From b55df5c62648ceaae5bd8558c7a3ebaecfe5f3a2 Mon Sep 17 00:00:00 2001
From: Christian Decker <decker.christian@gmail.com>
Date: Tue, 26 Jul 2022 13:20:03 +0200
Subject: [PATCH] msggen: Use tempfile + rename to make changes to .msggen.json
 atomic

This was causing issues when multiple instances of msggen were running
in parallel on CI.

Changelog-None
---
 contrib/msggen/msggen/__main__.py | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/contrib/msggen/msggen/__main__.py b/contrib/msggen/msggen/__main__.py
index e6257efcf..cb221f3b6 100644
--- a/contrib/msggen/msggen/__main__.py
+++ b/contrib/msggen/msggen/__main__.py
@@ -1,4 +1,5 @@
 import json
+import os
 from msggen.gen.grpc import GrpcGenerator, GrpcConverterGenerator, GrpcUnconverterGenerator, GrpcServerGenerator
 from msggen.gen.grpc2py import Grpc2PyGenerator
 from msggen.gen.rust import RustGenerator
@@ -41,8 +42,10 @@ def load_msggen_meta():
 
 
 def write_msggen_meta(meta):
-    with open('.msggen.json', 'w') as f:
+    pid = os.getpid()
+    with open(f'.msggen.json.tmp.{pid}', 'w') as f:
         json.dump(meta, f, sort_keys=True, indent=4)
+    os.rename(f'.msggen.json.tmp.{pid}', '.msggen.json')
 
 
 def run():