PTHREAD_BARRIER(3) BSD Library Functions Manual PTHREAD_BARRIER(3)
pthread_barrier_destroy, pthread_barrier_init, pthread_barrier_wait -- destroy, initialize or wait on a barrier object
POSIX Threads Library (libpthread, -lpthread)
pthread_barrier_init(pthread_barrier_t *barrier, const pthread_barrierattr_t *attr, unsigned count);
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.
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.
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.
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.
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.
February 19, 2004 BSD