Different way to calculate struct size

sizes.py

import gc
import sys
import types
from collection import deque
import random


def getsize(obj):
    BLACKLIST = type, types.ModuleType, types.FunctionType
    if isinstance(obj, BLACKLIST):
        raise TypeError("getsize() does not take argument of type: " + str(type(obj)))

    seen_ids, size, objects = set(), 0, [obj]
    while objects:
        need_referents = []
        for obj in objects:
            if not isinstance(obj, BLACKLIST) and id(obj) not in seen_ids:
                seen_ids.add(id(obj))
                size += sys.getsizeof(obj)
                need_referents.append(obj)
        objects = gc.get_referents(*need_referents)
    return size


def json_size_d(obj):
    size, todo = 0, deque([obj])
    while todo:
        obj = todo.pop()
        if isinstance(obj, (bool, int, float)):
            size += len(str(obj))
        elif isinstance(obj, str):
            size += len(obj) + 2
        elif isinstance(obj, (list, tuple, set)):
            size += len(obj) * 2
            todo.extend(obj)
        elif isinstance(obj, dict):
            size += len(obj) * 6 + sum(len(str(k)) for k in obj)
            todo.extend(obj.values())
        else:
            raise TypeError("Can't get json_size() of " + str(type(obj)))
    return size


def json_size_dd(obj, cache=None):
    """A slower version of len(json.dumps(obj)), which doesn't require much extra memory"""
    literals = (bool, int, float, type(None), datetime)
    size, todo = 0, [(set(), [obj])]
    while todo:
        path, objects = todo.pop()
        for obj in objects:
            if isinstance(obj, literals):
                size += len(str(obj))
            elif isinstance(obj, str):
                size += len(obj) + 2
            else:
                obj_id = id(obj)
                if obj_id in path:
                    raise ValueError("Circular reference found")
                elif cache and obj_id in cache:
                    size += cache[obj_id]
                elif isinstance(obj, (list, tuple, set)):
                    size += len(obj) * 2
                    todo.append((path | {obj_id}, obj))
                elif isinstance(obj, dict):
                    size += len(obj) * 6 + sum(len(str(k)) for k in obj)
                    todo.append((path | {obj_id}, obj.values()))
                else:
                    raise TypeError("Can't get json_size() of " + str(type(obj)))
    return size


def json_size(obj):
    if isinstance(obj, (bool, int, float)):
        return len(str(obj))
    elif isinstance(obj, str):
        return len(obj) + 2
    elif isinstance(obj, (list, tuple, set, dict)):
        n = len(obj)
        if n == 0:
            return 2
        elif isinstance(obj, dict):
            return len(obj) * 6 + sum(len(str(k)) for k in obj) + sum(map(json_size, obj.values()))
        else:
            return len(obj) * 2 + sum(map(json_size, obj))
    else:
        raise TypeError("Can't get json_size() of " + str(type(obj)))


def json_size_hint(obj, sample_size=10):
    if isinstance(obj, (bool, int, float)):
        return len(str(obj))
    elif isinstance(obj, str):
        return len(obj) + 2
    elif isinstance(obj, (list, tuple, set, dict)):
        n = len(obj)
        if n == 0:
            return 2
        elif isinstance(obj, dict):
            sample = obj.items() if n <= sample_size else random.sample(obj.items(), sample_size)
            return n * 6 + sum(len(str(k)) + json_size_hint(v) for k, v in sample) * n / len(sample)
        else:
            sample = obj if n <= sample_size else random.sample(obj, sample_size)
            return n * 2 + sum(map(json_size_hint, sample)) * n / len(sample)
    else:
        raise TypeError("Can't get json_size() of " + str(type(obj)))