itkThreadSupport.h

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/*=========================================================================
 *
 *  Copyright Insight Software Consortium
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0.txt
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *=========================================================================*/
#ifndef itkThreadSupport_h
#define itkThreadSupport_h

#include <cstdlib>

// This implementation uses a routine called SignalObjectAndWait()
// which is only defined on WinNT 4.0 or greater systems.  We need to
// define this symbol in order to get the prototype for the
// routine. This needs to be done before we load any system headers.
#ifdef ITK_USE_WIN32_THREADS
#ifndef _WIN32_WINNT
#define _WIN32_WINNT 0x0501 //TBB 4.4 requires WinXP (0x0501 or greater)
#endif
#endif

#if defined(ITK_USE_PTHREADS)
#include <pthread.h>
#elif defined(ITK_USE_WIN32_THREADS)
#include "itkWindows.h"
#include <winbase.h>
#endif


namespace itk
{
#if defined(ITK_USE_PTHREADS)
  constexpr std::size_t ITK_MAX_THREADS = 128;
  using MutexType = pthread_mutex_t;
  using FastMutexType = pthread_mutex_t;
  using ThreadFunctionType = void *(*)(void *);
  using ThreadProcessIdType = pthread_t;
  constexpr ThreadProcessIdType ITK_DEFAULT_THREAD_ID = 0;
  using ITK_THREAD_RETURN_TYPE = void *;
  constexpr ITK_THREAD_RETURN_TYPE ITK_THREAD_RETURN_DEFAULT_VALUE = NULL; /* This is from a c library, and always needs to be NULL, not nullptr */
  using itk::ITK_THREAD_RETURN_DEFAULT_VALUE;  //We need this out of the itk namespace for #define to work below
  using ITK_THREAD_RETURN_FUNCTION_CALL_CONVENTION = itk::ITK_THREAD_RETURN_TYPE;
#elif defined(ITK_USE_WIN32_THREADS)


  constexpr std::size_t ITK_MAX_THREADS = 128;
  using MutexType = HANDLE;
  using FastMutexType = CRITICAL_SECTION;
  typedef unsigned(__stdcall * ThreadFunctionType)(void *);
  using ThreadProcessIdType = HANDLE;
  static const ThreadProcessIdType ITK_DEFAULT_THREAD_ID = INVALID_HANDLE_VALUE;
  using ITK_THREAD_RETURN_TYPE = unsigned;
  constexpr ITK_THREAD_RETURN_TYPE ITK_THREAD_RETURN_DEFAULT_VALUE = 0;
  // WINAPI expands to __stdcall which specifies a function call convention and has little no meaning on variable declarations
  #define ITK_THREAD_RETURN_FUNCTION_CALL_CONVENTION itk::ITK_THREAD_RETURN_TYPE __stdcall
#else

  constexpr std::size_t ITK_MAX_THREADS = 1;
  using MutexType = int;
  using FastMutexType = int;
  typedef void ( *ThreadFunctionType )(void *);
  using ThreadProcessIdType = int;
  constexpr ThreadProcessIdType ITK_DEFAULT_THREAD_ID = 0;
  using ITK_THREAD_RETURN_TYPE = void;
  #define ITK_THREAD_RETURN_DEFAULT_VALUE
  using ITK_THREAD_RETURN_FUNCTION_CALL_CONVENTION = itk::ITK_THREAD_RETURN_TYPE;
#endif


#if defined(ITK_USE_PTHREADS)
  typedef struct {
  pthread_cond_t m_ConditionVariable;
  } ConditionVariableType;
#elif defined(ITK_USE_WIN32_THREADS)
  typedef struct {
  int m_NumberOfWaiters;                   // number of waiting threads
  CRITICAL_SECTION m_NumberOfWaitersLock;  // Serialize access to
                                           // m_NumberOfWaiters

  HANDLE m_Semaphore;                      // Semaphore to queue threads
  HANDLE m_WaitersAreDone;                 // Auto-reset event used by the
                                           // broadcast/signal thread to
                                           // wait for all the waiting
                                           // threads to wake up and
                                           // release the semaphore

  int m_WasBroadcast;                      // Used as boolean. Keeps track of whether
                                           // we were broadcasting or signaling
  } ConditionVariableType;
#else
  using ConditionVariableType = struct { };
#endif

}

// Compile-time conditional code for different threading models
// require that some items are #defines (always global scope) or
// can sometimes be rigorously typed.  When rigorously typed,
// we need to re-exposed to the global namespace to keep the
// use of these items consistent.
#if defined(ITK_USE_PTHREADS)
using itk::ITK_THREAD_RETURN_FUNCTION_CALL_CONVENTION;
using itk::ITK_THREAD_RETURN_DEFAULT_VALUE;  //We need this out of the itk namespace for #define to work below
#elif defined(ITK_USE_WIN32_THREADS)
using itk::ITK_THREAD_RETURN_DEFAULT_VALUE;  //We need this out of the itk namespace for #define to work below
#else
using itk::ITK_THREAD_RETURN_FUNCTION_CALL_CONVENTION;
#endif

// For backwards compatiblity
#if ! defined ( ITK_FUTURE_LEGACY_REMOVE )
  using itk::ITK_MAX_THREADS;
  using itk::ITK_DEFAULT_THREAD_ID;
#endif

#endif