Add session lock

HTTP requests can be processed in parallel, but we only have one IMAP
connection per session.

Closes: https://todo.sr.ht/~sircmpwn/koushin/12

1 files changed, 8 insertions, 0 deletions

diff --git a/conn_pool.go b/conn_pool.go
index 1ccc879..69281af 100644
--- a/conn_pool.go
+++ b/conn_pool.go
@@ -21,10 +21,18 @@ func generateToken() (string, error) {
 var ErrSessionExpired = errors.New("session expired")
 
 type Session struct {
+	locker sync.Mutex
 	imapConn           *imapclient.Client
 	username, password string
 }
 
+func (s *Session) Do(f func(*imapclient.Client) error) error {
+	s.locker.Lock()
+	defer s.locker.Unlock()
+
+	return f(s.imapConn)
+}
+
 // TODO: expiration timer
 type ConnPool struct {
 	locker   sync.Mutex