process: Gracefully shutdown processes

Signed-off-by: Thomas Klaehn <thomas.klaehn@perinet.io>

src/app/process/process.go

@@ -5,6 +5,7 @@ import (
 	"io"
 	"log"
 	"os/exec"
+	"sync"
 )
 
 var (
@@ -22,6 +23,9 @@ type Process struct {
 	process *exec.Cmd
 	stdout  io.ReadCloser
 	stderr  io.ReadCloser
+
+	wg_exit *sync.WaitGroup
+	exit    chan struct{}
 }
 
 func NewProcess(command string) *Process {
@@ -38,40 +42,57 @@ func NewProcess(command string) *Process {
 	}
 	p.StdoutChannel = make(chan string)
 	p.StderrChannel = make(chan string)
+	p.wg_exit = &sync.WaitGroup{}
+	p.exit = make(chan struct{})
 	return p
 }
 
-func (p Process) Start() error {
+func (p *Process) Start() error {
 	err := p.process.Start()
 	if err != nil {
 		return err
 	}
-	return nil
-}
 
-func (p Process) Observe() {
+	p.wg_exit.Add(2)
 	go func() {
 		scanner := bufio.NewScanner(p.stdout)
-		for scanner.Scan() {
-			p.StdoutChannel <- scanner.Text()
+		for {
+			select {
+			case <-p.exit:
+				p.wg_exit.Done()
+				return
+			default:
+				for scanner.Scan() {
+					p.StdoutChannel <- scanner.Text()
+				}
+			}
 		}
 	}()
 	go func() {
 		scanner := bufio.NewScanner(p.stderr)
-		for scanner.Scan() {
-			p.StderrChannel <- scanner.Text()
+		for {
+			select {
+			case <-p.exit:
+				p.wg_exit.Done()
+				return
+			default:
+				for scanner.Scan() {
+					p.StderrChannel <- scanner.Text()
+				}
+			}
 		}
 	}()
+
+	return nil
 }
 
-func (p Process) Kill() {
+func (p Process) Stop() {
 	p.process.Process.Kill()
 }
 
-func (p Process) Wait() error {
-	err := p.process.Wait()
-	if err != nil {
-		return err
-	}
-	return nil
+func (p *Process) Wait() error {
+	_, err := p.process.Process.Wait()
+	close(p.exit)
+	p.wg_exit.Wait()
+	return err
 }