Mutex.h

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//     ____   ______ __
//    / __ \ / ____// /
//   / /_/ // /    / /
//  / ____// /___ / /___   PixInsight Class Library
// /_/     \____//_____/   PCL 2.7.0
// ----------------------------------------------------------------------------
// pcl/Mutex.h - Released 2024-06-18T15:48:54Z
// ----------------------------------------------------------------------------
// 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 spinCount = 4000, int spinCountDelta = 1000, int spinCountMax = 12000 )
      : m_spinCount( Max( 0, spinCount ) )
      , m_spinCountDelta( Max( 0, spinCountDelta ) )
      , m_spinCountMax( Max( 0, spinCountMax ) )
   {
#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 );
            // If we are spinning, the spin count was too low. We can increase
            // it to make the spinning mutex adaptive.
            if ( m_spinCount > 0 )
               if ( m_spinCount < m_spinCountMax )
                  m_spinCount += m_spinCountDelta;
            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 = 4000;
   int m_spinCountDelta = 1000;
   int m_spinCountMax = 12000;
};
 
// ----------------------------------------------------------------------------
 
} // pcl
 
#endif   // __PCL_Mutex_h
 
// ----------------------------------------------------------------------------
// EOF pcl/Mutex.h - Released 2024-06-18T15:48:54Z