Merge pull request #11706 from gyuho/fix-race

clientv3: fix racy writes to context key
etcd-io · Mar 19, 2020 · 45a45d3 · 45a45d3
2 parents bf883bd + b6d9871
commit 45a45d3
Show file tree

Hide file tree

Showing 2 changed files with 7 additions and 4 deletions.
diff --git a/.words b/.words
@@ -46,6 +46,7 @@ mutex
 prefetching
 protobuf
 prometheus
+racey
 rafthttp
 repin
 rpc

diff --git a/clientv3/ctx.go b/clientv3/ctx.go
@@ -30,9 +30,10 @@ func WithRequireLeader(ctx context.Context) context.Context {
 		md = metadata.Pairs(rpctypes.MetadataRequireLeaderKey, rpctypes.MetadataHasLeader)
 		return metadata.NewOutgoingContext(ctx, md)
 	}
+	copied := md.Copy() // avoid racey updates
 	// overwrite/add 'hasleader' key/value
-	md.Set(rpctypes.MetadataRequireLeaderKey, rpctypes.MetadataHasLeader)
-	return metadata.NewOutgoingContext(ctx, md)
+	copied.Set(rpctypes.MetadataRequireLeaderKey, rpctypes.MetadataHasLeader)
+	return metadata.NewOutgoingContext(ctx, copied)
 }
 
 // embeds client version
@@ -42,7 +43,8 @@ func withVersion(ctx context.Context) context.Context {
 		md = metadata.Pairs(rpctypes.MetadataClientAPIVersionKey, version.APIVersion)
 		return metadata.NewOutgoingContext(ctx, md)
 	}
+	copied := md.Copy() // avoid racey updates
 	// overwrite/add version key/value
-	md.Set(rpctypes.MetadataClientAPIVersionKey, version.APIVersion)
-	return metadata.NewOutgoingContext(ctx, md)
+	copied.Set(rpctypes.MetadataClientAPIVersionKey, version.APIVersion)
+	return metadata.NewOutgoingContext(ctx, copied)
 }