'>>> driver = DummyStorageDriver(\'key\', \'secret\')
>>> driver.get_meta_data()[\'object_count\']
0
>>> driver.get_meta_data()[\'container_count\']
0
>>> driver.get_meta_data()[\'bytes_used\']
0
>>> container_name = \'test container 1\'
>>> container = driver.create_container(container_name=container_name)
>>> container_name = \'test container 2\'
>>> container = driver.create_container(container_name=container_name)
>>> obj = container.upload_object_via_stream(
...  object_name=\'test object\', iterator=DummyFileObject(5, 10),
...  extra={})
>>> driver.get_meta_data()[\'object_count\']
1
>>> driver.get_meta_data()[\'container_count\']
2
>>> driver.get_meta_data()[\'bytes_used\']
50
:rtype: ``dict``'

def get_meta_data(self):

    container_count = len(self._containers)
    object_count = sum([len(self._containers[container]['objects']) for container in self._containers])
    bytes_used = 0
    for container in self._containers:
        objects = self._containers[container]['objects']
        for (_, obj) in objects.items():
            bytes_used += obj.size
    return {'container_count': int(container_count), 'object_count': int(object_count), 'bytes_used': int(bytes_used)}
