在 Django 中缓存包含一些常量的函数

Question

在我维护的一个 Django 网站（v 1.7）中，我将每天 24 小时分成不同的时间窗口，然后根据用户登录的时间窗口，我为所述用户处理一些内容。日期无关紧要，重要的是时间窗口。

目前，时间窗口及其相关处理是在我的 views.py 中的一个函数中完成的，如下所示：

from datetime import time as time_object

def WhichWindow(time_now):
    window1_least = time_object(hour=0, minute=0)
    window1_most = time_object(hour=3, minute=0) 
    window2_least = time_object(hour=3, minute=0)
    window2_most = time_object(hour=6, minute=30)
    window3_least = time_object(hour=6, minute=30) 
    window3_most = time_object(hour=11, minute=50)
    window4_least = time_object(hour=11, minute=50)
    window4_most = time_object(hour=14, minute=55)
    window5_least = time_object(hour=14, minute=55)
    window5_most = time_object(hour=16, minute=55)
    window6_least = time_object(hour=16, minute=55)
    window6_most = time_object(hour=20, minute=0)
    window7_least = time_object(hour=20, minute=0)
    window7_most = time_object(hour=0, minute=0)
    if window1_least <= time_now < window1_most:
        variable1 = #something
        variable2 = #something
        variable3 = #something
    elif window2_least <= time_now < window2_most:
        variable1 = #something
        variable2 = #something
        variable3 = #something
    elif window3_least <= time_now < window3_most:
        variable1 = #something
        variable2 = #something
        variable3 = #something
    elif window4_least <= time_now < window4_most:
        variable1 = #something
        variable2 = #something
        variable3 = #something
    elif window5_least <= time_now < window5_most:
        variable1 = #something
        variable2 = #something
        variable3 = #something
    elif window6_least <= time_now < window6_most:
        variable1 = #something
        variable2 = #something
        variable3 = #something
    elif window7_least <= time_now < window7_most:
        variable1 = #something
        variable2 = #something
        variable3 = #something
    else:
        variable1 = #something
        variable2 = #something
        variable3 = #something
    return variable1, variable2, variable3

注意：函数中的time_now本质上是datetime.now().time()。

每个用户都非常频繁地访问上述功能。我觉得如果我 cache 我的时间窗口定义，这将是一个性能提升。

我该怎么办？我是否应该在此函数之上简单地添加 @cache_page(60 * 60 * 24) 装饰器？我觉得如果我这样做，那也会缓存这个函数的结果，而我只想缓存时间窗口定义。所以我该怎么做？

请提供实现此目的的最佳执行方式，并提供说明性示例。我是一个新手，并且仍然围绕着这些概念中的大多数。

Answer 1

如果您确实需要提高性能，您应该考虑重新组织窗口，因为它们是从午夜开始检查的（这可能不是您拥有最多流量的时间）。

只是提供第二种方法，您可以这样做：

from datetime import datetime, time

windows = {}

window1_least = time(hour=0, minute=0)
window1_most = time(hour=3, minute=0)
window2_least = time(hour=3, minute=0)
window2_most = time(hour=6, minute=30)
window3_least = time(hour=6, minute=30)
window3_most = time(hour=11, minute=50)
window4_least = time(hour=11, minute=50)
window4_most = time(hour=14, minute=55)
window5_least = time(hour=14, minute=55)
window5_most = time(hour=16, minute=55)
window6_least = time(hour=16, minute=55)
window6_most = time(hour=20, minute=0)
window7_least = time(hour=20, minute=0)
window7_most = time(hour=0, minute=0)


def which_window(minutes):
    hour = minutes // 60
    minute = minutes % 60
    curent_time = time(hour=hour, minute=minute)
    if window1_least <= curent_time < window1_most:
        return 1
    elif window2_least <= curent_time < window2_most:
        return 2
    elif window3_least <= curent_time < window3_most:
        return 3
    elif window4_least <= curent_time < window4_most:
        return 4
    elif window5_least <= curent_time < window5_most:
        return 5
    elif window6_least <= curent_time < window6_most:
        return 6
    elif window7_least <= curent_time < window7_most:
        return 7


windows = {minute: which_window(minute) for minute in range(1440)}

def get_current_window():
    current_minute = datetime.now().hour * 60 + datetime.now().minute
    return windows[current_minute]

# Just for testing
print get_current_window()

通过这种方式，您正在创建一个长字典来保存一天中的每一分钟，但它会发生一次（当服务器启动时），然后您的性能会好得多，O(1)，因为您是使用字典。

一旦你有了这个，你可以根据需要创建一个 1k 的窗口，检查将保持“即时”

Answer 2

如果声明是静态的，您可以将它们放在函数之外。因此，它们不会在每次函数运行时都被执行：

from datetime import time as time_object


window1_least = time_object(hour=0, minute=0)
window1_most = time_object(hour=3, minute=0) 
window2_least = time_object(hour=3, minute=0)
window2_most = time_object(hour=6, minute=30)
window3_least = time_object(hour=6, minute=30) 
window3_most = time_object(hour=11, minute=50)
window4_least = time_object(hour=11, minute=50)
window4_most = time_object(hour=14, minute=55)
window5_least = time_object(hour=14, minute=55)
window5_most = time_object(hour=16, minute=55)
window6_least = time_object(hour=16, minute=55)
window6_most = time_object(hour=20, minute=0)
window7_least = time_object(hour=20, minute=0)
window7_most = time_object(hour=0, minute=0)


def WhichWindow(time_now):

    if window1_least <= time_now < window1_most:
        variable1 = #something
        variable2 = #something
        variable3 = #something
    elif window2_least <= time_now < window2_most:
        variable1 = #something
        variable2 = #something
        variable3 = #something
    elif window3_least <= time_now < window3_most:
        variable1 = #something
        variable2 = #something
        variable3 = #something
    elif window4_least <= time_now < window4_most:
        variable1 = #something
        variable2 = #something
        variable3 = #something
    elif window5_least <= time_now < window5_most:
        variable1 = #something
        variable2 = #something
        variable3 = #something
    elif window6_least <= time_now < window6_most:
        variable1 = #something
        variable2 = #something
        variable3 = #something
    elif window7_least <= time_now < window7_most:
        variable1 = #something
        variable2 = #something
        variable3 = #something
    else:
        variable1 = #something
        variable2 = #something
        variable3 = #something
    return variable1, variable2, variable3

当然你也可以把它们放在模块、类、列表中……

通过 PEP8 模块级别的常量应该是大写的。