StackThreads/MP: version 0.77 User's Guide

3.9.1: Create A Group

        #include <st_foreign.h>
@        void* stf_create_sync_worker_group(wgc, n, f, a0, a1, a2, a3)
@        void  stf_create_async_worker_group(wg, wgc, n, f, a0, a1, a2, a3)
@        void* stf_wait_for_wg_to_exit(wg)
@        int   stf_did_wg_exit(wg)
@                struct worker_group * wg; 
@                struct worker_group_conf * wgc; 
@                int n;
@                void * (*f)(void *, void *, void *, void*);
@                void * a0, * a1, * a2, * a3;

Both stf_create_sync_worker_group and stf_create_async_worker_group create a group of workers that initially consists of n workers. f specifies the entry function and a0 ... a3 its arguments; the group as a whole performs f(a0, a1, a2, a3), sharing threads created directly or indirectly from f. wg is a pointer to an uninitialized storage of type struct worker_group.

Created workers exit when f returns, no matter whether there are running threads that belong to the group. stf_create_sync_worker_group returns when workers exit. The return value is the return value of f.

On the other hand, stf_create_async_worker_group returns immediately. stf_wait_for_wg_to_exit(wg) waits for workers that belong to wg to exit (by blocking the underlying worker) and returns the return value of the entry function of wg. stf_did_wg_exit(wg) returns 1 if workers that belong to wg have already exited and 0 otherwise.