Fix multiple window issue

Author: ancientlore

config.go

@@ -72,37 +72,6 @@ func readConfig(file string) (*config, error) {
 	return &c, nil
 }
 
-// Start starts all of the processes in a configuration.
-func (c *config) Start() error {
-	var merr multiError
-	for _, p := range c.Processes {
-		err := p.Start(os.Stdout, os.Stderr)
-		if err != nil {
-			merr = append(merr, err)
-		}
-	}
-	if len(merr) > 0 {
-		c.Wait()
-		return merr
-	}
-	return nil
-}
-
-// Wait completes all of the processes in a configuration.
-func (c *config) Wait() error {
-	var merr multiError
-	for _, p := range c.Processes {
-		err := p.Wait()
-		if err != nil {
-			merr = append(merr, err)
-		}
-	}
-	if len(merr) > 0 {
-		return merr
-	}
-	return nil
-}
-
 // Validate checks for inconsistencies in the config.
 func (c *config) Validate() error {
 	var m multiError

demon.slide

@@ -137,7 +137,7 @@ See [[https://golang.org/pkg/os/exec/][golang.org/pkg/os/exec]]
 
 
 * Websockets - Upgrading the connection
-.code socket.go /ServeHTTP/,/stdoutDone/
+.code socket.go /ServeHTTP/,/p\.Wait/
 .background media/plane_bg.png
 
 : Websocket code borrowed largely from https://github.com/gorilla/websocket/tree/master/examples/command.

main.go

@@ -66,7 +66,7 @@ func main() {
 	fmt.Scanln()
 
 	log.Print("Stopping server...")
-	err = conf.Wait()
+	err = closeProcesses()
 	if err != nil {
 		log.Print(err)
 	}

process.go

@@ -12,11 +12,26 @@ import (
 	"time"
 )
 
+// Clone makes a copy of the process, ready to be started.
+func (p *process) Clone() *process {
+	return &process{
+		Title:     p.Title,
+		Command:   p.Command,
+		Dir:       p.Dir,
+		Position:  p.Position,
+		ExitInput: p.ExitInput,
+	}
+}
+
 // Start starts a process after processing environment variables in the command line
 // and connecting pipes for I/O.
 func (p *process) Start(dest, errDest io.Writer) error {
 	var err error
 
+	if p.cmd != nil {
+		return fmt.Errorf(p.Title, ": Process already started")
+	}
+
 	name := p.Command[0]
 	args := make([]string, len(p.Command)-1)
 	copy(args, p.Command[1:])

socket.go

@@ -5,6 +5,7 @@ import (
 	"io"
 	"log"
 	"net/http"
+	"sync"
 	"time"
 
 	"github.com/gorilla/websocket"
@@ -87,13 +88,46 @@ func ping(ws *websocket.Conn, done chan struct{}) {
 	}
 }
 
+var (
+	// Slice of processes to close on exit. In a real high-capacity site, you'd
+	// want to manage this list more carefully. But for our purposes, it's not
+	// very significant.
+	procsToClose []*process
+
+	// This mutex protects the above slice if multiple callers are trying to use it.
+	procsToCloseMutex sync.Mutex
+)
+
+func closeProcesses() error {
+	procsToCloseMutex.Lock()
+	defer procsToCloseMutex.Unlock()
+
+	var merr multiError
+	for _, p := range procsToClose {
+		err := p.Wait()
+		if err != nil {
+			merr = append(merr, err)
+		}
+	}
+	if len(merr) > 0 {
+		return merr
+	}
+	return nil
+}
+
 func (p *process) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	ws, err := upgrader.Upgrade(w, r, nil)
 	if err != nil {
 		log.Print("upgrade: ", err)
 		return
 	}
 
+	// Clone and add to list of processes to close later.
+	p = p.Clone()
+	procsToCloseMutex.Lock()
+	procsToClose = append(procsToClose, p)
+	procsToCloseMutex.Unlock()
+
 	defer ws.Close()
 
 	rdr, wtr := io.Pipe()