start distributed hochwasser

only RPC plumbing for now.

naming: https://en.wikipedia.org/wiki/Nine_Daughters_of_%C3%86gir_and_R%C3%A1n

main.go

@@ -10,6 +10,7 @@ import (
 	"time"
 
 	"github.com/SpeckiJ/Hochwasser/pixelflut"
+	"github.com/SpeckiJ/Hochwasser/rpc"
 )
 
 var err error
@@ -22,6 +23,8 @@ var address = flag.String("host", "127.0.0.1:1337", "Server address")
 var runtime = flag.String("runtime", "60s", "exit after timeout")
 var shuffle = flag.Bool("shuffle", false, "pixel send ordering")
 var fetchImgPath = flag.String("fetch-image", "", "path to save the fetched pixel state to")
+var rán = flag.String("rán", "", "enable rpc server to distribute jobs, listening on the given address/port")
+var hevring = flag.String("hevring", "", "connect to rán rpc server at given address")
 
 func main() {
 	flag.Parse()
@@ -47,6 +50,13 @@ func main() {
 		defer pprof.StopCPUProfile()
 	}
 
+	if *rán != "" { // @fixme: should validate proper address?
+		rpc.StartRán(*rán)
+	}
+	if *hevring != "" { // @fixme: should validate proper address?
+		rpc.ConnectHevring(*hevring)
+	}
+
 	offset := image.Pt(*image_offsetx, *image_offsety)
 	img := readImage(*image_path)
 

rpc/dottir.go

@@ -0,0 +1,28 @@
+package rpc
+
+import (
+	"fmt"
+	"log"
+	"net/rpc"
+)
+
+func ConnectHevring(ránAddress string) {
+	fmt.Printf("[hevring] connecting to %s\n", ránAddress)
+
+	client, err := rpc.Dial("tcp", ránAddress)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	job := RánJob{}
+	err = client.Call("Rán.Hello", RánHelloReq{}, &job)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	if (job == RánJob{}) {
+		fmt.Printf("[hevring] Rán has no job for us. :(\n")
+	} else {
+		fmt.Printf("[hevring] Rán gave us /w o r k/! %v\n", job)
+	}
+}

rpc/rán.go

@@ -0,0 +1,56 @@
+package rpc
+
+import (
+	"fmt"
+	"image"
+	"log"
+	"net"
+	"net/rpc"
+)
+
+func StartRán(address string) {
+	rán := new(Rán)
+	rpc.Register(rán)
+
+	l, err := net.Listen("tcp", address)
+	if err != nil {
+		log.Fatal(err)
+	}
+	fmt.Printf("[rán] rpc server listening on %s\n", l.Addr())
+
+	go func() {
+		for {
+			conn, err := l.Accept()
+			if err != nil {
+				log.Fatal(err)
+			}
+			rán.clientAddresses = append(rán.clientAddresses, conn.RemoteAddr())
+			fmt.Printf("[rán] client connected (%v)\n", rán.clientAddresses)
+
+			// @incomplete: detect client disconnect, update clients.
+			go rpc.ServeConn(conn)
+
+			// @bug: second connection does not send Hello..?!
+		}
+	}()
+}
+
+type Rán struct {
+	clientAddresses []net.Addr
+}
+
+type RánHelloReq struct{}
+
+type RánJob struct {
+	Address  string
+	MaxConns int
+	Img      image.Image
+	Bounds   image.Rectangle
+	Shuffle  bool
+}
+
+func (z *Rán) Hello(args RánHelloReq, reply *RánJob) error {
+	fmt.Printf("[rán] a client said hello!\n")
+	reply = nil
+	return nil
+}