Nils O. Selåsdal
46 lines
1.2 KiB
C
46 lines
1.2 KiB
C
#ifndef UC_TICKET_LOCK_H_
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#define UC_TICKET_LOCK_H_
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#include <pthread.h>
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/** An fair alternative to a bare pthread_mutex_t to prevent starvation.
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* The members of UCTicketLock must never be accessed directly.
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*/
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struct UCTicketLock {
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pthread_cond_t cond;
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pthread_mutex_t mutex;
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unsigned long queue_head, queue_tail;
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};
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/** Static initializer for an UCTicketLock. Use as e.g
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*
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* struct UCTicketLock my_lock = UC_TICKET_LOCK_INITIALIZER;
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*/
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#define UC_TICKET_LOCK_INITIALIZER { PTHREAD_COND_INITIALIZER, PTHREAD_MUTEX_INITIALIZER,0, 0}
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/** Initialize a UCTicketLock.
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* The default attributes for the pthread mutex and condition variable is used.
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*
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* @return 0 on success, errno value on failure
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*/
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int uc_ticket_lock_init(struct UCTicketLock *lock);
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/** Initialize a UCTicketLock with attributes
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*
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* @param mattr attribute used for the mutex, or NULL
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* @param cattr attribute used for the condition variable, or NULL
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*
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* @return 0 on success, errno value on failure
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*/
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int uc_ticket_lock_init_ex(struct UCTicketLock *lock, pthread_mutexattr_t *mattr, pthread_condattr_t *cattr);
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/** Acquire the lock
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*/
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void uc_ticket_lock(struct UCTicketLock *lock);
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/** Release the lock
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*/
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void uc_ticket_unlock(struct UCTicketLock *lock);
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#endif
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