/** @file rwlock_type.h
 *  @brief This file defines the type for reader/writer locks.
 *  @author Meng Jun Zheng (mzheng)
 */

#ifndef _RWLOCK_TYPE_H
#define _RWLOCK_TYPE_H

#include <cond.h>
#include <mutex.h>

#define RWLOCK_SUCCESS 0
#define RWLOCK_ERROR -1

/** @brief Read/Write lock structure */
typedef struct rwlock {
	int num_writers; /* includes waiting writers and sometimes current writer */
	int curr_readers; /* includes current readers */
	mutex_t writer_mu; /* mutex for exclusive writer lock */
	mutex_t reader_mu; /* mutex to protect curr_readers and num_writers */
	cond_t writer_cond; /* stores a queue of waiting writers */
	cond_t reader_cond; /* stores a queue of waiting readers */
} rwlock_t;

#endif /* _RWLOCK_TYPE_H */