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# XMLRegisterCleanup.hpp

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    00001 /*
    00002  * The Apache Software License, Version 1.1
    00003  *
    00004  * Copyright (c) 1999-2000 The Apache Software Foundation.  All rights
    00005  * reserved.
    00006  *
    00007  * Redistribution and use in source and binary forms, with or without
    00008  * modification, are permitted provided that the following conditions
    00009  * are met:
    00010  *
    00011  * 1. Redistributions of source code must retain the above copyright
    00012  *    notice, this list of conditions and the following disclaimer.
    00013  *
    00014  * 2. Redistributions in binary form must reproduce the above copyright
    00015  *    notice, this list of conditions and the following disclaimer in
    00016  *    the documentation and/or other materials provided with the
    00017  *    distribution.
    00018  *
    00019  * 3. The end-user documentation included with the redistribution,
    00020  *    if any, must include the following acknowledgment:
    00021  *       "This product includes software developed by the
    00022  *        Apache Software Foundation (http://www.apache.org/)."
    00023  *    Alternately, this acknowledgment may appear in the software itself,
    00024  *    if and wherever such third-party acknowledgments normally appear.
    00025  *
    00026  * 4. The names "Xerces" and "Apache Software Foundation" must
    00027  *    not be used to endorse or promote products derived from this
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    00029  *    permission, please contact apache\@apache.org.
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    00031  * 5. Products derived from this software may not be called "Apache",
    00032  *    nor may "Apache" appear in their name, without prior written
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    00035  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
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    00037  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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    00045  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
    00046  * SUCH DAMAGE.
    00047  * ====================================================================
    00048  *
    00049  * This software consists of voluntary contributions made by many
    00050  * individuals on behalf of the Apache Software Foundation, and was
    00051  * originally based on software copyright (c) 1999, International
    00052  * Business Machines, Inc., http://www.ibm.com .  For more information
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    00056
    00057 /*
    00058  * $Id: XMLRegisterCleanup.hpp,v 1.3 2004/01/29 11:48:47 cargilld Exp $
    00059  * $Log: XMLRegisterCleanup.hpp,v $
    00060  * Revision 1.3  2004/01/29 11:48:47  cargilld
    00061  * Code cleanup changes to get rid of various compiler diagnostic messages.
    00062  *
    00063  * Revision 1.2  2002/11/04 15:22:05  tng
    00064  * C++ Namespace Support.
    00065  *
    00066  * Revision 1.1.1.1  2002/02/01 22:22:15  peiyongz
    00067  * sane_include
    00068  *
    00069  * Revision 1.4  2001/10/25 21:55:29  peiyongz
    00070  * copy ctor explicity declared private to prevent supprise.
    00071  *
    00072  * Revision 1.3  2001/10/24 18:13:06  peiyongz
    00073  * CVS tag added
    00074  *
    00075  *
    00076  */
    00077
    00078 #if !defined(XMLREGISTERCLEANUP_HPP)
    00079 #define XMLREGISTERCLEANUP_HPP
    00080
    00081 #include <xercesc/util/Mutexes.hpp>
    00082
    00083 XERCES_CPP_NAMESPACE_BEGIN
    00084
    00085 // This is a mutex for exclusive use by this class
    00086 extern XMLMutex* gXMLCleanupListMutex;
    00087
    00088 // This is the head of a list of XMLRegisterCleanup objects that
    00089 // is used during XMLPlatformUtils::Terminate() to find objects to
    00090 // clean up
    00091 class XMLRegisterCleanup;
    00092 extern XMLRegisterCleanup* gXMLCleanupList;
    00093
    00094 //
    00095 //  For internal use only.
    00096 //
    00097 //  This class is used by the platform utilities class to support
    00098 //  reinitialisation of global/static data which is lazily created.
    00099 //  Since that data is widely spread out the platform utilities
    00100 //  class cannot know about them directly. So, the code that creates such
    00101 //  objects creates an registers a cleanup for the object. The platform
    00102 //  termination call will iterate the list and delete the objects.
    00103 //
    00104 //  N.B. These objects need to be statically allocated.  I couldn't think
    00105 //  of a neat way of ensuring this - can anyone else?
