Mthreads

NAME

new_barrier - allocate a new barrier

delete_barrier - delete a barrier

barrier_init - initialize a barrier

barrier_check - wait until all other threads have reached the barrier

SYNOPSIS

#include <mthread.h>

barr_p new_barrier(int n);

void delete_barrier(barr_p bp);

barr_p barrier_init(barr_p bp, int n);

void barrier_check(barr_p bp);

DESCRIPTION

Barriers are usually used when it should be assured that a couple of threads have reached at a specific point in their computation. All, except the last thread reaching the barrier will be blocked. If the last thread arrives it deblockes all the other threads.

new_barrier(int n) allocates a new barrier and initializes it for use by n threads.

delete_barrier() deletes a barrier that has been allocated by new_barrier().

barrier_init() can be used to reinitialize a barrier that has already been allocated. This is necessary if the barrier will be used with a different number of threads than it has been created for.

barrier_check() is used to notice the calling thread's arrival to the barrier. If it's not the last thread it will get blocked. Otherwise it will unblock all other threads and reinitialize the barrier for its next use.

RETURN VALUES

Upon successful completion both new_barrier() and barrier_init() return with a valid barrier handle. Otherwise, a null handle will be returned and merrno set to indicate the error.

ERRORS

new_barrier() will fail if one of the following is true:

[MENOMEM] there is unsufficient memory to allocate the barrier
[MEVALUE] the number of threads must be greater than 1

barrier_init() will fail if one of the following is true:

[MEVALUE] the number of threads must be greater than 1