From d6457ee48595a392f74f41eb66768497be9f0014 Mon Sep 17 00:00:00 2001
From: Leonard Lyubich <leonard@nspcc.ru>
Date: Thu, 11 Nov 2021 16:54:36 +0300
Subject: [PATCH] [#922] shard: Allow multiple gc.stop() calls

Use `sync.Once` to prevent locks of stopping GC. It will also allow to
safely call `Shard.Close` multiple  times.

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
---
 pkg/local_object_storage/shard/gc.go | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/pkg/local_object_storage/shard/gc.go b/pkg/local_object_storage/shard/gc.go
index f1c832f89..4a3666a76 100644
--- a/pkg/local_object_storage/shard/gc.go
+++ b/pkg/local_object_storage/shard/gc.go
@@ -52,6 +52,7 @@ type eventHandlers struct {
 type gc struct {
 	*gcCfg
 
+	onceStop    sync.Once
 	stopChannel chan struct{}
 
 	workerPool util.WorkerPool
@@ -163,7 +164,9 @@ func (gc *gc) tickRemover() {
 }
 
 func (gc *gc) stop() {
-	gc.stopChannel <- struct{}{}
+	gc.onceStop.Do(func() {
+		gc.stopChannel <- struct{}{}
+	})
 }
 
 // iterates over metabase graveyard and deletes objects