[#312] wc: Add metrics

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

pkg/local_object_storage/writecache/delete.go

@@ -2,6 +2,7 @@ package writecache
 
 import (
 	"context"
+	"time"
 
 	"git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/pkg/tracing"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/common"
@@ -22,6 +23,13 @@ func (c *cache) Delete(ctx context.Context, addr oid.Address) error {
 		))
 	defer span.End()
 
+	deleted := false
+	storageType := storageTypeUndefined
+	startedAt := time.Now()
+	defer func() {
+		c.metrics.Delete(time.Since(startedAt), deleted, storageType)
+	}()
+
 	c.modeMtx.RLock()
 	defer c.modeMtx.RUnlock()
 	if c.readOnly() {
@@ -30,15 +38,15 @@ func (c *cache) Delete(ctx context.Context, addr oid.Address) error {
 
 	saddr := addr.EncodeToString()
 
-	// Check disk cache.
-	var has int
+	var dataSize int
 	_ = c.db.View(func(tx *bbolt.Tx) error {
 		b := tx.Bucket(defaultBucket)
-		has = len(b.Get([]byte(saddr)))
+		dataSize = len(b.Get([]byte(saddr)))
 		return nil
 	})
 
-	if 0 < has {
+	if dataSize > 0 {
+		storageType = storageTypeDB
 		err := c.db.Update(func(tx *bbolt.Tx) error {
 			b := tx.Bucket(defaultBucket)
 			err := b.Delete([]byte(saddr))
@@ -52,10 +60,12 @@ func (c *cache) Delete(ctx context.Context, addr oid.Address) error {
 			storagelog.StorageTypeField(wcStorageType),
 			storagelog.OpField("db DELETE"),
 		)
+		deleted = true
 		c.objCounters.DecDB()
 		return nil
 	}
 
+	storageType = storageTypeFSTree
 	_, err := c.fsTree.Delete(ctx, common.DeletePrm{Address: addr})
 	if err == nil {
 		storagelog.Write(c.log,
@@ -64,6 +74,7 @@ func (c *cache) Delete(ctx context.Context, addr oid.Address) error {
 			storagelog.OpField("fstree DELETE"),
 		)
 		c.objCounters.DecFS()
+		deleted = true
 	}
 
 	return err