Tornado之自定义session

Posted 2020-09-07 失落的黎明

面向对象基础

面向对象中通过索引的方式访问对象，需要内部实现 __getitem__ 、__delitem__、__setitem__方法

#!/usr/bin/env python
# -*- coding:utf-8 -*-
   
class Foo(object):
   
    def __getitem__(self, key):
        print  ‘__getitem__‘,key
   
    def __setitem__(self, key, value):
        print ‘__setitem__‘,key,value
   
    def __delitem__(self, key):
        print ‘__delitem__‘,key
   
   
   
obj = Foo()
result = obj[‘k1‘]
#obj[‘k2‘] = ‘wupeiqi‘
#del obj[‘k1‘]

Tornado扩展

在tornado的源码中,默认执行Handler的get/post等方法之前默认会执行 initialize方法，所以可以通过自定义的方式使得所有请求在处理前执行操作.

class BaseHandler(tornado.web.RequestHandler):
   
    def initialize(self):
        self.xxoo = "wupeiqi"
   
   
class MainHandler(BaseHandler):
   
    def get(self):
        print(self.xxoo)
        self.write(‘index‘)
 
class IndexHandler(BaseHandler):
   
    def get(self):
        print(self.xxoo)
        self.write(‘index‘)

session

session其实就是定义在服务器端用于保存用户回话的容器，其必须依赖cookie才能实现。

自定义session_1

#!/usr/bin/env python
# -*- coding:utf-8 -*-
import config
from hashlib import sha1
import os
import time

#生成一个随机的session_id
create_session_id = lambda: sha1(bytes(‘%s%s‘ % (os.urandom(16), time.time()), encoding=‘utf-8‘)).hexdigest()

#根据定义好的session存储方式,选择对应的处理方式
class SessionFactory:

    @staticmethod
    def get_session_obj(handler):
        obj = None

        if config.SESSION_TYPE == "cache":
            obj = CacheSession(handler)
        elif config.SESSION_TYPE == "memcached":
            obj = MemcachedSession(handler)
        elif config.SESSION_TYPE == "redis":
            obj = RedisSession(handler)
        return obj


class CacheSession:
    session_container = {}
    session_id = "__sessionId__"

    def __init__(self, handler):
        self.handler = handler
        client_random_str = handler.get_cookie(CacheSession.session_id, None)
        if client_random_str and client_random_str in CacheSession.session_container:
            self.random_str = client_random_str
        else:
            self.random_str = create_session_id()
            CacheSession.session_container[self.random_str] = {}

        expires_time = time.time() + config.SESSION_EXPIRES
        handler.set_cookie(CacheSession.session_id, self.random_str, expires=expires_time)

    def __getitem__(self, key):
        ret = CacheSession.session_container[self.random_str].get(key, None)
        return ret

    def __setitem__(self, key, value):
        CacheSession.session_container[self.random_str][key] = value

    def __delitem__(self, key):
        if key in CacheSession.session_container[self.random_str]:
            del CacheSession.session_container[self.random_str][key]


class RedisSession:
    def __init__(self, handler):
        pass


class MemcachedSession:
    def __init__(self, handler):
        pass

其中os.urandom(n): 返回n个随机byte值的string，作为加密使用

自定义session_2(定义存储方式)

session_app.py:

#!/usr/bin/env python
# -*- coding:utf-8 -*-
# pip3 install tornado
import tornado.ioloop
import tornado.web
from Session.session import SessionHandler
class MainHandler(SessionHandler,tornado.web.RequestHandler):

    def get(self):
        self.render(‘login.html‘)

    def post(self, *args, **kwargs):
        user = self.get_argument(‘username‘)
        pwd = self.get_argument(‘password‘)
        if user == ‘alex‘ and pwd == ‘123‘:
            self.session_obj[‘is_login‘] = True
            self.session_obj[‘user‘] = user
            self.redirect(‘/index‘)
        else:
            self.redirect(‘/main‘)

class IndexHandler(SessionHandler,tornado.web.RequestHandler):
    def get(self):
        current_user = self.session_obj[‘user‘]
        del self.session_obj[‘user‘]
        if current_user:
            self.write(current_user)
        else:
            self.write(‘滚‘)

