man pages section 3: Basic Library Functions

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Updated: July 2014
 
 

pthread_once(3C)

Name

pthread_once - initialize dynamic package

Synopsis

cc –mt [ flag... ] file... [ library... ]

#include <pthread.h> 
pthread_once_t once_control = PTHREAD_ONCE_INIT;

int pthread_once(pthread_once_t *once_control,
     void (*init_routine)(void));

Description

If any thread in a process with a once_control parameter makes a call to pthread_once(), the first call will summon the init_routine(), but subsequent calls will not. The once_control parameter determines whether the associated initialization routine has been called. The init_routine() is complete upon return of pthread_once().

pthread_once() is not a cancellation point; however, if the function init_routine() is a cancellation point and is canceled, the effect on once_control is the same as if pthread_once() had never been called.

The constant PTHREAD_ONCE_INIT is defined in the <pthread.h> header.

If once_control has automatic storage duration or is not initialized by PTHREAD_ONCE_INIT, the behavior of pthread_once() is undefined.

Return Values

Upon successful completion, pthread_once() returns 0. Otherwise, an error number is returned to indicate the error.

Errors

EINVAL

once_control or init_routine is NULL.

Attributes

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPE
ATTRIBUTE VALUE
Interface Stability
Committed
MT-Level
MT-Safe
Standard

See Also

attributes(5), standards(5)

Notes

Solaris threads do not offer this functionality.