[#373] blobovniczatree: Add metrics

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

pkg/local_object_storage/blobstor/blobovniczatree/exists.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"encoding/hex"
 	"path/filepath"
+	"time"
 
 	"git.frostfs.info/TrueCloudLab/frostfs-node/internal/logs"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobovnicza"
@@ -16,8 +17,18 @@ import (
 
 // Exists implements common.Storage.
 func (b *Blobovniczas) Exists(ctx context.Context, prm common.ExistsPrm) (common.ExistsRes, error) {
+	var (
+		startedAt = time.Now()
+		success   = false
+		found     = false
+	)
+	defer func() {
+		b.metrics.Exists(time.Since(startedAt), success, prm.StorageID != nil)
+	}()
+
 	ctx, span := tracing.StartSpanFromContext(ctx, "Blobovniczas.Exists",
 		trace.WithAttributes(
+			attribute.String("path", b.rootPath),
 			attribute.String("address", prm.Address.EncodeToString()),
 			attribute.String("storage_id", hex.EncodeToString(prm.StorageID)),
 		))
@@ -39,7 +50,6 @@ func (b *Blobovniczas) Exists(ctx context.Context, prm common.ExistsPrm) (common
 	var gPrm blobovnicza.GetPrm
 	gPrm.SetAddress(prm.Address)
 
-	var found bool
 	err := b.iterateSortedLeaves(ctx, &prm.Address, func(p string) (bool, error) {
 		dirPath := filepath.Dir(p)
 
@@ -59,5 +69,6 @@ func (b *Blobovniczas) Exists(ctx context.Context, prm common.ExistsPrm) (common
 		return found, nil
 	})
 
+	success = err == nil
 	return common.ExistsRes{Exists: found}, err
 }