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// IBM_PROLOG_BEGIN_TAG
// This is an automatically generated prolog.
//
// $Source: src/include/util/lockfree/atomic_construct.H $
//
// IBM CONFIDENTIAL
//
// COPYRIGHT International Business Machines Corp. 2011
//
// p1
//
// Object Code Only (OCO) source materials
// Licensed Internal Code Source Materials
// IBM HostBoot Licensed Internal Code
//
// The source code for this program is not published or other-
// wise divested of its trade secrets, irrespective of what has
// been deposited with the U.S. Copyright Office.
//
// Origin: 30
//
// IBM_PROLOG_END
#ifndef __UTIL_LOCKFREE_ATOMIC_CONSTRUCT_H
#define __UTIL_LOCKFREE_ATOMIC_CONSTRUCT_H
namespace Util
{
namespace Lockfree
{
/** @brief Atomically construct an object and assign it to a pointer.
*
* This function will check if a pointer is still NULL and
* construct an object, atomically, if needed. If the pointer is
* not NULL, the current instance will be left alone.
*
* @param[in] ptr - Pointer-pointer to the object.
*
* Example:
* Foo* iv_foo; //<--- instance variable in class.
* atomic_construct(&iv_foo);
*
* @note It is possible for multiple instances to temporarily exist,
* if this code is called from multiple CPUs, but only the one
* instance will exist outside the lifetime of this function.
*/
template<typename _T>
void atomic_construct(_T** ptr)
{
if (__sync_bool_compare_and_swap(ptr, NULL, NULL))
{
_T* instance = new _T();
if (!__sync_bool_compare_and_swap(ptr, NULL, instance))
{
delete instance;
}
}
}
};
};
#endif
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