From 5f511deefcc247677e963e37986b076646a2f080 Mon Sep 17 00:00:00 2001
From: Daniel Lee <dan.limerick@gmail.com>
Date: Wed, 14 Mar 2018 12:26:59 +0100
Subject: [PATCH] middleware: recover and retry on session start

Partial fix for #11155 - the Macaron session middleware
panics if mysql returns an error. This fix recovers from
the panic and retries once
---
 pkg/services/session/session.go | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/pkg/services/session/session.go b/pkg/services/session/session.go
index 2ca9296b97f..bfdc58bc5cc 100644
--- a/pkg/services/session/session.go
+++ b/pkg/services/session/session.go
@@ -105,6 +105,18 @@ type SessionWrapper struct {
 }
 
 func (s *SessionWrapper) Start(c *macaron.Context) error {
+	// See https://github.com/grafana/grafana/issues/11155 for details on why
+	// a recover and retry is needed
+	defer func() error {
+		if err := recover(); err != nil {
+			var retryErr error
+			s.session, retryErr = s.manager.Start(c)
+			return retryErr
+		}
+
+		return nil
+	}()
+
 	var err error
 	s.session, err = s.manager.Start(c)
 	return err