source: doc/theses/colby_parsons_MMAth/benchmarks/channels/go/churn/churn.go@ dd1ebb1

package main

import (
        "fmt"
        "sync"
        "math/rand"
        "time"
        "runtime"
        "os"
        "strconv"
)

var Processors, Channels, Producers, Consumers, ChannelSize int = 1, 4, 1, 1, 128
var cons_done, prod_done bool = false, false;
var total_operations, cons_check, prod_check uint64 = 0, 0, 0
var m sync.Mutex

var prodJoin chan int = make(chan int, Producers + 1)
var consJoin chan int = make(chan int, Consumers + 1)

func getRandArray() []int {
        chanIndices := make( [] int, Channels )
        for i := 0; i < Channels; i += 1 {
                chanIndices[i] = i
        }
        for i := 0; i < Channels; i += 1 {
                var loc_1 int  = rand.Intn(Channels) % Channels
        var loc_2 int  = rand.Intn(Channels) % Channels;
        var temp int = chanIndices[loc_1]
        chanIndices[loc_1] = chanIndices[loc_2]
        chanIndices[loc_2] = temp
        }
        return chanIndices
}

func consumer( chans [] chan uint64 ) {
        var count uint64 = 0
        var checksum uint64 = 0
        var i int = 0
        chanIndices := getRandArray()
        for {
                if cons_done { break }
                j := <- chans[ chanIndices[ i ] ]
                i = (i + 1) % Channels
                checksum = checksum ^ j
                if ! prod_done { count++ }
        }
        m.Lock()
        total_operations += count
        cons_check = cons_check ^ checksum
        m.Unlock()
        consJoin <- 0
}

func producer( chans [] chan uint64 ) {
        var count uint64 = 0
        var i int = 0
        var checksum uint64 = 0
        chanIndices := getRandArray()
        for {
                if prod_done { break }
                chans[ chanIndices[ i ] ] <- count
                i = (i + 1) % Channels
                checksum = checksum ^ count
                count++
        }
        m.Lock()
        total_operations += count
        prod_check = prod_check ^ checksum
        m.Unlock()
        prodJoin <- 0
}

func usage() {
        fmt.Printf( "Usage: %v " +
                "[ processors (> 0) | 'd' (default %v) ] " +
                "[ ChannelSize (> 0) | 'd' (default %v) ]\n",
                os.Args[0], Processors, ChannelSize );
        os.Exit( 1 );
}

func main() {
        switch len( os.Args ) {
                case 3:
                        if os.Args[2] != "d" {                                                  // default ?
                                Channels, _ = strconv.Atoi( os.Args[2] )
                                        if Channels < 0 { usage(); }
                        } // if
                fallthrough
                case 2:
                        if os.Args[1] != "d" {                                                  // default ?
                                Processors, _ = strconv.Atoi( os.Args[1] )
                                if Processors < 1 { usage(); }
                        } // if
                case 1:                                                                                 // use defaults
                default:
                usage();
        } // switch
        runtime.GOMAXPROCS( Processors );
        Producers = Processors /2
        Consumers = Processors /2

        // fmt.Println("Processors: ",Processors," Channels: ",Channels," Prods: ",Producers," Cons: ",Consumers," Channel Size: ",ChannelSize)

        chans := make( [] chan uint64, Channels )
        for i := range chans {
                chans[i] = make(chan uint64, ChannelSize)
        }

        for j := 0; j < Consumers; j++ {
                go consumer( chans )
        }

        for j := 0; j < Producers; j++ {
                go producer( chans )
        }

        // wait 10 seconds
        time.Sleep(time.Second * 10)
        prod_done = true

        for j := 0; j < Producers; j++ {
                <-prodJoin
        }

        cons_done = true

        for i := range chans {
                for j := 0; j < Consumers; j++ {
                        select {
                                case chans[i] <- 0:
                                        
                                default:
                                        break
                        }
                }
        }
        for j := 0; j < Consumers; j++{
                <-consJoin
        }
        for i := range chans {
                L: for {
                        select {
                                case k := <-chans[i]:
                                        cons_check = cons_check ^ k
                                default:
                                        break L
                        }
                }
        }
        if cons_check != prod_check {
                fmt.Println("\nChecksum mismatch: Cons: %d, Prods: %d", cons_check, prod_check)
        }

    fmt.Println(total_operations)
}