feat(experiment/bg): added bg utility to help pid proxy testing

feat(experiment/starter): added option to skip waiting for child process

cmd/experiment/starter/starter.go

@@ -4,55 +4,90 @@ import (
 	"bufio"
 	"io"
 	"log"
+	"os"
 	"os/exec"
 	"sync"
 
 	"gitea.suyono.dev/suyono/wingmate"
+	"gitea.suyono.dev/suyono/wingmate/cmd/cli"
+	"github.com/spf13/pflag"
 	"github.com/spf13/viper"
 )
 
 const (
-	// DummyPath = "/workspaces/wingmate/cmd/experiment/dummy/dummy"
 	DummyPath    = "/usr/local/bin/wmdummy"
 	EnvDummyPath = "DUMMY_PATH"
+	NoWaitFlag   = "no-wait"
 )
 
 func main() {
 	var (
-		stdout  io.ReadCloser
-		stderr  io.ReadCloser
-		wg      *sync.WaitGroup
-		err     error
-		exePath string
+		stdout    io.ReadCloser
+		stderr    io.ReadCloser
+		wg        *sync.WaitGroup
+		err       error
+		exePath   string
+		selfArgs  []string
+		childArgs []string
+		flagSet   *pflag.FlagSet
+		noWait    bool
+		cmd       *exec.Cmd
 	)
+	if selfArgs, childArgs, err = cli.SplitArgs(os.Args); err == nil {
+		flagSet = pflag.NewFlagSet(selfArgs[0], pflag.ExitOnError)
+		flagSet.Bool(NoWaitFlag, false, "do not wait for the child process")
+		if err = flagSet.Parse(selfArgs[1:]); err != nil {
+			log.Printf("invalid argument: %+v", err)
+			return
+		}
+	} else {
+		flagSet = pflag.NewFlagSet(os.Args[0], pflag.ExitOnError)
+		flagSet.Bool(NoWaitFlag, false, "do not wait for the child process")
+		if err = flagSet.Parse(selfArgs[1:]); err != nil {
+			log.Printf("invalid argument: %+v", err)
+			return
+		}
+	}
+	viper.BindPFlag(NoWaitFlag, flagSet.Lookup(NoWaitFlag))
+	noWait = viper.GetBool(NoWaitFlag)
+
 	viper.SetEnvPrefix(wingmate.EnvPrefix)
 	viper.BindEnv(EnvDummyPath)
 	viper.SetDefault(EnvDummyPath, DummyPath)
 
 	exePath = viper.GetString(EnvDummyPath)
 
-	cmd := exec.Command(exePath)
-
-	if stdout, err = cmd.StdoutPipe(); err != nil {
-		log.Panic(err)
+	if len(childArgs) > 0 {
+		cmd = exec.Command(childArgs[0], childArgs[1:]...)
+	} else {
+		cmd = exec.Command(exePath)
 	}
 
-	if stderr, err = cmd.StderrPipe(); err != nil {
-		log.Panic(err)
-	}
+	if !noWait {
+		if stdout, err = cmd.StdoutPipe(); err != nil {
+			log.Panic(err)
+		}
 
-	wg = &sync.WaitGroup{}
-	wg.Add(2)
-	go pulley(wg, stdout, "stdout")
-	go pulley(wg, stderr, "stderr")
+		if stderr, err = cmd.StderrPipe(); err != nil {
+			log.Panic(err)
+		}
+
+		wg = &sync.WaitGroup{}
+		wg.Add(2)
+		go pulley(wg, stdout, "stdout")
+		go pulley(wg, stderr, "stderr")
+	}
 
 	if err = cmd.Start(); err != nil {
 		log.Panic(err)
 	}
-	wg.Wait()
 
-	if err = cmd.Wait(); err != nil {
-		log.Printf("got error when Waiting for child process: %#v\n", err)
+	if !noWait {
+		wg.Wait()
+
+		if err = cmd.Wait(); err != nil {
+			log.Printf("got error when Waiting for child process: %#v\n", err)
+		}
 	}
 }