someBodyOp(). - */ - SingletonClass* operator->() const - { - // GLOBAL SAFE -> - ::osl::MutexGuard aLock(SingletonRef::ownStaticLock()); - return m_pInstance; - // <- GLOBAL SAFE - } - - //--------------------------------------- - - /** @short Allows (*rSingle).someBodyOp(). - */ - SingletonClass& operator*() const - { - // GLOBAL SAFE -> - ::osl::MutexGuard aLock(SingletonRef::ownStaticLock()); - return *m_pInstance; - // <- GLOBAL SAFE - } - - //------------------------------------------- - // helper - - private : - - //--------------------------------------- - - /** @short creates an own mutex for guarding static contents. - - The global mutex the osl library is used one times - only to create an own static mutex, which can be used - next time to guard own static member operations. - */ - struct SingletonLockInit - { - ::osl::Mutex* operator()() - { - static ::osl::Mutex aInstance; - return &aInstance; - } - }; - - ::osl::Mutex& ownStaticLock() const - { - return *rtl_Instance< ::osl::Mutex, - SingletonLockInit, - ::osl::MutexGuard, - ::osl::GetGlobalMutex >::create(SingletonLockInit(), ::osl::GetGlobalMutex()); - } -}; - -template< class SingletonClass > -SingletonClass* SingletonRef< SingletonClass >::m_pInstance = 0; - -template< class SingletonClass > -sal_Int32 SingletonRef< SingletonClass >::m_nRef = 0; - -} // namespace salhelper - -#endif // _SALHELPER_SINGLETONREF_HXX_ - -/* vim:set shiftwidth=4 softtabstop=4 expandtab: */ |