Better handle errors in setChannels

cmd/treatment/main.go

@@ -35,6 +35,7 @@ import (
 	"io"
 	"os/exec"
 	"strconv"
+	"strings"
 	"time"
 
 	"bitbucket.org/ausocean/av/container/mts"
@@ -87,7 +88,7 @@ const (
 
 // Variable map to send to netreceiver/vidgrind.
 var varMap = map[string]string{
-	"speakerMode":    "enum:Stereo,LeftMono,RightMono,Mute",
+	"SpeakerMode":    "enum:"+strings.Join([]string{modeStereo, modeLeft, modeRight, modeMute}, ","),
 	"AudioFilePath":  "string",
 }
 
@@ -131,7 +132,7 @@ func main() {
 		log.Fatal("could not initialise revid", "error", err)
 	}
 
-	// Play the audio (audio will play even whilst muted).
+	// Play the audio (audio will play even while muted).
 	log.Debug("Playing the audio")
 	go playAudio(filePtr, log)
 
@@ -143,9 +144,7 @@ func main() {
 // run starts a control loop that runs netsender, sends logs, checks for var changes, and
 // if var changes, changes current mode (paused,audio playback or soundcheck)
 func run(rv *revid.Revid, ns *netsender.Sender, file *string, l logging.Logger, nl *netlogger.Logger) {
-	var (
-		vs	int
-	)
+	var vs int
 
 	for {
 		l.Debug("running netsender")
@@ -208,32 +207,26 @@ func run(rv *revid.Revid, ns *netsender.Sender, file *string, l logging.Logger,
 		}
 
 		l.Debug("checking mode")
-		setChannels(vars["speakerMode"], l)
-		// l.Info("revid updated with new mode")
+		_ = setChannels(vars["SpeakerMode"], l)
 		sleep(ns, l)
 	}
 }
 
-// setChannels handles the muting of one, both, or neither of the channels. It takes in speakerMode
+// setChannels handles the muting of one, both, or neither of the channels. It takes in SpeakerMode
 // and sets the relevant volumes.
-func setChannels(mode string, l logging.Logger) {
-	vols := ""
-	
+func setChannels(mode string, l logging.Logger) error {	
 	l.Info("mode is", "mode", mode)
 
 	// Set the volume of each channel.
-	switch mode {
-	case modeStereo:
-		vols = "100%,100%"
-	case modeLeft:
-		vols = "0%,100%"
-	case modeRight:
-		vols = "100%,0%"
-	case modeMute:
-		vols = "0%,0%"
-	default:
-		// If an invalid option has been chosen, keep the previous setting.
-		return
+	vols := map[string]string{
+		modeStereo: "100%,100%",
+		modeLeft: "0%,100%",
+		modeRight: "100%,0%",
+		modeMute: "0%,0%",
+	}[mode]
+	if vols == "" {
+		l.Warning("invalid SpeakeMode", "SpeakerMode", mode)
+		return fmt.Errorf("invalid SpeakerMode: %s", mode)
 	}
 
 	// Create the command to change the channel volumes.
@@ -242,17 +235,20 @@ func setChannels(mode string, l logging.Logger) {
 	// Pipe the output to stdout and stderr.
 	outPipe, err := cmd.StdoutPipe()
 	if err != nil {
-		l.Error("failed to pipe stdout", "error", err)
+		l.Error("unable to setup pipe to stdout", "error", err)
+		return fmt.Errorf("unable to setup pipe to stdout: %w", err)
 	}
 	errPipe, err := cmd.StderrPipe()
 	if err != nil {
-		l.Error("failed to pipe stderr", "error", err)
+		l.Error("unable to setup pipe to stderr", "error", err)
+		return fmt.Errorf("unable to setup pipe to stderr: %w", err)
 	}
 
 	// Execute the channel setting command.
 	err = cmd.Start()
 	if err != nil {
-		l.Error("channel setting failed", "error", err)
+		l.Error("unable to set channel", "error", err)
+		return fmt.Errorf("unable to set channel: %w", err)
 	}
 
 	// Copy any std out to a buffer for logging.
@@ -262,6 +258,7 @@ func setChannels(mode string, l logging.Logger) {
 		if err != nil {
 			l.Error("failed to copy out pipe", "error", err)
 		}
+		l.Info("command run", "stdout", outBuff)
 	}()
 
 	// Copy any std error to a buffer for logging.
@@ -271,12 +268,18 @@ func setChannels(mode string, l logging.Logger) {
 		if err != nil {
 			l.Error("failed to copy error pipe", "error", err)
 		}
+		l.Error("command failed", "stderr", errBuff)
 	}()
+	if errBuff.String() != "" {
+		return fmt.Errorf("channel set command failed: %s", &errBuff)
+	}
+
 
 	l.Info("mode set to", "mode", mode)
+	return nil
 }
 
-// playAudio is intended to be run as a routine. It will continuously run even whilst muted.
+// playAudio is intended to be run as a routine. It will continuously run even while muted.
 func playAudio(file *string, l logging.Logger) {
 	var numPlays int
 	for {