From d5aeb6c0bccf6ede1a36787aaf45f120b0142b77 Mon Sep 17 00:00:00 2001
From: Simon Ruderich <simon@ruderich.org>
Date: Tue, 28 May 2024 08:59:06 +0200
Subject: [PATCH] visualizer: make it optional to dup JSON to file

---
 impl/utils/visualizer/main.go | 34 ++++++++++++++++++++++------------
 1 file changed, 22 insertions(+), 12 deletions(-)

diff --git a/impl/utils/visualizer/main.go b/impl/utils/visualizer/main.go
index c2b0b21..4cfc454 100644
--- a/impl/utils/visualizer/main.go
+++ b/impl/utils/visualizer/main.go
@@ -24,9 +24,9 @@ import (
 var static embed.FS
 
 func main() {
-	if len(os.Args) != 3 {
+	if len(os.Args) != 2 && len(os.Args) != 3 {
 		log.SetFlags(0)
-		log.Fatalf("usage: %s <fifo> <json-dup-prefix>", os.Args[0])
+		log.Fatalf("usage: %s <fifo> [<json-dup-prefix>]", os.Args[0])
 	}
 
 	var mutex sync.Mutex
@@ -35,15 +35,21 @@ func main() {
 	go func() {
 		for {
 			path := os.Args[1]
-			dupPath := os.Args[2] + "." + time.Now().Format(time.RFC3339)
+			var dupPath string
+			if len(os.Args) == 3 {
+				dupPath = os.Args[2] + "." + time.Now().Format(time.RFC3339)
+			}
 
 			fh, err := os.Open(path)
 			if err != nil {
 				log.Fatal(err)
 			}
-			dupFh, err := os.Create(dupPath)
-			if err != nil {
-				log.Fatal(err)
+			var dupFh *os.File
+			if dupPath != "" {
+				dupFh, err = os.Create(dupPath)
+				if err != nil {
+					log.Fatal(err)
+				}
 			}
 
 			r := bufio.NewReader(fh)
@@ -56,9 +62,11 @@ func main() {
 
 				// Duplicate JSON input to a file so it can be replayed later
 				// if necessary
-				_, err = dupFh.WriteString(line)
-				if err != nil {
-					log.Fatalf("write %q: %v", dupPath, err)
+				if dupFh != nil {
+					_, err = dupFh.WriteString(line)
+					if err != nil {
+						log.Fatalf("write %q: %v", dupPath, err)
+					}
 				}
 
 				// Send to all listeners
@@ -73,9 +81,11 @@ func main() {
 			if err != nil {
 				log.Fatalf("close %q: %v", path, err)
 			}
-			err = dupFh.Close()
-			if err != nil {
-				log.Fatalf("close %q: %v", dupPath, err)
+			if dupFh != nil {
+				err = dupFh.Close()
+				if err != nil {
+					log.Fatalf("close %q: %v", dupPath, err)
+				}
 			}
 		}
 	}()