#pragma once
//-
// ===========================================================================
// Copyright 2018 Autodesk, Inc. All rights reserved.
//
// Use of this software is subject to the terms of the Autodesk license
// agreement provided at the time of installation or download, or which
// otherwise accompanies this software in either electronic or hard copy form.
// ===========================================================================
//+
//
// CLASS:    MThreadUtils
//
// ****************************************************************************

#include <maya/MGlobal.h>
#include <maya/MDeprecate.h>

#ifdef _OPENMP
#include <omp.h>
#endif


OPENMAYA_MAJOR_NAMESPACE_OPEN

// ****************************************************************************
// CLASS DECLARATION (MThreadUtils)

//! \ingroup OpenMaya
//! \brief Helper methods for threaded plugins
/*!

   <b>Thread count controls</b>

   The user can control the number of threads currently running in
   Maya. This is useful for example to run rendering in a single
   thread when multiple frames are being rendered in parallel by
   different instances of Maya. All code should respect this thread
   count, so if a plugin is threaded, it needs to query the current
   thread count being used by Maya and set that threadcount for
   itself.

   For a plugin-local thread pool using Win32 or pthreads, use the
   getNumThreads() method to check the required number of threads and
   set the number of threads in the plugin thread pool appropriately.

   If using the Maya API MThreadPool class there is no need to do
   anything as this is an internal Maya thread pool that respects
   the user-defined thread count setting.

   If using the Intel compiler, there is no need to do anything as
   the threadcount is set globally for the Intel compiler.

   If using OpenMP with gcc on OSX and Linux, or Visual C++ on
   Windows, it is necessary to call the syncNumOpenMPThreads to
   ensure the correct threadcount is set in the plugin.

   <b>Cache line size control</b>

   The cache line size is important information when code may have
   false sharing problems. Use the query method to ensure data that
   will be modified by multiple threads is on separate cache lines.

*/

class OPENMAYA_EXPORT MThreadUtils
{
public:

	static int getNumThreads();

	OPENMAYA_DEPRECATED(2022, "Does nothing. Present for backward-compatibility purposes only.")
	static void syncNumOpenMPThreads();

	static int getCacheLineSize();

};

/*!
    Maya uses the Intel compiler for OpenMP internally. A plugin may
    be built using VC++ or gcc, both of which have OpenMP thread pools
    that are incompatible with Intel's. For these thread pools to
    respect the Maya thread count, it is important to initialize the
    number of threads explicitly for these implementations of
    OpenMP. This is done by calling this function in the plugin, which
    queries the current the threadcount from Maya and applies it to the
    plugin OpenMP implementation.

	This function does not need to be called if the plugin is compiled
	with the Intel compiler.
*/
inline void MThreadUtils::syncNumOpenMPThreads()
{
#ifdef _OPENMP
		int numThreads = getNumThreads();
		omp_set_num_threads(numThreads);
#endif
}

OPENMAYA_NAMESPACE_CLOSE