source: benchmark/readyQ/transfer.go @ 5007618

package main

import (
        "flag"
        "fmt"
        "math/rand"
        "os"
        "regexp"
        "runtime"
        "sync/atomic"
        "time"
        "golang.org/x/text/language"
        "golang.org/x/text/message"
)

type LeaderInfo struct {
        id uint64
        idx uint64
        estop uint64
        seed uint64
}

func __xorshift64( state * uint64 ) (uint64) {
        x := *state
        x ^= x << 13
        x ^= x >> 7
        x ^= x << 17
        *state = x
        return x
}

func (this * LeaderInfo) next(len uint64) {
        n := __xorshift64( &this.seed )
        atomic.StoreUint64( &this.id, n % len )
}

func NewLeader(size uint64) (*LeaderInfo) {
        this := &LeaderInfo{0, 0, 0, uint64(os.Getpid())}

        r := rand.Intn(10)

        for i := 0; i < r; i++ {
                this.next( uint64(nthreads) )
        }

        return this
}

type MyThread struct {
        id uint64
        idx uint64
        sem chan struct{}
}

func waitgroup(leader * LeaderInfo, idx uint64, threads [] MyThread, main_sem chan struct {}) {
        start := time.Now()
        Outer:
        for i := 0; i < len(threads); i++ {
                // fmt.Fprintf(os.Stderr, "Waiting for :%d (%d)\n", threads[i].id, atomic.LoadUint64(&threads[i].idx) );
                for atomic.LoadUint64( &threads[i].idx ) != idx {
                        // hint::spin_loop();
                        end := time.Now()
                        delta := end.Sub(start)
                        if delta.Seconds() > 5 {
                                fmt.Fprintf(os.Stderr, "Programs has been blocked for more than 5 secs")
                                atomic.StoreUint64(&leader.estop, 1);
                                main_sem <- (struct {}{})
                                break Outer
                        }
                }
        }
        // debug!( "Waiting done" );
}

func wakegroup(exhaust bool, me uint64, threads [] MyThread) {
        if !exhaust { return; }

        for i := uint64(0); i < uint64(len(threads)); i++ {
                if i != me {
                        // debug!( "Leader waking {}", i);
                        defer func() {
                                if err := recover(); err != nil {
                                        fmt.Fprintf(os.Stderr, "Panic occurred: %s\n", err)
                                }
                        }()
                        threads[i].sem <- (struct {}{})
                }
        }
}

func lead(exhaust bool, leader * LeaderInfo, this * MyThread, threads [] MyThread, main_sem chan struct {}) {
        nidx := atomic.LoadUint64(&leader.idx) + 1;
        atomic.StoreUint64(&this.idx, nidx);
        atomic.StoreUint64(&leader.idx, nidx);

        if nidx > stop_count || atomic.LoadUint64(&leader.estop) != 0 {
                // debug!( "Leader {} done", this.id);
                main_sem <- (struct {}{})
                return
        }

        // debug!( "====================\nLeader no {} : {}", nidx, this.id);

        waitgroup(leader, nidx, threads, main_sem);

        leader.next( uint64(len(threads)) );

        wakegroup(exhaust, this.id, threads);

        // debug!( "Leader no {} : {} done\n====================", nidx, this.id);
}

func waitleader(exhaust bool, leader * LeaderInfo, this * MyThread, rechecks * uint64) {
        runtime.Gosched()

        if atomic.LoadUint64(&leader.idx) == atomic.LoadUint64(&this.idx) {
                // debug!("Waiting {} recheck", this.id);
                *rechecks += uint64(1)
                return
        }

        // debug!("Waiting {}", this.id);

        // debug_assert!( (leader.idx.load(Ordering::Relaxed) - 1) == this.idx.load(Ordering::Relaxed) );
        atomic.AddUint64(&this.idx, 1)
        if exhaust {
                // debug!("Waiting {} sem", this.id);
                <- this.sem
        } else {
                // debug!("Waiting {} yield", this.id);
                runtime.Gosched()
        }

        // debug!("Waiting {} done", this.id);
}

func transfer_main( result chan uint64, me uint64, leader * LeaderInfo, threads [] MyThread, exhaust bool, start chan struct{}, main_sem chan struct{}) {
        // assert!( me == threads[me].id );

        // debug!("Ready {}: {:p}", me, &threads[me].sem as *const sync::Semaphore);

        // Wait for start
        <- start

        // debug!( "Start {}", me );

        // Prepare results
        r := uint64(0)

        // Main loop
        for true {
                if atomic.LoadUint64(&leader.id) == me {
                        lead( exhaust, leader, &threads[me], threads, main_sem )
                        runtime.Gosched()
                } else {
                        waitleader( exhaust, leader, &threads[me], &r )
                }
                if atomic.LoadUint64(&leader.idx) > stop_count || atomic.LoadUint64(&leader.estop) != 0 { break; }
        }

        // return result
        result <- r
}

func main() {
        // Benchmark specific command line arguments
        exhaustOpt := flag.String("e", "no", "Whether or not threads that have seen the new epoch should park instead of yielding.")

        // General benchmark initialization and deinitialization
        bench_init()

        exhaustVal := *exhaustOpt;

        var exhaust bool
        re_yes := regexp.MustCompile("[Yy]|[Yy][Ee][Ss]")
        re_no  := regexp.MustCompile("[Nn]|[Nn][Oo]")
        if re_yes.Match([]byte(exhaustVal)) {
                exhaust = true
        } else if re_no.Match([]byte(exhaustVal)) {
                exhaust = false
        } else {
                fmt.Fprintf(os.Stderr, "Unrecognized exhaust(-e) option '%s'\n", exhaustVal)
                os.Exit(1)
        }

        if clock_mode {
                fmt.Fprintf(os.Stderr, "Programs does not support fixed duration mode\n")
                os.Exit(1)
        }

        var es string
        if exhaust {
                es = "with"
        } else {
                es = "without"
        }
        fmt.Printf("Running %d threads on %d processors, doing %d iterations, %s exhaustion\n", nthreads, nprocs, stop_count, es );

        main_sem := make(chan struct{})
        leader := NewLeader(uint64(nthreads))
        barr := make(chan struct{})
        result := make(chan uint64)

        thddata := make([]MyThread, nthreads)
        for i := range thddata {
                thddata[i] = MyThread{ uint64(i), 0, make(chan struct {}) }
        }

        rechecks := uint64(0)
        for i := range thddata {
                go transfer_main(result, uint64(i), leader, thddata, exhaust, barr, main_sem)
        }
        fmt.Printf("Starting\n");

        start := time.Now()
        close(barr) // release barrier

        <- main_sem

        end := time.Now()
        delta := end.Sub(start)

        fmt.Printf("\nDone\n")

        // release all the blocked threads
        for i := range thddata {
                close(thddata[i].sem)
        }
        for range thddata {
                rechecks += <- result
        }

        p := message.NewPrinter(language.English)
        var ws string
        if exhaust {
                ws = "yes"
        } else {
                ws = "no"
        }
        p.Printf("Duration (ms)           : %d\n", delta.Milliseconds() )
        p.Printf("Number of processors    : %d\n", nprocs )
        p.Printf("Number of threads       : %d\n", nthreads )
        p.Printf("Total Operations(ops)   : %15d\n", (leader.idx - 1) )
        p.Printf("Threads parking on wait : %s\n", ws)
        p.Printf("Rechecking              : %d\n", rechecks )
        p.Printf("ms per transfer         : %f\n", float64(delta.Milliseconds()) / float64(leader.idx) )
}