内存缓存没有按预期工作

Question

我们在 Python 中有一个针对 Google App Engine 的小应用程序，我们正在使用内存缓存。但是内存缓存键甚至在 memcache.delete 之后仍然存在，而且内存缓存 return 是一个数字 (0)，而我希望它是 return 一个字符串 ("undefined")。这是我的代码：

check_feature.py:

import sys
sys.path.insert(0, 'libs')

import webapp2
import json
from google.appengine.api import memcache
from models.shard_counter import GeneralCounterShard
from models.check_feature_limit import CheckFeatureLimit


class CheckFeatureHandler(webapp2.RequestHandler):
    def get_number_of_users_enabled(self, feature_name):
        """
        Get the number of users enabled for the given feature name.
        """
        number_of_users_enabled_undefined = "undefined"
        number_of_users_enabled = memcache.get(key=feature_name)
        if (number_of_users_enabled is None):
            check_feature_limit = None
            check_feature_limits = CheckFeatureLimit.gql("WHERE feature_name=:1 ORDER BY last_modified DESC LIMIT 1", feature_name)
            if (check_feature_limits.count() > 0):
                check_feature_limit = check_feature_limits.get()
            if (check_feature_limit):
                number_of_users_enabled = check_feature_limit.number_of_users_enabled
            if (number_of_users_enabled is None):
                number_of_users_enabled = number_of_users_enabled_undefined
            memcache.add(key=feature_name, value=number_of_users_enabled, time=3600)
        if (number_of_users_enabled == number_of_users_enabled_undefined):
            number_of_users_enabled = None
        return number_of_users_enabled

admin.py:

import sys
sys.path.insert(0, 'libs')

import webapp2
import json
import requests
from google.appengine.ext.webapp import template
from google.appengine.api import memcache
from models.shard_counter import GeneralCounterShard
from models.check_feature_limit import CheckFeatureLimit

template.register_template_library("tags.tags")


class AdminHandler(webapp2.RequestHandler):
    def get(self):
        self.post()

    def post(self):
        params = {}
        number_of_users_enabled_dict = {}
        number_of_users_dict = {}
        r = requests.get(url="http://jsons.[part_of_link_suppressed].com.s3.amazonaws.com/flags.json")
        flags = json.loads(r.text)
        if ((flags) and ("depending_on_counter" in flags) and (len(flags["depending_on_counter"]) > 0)):
            for feature_name in flags["depending_on_counter"]:
                check_feature_limit = None
                check_feature_limits = CheckFeatureLimit.gql("WHERE feature_name=:1 ORDER BY last_modified DESC LIMIT 1", feature_name)
                if (check_feature_limits.count() > 0):
                    check_feature_limit = check_feature_limits.get()
                number_of_users_enabled = self.request.get(feature_name + "_number_of_users_enabled")
                if (number_of_users_enabled):
                    number_of_users_enabled = int(number_of_users_enabled)
                    if (not(check_feature_limit)):
                        check_feature_limit = CheckFeatureLimit(feature_name=feature_name)
                    check_feature_limit.number_of_users_enabled = number_of_users_enabled
                    check_feature_limit.put()
                    memcache.delete(key=feature_name) # I don't think it works.
                number_of_users_enabled = None
                if (check_feature_limit):
                    number_of_users_enabled = check_feature_limit.number_of_users_enabled
                if (not(number_of_users_enabled is None)):
                    number_of_users_enabled_dict[feature_name] = number_of_users_enabled
                number_of_users = GeneralCounterShard.get_count(feature_name)
                number_of_users_dict[feature_name] = number_of_users
            params["depending_on_counter"] = flags["depending_on_counter"]
            params["number_of_users_enabled_dict"] = number_of_users_enabled_dict
            params["number_of_users_dict"] = number_of_users_dict
        html = template.render("admin/admin.html", params)
        self.response.out.write(html)

app = webapp2.WSGIApplication([
    ("/admin", AdminHandler)
], debug=True)

test_counter_feature_1（要启用的用户数）的值为 2，test_counter_feature_2 为 4，test_counter_feature_3 未定义（没有对象），但在 memcache 中值分别为 2、3 和 0，即使在我保存表单之后（因此应该删除内存缓存）。问题是什么？我希望 test_counter_feature_3 的值是 "undefined"，而不是 0。另外两个值应该在保存表格后删除。

Answer 1

好的，我找到问题了。 GeneralCounterShard 还将相同的密钥保存到内存缓存中，因此我重命名了该密钥，现在一切正常。新密钥是 feature_name + "_number_of_users_enabled"，而不是以前的 feature_name。所以我用新密钥替换了所有对内存缓存的调用，现在它可以工作了。谢谢！

内存缓存没有按预期工作

memcache doesn't work as expected

python

django

google-app-engine

memcached