pthread_barrier_init(3) [netbsd man page]

PTHREAD_BARRIER(3)					   BSD Library Functions Manual 					PTHREAD_BARRIER(3)

NAME

     pthread_barrier -- barrier interface

LIBRARY

     POSIX Threads Library (libpthread, -lpthread)

SYNOPSIS

     #include <pthread.h>

     int
     pthread_barrier_init(pthread_barrier_t * restrict barrier, const pthread_barrierattr_t * restrict attr, unsigned int count);

     int
     pthread_barrier_destroy(pthread_barrier_t *barrier);

     int
     pthread_barrier_wait(pthread_barrier_t *barrier);

DESCRIPTION

     The pthread_barrier_init() function creates a new barrier with attributes attr and count.	The count parameter indicates the number of
     threads which will participate in the barrier.  The pthread_barrierattr_init(3) function may be used to specify the attributes supplied in
     attr.  If attr is NULL, the default attributes are used.  Barriers are most commonly used in the decomposition of parallel loops.

     The pthread_barrier_destroy() function causes the resources allocated to barrier to be released.  No threads should be blocked on barrier.

     The pthread_barrier_wait() function causes the current thread to wait on the barrier specified.  Once as many threads as specified by the
     count parameter to the corresponding pthread_barrier_init() call have called pthread_barrier_wait(), all threads will wake up, return from
     their respective pthread_barrier_wait() calls and continue execution.

RETURN VALUES

     If successful, pthread_barrier_init() will return zero and put the new barrier id into barrier, otherwise an error number will be returned to
     indicate the error.

     If successful, pthread_barrier_destroy() will return zero.  Otherwise an error value will be returned.

     If successful, pthread_barrier_wait() will return zero for all waiting threads except for one.  One thread will receive status
     PTHREAD_BARRIER_SERIAL_THREAD, which is intended to indicate that this thread may be used to update shared data.  It is the responsibility of
     this thread to insure the visibility and atomicity of any updates to shared data with respect to the other threads participating in the bar-
     rier.  In the case of failure, an error value will be returned.

ERRORS

     The pthread_barrier_init() function may fail if:

     [EINVAL]		The value specified by count is zero or attr is invalid.

     The pthread_barrier_destroy() function may fail if:

     [EBUSY]		The barrier still has active threads associated with it.

     [EINVAL]		The value specified by barrier is invalid.

     The pthread_barrier_wait() function may fail if:

     [EINVAL]		The value specified by barrier is invalid.

SEE ALSO

     pthread_barrierattr(3), pthread_cond(3), pthread_mutex(3)

STANDARDS

     These functions conform to IEEE Std 1003.1-2001 (``POSIX.1'').

BSD
								   July 8, 2010 							       BSD

pthread_barrier_destroy(3C)				   Standard C Library Functions 			       pthread_barrier_destroy(3C)

NAME

       pthread_barrier_destroy, pthread_barrier_init - destroy and initialize a barrier object

SYNOPSIS

       cc -mt [ flag... ] file... [ library... ]
       #include <pthread.h>

       int pthread_barrier_destroy(pthread_barrier_t *barrier);

       int pthread_barrier_init(pthread_barrier_t *barrier,
	    const pthread_barrierattr_t *restrict attr, unsigned count);

DESCRIPTION

       The  pthread_barrier_destroy()  function  destroys  the	barrier  referenced by barrier and releases any resources used by the barrier. The
       effect of subsequent use of the barrier is undefined until the barrier is reinitialized	by  another  call  to  pthread_barrier_init().	An
       implementation  can  use this function to set barrier to an invalid value. The results are undefined if pthread_barrier_destroy() is called
       when any thread is blocked on the barrier, or if this function is called with an uninitialized barrier.

       The pthread_barrier_init() function allocates any resources required to use the barrier referenced by barrier and initializes  the  barrier
       with attributes referenced by attr. If attr is NULL, the default barrier attributes are used; the effect is the same as passing the address
       of a default barrier attributes object. The results are undefined if pthread_barrier_init() is called when any thread  is  blocked  on  the
       barrier	(that  is,  has not returned from the pthread_barrier_wait(3C) call). The results are undefined if a barrier is used without first
       being initialized. The results are undefined if pthread_barrier_init() is called specifying an already initialized barrier.

       The count argument specifies the number of threads that must call pthread_barrier_wait() before any of them successfully  return  from  the
       call. The value specified by count must be greater than 0.

       If the pthread_barrier_init() function fails, the barrier is not initialized and the contents of barrier are undefined.

       Only the object referenced by barrier can be used for performing synchronization. The result of referring to copies of that object in calls
       to pthread_barrier_destroy() or pthread_barrier_wait() is undefined.

RETURN VALUES

       Upon successful completion, these functions returns 0. Otherwise, an error number is returned to indicate the error.

ERRORS

       The pthread_barrier_init() function will fail if:

       EAGAIN	 The system lacks the necessary resources to initialize another barrier.

       EINVAL	 The value specified by count is equal to 0.

       ENOMEM	 Insufficient memory exists to initialize the barrier.

       The pthread_barrier_init() function may fail if:

       EBUSY	 The implementation has detected an attempt to destroy a barrier while	it  is	in  use  (for  example,  while	being  used  in  a
		 pthread_barrier_wait() call) by another thread.

       EINVAL	 The value specified by attr is invalid.

       The pthread_barrier_destroy() function may fail if:

       EBUSY	 The  implementation  has  detected  an  attempt  to  destroy  a  barrier  while  it is in use (for example, while being used in a
		 pthread_barrier_wait() call) by another thread.

       EINVAL	 The value specified by barrier is invalid.

ATTRIBUTES

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

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       pthread_barrier_wait(3C), attributes(5), standards(5)

SunOS 5.11							    30 Jan 2004 				       pthread_barrier_destroy(3C)