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author | Sander Vesik <svesik@openoffice.org> | 2004-04-21 11:30:03 +0000 |
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committer | Sander Vesik <svesik@openoffice.org> | 2004-04-21 11:30:03 +0000 |
commit | 00835da0c1d6ebf4970b7c4a991d175b6a343b63 (patch) | |
tree | 18101586ee475e33417a5670518e7ac3e0885a5a /salhelper/inc | |
parent | INTEGRATION: CWS loadenv01 (1.1.2); FILE ADDED (diff) | |
download | core-00835da0c1d6ebf4970b7c4a991d175b6a343b63.tar.gz core-00835da0c1d6ebf4970b7c4a991d175b6a343b63.zip |
INTEGRATION: CWS loadenv01 (1.1.2); FILE ADDED
2004/03/29 08:52:44 as 1.1.2.1: #i24378# move Singleton helper from comphelper to salhlper
Diffstat (limited to 'salhelper/inc')
-rw-r--r-- | salhelper/inc/salhelper/singletonref.hxx | 251 |
1 files changed, 251 insertions, 0 deletions
diff --git a/salhelper/inc/salhelper/singletonref.hxx b/salhelper/inc/salhelper/singletonref.hxx new file mode 100644 index 000000000000..06603e6705f6 --- /dev/null +++ b/salhelper/inc/salhelper/singletonref.hxx @@ -0,0 +1,251 @@ +/************************************************************************* + * + * $RCSfile: singletonref.hxx,v $ + * + * $Revision: 1.2 $ + * + * last change: $Author: svesik $ $Date: 2004-04-21 12:30:03 $ + * + * The Contents of this file are made available subject to the terms of + * either of the following licenses + * + * - GNU Lesser General Public License Version 2.1 + * - Sun Industry Standards Source License Version 1.1 + * + * Sun Microsystems Inc., October, 2000 + * + * GNU Lesser General Public License Version 2.1 + * ============================================= + * Copyright 2000 by Sun Microsystems, Inc. + * 901 San Antonio Road, Palo Alto, CA 94303, USA + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License version 2.1, as published by the Free Software Foundation. + * + * This library 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 GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this library; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, + * MA 02111-1307 USA + * + * + * Sun Industry Standards Source License Version 1.1 + * ================================================= + * The contents of this file are subject to the Sun Industry Standards + * Source License Version 1.1 (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.openoffice.org/license.html. + * + * Software provided under this License is provided on an "AS IS" basis, + * WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, + * WITHOUT LIMITATION, WARRANTIES THAT THE SOFTWARE IS FREE OF DEFECTS, + * MERCHANTABLE, FIT FOR A PARTICULAR PURPOSE, OR NON-INFRINGING. + * See the License for the specific provisions governing your rights and + * obligations concerning the Software. + * + * The Initial Developer of the Original Code is: Sun Microsystems, Inc. + * + * Copyright: 2000 by Sun Microsystems, Inc. + * + * All Rights Reserved. + * + * Contributor(s): _______________________________________ + * + * + ************************************************************************/ + +#ifndef _SALHELPER_SINGLETONREF_HXX_ +#define _SALHELPER_SINGLETONREF_HXX_ + +//_______________________________________________ +// includes + +#ifndef _OSL_MUTEX_HXX_ +#include <osl/mutex.hxx> +#endif + +#ifndef INCLUDED_RTL_INSTANCE_HXX +#include "rtl/instance.hxx" +#endif + +#ifndef INCLUDED_OSL_GETGLOBALMUTEX_HXX +#include "osl/getglobalmutex.hxx" +#endif + +//_______________________________________________ +// namespace + +namespace salhelper{ + +//_______________________________________________ +// definitions + +/** @short template for implementing singleton classes. + + @descr 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. + + @descr 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. + + @descr 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. + + @descr 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_ |