my_atomic.h

#ifndefMY_ATOMIC_INCLUDED
#defineMY_ATOMIC_INCLUDED

/* Copyright (c) 2006, 2025, Oracle and/or its affiliates.

 This program is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License, version 2.0,
 as published by the Free Software Foundation.

 This program is designed to work with certain software (including
 but not limited to OpenSSL) that is licensed under separate terms,
 as designated in a particular file or component or in included license
 documentation. The authors of MySQL hereby grant you an additional
 permission to link the program and your derivative works with the
 separately licensed software that they have either included with
 the program or referenced in the documentation.

 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 GNU General Public License, version 2.0, for more details.

 You should have received a copy of the GNU General Public License
 along with this program; if not, write to the Free Software
 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */

/**
 @file include/my_atomic.h
*/

#if defined(_MSC_VER)

#include<windows.h>

/*
 my_yield_processor (equivalent of x86 PAUSE instruction) should be used
 to improve performance on hyperthreaded CPUs. Intel recommends to use it in
 spin loops also on non-HT machines to reduce power consumption (see e.g
 http://softwarecommunity.intel.com/articles/eng/2004.htm)

 Running benchmarks for spinlocks implemented with InterlockedCompareExchange
 and YieldProcessor shows that much better performance is achieved by calling
 YieldProcessor in a loop - that is, yielding longer. On Intel boxes setting
 loop count in the range 200-300 brought best results.
 */
#defineYIELD_LOOPS 200

staticinlineintmy_yield_processor() {
inti;
for (i=0; i<YIELD_LOOPS; i++) {
YieldProcessor();
 }
return1;
}

#defineLF_BACKOFF my_yield_processor()

#else// !defined(_MSC_VER)

#defineLF_BACKOFF (1)

#endif

#endif/* MY_ATOMIC_INCLUDED */