swarm/storage: added metrics for db entry count (#17589)

swarm/storage/ldbstore.go

@@ -48,6 +48,10 @@ const (
 	maxGCitems       = 5000 // max number of items to be gc'd per call to collectGarbage()
 )
 
+var (
+	dbEntryCount = metrics.NewRegisteredCounter("ldbstore.entryCnt", nil)
+)
+
 var (
 	keyIndex       = byte(0)
 	keyOldData     = byte(1)
@@ -495,6 +499,7 @@ func (s *LDBStore) delete(idx uint64, idxKey []byte, po uint8) {
 	batch.Delete(idxKey)
 	batch.Delete(getDataKey(idx, po))
 	s.entryCnt--
+	dbEntryCount.Dec(1)
 	s.bucketCnt[po]--
 	cntKey := make([]byte, 2)
 	cntKey[0] = keyDistanceCnt
@@ -566,6 +571,7 @@ func (s *LDBStore) doPut(chunk *Chunk, index *dpaDBIndex, po uint8) {
 	index.Idx = s.dataIdx
 	s.bucketCnt[po] = s.dataIdx
 	s.entryCnt++
+	dbEntryCount.Inc(1)
 	s.dataIdx++
 
 	cntKey := make([]byte, 2)