1%3 = 1    
1%4 = 1
2%3 = 2    
2%4 = 2
3%3 = 0    
3%4 = 3
4%4 = 1    
4%4 = 0
#以此类推

$ sudo apt-get install memcached
$ memcached -m 32 -p 11211 -d
# memcached将会以守护程序的形式启动 memcached（-d），为其分配32M内存（-m 32），并指定监听 localhost的11211端口。

#!/usr/bin/env pythonimport memcache

mc = memcache.Client(['127.0.0.1:12000'],debug=0)

mc.set("some_key", "Some value")
value = mc.get("some_key")

mc.set("another_key", 3)
mc.delete("another_key")

mc.set("key", "1")   # note that the key used for incr/decr must be a string.
mc.incr("key")
mc.decr("key")

    def _get_server(self, key):
        if isinstance(key, tuple):
            serverhash, key = key        
            else:
            serverhash = serverHashFunction(key)        
            if not self.buckets:            
            return None, None

        for i in range(Client._SERVER_RETRIES):
            server = self.buckets[serverhash % len(self.buckets)]            
            if server.connect():                
            # print("(using server %s)" % server,)
                return server, key
            serverhash = serverHashFunction(str(serverhash) + str(i))        
            return None, None

import memcacheimport typesfrom hash_ring import HashRingclass MemcacheRing(memcache.Client):
    """Extends python-memcache so it uses consistent hashing to
    distribute the keys.
    """
    def init(self, servers, *k, **kw):
        self.hash_ring = HashRing(servers)
        memcache.Client.init(self, servers, *k, **kw)
        self.server_mapping = {}        
        for server_uri, server_obj in zip(servers, self.servers):
            self.server_mapping[server_uri] = server_obj    
            def _get_server(self, key):
        if type(key) == types.TupleType:            
        return memcache.Client._get_server(key)        
        for i in range(self._SERVER_RETRIES):
            iterator = self.hash_ring.iterate_nodes(key)            
            for server_uri in iterator:
                server_obj = self.server_mapping[server_uri]                
                if server_obj.connect():                    
                return server_obj, key        
                return None, None

# coding: utf-8import sysimport tornado.ioloopimport tornado.webimport loggingimport memcacheimport jsonimport urllib# 初始化memcache clientmc = memcache.Client(['127.0.0.1:11211'], debug=0)
mc_prefix = 'demo'class BaseHandler(tornado.web.RequestHandler):
    """ 把缓存处理抽象到BaseHandler基类 """
    USE_CACHE = False  # 控制是否使用缓存

    def format_args(self):
        arg_list = []        
        for a in self.request.arguments:            
        for value in self.request.arguments[a]:
                arg_list.append('%s=%s' % (a, urllib.quote(value.replace(' ', ''))))        
                # 根据请求的URL产生key
        arg_list.sort()
        key = '%s?%s' % (self.request.path, '&'.join(arg_list)) if arg_list else self.request.path
        key = '%s_%s' % (mc_prefix, key)        
        # key太长，不进行缓存处理
        if len(key) > 250:
            logging.error('key out of length: %s', key)            
            return None

        return key    def get(self, *args, **kwargs):
        if self.USE_CACHE:            
        try:                
        # 根据请求获取key
                self.key = self.format_args()                
                if self.key:
                    data = mc.get(self.key)  
                    # 若缓存命中，则直接返回数据
                    if data:
                        logging.info('get data from memecahce')
                        self.finish(data)                        
                        return
            except Exception, e:
                logging.exception(e)        
                # 若未命中缓存，调用do_get处理请求，获取数据
        data = self.do_get()
        data_str = json.dumps(data)        
        # 把成功获取到的数据，放入memcache缓存
        if self.USE_CACHE and data and data.get('result', -1) == 0 and self.key:            
        try:
                mc.set(self.key, data_str, 60)            
                except Exception, e:
                logging.exception(e)

        self.finish(data_str)    def do_get(self):
        return Noneclass DemoHandler(BaseHandler):
    USE_CACHE = True

    def do_get(self):
        a = self.get_argument('a', 'test')
        b = self.get_argument('b', 'test')        
        # 访问数据库获取数据，此处略去
        data = {'result': 0, 'a': a, 'b': b}        return datadef make_app():
    return tornado.web.Application([
        (r"/", DemoHandler),
    ])if name == "main":
    logging.basicConfig(stream=sys.stdout, level=logging.INFO,
                    format='%(asctime)s %(levelno)s %(message)s',
                    )

    app = make_app()
    app.listen(8888)
    tornado.ioloop.IOLoop.current().start()

2017-02-21 22:45:05,987 20 304 GET /?a=1&b=2 (127.0.0.1) 3.11ms
2017-02-21 22:45:07,427 20 get data from memecahce
2017-02-21 22:45:07,427 20 304 GET /?a=1&b=2 (127.0.0.1) 0.71ms
2017-02-21 22:45:10,350 20 200 GET /?a=1&b=3 (127.0.0.1) 0.82ms
2017-02-21 22:45:13,586 20 get data from memecahce