You'll need to add a mutex to this and lock every public function here as this sucker is going to be passed around like the village bicycle and will end up being called from multiple threads thanks to the backups functionality (example: https://github.com/TimSimpsonR/sneaky-pete/blob/master/src/nova/guest/mysql/MySqlAppStatus.cc#L119)  

You'll also need to write some tests to make sure the send functions can be safely called from several threads concurrently. (Example, but don't look too long or your face might burn off Raiders of the Lost Ark style: https://github.com/TimSimpsonR/sneaky-pete/blob/master/tests/log_tests.cc)