semaphore

Semaphore for managing shared resources. More...

Functions
int	ua_sem_create (ua_sem_t *sem, int shared, unsigned int value, const char *name)
	Initialize a semaphore. More...
int	ua_sem_destroy (ua_sem_t *sem)
	Clear a semaphore. More...
int	ua_sem_post (ua_sem_t *sem)
	Post (increment/unlock) a semaphore. More...
int	ua_sem_wait (ua_sem_t *sem)
	Decrement/lock a semaphore. More...
int	ua_sem_trywait (ua_sem_t *sem)
	Decrement/lock a semaphore. More...
int	ua_sem_timedwait (ua_sem_t *sem, int ms_timeout)
	Decrement/lock a semaphore. More...

Detailed Description

Semaphore for managing shared resources.

Function Documentation

int ua_sem_create	(	ua_sem_t *	sem,
		int	shared,
		unsigned int	value,
		const char *	name
	)

Initialize a semaphore.

Parameters

sem	Semaphore to initialize.
shared	1 if the semaphore should be shared.
value	Initial value of the semaphore.
name	Unique name for the semaphore

Returns

Zero on success or errorcode on failure.

int ua_sem_destroy

(

ua_sem_t *

sem

)

Clear a semaphore.

The semaphore shall no longer be used.

Parameters

sem	Semaphore to clear.

Returns

Zero on success or errorcode on failure.

int ua_sem_post

(

ua_sem_t *

sem

)

Post (increment/unlock) a semaphore.

Parameters

sem	Semaphore to post.

Returns

Zero on success or errorcode on failure.

int ua_sem_timedwait	(	ua_sem_t *	sem,
		int	ms_timeout
	)

Decrement/lock a semaphore.

If the value of the semaphore is zero the function waits (blocks) for the given timeout. If the value could not be decremented in the given time the errorcode UA_EBADOPTIMEOUT is returned.

Parameters

sem	Semaphore to decrement.
timeout	Time in milliseconds to wait.

Returns

Zero on success or errorcode on failure.

int ua_sem_trywait

(

ua_sem_t *

sem

)

Decrement/lock a semaphore.

If the value of the semaphore is zero the function returns with the errorcode UA_EBADAGAIN instead of waiting.

Parameters

sem	Semaphore to decrement.

Returns

Zero on success or errorcode on failure.

int ua_sem_wait

(

ua_sem_t *

sem

)

Decrement/lock a semaphore.

If the value of the semaphore is zero the function waits (blocks) until the value becomes greater than zero.

Parameters

sem	Semaphore to decrement/wait.

Returns

Zero on success or errorcode on failure.