#ifndef GLTB_RWLOCK_H_
#define GLTB_RWLOCK_H_

#ifdef WIN32
#include <windows.h>
#else
#include <pthread.h>
#endif

#include "referencedobject.h"
#include "refptr.h"

namespace gltb {

	/**
	 * A simple read/write lock class. It behaves as you expect: you can have
	 * multiple read locks at the same time, but only one exclusive write lock.
	 * However, there are important restrictions that you have to be aware of:
	 *
	 *  - requesting the write lock in a thread that currently holds a read
	 *    lock causes a deadlock
	 *  - _Win32_: the read lock is non-reentrant on the same thread
	 *  - _POSIX_: the read lock is reentrant, but the number of unlocks must be
	 *    the same as the number of locks on the same thread
	 */
	class RWLock : public ReferencedObject {
	public:
		RWLock();
		~RWLock();

		void readLock();
		void readUnlock();
		void writeLock();
		void writeUnlock();

		static RefPtr<RWLock> createRWLock();

	private:
#ifdef WIN32
		SRWLOCK rwLock;
#else
		pthread_rwlock_t rwLock;
#endif
	};

	class RWLockGuard {
	public:
		enum LockType {
			Read,
			Write
		};

		RWLockGuard(gltb::RefPtr<RWLock> lock, LockType lockType) 
			: lock(lock), lockType(lockType) 
		{
			switch(lockType) {
			case Read:
				lock->readLock();
				break;
			case Write:
				lock->writeLock();
				break;
			}
		}
		 
		~RWLockGuard() {
			switch(lockType) {
			case Read:
				lock->readUnlock();
				break;
			case Write:
				lock->writeUnlock();
				break;
			}
		}

	private:
		gltb::RefPtr<RWLock> lock;
		LockType lockType;
	};
}

#endif