def expire_data(self):
        """Expire data within the samples collection."""

        # Do we need to start deleting stuff?
        while self.sample_storage_size() > self.samples_cap:

            # This should return the 'oldest' record in samples
            record = self.database[self.sample_collection].find().sort('import_time',pymongo.ASCENDING).limit(1)[0]
            self.remove_sample(record['md5'])
Expire data within the samples collection.