pthread_barrier_wait(3) [freebsd man page]

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

NAME

     pthread_barrier_destroy, pthread_barrier_init, pthread_barrier_wait -- destroy, initialize or wait on a barrier object

LIBRARY

     POSIX Threads Library (libpthread, -lpthread)

SYNOPSIS

     #include <pthread.h>

     int
     pthread_barrier_destroy(pthread_barrier_t *barrier);

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

     int
     pthread_barrier_wait(pthread_barrier_t *barrier);

DESCRIPTION

     The pthread_barrier_init() function will initialize barrier with attributes specified in attr, or if it is NULL, with default attributes.
     The number of threads that must call pthread_barrier_wait() before any of the waiting threads can be released is specified by count.  The
     pthread_barrier_destroy() function will destroy barrier and release any resources that may have been allocated on its behalf.

     The pthread_barrier_wait() function will synchronize calling threads at barrier.  The threads will be blocked from making further progress
     until a sufficient number of threads calls this function.	The number of threads that must call it before any of them will be released is
     determined by the count argument to pthread_barrier_init().  Once the threads have been released the barrier will be reset.

IMPLEMENTATION NOTES

     In both N:M Threading Library (libkse, -lkse) and 1:1 Threading Library (libthr, -lthr) the PTHREAD_BARRIER_SERIAL_THREAD return value will
     always be returned by the last thread to reach the barrier.

RETURN VALUES

     If successful, both pthread_barrier_destroy() and pthread_barrier_init() will return zero.  Otherwise, an error number will be returned to
     indicate the error.  If the call to pthread_barrier_wait() is successful, all but one of the threads will return zero.  That one thread will
     return PTHREAD_BARRIER_SERIAL_THREAD.  Otherwise, an error number will be returned to indicate the error.

     None of these functions will return EINTR.

ERRORS

     The pthread_barrier_destroy() function will fail if:

     [EBUSY]		An attempt was made to destroy barrier while it was in use.

     The pthread_barrier_destroy() and pthread_barrier_wait() functions may fail if:

     [EINVAL]		The value specified by barrier is invalid.

     The pthread_barrier_init() function will fail if:

     [EAGAIN]		The system lacks resources, other than memory, to initialize barrier.

     [EINVAL]		The count argument is less than 1.

     [ENOMEM]		Insufficient memory to initialize barrier.

SEE ALSO

     pthread_barrierattr(3)

HISTORY

     The pthread_barrier_destroy(), pthread_barrier_init() and pthread_barrier_wait() functions first appeared in N:M Threading Library (libkse,
     -lkse) in FreeBSD 5.2, and in 1:1 Threading Library (libthr, -lthr) in FreeBSD 5.3.

BSD
								 February 19, 2004							       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)