From 09ce4ac1ca1b1c99f1d3f4516c14b65f1a5ecbf2 Mon Sep 17 00:00:00 2001
From: Ankur Shrivastava <ankur@ankurs.com>
Date: Sat, 4 Apr 2026 22:21:38 +0800
Subject: [PATCH] perf: fast-path in validateTraceID for already-valid trace
 IDs

Add a pre-scan loop that checks if all bytes are printable ASCII
before allocating a strings.Builder. Most trace IDs (UUIDs, hex)
are already clean, so this avoids one allocation per request.
---
 notifier/notifier.go | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/notifier/notifier.go b/notifier/notifier.go
index 11a1146..6ddc0c4 100644
--- a/notifier/notifier.go
+++ b/notifier/notifier.go
@@ -634,6 +634,19 @@ func validateTraceID(id string) string {
 	if len(id) > 128 {
 		id = id[:128]
 	}
+	// Fast path: most trace IDs (UUIDs, hex) are already clean.
+	// Scan first to avoid strings.Builder allocation.
+	clean := true
+	for i := 0; i < len(id); i++ {
+		if id[i] < 0x20 || id[i] > 0x7E {
+			clean = false
+			break
+		}
+	}
+	if clean {
+		return id
+	}
+	// Slow path: sanitize dirty input.
 	var b strings.Builder
 	b.Grow(len(id))
 	for i := 0; i < len(id); i++ {