#ifndef UC_TICKET_LOCK_H_
#define UC_TICKET_LOCK_H_

#include <pthread.h>

/** An fair alternative to a bare pthread_mutex_t to prevent starvation*/
struct UCTicketLock {
    pthread_cond_t cond;
    pthread_mutex_t mutex;
    unsigned long queue_head, queue_tail;
};

/** Static initializer for an UCTicketLock. Use as e.g
 *
 * struct UCTicketLock my_lock = UC_TICKET_LOCK_INITIALIZER;
 */
#define UC_TICKET_LOCK_INITIALIZER { PTHREAD_COND_INITIALIZER, PTHREAD_MUTEX_INITIALIZER,0, 0}

/** Initialize a UCTicketLock. 
 * The default attributes for the pthread mutex and condition variable is used.
 *
 * @return 0 on success, errno value on failure
*/
int uc_ticket_lock_init(struct UCTicketLock *lock);

/** Initialize a UCTicketLock with attributes
 *
 * @param mattr attribute used for the mutex, or NULL
 * @param cattr attribute used for the condition variable, or NULL
 *
 * @return 0 on success, errno value on failure
*/
int uc_ticket_lock_init_ex(struct UCTicketLock *lock, pthread_mutexattr_t *mattr, pthread_condattr_t *cattr);

/** Acquire the lock
 */
void uc_ticket_lock(struct UCTicketLock *lock);

/** Release the lock
 */
void uc_ticket_unlock(struct UCTicketLock *lock);

#endif