From 7f0000f0784199429e61035f39d9562905e2e049 Mon Sep 17 00:00:00 2001
From: rickypfyt <90169100+rickypfyt@users.noreply.github.com>
Date: Mon, 3 Feb 2025 12:13:51 +0800
Subject: [PATCH] Add sorting

---
 field_map.go |  9 +++++++--
 message.go   | 10 +++++-----
 2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/field_map.go b/field_map.go
index 4aac64b1d..50a8492d1 100644
--- a/field_map.go
+++ b/field_map.go
@@ -366,11 +366,16 @@ func (m *FieldMap) sortedTags() []Tag {
 	return m.tags
 }
 
-func (m FieldMap) write(buffer *bytes.Buffer) {
+func (m FieldMap) write(buffer *bytes.Buffer, sorted bool) {
 	m.rwLock.Lock()
 	defer m.rwLock.Unlock()
 
-	for _, tag := range m.sortedTags() {
+	tags := m.tags
+	if sorted {
+		tags = m.sortedTags()
+	}
+
+	for _, tag := range tags {
 		if f, ok := m.tagLookup[tag]; ok {
 			writeField(f, buffer)
 		}
diff --git a/message.go b/message.go
index 3e1e7202b..bdc7ca564 100644
--- a/message.go
+++ b/message.go
@@ -591,9 +591,9 @@ func (m *Message) build() []byte {
 	m.cook()
 
 	var b bytes.Buffer
-	m.Header.write(&b)
-	m.Body.write(&b)
-	m.Trailer.write(&b)
+	m.Header.write(&b, true /* sorted */)
+	m.Body.write(&b, false /* sorted */)
+	m.Trailer.write(&b, true /* sorted */)
 	return b.Bytes()
 }
 
@@ -606,9 +606,9 @@ func (m *Message) buildWithBodyBytes(bodyBytes []byte) []byte {
 	m.cook()
 
 	var b bytes.Buffer
-	m.Header.write(&b)
+	m.Header.write(&b, true /* sorted */)
 	b.Write(bodyBytes)
-	m.Trailer.write(&b)
+	m.Trailer.write(&b, true /* sorted */)
 	return b.Bytes()
 }