    00106
    00107 class XMLRegisterCleanup
    00108 {
    00109 public :
    00110     // The cleanup function to be called on XMLPlatformUtils::Terminate()
    00111     typedef void (*XMLCleanupFn)();
    00112
    00113     void doCleanup() {
    00114         // When performing cleanup, we only do this once, but we can
    00115         // cope if somehow we have been called twice.
    00116         if (m_cleanupFn)
    00117             m_cleanupFn();
    00118
    00119         // We need to remove "this" from the list
    00120         // irregardless of the cleanup Function
    00121         unregisterCleanup();
    00122     }
    00123
    00124     // This function is called during initialisation of static data to
    00125     // register a function to be called on XMLPlatformUtils::Terminate.
    00126     // It gives an object that uses static data an opportunity to reset
    00127     // such data.
    00128     void registerCleanup(XMLCleanupFn cleanupFn) {
    00129         // Store the cleanup function
    00130         m_cleanupFn = cleanupFn;
    00131
    00132         // Add this object to the list head, if it is not already
    00133         // present - which it shouldn't be.
    00134         // This is done under a mutex to ensure thread safety.
    00135         gXMLCleanupListMutex->lock();
    00136         if (!m_nextCleanup && !m_prevCleanup) {
    00137             m_nextCleanup = gXMLCleanupList;
    00138             gXMLCleanupList = this;
    00139
    00140             if (m_nextCleanup)
    00141                 m_nextCleanup->m_prevCleanup = this;
    00142         }
    00143         gXMLCleanupListMutex->unlock();
    00144     }
    00145
    00146     // This function can be called either from XMLPlatformUtils::Terminate
    00147     // to state that the cleanup has been performed and should not be
    00148     // performed again, or from code that you have written that determines
    00149     // that cleanup is no longer necessary.
    00150     void unregisterCleanup() {
    00151         gXMLCleanupListMutex->lock();
    00152
    00153         //
    00154         // To protect against some compiler's (eg hp11) optimization
    00155         // to change "this" as they update gXMLCleanupList
    00156         //
    00157         // refer to
    00158         // void XMLPlatformUtils::Terminate()
    00159         //       ...
    00160         //       while (gXMLCleanupList)
    00161         //            gXMLCleanupList->doCleanup();
    00162         //
    00163
    00164         XMLRegisterCleanup *tmpThis = (XMLRegisterCleanup*) this;
    00165
    00166         // Unlink this object from the cleanup list
    00167         if (m_nextCleanup) m_nextCleanup->m_prevCleanup = m_prevCleanup;
    00168
    00169         if (!m_prevCleanup) gXMLCleanupList = m_nextCleanup;
    00170         else m_prevCleanup->m_nextCleanup = m_nextCleanup;
    00171
    00172         gXMLCleanupListMutex->unlock();
    00173
    00174         // Reset the object to the default state
    00175         tmpThis->resetCleanup();
    00176     }
    00177
    00178     // The default constructor sets a state that ensures that this object
    00179     // will do nothing
    00180     XMLRegisterCleanup()
    00181     {
    00182         resetCleanup();
    00183     }
    00184
    00185 private:
    00186     // -----------------------------------------------------------------------
    00187     //  Unimplemented constructors and operators
    00188     // -----------------------------------------------------------------------
    00189     XMLRegisterCleanup(const XMLRegisterCleanup&);
    00190     XMLRegisterCleanup& operator=(const XMLRegisterCleanup&);
    00191
    00192     // This is the cleanup function to be called
    00193     XMLCleanupFn m_cleanupFn;
    00194
    00195     // These are list pointers to the next/prev cleanup function to be called
    00196     XMLRegisterCleanup *m_nextCleanup, *m_prevCleanup;
    00197
    00198     // This function reinitialises the object to the default state
    00199     void resetCleanup() {
    00200         m_nextCleanup = 0;
    00201         m_prevCleanup = 0;
    00202         m_cleanupFn = 0;
    00203     }
    00204 };
    00205
    00206 XERCES_CPP_NAMESPACE_END
    00207
    00208 #endif

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