class MainHandler1(SessionHandler,tornado.web.RequestHandler):
    def get(self):

        self.write(‘ok‘)

class MainHandler2(SessionHandler,tornado.web.RequestHandler):
    def get(self):
        print(‘ok‘)
        self.write(‘ok‘)
# obj = MainHandler() # 执行构造方法
# obj.get()
# func = getattr(obj, ‘get‘)
# func()
application = tornado.web.Application([
    (r"/main", MainHandler),
    (r"/index", IndexHandler),
])

if __name__ == "__main__":
    application.listen(8888)
    tornado.ioloop.IOLoop.instance().start()

Session/session.py:

import hashlib
import time
from Session import conf

class SessionHandler:
    def initialize(self):
        self.session_obj = SessionFacotory.get_session_obj(self)


class SessionFacotory:
    @staticmethod
    def get_session_obj(handler):
        if conf.session_type == ‘redis‘:
            return RedisSession(handler)
        elif conf.session_type == ‘memcache‘:
            return RedisSession(handler)
        else:
            return MemorySession(handler)


def md5():
    m = hashlib.md5()
    m.update(bytes(str(time.time()),encoding=‘utf-8‘))
    return m.hexdigest()

class MemorySession:
    container = {

    }
    # self.r_str当前用户的随机字符串
    def __init__(self,handler):

        random_str = handler.get_cookie(‘___session_id___‘)
        if random_str:
            # 客户端有cookie
            # 合法cookie
            if random_str in MemorySession.container:
                self.r_str = random_str

            else:
                # 非法cookie
                random_str = md5()
                MemorySession.container[random_str] = {}
                self.r_str = random_str
        else:
            # 客户端无cookie，表示是新用户的到来
            random_str = md5()
            MemorySession.container[random_str] = {}
            self.r_str = random_str

        handler.set_cookie(‘___session_id___‘, random_str, expires=time.time() + 200)

    def __setitem__(self, key, value):
        MemorySession.container[self.r_str][key] = value

    def __getitem__(self, item):
        return MemorySession.container[self.r_str].get(item,None)

    def __delitem__(self, key):
        del MemorySession.container[self.r_str][key]


class RedisSession:
    def __init__(self):
        pass
    def __getitem__(self, item):
        pass

    def __setitem__(self, key, value):
        pass

    def __delitem__(self, key):
        pass

Session/conf.py:

session_type = ‘redis‘

分布式session

一致性哈希:

#!/usr/bin/env python
#coding:utf-8

import sys
import math
from bisect import bisect


if sys.version_info >= (2, 5):
    import hashlib
    md5_constructor = hashlib.md5
else:
    import md5
    md5_constructor = md5.new


class HashRing(object):
    """一致性哈希"""
    
    def __init__(self,nodes):
        ‘‘‘初始化
        nodes : 初始化的节点，其中包含节点已经节点对应的权重
                默认每一个节点有32个虚拟节点
                对于权重，通过多创建虚拟节点来实现
                如：nodes = [
                        {‘host‘:‘127.0.0.1:8000‘,‘weight‘:1},
                        {‘host‘:‘127.0.0.1:8001‘,‘weight‘:2},
                        {‘host‘:‘127.0.0.1:8002‘,‘weight‘:1},
                    ]
        ‘‘‘
        
        self.ring = dict()
        self._sorted_keys = []

        self.total_weight = 0
        
        self.__generate_circle(nodes)
        
