/*=========================================================================

  Program:   Insight Segmentation & Registration Toolkit
  Module:    $RCSfile: itkSemaphore.cxx,v $
  Language:  C++
  Date:      $Date: 2006-02-06 22:08:11 $
  Version:   $Revision: 1.14 $

  Copyright (c) Insight Software Consortium. All rights reserved.
  See ITKCopyright.txt or http://www.itk.org/HTML/Copyright.htm for details.

     This software is distributed WITHOUT ANY WARRANTY; without even 
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR 
     PURPOSE.  See the above copyright notices for more information.

=========================================================================*/
#include "itkConfigure.h"
#include "itkSemaphore.h"

#ifdef __APPLE__
extern "C" {
#include <stdio.h>
#include <time.h>
}
#endif

/// DEBUG
extern "C" {
#include <stdio.h>
#include <errno.h>
}
///

namespace itk {

#ifdef __APPLE__
int Semaphore::m_SemaphoreCount = 0;
#endif

#ifdef ITK_USE_UNIX_IPC_SEMAPHORES
int Semaphore::m_IPCSemaphoreKey = 12345;
SimpleMutexLock Semaphore::m_Mutex;
#endif

#ifdef __APPLE__
std::string Semaphore::GetUniqueName()
{
  char s[255];  
  time_t t = time(0);
  snprintf(s,254,"MACSEM%d%d",static_cast<int>(t),m_SemaphoreCount); 
  return std::string(s); 
}
#endif

Semaphore::Semaphore ()
{
#ifdef ITK_USE_UNIX_IPC_SEMAPHORES
  m_Sema= -1;
#endif


#ifdef __APPLE__
  m_Sema = 0;
  m_SemaphoreCount++;
  m_SemaphoreName = Semaphore::GetUniqueName();
#endif
  
#ifndef ITK_USE_UNIX_IPC_SEMAPHORES  

#ifdef ITK_USE_SPROC
  m_Sema = 0;
#endif

#endif
  
#ifdef ITK_USE_WIN32_THREADS
  m_Sema = 0;
#endif

#ifdef ITK_USE_PTHREADS
  m_PThreadsSemaphoreRemoved = false;
#endif
}
  
void Semaphore::Initialize(unsigned int value)
{
  
#ifdef ITK_USE_UNIX_IPC_SEMAPHORES
  // Obtain a lock over the m_IPCSemaphoreKey so that the new semaphore is
  // created with a unique unix_semaphore_key 
  Semaphore::m_Mutex.Lock();
  m_Sema = Semaphore::UnixIpcSemaphoreCreate(Semaphore::m_IPCSemaphoreKey);
  
  // by default the semaphore created has value 0
  Semaphore::m_IPCSemaphoreKey++;
  Semaphore::m_Mutex.Unlock();
  
  for (unsigned int i = 0; i < value; i++)
    {
    this->Up();
    }
#endif
  
#ifndef ITK_USE_UNIX_IPC_SEMAPHORES  
#ifdef ITK_USE_SPROC
  if (MultiThreader::GetInitialized() == false)
    {
      MultiThreader::Initialize();
    }

  m_Sema = usnewsema(MultiThreader::GetThreadArena(), static_cast<int>(value));
  if ( ! m_Sema )
    {
      itkExceptionMacro( << " sem_init call failed with code " << m_Sema );
    }
  
#endif
#ifdef ITK_USE_PTHREADS

m_PThreadsSemaphoreRemoved = false;

#if defined sun
  if ( sema_init(&m_Sema, 0, value, NULL ) != 0 )
    {
    itkExceptionMacro( << "sema_init call failed" );
    }
#elif defined  __APPLE__
  m_Sema  = sem_open( m_SemaphoreName.c_str(), O_CREAT, 0x0644, value );
  if ( m_Sema == (sem_t *)SEM_FAILED )
    {
    //  perror("FAILED WITH ERROR:" );
    itkExceptionMacro( << "sem_open call failed on " << m_SemaphoreName.c_str() );
    }
#else
  if ( sem_init(&m_Sema, 0, value) != 0 )
    {
      itkExceptionMacro( << "sem_init call failed" );
    }
#endif // if defined sun

