source: tests/concurrency/clib.c@ cef5bfc

#include <stdio.h>
#include <stdlib.h>
#include <clib/cfathread.h>
#include <bits/defs.hfa>

extern "C" {
void _exit(int status);
}

_Thread_local struct drand48_data buffer = { 0 };
int myrand() {
        long int result;
        lrand48_r(&buffer, &result);
        return result;
}


enum Constants { blocked_size = 20 };
cfathread_t volatile blocked[blocked_size];

void * Worker( void * ) {
        for(int i = 0; i < 1000; i++) {
                int idx = myrand() % blocked_size;
                if(blocked[idx]) {
                        cfathread_t thrd = __atomic_exchange_n(&blocked[idx], NULL, __ATOMIC_SEQ_CST);
                        cfathread_unpark( thrd );
                } else {
                        cfathread_t thrd = __atomic_exchange_n(&blocked[idx], cfathread_self(), __ATOMIC_SEQ_CST);
                        cfathread_unpark( thrd );
                        cfathread_park();
                }
        }
        printf("Done\n");
        return NULL;
}

volatile bool stop;
void * Unparker( void * ) {
        while(!stop) {
                int idx = myrand() % blocked_size;
                cfathread_t thrd = __atomic_exchange_n(&blocked[idx], NULL, __ATOMIC_SEQ_CST);
                cfathread_unpark( thrd );
                int r = myrand() % 20;
                for( int i = 0; i < r; i++ ) {
                        cfathread_yield();
                }
        }
        printf("Done Unparker\n");
        return NULL;
}


int main() {
        stop = false;
        for(int i = 0; i < blocked_size; i++) {
                blocked[i] = NULL;
        }

        cfathread_cluster_t cl = cfathread_cluster_self();

        cfathread_cluster_add_worker( cl, NULL, NULL, NULL );
        cfathread_cluster_add_worker( cl, NULL, NULL, NULL );
        cfathread_cluster_add_worker( cl, NULL, NULL, NULL );

        cfathread_attr_t attr;
        cfathread_attr_init(&attr);
        cfathread_attr_setcluster(&attr, cl);

        cfathread_t u;
        cfathread_create( &u, &attr, Unparker, NULL );
        {
                cfathread_t t[20];
                for(int i = 0; i < 20; i++) {
                        cfathread_create( &t[i], &attr, Worker, NULL );
                }
                for(int i = 0; i < 20; i++) {
                        cfathread_join( t[i], NULL );
                }
        }
        stop = true;
        cfathread_join(u, NULL);
        cfathread_attr_destroy(&attr);
        fflush(stdout);
        _exit(0);
}