            
            
    def __generate_circle(self,nodes):
        for node_info in nodes:
            self.total_weight += node_info.get(‘weight‘,1)
            
        for node_info in nodes:
            weight = node_info.get(‘weight‘,1)
            node = node_info.get(‘host‘,None)
                
            virtual_node_count = math.floor((32*len(nodes)*weight) / self.total_weight)
            for i in xrange(0,int(virtual_node_count)):
                key = self.gen_key_thirty_two( ‘%s-%s‘ % (node, i) )
                if self._sorted_keys.__contains__(key):
                    raise Exception(‘该节点已经存在.‘)
                self.ring[key] = node
                self._sorted_keys.append(key)
            
    def add_node(self,node):
        ‘‘‘ 新建节点
        node : 要添加的节点，格式为：{‘host‘:‘127.0.0.1:8002‘,‘weight‘:1}，其中第一个元素表示节点，第二个元素表示该节点的权重。
        ‘‘‘
        node = node.get(‘host‘,None)
        if not node:
                raise Exception(‘节点的地址不能为空.‘)
                
        weight = node.get(‘weight‘,1)
        
        self.total_weight += weight
        nodes_count = len(self._sorted_keys) + 1
        
        virtual_node_count = math.floor((32 * nodes_count * weight) / self.total_weight)
        for i in xrange(0,int(virtual_node_count)):
            key = self.gen_key_thirty_two( ‘%s-%s‘ % (node, i) )
            if self._sorted_keys.__contains__(key):
                raise Exception(‘该节点已经存在.‘)
            self.ring[key] = node
            self._sorted_keys.append(key)
        
    def remove_node(self,node):
        ‘‘‘ 移除节点
        node : 要移除的节点 ‘127.0.0.1:8000‘
        ‘‘‘
        for key,value in self.ring.items():
            if value == node:
                del self.ring[key]
                self._sorted_keys.remove(key)
    
    def get_node(self,string_key):
        ‘‘‘获取 string_key 所在的节点‘‘‘
        pos = self.get_node_pos(string_key)
        if pos is None:
            return None
        return self.ring[ self._sorted_keys[pos]].split(‘:‘)
    
    def get_node_pos(self,string_key):
        ‘‘‘获取 string_key 所在的节点的索引‘‘‘
        if not self.ring:
            return None
            
        key = self.gen_key_thirty_two(string_key)
        nodes = self._sorted_keys
        pos = bisect(nodes, key)
        return pos
    
    def gen_key_thirty_two(self, key):
        
        m = md5_constructor()
        m.update(key)
        return long(m.hexdigest(), 16)
        
    def gen_key_sixteen(self,key):
        
        b_key = self.__hash_digest(key)
        return self.__hash_val(b_key, lambda x: x)

    def __hash_val(self, b_key, entry_fn):
        return (( b_key[entry_fn(3)] << 24)|(b_key[entry_fn(2)] << 16)|(b_key[entry_fn(1)] << 8)| b_key[entry_fn(0)] )

    def __hash_digest(self, key):
        m = md5_constructor()
        m.update(key)
        return map(ord, m.digest())


"""
nodes = [
    {‘host‘:‘127.0.0.1:8000‘,‘weight‘:1},
    {‘host‘:‘127.0.0.1:8001‘,‘weight‘:2},
    {‘host‘:‘127.0.0.1:8002‘,‘weight‘:1},
]

ring = HashRing(nodes)
result = ring.get_node(‘98708798709870987098709879087‘)
print result

"""

分布式session:

from hashlib import sha1
import os, time


create_session_id = lambda: sha1(‘%s%s‘ % (os.urandom(16), time.time())).hexdigest()


class Session(object):

    session_id = "__sessionId__"

    def __init__(self, request):
        session_value = request.get_cookie(Session.session_id)
        if not session_value:
            self._id = create_session_id()
        else:
            self._id = session_value
        request.set_cookie(Session.session_id, self._id)

    def __getitem__(self, key):
        # 根据 self._id ，在一致性哈西中找到其对应的服务器IP
        # 找到相对应的redis服务器，如： r = redis.StrictRedis(host=‘localhost‘, port=6379, db=0)
        # 使用python redis api 链接
        # 获取数据，即：
        # return self._redis.hget(self._id, name)

    def __setitem__(self, key, value):
        # 根据 self._id ，在一致性哈西中找到其对应的服务器IP
        # 使用python redis api 链接
        # 设置session
        # self._redis.hset(self._id, name, value)


    def __delitem__(self, key):
        # 根据 self._id 找到相对应的redis服务器
        # 使用python redis api 链接
        # 删除，即：
        return self._redis.hdel(self._id, name)