From 2530b446569e7dad98186095f749baf4baeaa4aa Mon Sep 17 00:00:00 2001
From: Cole Faust <colefaust@google.com>
Date: Thu, 13 Jun 2024 16:56:24 -0700
Subject: [PATCH] Only write release config files if they've changed

Currently, when you do `m` repeatedly, it does a little bit of
rebuilding to copy release config files around. If we change
release-config to only rewrite the files if they've changed, we
get a proper "ninja: no work to do." message.

Bug: 346757289
Test: m repeatedly
Change-Id: I9c1f6d34ec20d14b684a0183c5ec457ea92440f9
---
 cmd/release_config/release_config_lib/Android.bp | 1 +
 cmd/release_config/release_config_lib/util.go    | 3 ++-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/cmd/release_config/release_config_lib/Android.bp b/cmd/release_config/release_config_lib/Android.bp
index 0c67e1106..17251bdba 100644
--- a/cmd/release_config/release_config_lib/Android.bp
+++ b/cmd/release_config/release_config_lib/Android.bp
@@ -24,6 +24,7 @@ bootstrap_go_package {
         "golang-protobuf-reflect-protoreflect",
         "golang-protobuf-runtime-protoimpl",
         "soong-cmd-release_config-proto",
+        "blueprint-pathtools",
     ],
     srcs: [
         "flag_artifact.go",
diff --git a/cmd/release_config/release_config_lib/util.go b/cmd/release_config/release_config_lib/util.go
index 0a19efe01..9919c7081 100644
--- a/cmd/release_config/release_config_lib/util.go
+++ b/cmd/release_config/release_config_lib/util.go
@@ -25,6 +25,7 @@ import (
 	"slices"
 	"strings"
 
+	"github.com/google/blueprint/pathtools"
 	"google.golang.org/protobuf/encoding/prototext"
 	"google.golang.org/protobuf/proto"
 )
@@ -101,7 +102,7 @@ func WriteFormattedMessage(path, format string, message proto.Message) (err erro
 	if err != nil {
 		return err
 	}
-	return os.WriteFile(path, data, 0644)
+	return pathtools.WriteFileIfChanged(path, data, 0644)
 }
 
 // Read a message from a file.