itkSemaphore.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 __itkSemaphore_h
#define __itkSemaphore_h

# include "itkObjectFactory.h"
#include <string>

#ifdef ITK_USE_UNIX_IPC_SEMAPHORES
#include "itkMutexLock.h"
#include <stdio.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/sem.h>
#include <errno.h>
#endif

#ifndef ITK_USE_UNIX_IPC_SEMAPHORES
#ifdef ITK_USE_PTHREADS
#ifdef sun
#include <synch.h>
#else
#include <semaphore.h>
#endif
#endif
#endif

#ifdef ITK_USE_WIN32_THREADS
# include "itkWindows.h"
#endif

namespace itk
{
#ifdef ITK_USE_UNIX_IPC_SEMAPHORES
typedef int SemaphoreType;
#endif

#ifndef ITK_USE_UNIX_IPC_SEMAPHORES
#ifdef ITK_USE_PTHREADS
#ifdef sun
typedef sema_t SemaphoreType;
#else
#ifdef __APPLE__
typedef sem_t *SemaphoreType;
#else
typedef sem_t SemaphoreType;
#endif
#endif
#endif
#endif

#ifdef ITK_USE_WIN32_THREADS
typedef HANDLE SemaphoreType;
#endif

#ifndef ITK_USE_UNIX_IPC_SEMAPHORES
#ifndef ITK_USE_PTHREADS
#ifndef ITK_USE_WIN32_THREADS
typedef int SemaphoreType;
#endif
#endif
#endif

class ITK_EXPORT Semaphore:public LightObject
{
public:
  typedef Semaphore                  Self;
  typedef LightObject                Superclass;
  typedef SmartPointer< Self >       Pointer;
  typedef SmartPointer< const Self > ConstPointer;

  itkNewMacro(Self);

  itkTypeMacro(Semaphore, LightObject);

  void Initialize(unsigned int value);

  void Up();

  void Down();

  void Remove();

protected:
  Semaphore ();
  ~Semaphore();
  // Newer compilers do agreessive dead code checking.
  // function is only to avoid the detection that
  // warning: private field 'm_Pad1' is not used
  // warning: private field 'm_Pad2' is not used
  std::string NeverUseThisCompilerWarningAvoidanceFunctionForPad1Pad2(void) const
    {
    return std::string(this->m_Pad1)+"-"+std::string(this->m_Pad2);
    }
private:

#ifdef ITK_USE_UNIX_IPC_SEMAPHORES

  static int m_IPCSemaphoreKey;

  static SimpleMutexLock m_Mutex;

  int  UnixIpcSemaphoreCreate(int unix_semaphore_key);

  void UnixIpcSemaphoreRemove(int sid);

  void UnixIpcSemaphoreCall(int sid, int op);

  void UnixIpcSemaphoreDown(int sid);

  void UnixIpcSemaphoreUp(int sid);

#endif

  char m_Pad1[128]; // to avoid false sharing in case of shared memory
                    // multiprocessor systems

  SemaphoreType m_Sema;

  char m_Pad2[128]; // to avoid false sharing in case of shared memory
                    // multiprocessor systems

#ifdef __APPLE__
  std::string GetUniqueName();

  static int  m_SemaphoreCount;
  std::string m_SemaphoreName;
#endif

#ifdef ITK_USE_PTHREADS
  bool m_PThreadsSemaphoreRemoved;
#endif
};
} //itk

#endif