Scriptionary Blog

What: A C++ wrapper around both WINAPI (Microsoft Windows) and PThreads (POSIX threads) functionality.
Why: To abstract cross platform functionality.
Remarks: On windows, CRITICAL_SECTION objects cannot be shared cross-process. This means that the class is tied to your application or DLL process. Comments are in Doxygen/Javadoc style.

#ifdef _WIN32
#include <windows.h>
#else
#include <unistd.h>
#include <pthread.h>
#endif

/**
 * @class A wrapper-class around Critical Section functionality, WIN32 & PTHREADS.
 */
class CriticalSection
{
public:
	/**
	 * @brief CriticalSection class constructor.
	 */
	explicit CriticalSection(void)
	{
	#ifdef _WIN32
		if (0 == InitializeCriticalSectionAndSpinCount(&this->m_cSection, 0))
			throw("Could not create a CriticalSection");
	#else
		if (pthread_mutex_init(&this->m_cSection, NULL) != 0)
			throw("Could not create a CriticalSection");
	#endif
	}; // CriticalSection()

	/**
	 * @brief CriticalSection class destructor
	 */
	~CriticalSection(void)
	{
		this->WaitForFinish(); // acquire ownership
	#ifdef _WIN32
		DeleteCriticalSection(&this->m_cSection);
	#else
		pthread_mutex_destroy(&this->m_cSection);
	#endif
	}; // ~CriticalSection()

	/**
	 * @fn void WaitForFinish(void)
	 * @brief Waits for the critical section to unlock.
	 * This function puts the waiting thread in a waiting
	 * state.
	 * @see TryEnter()
	 * @return void
	 */
	void WaitForFinish(void)
	{
		while(!this->TryEnter())
		{
		#ifdef _WIN32
			Sleep(1); // put waiting thread to sleep for 1ms
		#else
			usleep(1000); // put waiting thread to sleep for 1ms (1000us)
		#endif
		};
	}; // WaitForFinish()

	/**
	 * @fn void Enter(void)
	 * @brief Wait for unlock and enter the CriticalSection object.
	 * @see TryEnter()
	 * @return void
	 */
	void Enter(void)
	{
		this->WaitForFinish(); // acquire ownership
	#ifdef _WIN32
		EnterCriticalSection(&this->m_cSection);
	#else
		pthread_mutex_lock(&this->m_cSection);
	#endif
	}; // Enter()

	/**
	 * @fn void Leave(void)
	 * @brief Leaves the critical section object.
	 * This function will only work if the current thread
	 * holds the current lock on the CriticalSection object
	 * called by Enter()
	 * @see Enter()
	 * @return void
	 */
	void Leave(void)
	{
	#ifdef _WIN32
		LeaveCriticalSection(&this->m_cSection);
	#else
		pthread_mutex_unlock(&this->m_cSection);
	#endif
	}; // Leave()

	/**
	 * @fn bool TryEnter(void)
	 * @brief Attempt to enter the CriticalSection object
	 * @return bool(true) on success, bool(false) if otherwise
	 */
	bool TryEnter(void)
	{
		// Attempt to acquire ownership:
	#ifdef _WIN32
		return(TRUE == TryEnterCriticalSection(&this->m_cSection));
	#else
		return(0 == pthread_mutex_trylock(&this->m_cSection));
	#endif
	}; // TryEnter()

private:
#ifdef _WIN32
	CRITICAL_SECTION m_cSection; //!< internal system critical section object (windows)
#else
	pthread_mutex_t m_cSection; //!< internal system critical section object (*nix)
#endif
}; // class CriticalSection