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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
    00028  *    software without prior written permission. For written
    00029  *    permission, please contact apache\@apache.org.
    00030  *
    00031  * 5. Products derived from this software may not be called "Apache",
    00032  *    nor may "Apache" appear in their name, without prior written
    00033  *    permission of the Apache Software Foundation.
    00034  *
    00035  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
    00036  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
    00037  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
    00038  * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
    00039  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
    00040  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
    00041  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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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
    00053  * on the Apache Software Foundation, please see
    00054  * <http://www.apache.org/>.
    00055  */
    00056
    00057 /*
    00058  * $Id: XMLRegisterCleanup.hpp,v 1.1.1.1 2002/02/01 22:22:15 peiyongz Exp $
    00059  * $Log: XMLRegisterCleanup.hpp,v $
    00060  * Revision 1.1.1.1  2002/02/01 22:22:15  peiyongz
    00061  * sane_include
    00062  *
    00063  * Revision 1.4  2001/10/25 21:55:29  peiyongz
    00064  * copy ctor explicity declared private to prevent supprise.
    00065  *
    00066  * Revision 1.3  2001/10/24 18:13:06  peiyongz
    00067  * CVS tag added
    00068  *
    00069  *
    00070  */
    00071
    00072 #if !defined(XMLREGISTERCLEANUP_HPP)
    00073 #define XMLREGISTERCLEANUP_HPP
    00074
    00075 #include <xercesc/util/Mutexes.hpp>
    00076
    00077 // This is a mutex for exclusive use by this class
    00078 extern XMLMutex* gXMLCleanupListMutex;
    00079
    00080 // This is the head of a list of XMLRegisterCleanup objects that
    00081 // is used during XMLPlatformUtils::Terminate() to find objects to
    00082 // clean up
    00083 class XMLRegisterCleanup;
    00084 extern XMLRegisterCleanup* gXMLCleanupList;
    00085
    00086 //
    00087 //  For internal use only.
    00088 //
    00089 //  This class is used by the platform utilities class to support
    00090 //  reinitialisation of global/static data which is lazily created.
    00091 //  Since that data is widely spread out the platform utilities
    00092 //  class cannot know about them directly. So, the code that creates such
    00093 //  objects creates an registers a cleanup for the object. The platform
    00094 //  termination call will iterate the list and delete the objects.
    00095 //
    00096 //  N.B. These objects need to be statically allocated.  I couldn't think
    00097 //  of a neat way of ensuring this - can anyone else?
    00098
    00099 class XMLRegisterCleanup
    00100 {
    00101 public :
    00102     // The cleanup function to be called on XMLPlatformUtils::Terminate()
    00103     typedef void (*XMLCleanupFn)();
    00104
    00105     void doCleanup() {
    00106         // When performing cleanup, we only do this once, but we can
    00107         // cope if somehow we have been called twice.
    00108         if (m_cleanupFn)
    00109             m_cleanupFn();
    00110
    00111         // We need to remove "this" from the list
    00112         // irregardless of the cleanup Function
    00113         unregisterCleanup();
    00114     }
    00115
    00116     // This function is called during initialisation of static data to
    00117     // register a function to be called on XMLPlatformUtils::Terminate.
    00118     // It gives an object that uses static data an opportunity to reset
    00119     // such data.
    00120     void registerCleanup(XMLCleanupFn cleanupFn) {
    00121         // Store the cleanup function
    00122         m_cleanupFn = cleanupFn;
    00123
    00124         // Add this object to the list head, if it is not already
    00125         // present - which it shouldn't be.
    00126         // This is done under a mutex to ensure thread safety.
    00127         gXMLCleanupListMutex->lock();
    00128         if (!m_nextCleanup && !m_prevCleanup) {
    00129             m_nextCleanup = gXMLCleanupList;
    00130             gXMLCleanupList = this;
    00131
    00132             if (m_nextCleanup)
    00133                 m_nextCleanup->m_prevCleanup = this;
    00134         }
    00135         gXMLCleanupListMutex->unlock();
    00136     }
    00137
    00138     // This function can be called either from XMLPlatformUtils::Terminate
    00139     // to state that the cleanup has been performed and should not be
    00140     // performed again, or from code that you have written that determines
    00141     // that cleanup is no longer necessary.
    00142     void unregisterCleanup() {
    00143         gXMLCleanupListMutex->lock();
    00144
    00145         //
    00146         // To protect against some compiler's (eg hp11) optimization
    00147         // to change "this" as they update gXMLCleanupList
    00148         //
    00149         // refer to
    00150         // void XMLPlatformUtils::Terminate()
    00151         //       ...
    00152         //       while (gXMLCleanupList)
    00153         //            gXMLCleanupList->doCleanup();
    00154         //
    00155
    00156         XMLRegisterCleanup *tmpThis = (XMLRegisterCleanup*) this;
    00157
    00158         // Unlink this object from the cleanup list
    00159         if (m_nextCleanup) m_nextCleanup->m_prevCleanup = m_prevCleanup;
    00160
    00161         if (!m_prevCleanup) gXMLCleanupList = m_nextCleanup;
    00162         else m_prevCleanup->m_nextCleanup = m_nextCleanup;
    00163
    00164         gXMLCleanupListMutex->unlock();
    00165
    00166         // Reset the object to the default state
    00167         tmpThis->resetCleanup();
    00168     }
    00169
    00170     // The default constructor sets a state that ensures that this object
    00171     // will do nothing
    00172     XMLRegisterCleanup()
    00173     {
    00174         resetCleanup();
    00175     }
    00176
    00177 private:
    00178
    00179     //
    00180     // unsupported ctor and operator
    00181     //
    00182     XMLRegisterCleanup(const XMLRegisterCleanup&)
    00183     {}
    00184
    00185     // This is the cleanup function to be called
    00186     XMLCleanupFn m_cleanupFn;
    00187
    00188     // These are list pointers to the next/prev cleanup function to be called
    00189     XMLRegisterCleanup *m_nextCleanup, *m_prevCleanup;
    00190
    00191     // This function reinitialises the object to the default state
    00192     void resetCleanup() {
    00193         m_nextCleanup = 0;
    00194         m_prevCleanup = 0;
    00195         m_cleanupFn = 0;
    00196     }
    00197 };
    00198
    00199 #endif

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