#endif // ifdef ITK_USE_PTHREADS
#endif // ifndef ITK_USE_UNIX_IPC_SEMAPHORES
  
#ifdef ITK_USE_WIN32_THREADS
  m_Sema = CreateSemaphore( 0, value, 0x7FFFFFFF, 0);
  if (m_Sema == 0)
    {
      itkExceptionMacro( << "CreateSemaphore call failed" );
    }
#endif
}
  
void Semaphore::Up()
{
#ifdef ITK_USE_UNIX_IPC_SEMAPHORES
  Semaphore::UnixIpcSemaphoreUp(m_Sema);
#endif
  
#ifndef ITK_USE_UNIX_IPC_SEMAPHORES

#ifdef ITK_USE_SPROC
  if (usvsema(m_Sema) == -1)
    {
      itkExceptionMacro( << "usvsema call failed." );
    }
#endif
#ifdef ITK_USE_PTHREADS
#ifdef sun
  if ( sema_post(&m_Sema) != 0 )
    {
      itkExceptionMacro( << "sema_post call failed." );
    }
#else
#ifdef __APPLE__
  if ( sem_post(m_Sema) != 0 )
    {
    itkExceptionMacro( << "sem_post call failed." );
    }
#else
  if ( sem_post(&m_Sema) != 0 )
    {
      itkExceptionMacro( << "sem_post call failed." );
    }
#endif
#endif // ifdef sun
#endif

#endif  // ITK_USE_UNIX_SEMAPHORES
  
#ifdef ITK_USE_WIN32_THREADS
  if ( ! ReleaseSemaphore ((HANDLE) m_Sema, 1 , 0) )
    {
      itkExceptionMacro( << "Semaphore post call failed." );
    }
#endif
}

void Semaphore::Down()
{
#ifdef ITK_USE_UNIX_IPC_SEMAPHORES
  Semaphore::UnixIpcSemaphoreDown (m_Sema);
#endif
  
#ifndef ITK_USE_UNIX_IPC_SEMAPHORES
#ifdef ITK_USE_SPROC
  if (uspsema(m_Sema) == -1)
    {
      itkExceptionMacro( << "uspsema call failed." );
    }
#endif
#ifdef ITK_USE_PTHREADS
#ifdef sun
  if (sema_wait(&m_Sema) != 0)
    {
    itkExceptionMacro( << "sema_wait call failed." );
    }
#else
#ifdef __APPLE__
  if (sem_wait(m_Sema) != 0)
    {
      itkExceptionMacro( << "sem_wait call failed." );
    }
#else
  
  if (sem_wait(&m_Sema) != 0)
    {
      itkExceptionMacro( << "sem_wait call failed." );
    }
#endif
#endif
#endif
#endif

#ifdef ITK_USE_WIN32_THREADS
  if ( WaitForSingleObject(m_Sema, INFINITE) == WAIT_FAILED )
    {
      itkExceptionMacro( << "WaitForSingleObject call failed. ");
    }
#endif
}

Semaphore::~Semaphore()
{
#ifdef ITK_USE_UNIX_IPC_SEMAPHORES
  if (m_Sema != -1)
    {
      this->Remove();
    }
#endif
  
#ifndef ITK_USE_UNIX_IPC_SEMAPHORES  
#ifdef ITK_USE_SPROC
  if (m_Sema != 0)
    {
      this->Remove();
    }
#endif
#ifdef ITK_USE_PTHREADS  
  if(!m_PThreadsSemaphoreRemoved)
    {
    this->Remove();
    }
#endif
#endif
  
#ifdef ITK_USE_WIN32_THREADS
  if (m_Sema != 0)
    {
      this->Remove();
    }
#endif
}

void Semaphore::Remove()
{
#ifdef ITK_USE_UNIX_IPC_SEMAPHORES
  if (m_Sema != -1)
    {
      Semaphore::UnixIpcSemaphoreRemove(m_Sema);
      m_Sema= -1;
    }
#endif
  
#ifndef ITK_USE_UNIX_IPC_SEMAPHORES

#ifdef ITK_USE_SPROC
  if (MultiThreader::GetThreadArena() != 0)
    {
    if (m_Sema != 0)
      {
      usfreesema(m_Sema, MultiThreader::GetThreadArena());
      }
    m_Sema = 0;
    }
#endif

#ifdef ITK_USE_PTHREADS
m_PThreadsSemaphoreRemoved = true;
#ifdef sun
  if ( sema_destroy(&m_Sema) != 0 )
    {
    itkExceptionMacro( << "sema_destroy call failed. " );
    }
#else

