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python memcache详解

服务器连接

2023-03-02 10:29:26 时间

memcache是键值对key-value存储， 操作很简单方便， python支持对memcache操作，也很简单， 能够快速上手进行开发

安装

pip install python-memcached

入门程序：

import memcache
    
    mc = memcache.Client(['127.0.0.1:11211'], debug=0)
    
    print mc.set("xxxx", "test")
    
    print mc.get("xxxx")
    
    print help(mc)
    mc.disconnect_all()

--------------------

#### CLEINT 参数详解 ####

class Client(threading.local):
        """
        @group Setup: __init__, set_servers, forget_dead_hosts,
        disconnect_all, debuglog
        @group Insertion: set, add, replace, set_multi
        @group Retrieval: get, get_multi
        @group Integers: incr, decr
        @group Removal: delete, delete_multi
        
        _DEAD_RETRY = 30  # number of seconds before retrying a dead server.
    	_SOCKET_TIMEOUT = 3  # number of seconds before sockets timeout.
    
        """
    
        def __init__(self, servers, debug=0, pickleProtocol=0,
                     pickler=pickle.Pickler, unpickler=pickle.Unpickler,
                     compressor=zlib.compress, decompressor=zlib.decompress,
                     pload=None, pid=None,
                     server_max_key_length=None, server_max_value_length=None,
                     dead_retry=_DEAD_RETRY, socket_timeout=_SOCKET_TIMEOUT,
                     cache_cas=False, flush_on_reconnect=0, check_keys=True):
            """Create a new Client object with the given list of servers.
    
            @param servers: C{servers} is passed to L{set_servers}. 
            	一组set或者list的连接参数
            @param debug: whether to display error messages when a server
            can't be contacted.  
            	debug模式
            @param pickleProtocol: number to mandate protocol used by
            (c)Pickle.
            @param pickler: optional override of default Pickler to allow
            subclassing.
            @param unpickler: optional override of default Unpickler to
            allow subclassing.
            @param pload: optional persistent_load function to call on
            pickle loading.  Useful for cPickle since subclassing isn't
            allowed.
            @param pid: optional persistent_id function to call on pickle
            storing.  Useful for cPickle since subclassing isn't allowed.
            
            @param dead_retry: number of seconds before retrying a
            blacklisted server. Default to 30 s.
            	重试连接时间间隔， 默认30s
            @param socket_timeout: timeout in seconds for all calls to a
            server. Defaults to 3 seconds.
            	socket连接超时时间，默认3s
            @param cache_cas: (default False) If true, cas operations will
            be cached.  WARNING: This cache is not expired internally, if
            you have a long-running process you will need to expire it
            manually via client.reset_cas(), or the cache can grow
            unlimited.
            @param server_max_key_length: (default SERVER_MAX_KEY_LENGTH)
            Data that is larger than this will not be sent to the server.
            @param server_max_value_length: (default
            SERVER_MAX_VALUE_LENGTH) Data that is larger than this will
            not be sent to the server.
            	限制最大的发送字符的长度， 如果超过将不会被发送
            @param flush_on_reconnect: optional flag which prevents a
            scenario that can cause stale data to be read: If there's more
            than one memcached server and the connection to one is
            interrupted, keys that mapped to that server will get
            reassigned to another. If the first server comes back, those
            keys will map to it again. If it still has its data, get()s
            can read stale data that was overwritten on another
            server. This flag is off by default for backwards
            compatibility.
            重连刷新， 有多个memcache服务器， 一个终端后，keys将会映射到另外一个服务器上， 
            如果服务器回复， 那么这些keys将会被重新映射，如果这个服务器还保留有之前的key，那么key有可		  能被其他服务器重写了， 该参数用于该情况
            @param check_keys: (default True) If True, the key is checked
            to ensure it is the correct length and composed of the right
            characters.
            检察key
            """

