[#xxxx] meta: Fix MatchCommonPrefix operation

Return all the objects on the empty common prefix search.

Signed-off-by: Pavel Karpy <carpawell@nspcc.ru>

cmd/neofs-node/main.go

@@ -7,6 +7,7 @@ import (
 	"log"
 	"os"
 	"os/signal"
+	"runtime"
 	"syscall"
 
 	"github.com/nspcc-dev/neofs-node/misc"
@@ -34,6 +35,8 @@ func fatalOnErrDetails(details string, err error) {
 }
 
 func main() {
+	runtime.SetBlockProfileRate(1)
+
 	configFile := flag.String("config", "", "path to config")
 	versionFlag := flag.Bool("version", false, "neofs node version")
 	flag.Parse()

pkg/local_object_storage/metabase/db.go

@@ -209,6 +209,23 @@ func stringCommonPrefixMatcherBucket(b *bbolt.Bucket, fKey string, fVal string,
 		prefix = val[:len(val)-1]
 	}
 
+	if len(val) == 0 {
+		// empty common prefix, all the objects
+		// satisfy that filter
+		err := b.ForEach(func(k, v []byte) error {
+			if err := f(k, v); err != nil {
+				return err
+			}
+
+			return nil
+		})
+		if err != nil {
+			return err
+		}
+
+		return nil
+	}
+
 	c := b.Cursor()
 	for k, v := c.Seek(val); bytes.HasPrefix(k, prefix); k, v = c.Next() {
 		if checkLast && (len(k) == len(prefix) || k[len(prefix)]>>4 != val[len(val)-1]) {