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BUG#: 5314
TITLE: IPC Refactoring

DESCRIPTION: This patch cleans up the IPC related classes. It (1) reorganizes
related classes into their own headers, (2) makes the mutex class recursive to
eliminate recursive lock exclusion logic, (3) reimplements condition variables,
renames dozens of global functions.

//%2006////////////////////////////////////////////////////////////////////////
//
// Copyright (c) 2000, 2001, 2002 BMC Software; Hewlett-Packard Development
// Company, L.P.; IBM Corp.; The Open Group; Tivoli Systems.
// Copyright (c) 2003 BMC Software; Hewlett-Packard Development Company, L.P.;
// IBM Corp.; EMC Corporation, The Open Group.
// Copyright (c) 2004 BMC Software; Hewlett-Packard Development Company, L.P.;
// IBM Corp.; EMC Corporation; VERITAS Software Corporation; The Open Group.
// Copyright (c) 2005 Hewlett-Packard Development Company, L.P.; IBM Corp.;
// EMC Corporation; VERITAS Software Corporation; The Open Group.
// Copyright (c) 2006 Hewlett-Packard Development Company, L.P.; IBM Corp.;
// EMC Corporation; Symantec Corporation; The Open Group.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to
// deal in the Software without restriction, including without limitation the
// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
// sell copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
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// THE ABOVE COPYRIGHT NOTICE AND THIS PERMISSION NOTICE SHALL BE INCLUDED IN
// ALL COPIES OR SUBSTANTIAL PORTIONS OF THE SOFTWARE. THE SOFTWARE IS PROVIDED
// "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT
// LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
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//==============================================================================
//
// Author: Mike Brasher (m.brasher@inovadevelopment.com)
//
//%/////////////////////////////////////////////////////////////////////////////

#ifndef Pegasus_Once_h
#define Pegasus_Once_h

#include <Pegasus/Common/Config.h>
#include <Pegasus/Common/Linkage.h>
#include <Pegasus/Common/Mutex.h>

#define PEGASUS_ONCE_INITIALIZER { PEGASUS_MUTEX_INITIALIZER, 0 }

PEGASUS_NAMESPACE_BEGIN

/** Once implements the "once" concept as introduced by POSIX threads.
    That is, it arranges for a function to be called just once in a thread
    safe manner. The following example shows how to constuct an object of
    type X the first time any thread reaches the line that calls once().

        static Once _once = PEGASUS_ONCE_INITIALIZER;
        static static X* _ptr;

        static void _create_X()
        {
            ptr = new X;
        }

        ...

        once(&_once, _create_X());

    The _create_X() function is called exactly once no matter how many times
    once() is called on it. Also, once() may be called safely from multiple
    threads.

    CAUTION: Once instances must always be defined statically.
*/
struct Once
{
    MutexType mutex;
    int initialized;
};

void PEGASUS_COMMON_LINKAGE __once(Once* once, void (*function)());

inline void once(Once* once, void (*function)())
{
    if (once->initialized == 0)
        __once(once, function);
}

PEGASUS_NAMESPACE_END

#endif /* Pegasus_Once_h */