FDO API Reference | Feature Data Objects |
00001 #ifndef FDO_SEMAPHORE 00002 #define FDO_SEMAPHORE 00003 // 00004 00005 // 00006 // Copyright (C) 2004-2006 Autodesk, Inc. 00007 // 00008 // This library is free software; you can redistribute it and/or 00009 // modify it under the terms of version 2.1 of the GNU Lesser 00010 // General Public License as published by the Free Software Foundation. 00011 // 00012 // This library is distributed in the hope that it will be useful, 00013 // but WITHOUT ANY WARRANTY; without even the implied warranty of 00014 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 00015 // Lesser General Public License for more details. 00016 // 00017 // You should have received a copy of the GNU Lesser General Public 00018 // License along with this library; if not, write to the Free Software 00019 // Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA 00020 // 00021 00022 /// \cond DOXYGEN-IGNORE 00023 00024 /// \brief 00025 /// FdoSemaphore is a semaphore class. It is used to prevent operations 00026 /// from happening concurrently or re-entrantly. FdoSemaphore is not currently part 00027 /// of the FDO API but can be added if there is a demand. It is a wrapper class around 00028 /// a boolean semaphore. 00029 /// 00030 /// FdoSemaphore can be used to prevent a member function on another class from 00031 /// being called re-entrantly for the same object (see FdoXmlReaderXrcs::Parse()) 00032 /// for an example. This can be done by declaring a FdoSemaphoreP, at the start of the 00033 /// function, that takes a boolean member and an exception. The boolean member must initially 00034 /// be false. When the FdoSemaphoreP is created, the boolean member is set to true. When 00035 /// the function exits, FdoSemaphoreP goes out of scope and sets the boolean member back 00036 /// to false. However, if the function is called a second time before the first 00037 /// invokation finishes, the second FdoSemaphoreP created will detect that the boolean member 00038 /// is true, and it will throw the given exception, thus rejecting the re-entrant 00039 /// function call. 00040 class FdoSemaphore : public FdoIDisposable 00041 { 00042 public: 00043 /// \brief 00044 /// Constructs a new semaphore. 00045 /// \param semaphore 00046 /// Input the semaphore switch. If true, then the 00047 /// given exception is thrown. If false, then semaphore is set to true. 00048 /// semaphore is set back to false when this object is deleted. 00049 /// \param ex 00050 /// Input the exception to throw when semaphore is true. 00051 /// 00052 /// \return 00053 /// Returns FdoSemaphore 00054 /// 00055 static FdoSemaphore* Create( FdoBoolean& semaphore, FdoException* ex ) 00056 { 00057 return new FdoSemaphore( semaphore, ex ); 00058 } 00059 00060 protected: 00061 FdoSemaphore() {} 00062 FdoSemaphore( bool& semaphore, FdoException* ex ); 00063 virtual ~FdoSemaphore(); 00064 00065 virtual void Dispose() 00066 { 00067 delete this; 00068 } 00069 00070 private: 00071 /// Pointer to the bool semaphore, so that it can be reset on destruction 00072 /// of this object. 00073 FdoBoolean* mSemaphore; 00074 00075 }; 00076 00077 /// \brief 00078 /// FdoSemaphoreP is a FdoPtr on FdoSemaphore, provided for convenience. 00079 typedef FdoPtr<FdoSemaphore> FdoSemaphoreP; 00080 00081 /// \endcond 00082 00083 #endif 00084 00085
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