From 2e997410f28efe8106fc606d21cb655be1b05dee Mon Sep 17 00:00:00 2001
From: Hans Hasselberg <me@hans.io>
Date: Thu, 27 Feb 2020 06:19:10 -0500
Subject: [PATCH] futures can react to shutdown (#390)

---
 future.go   | 13 +++++++++----
 snapshot.go |  1 +
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/future.go b/future.go
index 6346b453b19c..6de2daea4f9a 100644
--- a/future.go
+++ b/future.go
@@ -84,9 +84,10 @@ func (e errorFuture) Index() uint64 {
 // deferError can be embedded to allow a future
 // to provide an error in the future.
 type deferError struct {
-	err       error
-	errCh     chan error
-	responded bool
+	err        error
+	errCh      chan error
+	responded  bool
+	ShutdownCh chan struct{}
 }
 
 func (d *deferError) init() {
@@ -103,7 +104,11 @@ func (d *deferError) Error() error {
 	if d.errCh == nil {
 		panic("waiting for response on nil channel")
 	}
-	d.err = <-d.errCh
+	select {
+	case d.err = <-d.errCh:
+	case <-d.ShutdownCh:
+		d.err = ErrRaftShutdown
+	}
 	return d.err
 }
 
diff --git a/snapshot.go b/snapshot.go
index f4c39451453c..805a09d7074b 100644
--- a/snapshot.go
+++ b/snapshot.go
@@ -146,6 +146,7 @@ func (r *Raft) takeSnapshot() (string, error) {
 	// We have to use the future here to safely get this information since
 	// it is owned by the main thread.
 	configReq := &configurationsFuture{}
+	configReq.ShutdownCh = r.shutdownCh
 	configReq.init()
 	select {
 	case r.configurationsCh <- configReq: