source: benchmark/readyQ/transfer.cfa

#include "rq_bench.hfa"
#include <fstream.hfa>
#include <locale.h>

Duration default_preemption() {
        return 0;
}

#define PRINT(...)

__uint128_t lead_seed;
volatile unsigned leader;
volatile size_t lead_idx;

bool exhaust = false;
volatile bool estop = false;


thread$ * the_main;

thread __attribute__((aligned(128))) MyThread {
        unsigned id;
        volatile size_t idx;
        bench_sem sem;
        size_t rechecks;
};

void ?{}( MyThread & this, unsigned id ) {
        ((thread&)this){ bench_cluster };
        this.id = id;
        this.idx = 0;
        this.rechecks = 0;
}

MyThread ** threads;

static void waitgroup() {
        Time start = timeHiRes();
        OUTER: for(i; nthreads) {
                PRINT( sout | "Waiting for :" | i | "(" | threads[i]->idx | ")"; )
                while( threads[i]->idx != lead_idx ) {
                        Pause();
                        if( (timeHiRes() - start) > 5`s ) {
                                print_stats_now( bench_cluster, CFA_STATS_READY_Q | CFA_STATS_IO );
                                serr | "Programs has been blocked for more than 5 secs";
                                estop = true;
                                unpark( the_main );
                                break OUTER;
                        }
                }
        }
        PRINT( sout | "Waiting done"; )
}

static void wakegroup(unsigned me) {
        if(!exhaust) return;

        for(i; nthreads) {
                if(i!= me) post( threads[i]->sem );
        }
}

static void lead(MyThread & this) {
        this.idx = ++lead_idx;
        if(lead_idx > stop_count || estop) {
                PRINT( sout | "Leader" | this.id | "done"; )
                unpark( the_main );
                return;
        }

        PRINT( sout | "Leader no" | this.idx| ":" | this.id; )

        waitgroup();

        unsigned nleader = lehmer64( lead_seed ) % nthreads;
        __atomic_store_n( &leader, nleader, __ATOMIC_SEQ_CST );

        wakegroup(this.id);
}

static void wait(MyThread & this) {
        yield();
        if(lead_idx == this.idx) {
                this.rechecks++;
                return;
        }

        assert( (lead_idx - 1) == this.idx );
        __atomic_add_fetch( &this.idx, 1, __ATOMIC_SEQ_CST );
        if(exhaust) wait( this.sem );
        else yield();
}

void main(MyThread & this) {
        park();

        unsigned me = this.id;

        for() {
                if(leader == me) {
                        lead( this );
                }
                else {
                        wait( this );
                }
                if(lead_idx > stop_count || estop) break;
        }
}

// ==================================================
int main(int argc, char * argv[]) {
        uint64_t lead_seed = getpid();
        for(10) lehmer64( lead_seed );
        unsigned nprocs = 2;

        cfa_option opt[] = {
                BENCH_OPT,
                { 'e', "exhaust", "Whether or not threads that have seen the new epoch should park instead of yielding.", exhaust, parse_yesno}
        };
        BENCH_OPT_PARSE("cforall transition benchmark");

        if(clock_mode) {
                serr | "This benchmark doesn't support duration mode";
                return 1;
        }

        if(nprocs < 2) {
                serr | "Must have at least 2 processors";
                return 1;
        }

        lead_idx = 0;
        leader = lehmer64( lead_seed ) % nthreads;

        size_t rechecks = 0;
        the_main = active_thread();

        Time start, end;
        {
                BenchCluster bc = { nprocs };
                {
                        threads = alloc(nthreads);
                        for(i; nthreads) {
                                threads[i] = malloc();
                                (*threads[i]){
                                        i
                                };
                        }

                        start = timeHiRes();
                        for(i; nthreads) {
                                unpark(*threads[i]);
                        }

                        park();
                        end = timeHiRes();

                        for(i; nthreads) {
                                post(threads[i]->sem);
                        }

                        for(i; nthreads) {
                                MyThread & thrd = join(*threads[i]);
                                PRINT( sout | i | "joined"; )
                                rechecks += thrd.rechecks;
                                ^( *threads[i] ){};
                                free(threads[i]);
                        }

                        free(threads);
                }
        }

        setlocale( LC_NUMERIC, getenv( "LANG" ) );
        sout | "Duration (ms)           : " | ws(3, 3, unit(eng((end - start)`dms)));
        sout | "Number of processors    : " | nprocs;
        sout | "Number of threads       : " | nthreads;
        sout | "Total Operations(ops)   : " | lead_idx - 1;
        sout | "Threads parking on wait : " | (exhaust ? "yes" : "no");
        sout | "Rechecking              : " | rechecks;
        sout | "us per transfer         : " | (end - start)`dus / lead_idx;


}