From c90ce90113e06b2a13c0658b2d720dc2c42df8ba Mon Sep 17 00:00:00 2001
From: Solomon Hykes <solomon@docker.com>
Date: Sun, 1 Jun 2014 22:34:03 +0000
Subject: [PATCH] WIP more beam conversion

---
 backends/backends.go | 40 +++++++++++++++++++++++++++-------------
 swarmd/swarmd.go     | 30 ++++++++++++++++++++++++++----
 2 files changed, 53 insertions(+), 17 deletions(-)

diff --git a/backends/backends.go b/backends/backends.go
index e363b10167..e7bbfbf392 100644
--- a/backends/backends.go
+++ b/backends/backends.go
@@ -1,6 +1,7 @@
 package backends
 
 import (
+	"io"
 	"fmt"
 	"github.com/docker/beam"
 	beamutils "github.com/docker/beam/utils"
@@ -17,18 +18,31 @@ import (
 // Example: `New().Job("debug").Run()`
 func New() beam.Sender {
 	backends := beamutils.NewHub()
-	backends.RegisterName("debug", func(msg *beam.Message, in beam.Receiver, out beam.Sender, next beam.Sender) (bool, error) {
-		backends.RegisterTask(func(r beam.Receiver, w beam.Sender) error {
-			for {
-				msg, msgr, msgw, err := r.Receive(beam.R | beam.W)
-				if err != nil {
-					return err
-				}
-				fmt.Printf("[DEBUG] %s %s\n", msg.Name, strings.Join(msg.Args, " "))
-				// FIXME: goroutine?
-				splice(w, msg, msgr, msgw)
+	backends.RegisterName("cd", func(msg *beam.Message, in beam.Receiver, out beam.Sender, next beam.Sender) (bool, error) {
+		return false, fmt.Errorf("no such backend: %s\n", strings.Join(msg.Args, " "))
+	})
+	backends.RegisterName("cd", func(msg *beam.Message, in beam.Receiver, out beam.Sender, next beam.Sender) (bool, error) {
+		if len(msg.Args) > 0 && msg.Args[0] == "debug" {
+			debugr, debugw, err := out.Send(&beam.Message{Name: "register"}, beam.R|beam.W)
+			if err != nil {
+				return false, err
 			}
-		})
+			go func() {
+				for {
+					msg, msgr, msgw, err := debugr.Receive(beam.R | beam.W)
+					if err == io.EOF {
+						return
+					}
+					if err != nil {
+						return
+					}
+					fmt.Printf("[DEBUG] %s %s\n", msg.Name, strings.Join(msg.Args, " "))
+					// FIXME: goroutine?
+					Splice(debugw, msg, msgr, msgw)
+				}
+			}()
+			return false, nil
+		}
 		return true, nil
 	})
 	backends.RegisterName("fakeclient", func(msg *beam.Message, in beam.Receiver, out beam.Sender, next beam.Sender) (bool, error) {
@@ -43,7 +57,7 @@ func New() beam.Sender {
 				if err != nil {
 					return err
 				}
-				go beamutils.Copy(beamutils.NopSender{}, containersR)
+				go beamutils.Copy(beam.NopSender{}, containersR)
 			}
 		})
 		return true, nil
@@ -51,7 +65,7 @@ func New() beam.Sender {
 	return backends
 }
 
-func splice(dst beam.Sender, msg *beam.Message, r beam.Receiver, w beam.Sender) error {
+func Splice(dst beam.Sender, msg *beam.Message, r beam.Receiver, w beam.Sender) error {
 	dstR, dstW, err := dst.Send(msg, beam.R|beam.W)
 	if err != nil {
 		return err
diff --git a/swarmd/swarmd.go b/swarmd/swarmd.go
index 90596d78d3..9369142ea1 100644
--- a/swarmd/swarmd.go
+++ b/swarmd/swarmd.go
@@ -154,7 +154,7 @@ func cmdDaemon(c *cli.Context) {
 	}
 
 	hub := beamutils.NewHub()
-	backends := backends.New()
+	back := backends.New()
 	// Load backends
 	for _, cmd := range c.Args() {
 		bName, bArgs, err := parseCmd(cmd)
@@ -162,12 +162,31 @@ func cmdDaemon(c *cli.Context) {
 			Fatalf("%v", err)
 		}
 		fmt.Printf("---> Loading backend '%s'\n", strings.Join(append([]string{bName}, bArgs...), " "))
-		_, backend, err := backends.Send(&beam.Message{Name: bName, Args: bArgs}, beam.W)
+		backendr, _, err := back.Send(&beam.Message{Name: "cd", Args: []string{bName}}, beam.R)
 		if err != nil {
 			Fatalf("%s: %v\n", bName, err)
 		}
-		if err := hub.Register(backend); err != nil {
-			Fatalf("%v", err)
+		// backendr will return either 'error' or 'register'.
+		for {
+			m, mr, mw, err := backendr.Receive(beam.R|beam.W)
+			if err != nil {
+				Fatalf("%v", err)
+			}
+			if m.Name == "error" {
+				Fatalf("%v", strings.Join(m.Args, " "))
+			}
+			if m.Name == "register" {
+				// FIXME: adapt the beam interface to allow the caller to
+				// (optionally) pass their own Sender/Receiver?
+				// Would make proxying/splicing easier.
+				hubr, hubw, err := hub.Send(m, beam.R|beam.W)
+				if err != nil {
+					Fatalf("%v", err)
+				}
+				fmt.Printf("successfully registered\n")
+				go beamutils.Copy(hubw, mr)
+				go beamutils.Copy(mw, hubr)
+			}
 		}
 	}
 	in, _, err := hub.Send(&beam.Message{Name: "start"}, beam.R)
@@ -176,6 +195,9 @@ func cmdDaemon(c *cli.Context) {
 	}
 	for {
 		msg, _, _, err := in.Receive(0)
+		if err == io.EOF {
+			break
+		}
 		if err != nil {
 			Fatalf("%v", err)
 		}