6c7659b584
Change-Id: Ib48a12e902f2311c295b2007f08f44dee28f431d Reviewed-on: https://gerrit.libreoffice.org/3499 Reviewed-by: David Tardon <dtardon@redhat.com> Tested-by: David Tardon <dtardon@redhat.com>
131 lines
4.5 KiB
C++
131 lines
4.5 KiB
C++
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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/*
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* This file is part of the LibreOffice project.
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*
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* This file incorporates work covered by the following license notice:
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed
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* with this work for additional information regarding copyright
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* ownership. The ASF licenses this file to you under the Apache
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* License, Version 2.0 (the "License"); you may not use this file
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* except in compliance with the License. You may obtain a copy of
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* the License at http://www.apache.org/licenses/LICENSE-2.0 .
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*/
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#ifndef _SALHELPER_SIMPLEREFERENCEOBJECT_HXX_
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#define _SALHELPER_SIMPLEREFERENCEOBJECT_HXX_
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#include "osl/interlck.h"
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#include "sal/types.h"
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#include "salhelperdllapi.h"
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#include <cstddef>
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#include <new>
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namespace salhelper {
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/** A simple base implementation for reference-counted objects.
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Classes that want to implement a reference-counting mechanism based on the
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acquire()/release() interface should derive from this class.
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The reason to have class local operators new and delete here is technical.
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Imagine a class D derived from SimpleReferenceObject, but implemented in
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another shared library that happens to use different global operators new
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and delete from those used in this shared library (which, sadly, seems to
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be possible with shared libraries). Now, without the class local
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operators new and delete here, a code sequence like "new D" would use the
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global operator new as found in the other shared library, while the code
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sequence "delete this" in release() would use the global operator delete
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as found in this shared library---and these two operators would not be
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guaranteed to match.
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There are no overloaded operators new and delete for placement new here,
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because it is felt that the concept of placement new does not work well
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with the concept of reference-counted objects; so it seems best to simply
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leave those operators out.
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The same problem as with operators new and delete would also be there with
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operators new[] and delete[]. But since arrays of reference-counted
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objects are of no use, anyway, it seems best to simply declare and not
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define (private) operators new[] and delete[].
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*/
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class SALHELPER_DLLPUBLIC SimpleReferenceObject
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{
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public:
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inline SimpleReferenceObject() SAL_THROW(()): m_nCount(0) {}
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/** @attention
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The results are undefined if, for any individual instance of
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SimpleReferenceObject, the total number of calls to acquire() exceeds
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the total number of calls to release() by a platform dependent amount
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(which, hopefully, is quite large).
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*/
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inline void acquire() SAL_THROW(())
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{ osl_atomic_increment(&m_nCount); }
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inline void release() SAL_THROW(())
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{ if (osl_atomic_decrement(&m_nCount) == 0) delete this; }
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/** see general class documentation
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*/
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static void * operator new(std::size_t nSize) SAL_THROW((std::bad_alloc));
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/** see general class documentation
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*/
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static void * operator new(std::size_t nSize,
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std::nothrow_t const & rNothrow)
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SAL_THROW(());
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/** see general class documentation
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*/
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static void operator delete(void * pPtr) SAL_THROW(());
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/** see general class documentation
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*/
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static void operator delete(void * pPtr, std::nothrow_t const & rNothrow)
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SAL_THROW(());
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protected:
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virtual ~SimpleReferenceObject() SAL_THROW(());
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private:
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oslInterlockedCount m_nCount;
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/** not implemented
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*/
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SALHELPER_DLLPRIVATE SimpleReferenceObject(SimpleReferenceObject &);
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/** not implemented
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*/
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SALHELPER_DLLPRIVATE void operator =(SimpleReferenceObject);
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/// @cond INTERNAL
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#ifdef _MSC_VER
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/* We can't now have these private with MSVC2008 at least, it leads to
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compilation errors in xmloff and other places.
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*/
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protected:
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#endif
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/** not implemented (see general class documentation)
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*/
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static void * operator new[](std::size_t);
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/** not implemented (see general class documentation)
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*/
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static void operator delete[](void * pPtr);
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/// @endcond
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};
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}
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#endif // _SALHELPER_SIMPLEREFERENCEOBJECT_HXX_
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/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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