[Snapshot] Performance impact for key & directory deleting service

Scenario:

1. Huge number of keys and directories are created in bucket (FSO)
2. Snapshot is taken for the bucket
3. Recursive delete of keys and directory
4. keys and directories are added to deletedTable and deletedDirectoryTable

KeyDeletingService:

• iterator all keys in deleted Table
  • if keys are present in snapshot, its skipped
  • else added for blockGroupList for deletion

DirectoryDeletingService:

• iterator all directory in deleted directory table
  • if directory is present in snapshot, its skipped
  • else perform further action for deletion

So if number of keys and directory are huge, it will keep iterating always to get candidate keys/directory for deletion.