Fix a crash

Author: hczhu-db

pkg/block/fetcher.go

@@ -223,15 +223,19 @@ type RecursiveLister struct {
 }
 
 func NewRecursiveLister(logger log.Logger, bkt objstore.InstrumentedBucketReader) *RecursiveLister {
-	level.Info(logger).Log("msg", "Using recursive block lister")
+	if logger != nil {
+		level.Info(logger).Log("msg", "Using recursive block lister")
+	}
 	return &RecursiveLister{
 		logger: logger,
 		bkt:    bkt,
 	}
 }
 
 func (f *RecursiveLister) GetActiveAndPartialBlockIDs(ctx context.Context, ch chan<- ulid.ULID) (partialBlocks map[ulid.ULID]bool, err error) {
-	level.Info(f.logger).Log("msg", "recursive block lister started")
+	if f.logger != nil {
+		level.Info(f.logger).Log("msg", "recursive block lister started")
+	}
 	start := time.Now()
 	partialBlocks = make(map[ulid.ULID]bool)
 	err = f.bkt.Iter(ctx, "", func(name string) error {
@@ -256,7 +260,9 @@ func (f *RecursiveLister) GetActiveAndPartialBlockIDs(ctx context.Context, ch ch
 		}
 		return nil
 	}, objstore.WithRecursiveIter())
-	level.Info(f.logger).Log("msg", "recursive block lister ended", "duration", time.Since(start))
+	if f.logger != nil {
+		level.Info(f.logger).Log("msg", "recursive block lister ended", "duration", time.Since(start))
+	}
 	return partialBlocks, err
 }
 
@@ -268,18 +274,18 @@ type ConcurrentLister struct {
 }
 
 func NewConcurrentLister(logger log.Logger, bkt objstore.InstrumentedBucketReader) *ConcurrentLister {
-	level.Info(logger).Log("msg", "Using concurrent block lister")
 	return &ConcurrentLister{
 		logger: logger,
 		bkt:    bkt,
 	}
 }
 
 func (f *ConcurrentLister) GetActiveAndPartialBlockIDs(ctx context.Context, ch chan<- ulid.ULID) (partialBlocks map[ulid.ULID]bool, err error) {
-	level.Info(f.logger).Log("msg", "concurrent block lister started")
 	start := time.Now()
 	defer func() {
-		level.Info(f.logger).Log("msg", "concurrent block lister end", "duration", time.Since(start))
+		if f.logger != nil {
+			level.Info(f.logger).Log("msg", "concurrent block lister end", "duration", time.Since(start))
+		}
 	}()
 	const concurrency = 64
 
@@ -529,7 +535,9 @@ func (f *BaseFetcher) fetchMetadata(ctx context.Context) (interface{}, error) {
 		ch  = make(chan ulid.ULID, f.concurrency)
 		mtx sync.Mutex
 	)
-	level.Info(f.logger).Log("msg", "fetching meta data", "concurrency", f.concurrency, "cache_dir", f.cacheDir)
+	if f.logger != nil {
+		level.Info(f.logger).Log("msg", "fetching meta data", "concurrency", f.concurrency, "cache_dir", f.cacheDir)
+	}
 	for i := 0; i < f.concurrency; i++ {
 		eg.Go(func() error {
 			numBlocks := 0