rework rpc

main.go

@@ -51,7 +51,7 @@ func main() {
 	}
 
 	if *rán != "" { // @fixme: should validate proper address?
-		rpc.StartRán(*rán)
+		rpc.SummonRán(*rán)
 	}
 	if *hevring != "" { // @fixme: should validate proper address?
 		rpc.ConnectHevring(*hevring)
@@ -60,10 +60,10 @@ func main() {
 	offset := image.Pt(*image_offsetx, *image_offsety)
 	img := readImage(*image_path)
 
-	var fetchedImg *image.NRGBA
 	if *fetchImgPath != "" {
-		fetchedImg = pixelflut.FetchImage(img.Bounds().Add(offset), *address, 1)
+		fetchedImg := pixelflut.FetchImage(img.Bounds().Add(offset), *address, 1)
 		*connections -= 1
+		defer writeImage(*fetchImgPath, fetchedImg)
 	}
 
 	// 🌊🌊🌊🌊🌊🌊🌊🌊🌊🌊🌊🌊🌊🌊🌊
@@ -75,8 +75,4 @@ func main() {
 		log.Fatal("Invalid runtime specified: " + err.Error())
 	}
 	time.Sleep(timer)
-
-	if *fetchImgPath != "" {
-		writeImage(*fetchImgPath, fetchedImg)
-	}
 }

rpc/dottir.go

@@ -3,26 +3,40 @@ package rpc
 import (
 	"fmt"
 	"log"
+	"net"
 	"net/rpc"
 )
 
+// const handshake_magick = "Sæl!"
+
 func ConnectHevring(ránAddress string) {
-	fmt.Printf("[hevring] connecting to %s\n", ránAddress)
+	rpc.Register(new(Hevring))
 
-	client, err := rpc.Dial("tcp", ránAddress)
+	fmt.Printf("[hevring] greeting Rán at %s\n", ránAddress)
+	conn, err := net.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)
-	}
+	go rpc.ServeConn(conn)
+	fmt.Printf("[hevring] awaiting task from Rán\n")
+}
+
+type Hevring struct {}
+
+type FlutAck struct{ Ok bool }
+
+func (h *Hevring) Flut(job RánJob, reply *FlutAck) error {
+	fmt.Printf("[hevring] Rán gave us /w o r k/! %v\n", job)
+	reply.Ok = true
+	return nil
+}
+
+func (h *Hevring) Status(x int, reply *FlutAck) error {
+	reply.Ok = true
+	return nil
+}
+
+func (h *Hevring) Stop(x int, reply *FlutAck) error {
+	reply.Ok = true
+	return nil
 }

rpc/ran.go

@@ -0,0 +1,73 @@
+package rpc
+
+import (
+	"fmt"
+	"image"
+	"log"
+	"net"
+	"net/rpc"
+	"time"
+)
+
+func SummonRán(address string) {
+	rán := new(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)
+			}
+			fmt.Printf("[rán] client connected (%v)\n", conn.RemoteAddr())
+
+			client := rpc.NewClient(conn)
+			rán.clientConns = append(rán.clientConns, client)
+
+			ack := FlutAck{}
+			err = client.Call("Hevring.Flut", RánJob{}, &ack)
+			if err != nil {
+				log.Fatal(err)
+			}
+			fmt.Printf("[rán] client accepted job: %v\n", ack.Ok)
+		}
+	}()
+
+	// poll clients
+	go func() {
+		for {
+			time.Sleep(500 * time.Millisecond)
+
+			var clients []*rpc.Client
+			for _, c := range rán.clientConns {
+				status := FlutAck{}
+				c.Call("Hevring.Status", 0, &status)
+				if status.Ok {
+					clients = append(clients, c)
+				}
+			}
+			rán.clientConns = clients
+			fmt.Printf("[rán] current clients: %v\n", clients)
+
+			// @incomplete: if clients changed, assign tasks anew
+		}
+	}()
+}
+
+
+type Rán struct {
+	clientConns []*rpc.Client
+}
+
+type RánJob struct {
+	Address  string
+	MaxConns int
+	Img      image.Image
+	Bounds   image.Rectangle
+	Shuffle  bool
+}

rpc/rán.go

@@ -1,56 +0,0 @@
-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
-}

rpc/test.sh

@@ -0,0 +1,29 @@
+#!/bin/bash
+
+# runs two instances of hochwasser (rpc server & client each) against a fake (iperf)
+# pixelflut server for a few seconds, and opens pprof afterwar
+
+runtime=${1:-"2s"}
+
+function cleanup {
+  kill ${pids[@]} > /dev/null 2>&1
+}
+trap cleanup EXIT
+
+wd=$(dirname "$0")
+pids=()
+
+iperf -p 1337 -s > /dev/null 2>&1 &
+pids+=($!)
+
+go run . -image $wd/../benchmarks/black_small.png -rán :1234 &
+pids+=($!)
+sleep 0.2
+
+go run . -image $wd/../benchmarks/white_small.png -hevring :1234 -runtime "$runtime" -cpuprofile hevring.prof
+pids+=($!)
+
+cleanup
+
+go tool pprof -http :8080 Hochwasser hevring.prof
+#go tool pprof -http :8081 Hochwasser ran.prof