// This may look like C code, but it is really -*- C++ -*-

//

// Copyright Bob Friesenhahn, 1999, 2000, 2001, 2002

//

// Implementation of thread support

//

#define MAGICK_IMPLEMENTATION

#define MAGICK_PLUSPLUS_IMPLEMENTATION

#include "Magick++/Thread.h"

#include "Magick++/Exception.h"

#include <string.h>

// Default constructor

Magick::MutexLock::MutexLock(void)

#if defined(HasPTHREADS)

  // POSIX threads

  : _mutex()

{

  ::pthread_mutexattr_t attr;

  int sysError;

  if ( (sysError = ::pthread_mutexattr_init( &attr )) == 0 )

    if ( (sysError = ::pthread_mutex_init( &_mutex, &attr )) == 0 )

      {

        ::pthread_mutexattr_destroy( &attr );

        return;

      }

  throwExceptionExplicit( OptionError, "mutex initialization failed",

                          strerror(sysError) );

}

#else

#if defined(_VISUALC_) && defined(_MT)

// Win32 threads

  : _mutex()

{

  SECURITY_ATTRIBUTES security;

  /* Allow the semaphore to be inherited */

  security.nLength = sizeof(security);

  security.lpSecurityDescriptor = NULL;

  security.bInheritHandle = TRUE;

  /* Create the semaphore, with initial value signaled */

  _mutex.id = ::CreateSemaphore(&security, 1, MAXSEMLEN, NULL);

  if ( _mutex.id != NULL )

    return;

  throwExceptionExplicit( OptionError, "mutex initialization failed" );

}

#else

// Threads not supported

{

}

#endif

#endif

// Destructor

Magick::MutexLock::~MutexLock(void)

{

#if defined(HasPTHREADS)

  int sysError;

  if ( (sysError = ::pthread_mutex_destroy( &_mutex )) == 0 )

    return;

  throwExceptionExplicit( OptionError, "mutex destruction failed",

                          strerror(sysError) );

#endif

#if defined(_MT) && defined(_VISUALC_)

  if ( ::CloseHandle(_mutex.id) != 0 )

    return;

  throwExceptionExplicit( OptionError, "mutex destruction failed" );

#endif

}

// Lock mutex

void Magick::MutexLock::lock(void)

{

#if defined(HasPTHREADS)

  int sysError;

  if ( (sysError = ::pthread_mutex_lock( &_mutex )) == 0)

    return;

  throwExceptionExplicit( OptionError, "mutex lock failed",

                          strerror(sysError));

#endif

#if defined(_MT) && defined(_VISUALC_)

#if 1

  if (WaitForSingleObject(_mutex.id,INFINITE) != WAIT_FAILED)

    return;

  throwExceptionExplicit( OptionError, "mutex lock failed" );

#else

  // Following code  is not known to work correctly yet.

  while(1)

  {

    DWORD status=MsgWaitForMultipleObjects(1, &_mutex.id, FALSE, INFINITE,

      QS_ALLEVENTS);

    // Loop if return was due to message received (which we don't care about).

    if (status == (WAIT_OBJECT_0+1))

      continue;

    // If return was due to handle state change, then object is available.

    if ((status - WAIT_OBJECT_0) == 0)

      return;

   }

  // If we get here, then there was an unexpected return value.

  throwExceptionExplicit( OptionError, "mutex lock failed" );

#endif

#endif

}

// Unlock mutex

void Magick::MutexLock::unlock(void)

{

#if defined(HasPTHREADS)

  int sysError;

  if ( (sysError = ::pthread_mutex_unlock( &_mutex )) == 0)

    return;

  throwExceptionExplicit( OptionError, "mutex unlock failed",

                          strerror(sysError) );

#endif

#if defined(_MT) && defined(_VISUALC_)

  if ( ReleaseSemaphore(_mutex.id, 1, NULL) == TRUE )

    return;

  throwExceptionExplicit( OptionError, "mutex unlock failed" );

#endif

}