Mutex.h

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//     ____   ______ __
//    / __ \ / ____// /
//   / /_/ // /    / /
//  / ____// /___ / /___   PixInsight Class Library
// /_/     \____//_____/   PCL 2.4.7
// ----------------------------------------------------------------------------
// pcl/Mutex.h - Released 2020-12-17T15:46:28Z
// ----------------------------------------------------------------------------
// This file is part of the PixInsight Class Library (PCL).
// PCL is a multiplatform C++ framework for development of PixInsight modules.
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// ----------------------------------------------------------------------------

#ifndef __PCL_Mutex_h
#define __PCL_Mutex_h


#include <pcl/Defs.h>
#include <pcl/Diagnostics.h>

#include <pcl/Utility.h>

#ifdef __PCL_UNIX
#  include <pcl/Atomic.h>
#  include <stdio.h>
#  include <pthread.h>
#endif

#ifdef __PCL_WINDOWS
#  include <windows.h>
#endif

namespace pcl
{

// ----------------------------------------------------------------------------

class PCL_CLASS Mutex
{
public:

   Mutex( int spin = 512 )
      : m_spinCount( Max( 0, spin ) )
   {
#ifdef __PCL_WINDOWS
      (void)InitializeCriticalSectionAndSpinCount( &criticalSection, DWORD( m_spinCount ) );
#else
      (void)PThreadInitMutex();
#endif
   }

   virtual ~Mutex()
   {
#ifdef __PCL_WINDOWS
      DeleteCriticalSection( &criticalSection );
#else
      (void)PThreadDestroyMutex();
#endif
   }

   Mutex( const Mutex& ) = delete;

   Mutex& operator =( const Mutex& ) = delete;

   void Lock()
   {
#ifdef __PCL_WINDOWS
      EnterCriticalSection( &criticalSection );
#else
      for ( int spin = m_spinCount; ; )
      {
         // Is the mutex free? If so, get it now and don't look back!
         if ( m_lockState.TestAndSet( 0, 1 ) )
         {
            (void)PThreadLockMutex();
            break;
         }

         if ( --spin < 0 )
         {
            // Either no spinning, or spinned to no avail...
            // Block thread until we can get this mutex. This is expensive.
            (void)PThreadLockMutex();
            m_lockState.Store( 1 );
            break;
         }
      }
#endif
   }

   void Unlock()
   {
#ifdef __PCL_WINDOWS
      LeaveCriticalSection( &criticalSection );
#else
      m_lockState.Store( 0 );
      (void)PThreadUnlockMutex();
#endif
   }

   void operator ()( bool lock = true )
   {
      if ( lock )
         Lock();
      else
         Unlock();
   }

   bool TryLock()
   {
#ifdef __PCL_WINDOWS
      return TryEnterCriticalSection( &criticalSection ) != FALSE;
#else
      // ### N.B.: This code is performance and stability critical. DO NOT
      // modify it unless you are absolutely sure of what you are doing.
      return m_lockState == 0 && m_lockState.TestAndSet( 0, 1 ) && PThreadLockMutex();
#endif
   }

   int SpinCount() const
   {
      return m_spinCount;
   }

private:

#ifdef __PCL_WINDOWS

   CRITICAL_SECTION criticalSection;

#else // Linux/UNIX

   AtomicInt       m_lockState; // 0=unlocked, 1=acquired
   pthread_mutex_t m_mutex;

   bool PThreadInitMutex()
   {
      return PThreadCheckError( pthread_mutex_init( &m_mutex, 0 ), "pthread_mutex_init" );
   }

   bool PThreadDestroyMutex()
   {
      return PThreadCheckError( pthread_mutex_destroy( &m_mutex ), "pthread_mutex_destroy" );
   }

   bool PThreadLockMutex()
   {
      return PThreadCheckError( pthread_mutex_lock( &m_mutex ), "pthread_mutex_lock" );
   }

   bool PThreadUnlockMutex()
   {
      return PThreadCheckError( pthread_mutex_unlock( &m_mutex ), "pthread_mutex_unlock" );
   }

   static bool PThreadCheckError( int errorCode, const char* funcName )
   {
      if ( errorCode == 0 )
         return true;
      fprintf( stderr, "%s() failed. Error code: %d\n", funcName, errorCode );
      return false;
   }

#endif   // __PCL_WINDOWS

   int m_spinCount = 512;
};

// ----------------------------------------------------------------------------

} // pcl

#endif   // __PCL_Mutex_h

// ----------------------------------------------------------------------------
// EOF pcl/Mutex.h - Released 2020-12-17T15:46:28Z