#ifndef __sgi
#ifndef __APPLE__
  // IRIX pthreads implementation of sem_destroy is buggy
  if ( sem_destroy(&m_Sema) != 0 )
    {
    itkExceptionMacro( << "sem_destroy call failed. " );
    }
#else //Still need to close semaphore and delete the file descriptor on MacOSX, otherwise the shared memory space is eventually exhosted.
  //Eventually (i.e. after several days of ITK regresssion testing) the semaphore creation process was failing with errno=ENOSPC
  //This implementation detail was taken from http://developer.apple.com/macosx/multithreadedprogramming.html
  if ( sem_close(this->m_Sema) !=0 )
      {
       itkExceptionMacro( << "sem_close call failed. " );
      }
  if ( sem_unlink(this->m_SemaphoreName.c_str()) !=0 )
      {
       itkExceptionMacro( << "sem_unlink call failed. " );
      }
#endif
#endif

#endif  // sun
#endif // pthreads
  
#endif // semaphores
  //#endif
  
#ifdef ITK_USE_WIN32_THREADS
  if (m_Sema != 0)
    {
    CloseHandle(m_Sema);
    }
  m_Sema= 0;
#endif
}

#ifdef ITK_USE_UNIX_IPC_SEMAPHORES

// UnixIpcSemaphoreCreate: will return the semaphore id (system wide)
// of the semaphore number (key) you give.
// If no semaphore has been established for this number, one is created.
int Semaphore::UnixIpcSemaphoreCreate(int unix_semaphore_key)
{
  int sid = -1;
  std::string s; 
 
  if( (sid = semget( (key_t)unix_semaphore_key, 1, 0666 | IPC_CREAT )) == -1 )
    {
    s =  "Error# %i in function UnixIpcSemaphoreCreate. - ";
    switch (errno)
      {
      case EEXIST:
        s += "Semaphore already exists. - ";
        break;
      case ENOSPC:
        s+= "System imposed limit on the number of semaphores is exceeded - ";
        break;
      case EACCES:
        s+= "Permission is denied - ";
        break;
      }
    itkExceptionMacro( << s.c_str() );
    }
  
  return( sid );
}

// UnixIpcSemaphoreDown: the semaphore signal operation.
// sid must be the system wide semaphore number
// returned by UnixIpcSemaphoreCreate above
void Semaphore::UnixIpcSemaphoreDown(int sid)
{
  Semaphore::UnixIpcSemaphoreCall(sid, -1);
}

// UnixIpcSemaphoreUp: the semaphore release operation.
// sid must be the system wide semaphore number
// returned by UnixIpcSemaphoreCreate above
void Semaphore::UnixIpcSemaphoreUp(int sid)
{
  Semaphore::UnixIpcSemaphoreCall(sid, 1);
}

// UixIpcSemaphoreRemove: remove a semaphore from the system.
// sid must be the system wide semaphore number
// returned from UnixIpcSemaphoreCreate
void Semaphore::UnixIpcSemaphoreRemove(int sid)
{
  std::string s;
  
  if( semctl( sid, 0, IPC_RMID, 0 ) == -1 )
    {
    s =  "Error removing semaphore %i - ";
    switch (errno)
      {
      case EINVAL:
        s +=  "Semaphore id# is not valid. - ";
        break;
      case EACCES:
        s+=  "Permission is denied - ";
        break;
      case EPERM:
        s+= "Permission is denied - ";
        break;
      }
    itkExceptionMacro ( << s.c_str() );
    }
}

// UnixIpcSemaphoreCall: makes the system call semop for your given
// semaphore and operation.
void Semaphore::UnixIpcSemaphoreCall (int sid, int op)
{
  struct sembuf sb;
  std::string s;
  
  sb.sem_num = 0;
  sb.sem_op = op;
  sb.sem_flg = 0;
  if( semop( sid, &sb, 1 ) == -1 )
    {
    
    if( op == -1 )
      {
      s =  "Error %i in UnixIpcSemaphoreDown call for semaphore %i - ";
      }
    else
      {
      s =  "Error %i in UnixIpcSemaphoreUp call for semaphore %i - ";
      }
    switch (errno)
      {
      case EINVAL:
        s +=  "Semaphore id# is not valid. -";
        break;
      case EFBIG:
        s +=  "Invalid sem_num for semaphore - ";
        break;
      case EACCES:
        s += "Permission denied for semaphore - ";
        break;
      case EAGAIN:
        s += "The operation would result in suspension of the calling process but NOWAIT is true.";
        break;
      case EIDRM:
        s += "The semid is removed from the system.";
        break;
      }
    itkExceptionMacro( << s.c_str() );
    }
}

#endif

}//end if namespace itk