| /************************************************************** |
| * |
| * 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 |
| * |
| * Unless required by applicable law or agreed to in writing, |
| * software distributed under the License is distributed on an |
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| * KIND, either express or implied. See the License for the |
| * specific language governing permissions and limitations |
| * under the License. |
| * |
| *************************************************************/ |
| |
| |
| |
| #ifndef _SALHELPER_SIMPLEREFERENCEOBJECT_HXX_ |
| #define _SALHELPER_SIMPLEREFERENCEOBJECT_HXX_ |
| |
| #include "osl/interlck.h" |
| #include "sal/types.h" |
| |
| #ifndef INCLUDED_CSTDDEF |
| #include <cstddef> |
| #define INCLUDED_CSTDDEF |
| #endif |
| #ifndef INCLUDED_NEW |
| #include <new> |
| #define INCLUDED_NEW |
| #endif |
| |
| namespace salhelper { |
| |
| /** A simple base implementation for reference-counted objects. |
| |
| Classes that want to implement a reference-counting mechanism based on the |
| acquire()/release() interface should derive from this class. |
| |
| The reason to have class local operators new and delete here is technical. |
| Imagine a class D derived from SimpleReferenceObject, but implemented in |
| another shared library that happens to use different global operators new |
| and delete from those used in this shared library (which, sadly, seems to |
| be possible with shared libraries). Now, without the class local |
| operators new and delete here, a code sequence like "new D" would use the |
| global operator new as found in the other shared library, while the code |
| sequence "delete this" in release() would use the global operator delete |
| as found in this shared library---and these two operators would not be |
| guaranteed to match. |
| |
| There are no overloaded operators new and delete for placement new here, |
| because it is felt that the concept of placement new does not work well |
| with the concept of reference-counted objects; so it seems best to simply |
| leave those operators out. |
| |
| The same problem as with operators new and delete would also be there with |
| operators new[] and delete[]. But since arrays of reference-counted |
| objects are of no use, anyway, it seems best to simply declare and not |
| define (private) operators new[] and delete[]. |
| */ |
| class SimpleReferenceObject |
| { |
| public: |
| inline SimpleReferenceObject() SAL_THROW(()): m_nCount(0) {} |
| |
| /** @ATTENTION |
| The results are undefined if, for any individual instance of |
| SimpleReferenceObject, the total number of calls to acquire() exceeds |
| the total number of calls to release() by a plattform dependent amount |
| (which, hopefully, is quite large). |
| */ |
| inline void acquire() SAL_THROW(()) |
| { osl_incrementInterlockedCount(&m_nCount); } |
| |
| inline void release() SAL_THROW(()) |
| { if (osl_decrementInterlockedCount(&m_nCount) == 0) delete this; } |
| |
| /** see general class documentation |
| */ |
| static void * operator new(std::size_t nSize) SAL_THROW((std::bad_alloc)); |
| |
| /** see general class documentation |
| */ |
| static void * operator new(std::size_t nSize, |
| std::nothrow_t const & rNothrow) |
| SAL_THROW(()); |
| |
| /** see general class documentation |
| */ |
| static void operator delete(void * pPtr) SAL_THROW(()); |
| |
| /** see general class documentation |
| */ |
| static void operator delete(void * pPtr, std::nothrow_t const & rNothrow) |
| SAL_THROW(()); |
| |
| protected: |
| virtual ~SimpleReferenceObject() SAL_THROW(()); |
| |
| private: |
| oslInterlockedCount m_nCount; |
| |
| /** not implemented |
| @internal |
| */ |
| SimpleReferenceObject(SimpleReferenceObject &); |
| |
| /** not implemented |
| @internal |
| */ |
| void operator =(SimpleReferenceObject); |
| |
| /** not implemented (see general class documentation) |
| @internal |
| */ |
| static void * operator new[](std::size_t); |
| |
| /** not implemented (see general class documentation) |
| @internal |
| */ |
| static void operator delete[](void * pPtr); |
| }; |
| |
| } |
| |
| #endif // _SALHELPER_SIMPLEREFERENCEOBJECT_HXX_ |