source: doc/theses/colby_parsons_MMAth/benchmarks/channels/go/hot_potato/hot_potato.go @ d24b1985

package main

import (
        "fmt"
        "time"
        "runtime"
        "sync"
        "os"
        "strconv"
)

var done bool = false;
var total_operations uint64 = 0
var Processors int = 1
var m sync.Mutex

var taskJoin chan int = make(chan int, 2)

func Task( chans [] chan uint64, id int ) {
        var count uint64 = 0
        right := (id + 1) % Processors
        for {
                if done { break }
                <-chans[id]
                chans[right]<-0
                count++;
        }
        m.Lock()
        total_operations += count
        m.Unlock()
        taskJoin <- 0
}

func main() {
        switch len( os.Args ) {
                case 2:
                        if os.Args[1] != "d" {                                                  // default ?
                                Processors, _ = strconv.Atoi( os.Args[1] )
                        } // if
                case 1:                                                                                 // use defaults
                default:
                        fmt.Printf( "Invalid args" );
                        os.Exit( 1 );
        } // switch
        runtime.GOMAXPROCS( Processors );

        taskJoin = make(chan int, Processors)
        chans := make( [] chan uint64, Processors )
        for i := range chans {
                chans[i] = make(chan uint64, 3)
        }

        chans[0] <- 0

        for i := 0; i < Processors; i++ {
                go Task( chans, i )
        }
                
        // wait 10 seconds
        time.Sleep(time.Second * 10)
        // fmt.Println("prod done\n")
        done = true

        for i := 0; i < Processors; i++ {
                chans[i] <- 0
        }
        for i := 0; i < Processors; i++ {
                <-taskJoin
        }

    fmt.Println(total_operations)
}