beam/examples/beamsh: more bells and whistles for demos

* Automatically switch to interactive mode when stdin is a terminal

* Basic implementation of "responses"

Docker-DCO-1.1-Signed-off-by: Solomon Hykes <solomon@docker.com> (github: shykes)

beam/examples/beamsh/beamsh.go

@@ -6,6 +6,7 @@ import (
 	"os"
 	"github.com/dotcloud/docker/pkg/dockerscript"
 	"github.com/dotcloud/docker/pkg/beam"
+	"github.com/dotcloud/docker/pkg/term"
 	"strings"
 	"sync"
 	"net"
@@ -16,28 +17,61 @@ import (
 )
 
 func main() {
-	script, err := dockerscript.Parse(os.Stdin)
-	if err != nil {
-		Fatal("parse error: %v\n", err)
-	}
-	Logf("%d commands:\n", len(script))
+	Logf("Initializing engine\n")
 	client, engine, err := beam.USocketPair()
 	if err != nil {
 		Fatal(err)
 	}
+	defer client.Close()
 	go func() {
-		Serve(engine)
+		Serve(engine, builtinsHandler)
+		Logf("Shutting down engine\n")
 		engine.Close()
 	}()
+	if term.IsTerminal(0) {
+		input := bufio.NewScanner(os.Stdin)
+		for {
+			os.Stdout.Write([]byte("beamsh> "))
+			if !input.Scan() {
+				break
+			}
+			line := input.Text()
+			if len(line) != 0 {
+				cmd, err := dockerscript.Parse(strings.NewReader(line))
+				if err != nil {
+					Logf("error: %v\n", err)
+					continue
+				}
+				executeScript(client, cmd)
+			}
+			if err := input.Err(); err == io.EOF {
+				break
+			} else if err != nil {
+				Fatal(err)
+			}
+		}
+	} else {
+		script, err := dockerscript.Parse(os.Stdin)
+		if err != nil {
+			Fatal("parse error: %v\n", err)
+		}
+		executeScript(client, script)
+	}
+}
+
+func executeScript(client *net.UnixConn, script []*dockerscript.Command) {
+	Logf("%d commands:\n", len(script))
 	for _, cmd := range script {
 		job, err := beam.SendPipe(client, []byte(strings.Join(cmd.Args, " ")))
 		if err != nil {
 			Fatal(err)
 		}
-		Serve(job)
+		// TODO: pass a default handler to deal with 'status'
+		// --> use beam chaining?
+		Logf("Listening for reply messages\n")
+		Serve(job, builtinsHandler)
 		Logf("[%s] done\n", strings.Join(cmd.Args, " "))
 	}
-	client.Close()
 }
 
 func parseMsgPayload(payload []byte) ([]string, error) {
@@ -75,11 +109,11 @@ func CmdEcho(args []string, f *os.File) {
 	if err != nil {
 		return
 	}
+	Logf("[CmdEcho] stdout pipe() r=%d w=%d\n", r.Fd(), w.Fd())
 	if err := beam.Send(resp, []byte("log stdout"), r); err != nil {
 		return
 	}
 	fmt.Fprintln(w, strings.Join(args[1:], " "))
-	fmt.Printf("waiting 5 seconds...\n")
 	w.Close()
 }
 
@@ -94,7 +128,29 @@ func CmdExit(args []string, f *os.File) {
 	os.Exit(status)
 }
 
+// 'status' is a notification of a job's status.
+// 
+func parseEnv(args []string) ([]string, map[string]string) {
+	var argsOut []string
+	env := make(map[string]string)
+	for _, word := range args[1:] {
+		if strings.Contains(word, "=") {
+			kv := strings.SplitN(word, "=", 2)
+			key := kv[0]
+			var val string
+			if len(kv) == 2 {
+				val = kv[1]
+			}
+			env[key] = val
+		} else {
+			argsOut = append(argsOut, word)
+		}
+	}
+	return argsOut, env
+}
+
 func CmdLog(args []string, f *os.File) {
+	defer Logf("CmdLog done\n")
 	name := args[1]
 	input := bufio.NewScanner(f)
 	for input.Scan() {
@@ -109,23 +165,28 @@ func CmdLog(args []string, f *os.File) {
 	}
 }
 
-func Serve(endpoint *net.UnixConn) error {
-	Logf("[Serve]\n")
-	defer Logf("[Serve] done\n")
+func Serve(endpoint *net.UnixConn, handler func([]string, *os.File)) error {
+	Logf("[Serve %#v]\n", handler)
+	defer Logf("[Serve %#v] done\n", handler)
 	var tasks sync.WaitGroup
 	defer tasks.Wait()
 	for {
-		Logf("[Serve] waiting for next message...\n")
 		payload, attachment, err := beam.Receive(endpoint)
 		if err != nil {
 			return err
 		}
 		tasks.Add(1)
+		// Handle new message
 		go func(payload []byte, attachment *os.File) {
+			Logf("---> Handling '%s' [fd=%d]\n", payload, attachment.Fd())
 			defer tasks.Done()
 			if attachment != nil {
-				defer fmt.Printf("closing request attachment %d\n", attachment.Fd())
-				attachment.Close()
+				defer func() {
+					Logf("---> Closing attachment [fd=%d] for msg '%s'\n", attachment.Fd(), payload)
+					attachment.Close()
+				}()
+			} else {
+				defer Logf("---> No attachment to close for msg '%s'\n", payload)
 			}
 			args, err := parseMsgPayload(payload)
 			if err != nil {
@@ -135,21 +196,26 @@ func Serve(endpoint *net.UnixConn) error {
 				}
 				return
 			}
-			Logf("beam message: %v\n", args)
-			if args[0] == "exit" {
-				CmdExit(args, attachment)
-			} else if args[0] == "cat" {
-				CmdCat(args, attachment)
-			} else if args[0] == "echo" {
-				CmdEcho(args, attachment)
-			} else if args[0] == "log" {
-				CmdLog(args, attachment)
-			}
+			Logf("---> calling handler for '%s'\n", args[0])
+			handler(args, attachment)
+			Logf("---> handler returned for '%s'\n", args[0])
 		}(payload, attachment)
 	}
 	return nil
 }
 
+func builtinsHandler(args []string, attachment *os.File) {
+	if args[0] == "exit" {
+		CmdExit(args, attachment)
+	} else if args[0] == "cat" {
+		CmdCat(args, attachment)
+	} else if args[0] == "echo" {
+		CmdEcho(args, attachment)
+	} else if args[0] == "log" {
+		CmdLog(args, attachment)
+	}
+}
+
 
 func Logf(msg string, args ...interface{}) (int, error) {
 	if len(msg) == 0 || msg[len(msg) - 1] != '\n' {