[#661] blobovniczatree: Make Rebuild concurrent

Different DBs can be rebuild concurrently.

Signed-off-by: Dmitrii Stepanov <d.stepanov@yadro.com>

pkg/local_object_storage/shard/shard.go

@@ -127,6 +127,8 @@ type cfg struct {
 	metricsWriter MetricsWriter
 
 	reportErrorFunc func(selfID string, message string, err error)
+
+	rebuildLimiter RebuildWorkerLimiter
 }
 
 func defaultCfg() *cfg {
@@ -135,6 +137,7 @@ func defaultCfg() *cfg {
 		log:             &logger.Logger{Logger: zap.L()},
 		gcCfg:           defaultGCCfg(),
 		reportErrorFunc: func(string, string, error) {},
+		rebuildLimiter:  &noopRebuildLimiter{},
 	}
 }
 
@@ -372,6 +375,14 @@ func WithExpiredCollectorWorkerCount(count int) Option {
 	}
 }
 
+// WithRebuildWorkerLimiter return option to set concurrent
+// workers count of storage rebuild operation.
+func WithRebuildWorkerLimiter(l RebuildWorkerLimiter) Option {
+	return func(c *cfg) {
+		c.rebuildLimiter = l
+	}
+}
+
 func (s *Shard) fillInfo() {
 	s.cfg.info.MetaBaseInfo = s.metaBase.DumpInfo()
 	s.cfg.info.BlobStorInfo = s.blobStor.DumpInfo()