--------------------

##### 方法详解 #####

初始化的时候 `set_servers, forget_dead_hosts`

1.  `def set_servers(self, servers):`

设置服务器

这个函数最好是设置为私有函数，这里作者设置的都可以访问，进行修改

1.  `forget_dead_hosts()`

移除故障节点

设置键值： `set, add, replace, set_multi`

1.  `def set(key, val, time=0, min_compress_len=0, noreply=False):`

如果set的key已经存在，该命令会更新该key所对应的原来的数据

1.  `def add(self, key, val, time=0, min_compress_len=0, noreply=False):`

新增， 如果之前的key是存在的，那么将不会更新原来的值

1.  `def replace(self, key, val, time=0, min_compress_len=0, noreply=False):`

更新, 用于更新已经存在的key的value， 如果key不存在，则会返回NOT\_STORED

1.  `def set_multi(self, mapping, time=0, key_prefix='', min_compress_len=0, noreply=False):`
    
    匹配设置，
    
    `mc.set_multi({'key1' : 'val1', 'key2' : 'val2'})`
    
    使用`mc.get_multi(['key1', 'key2'])` 获取

获取值： `get, get_multi`

1.  `def get(self, key):`
    
    获取值
2.  `def get_multi(self, keys, key_prefix='')`
    
    批量获取

数字加减： `incr, decr`

1.  `def incr(self, key, delta=1, noreply=False):`
    
    增加
2.  `def decr(self, key, delta=1, noreply=False)`
    
    减少

删除： `delete, delete_multi`

1.  `def delete(self, key, time=None, noreply=False)`
    
    删除key
2.  `def delete_multi(self, keys, time=None, key_prefix='', noreply=False)`
    
    批量删除
    
    `mc.delete_multi(['key1', 'key2'])`
3.  `prepend(self, key, val, time=0, min_compress_len=0, noreply=False)`
    
    在头部追加数据
4.  `append(self, key, val, time=0, min_compress_len=0, noreply=False)`
    
    在末尾追加更新
5.  `cas(self, key, val, time=0, min_compress_len=0, noreply=False)`
    
    cas
6.  `check_key(self, key, key_extra_len=0)`
    
    检察key
7.  `disconnect_all(self)`
    
    中断所有连接， 在程序结束的时候关闭连接
8.  `flush_all(self)`
    
    刷新所有key， 过期所有key， 清空memcache
9.  `get_slab_stats(self)`
    
    获取 slab stats
10. `get_slabs(self)`
    
    获取slab
11. `get_stats(self, stat_args=None)`
    
    status
12. `gets(self, key)`
    
    获取key
13. `reset_cas(self)`
    
    充值cas
14. `touch(self, key, time=0, noreply=False)`
    
    Updates the expiration time of a key in memcache.
    
    更新key的过期时间

--------------------

#### 示例程序 ####

# _ coding:utf-8 _*_
    import memcache
    
    mc = memcache.Client(['127.0.0.1:11211'], debug=0)
    mc.set_servers(['127.0.0.1:11211'])
    
    # -----  设置获取值 -------
    print "****" * 8
    print "set - m1 ", mc.set("m1", "test")
    print "get - m1 ", mc.get("m1")
    print "****" * 8
    # -----  更新、操作值 -------
    print "add - m2 ",mc.add("m2", "test2")
    print "get - m2 ", mc.get("m1")
    print " replace - m1 ", mc.replace("m1", "new1")
    print "get - m1 ", mc.get("m1")
    print mc.append("m1", "__end")
    print mc.prepend("m1", "start__")
    print "  - m ", mc.set_multi({"mt1": "1", "mt2": 2})
    print "  - m ", mc.get_multi(["mt1", "mt2"])
    print mc.set("count", 8)
    print "  - m ", mc.incr("count", 2)
    print "  - m ", mc.decr("count", "3")
    print mc.set("temp", 8)
    print "  - m ", mc.delete("temp")
    mc.set("temp1", 8)
    mc.set("temp2", 9)
    print "  - m ", mc.delete_multi(["temp1", "temp2"])
    print mc.get_stats()
    print mc.get_slabs()
    mc.forget_dead_hosts()
    mc.disconnect_all()

输出：

********************************
    set - m1  True
    get - m1  test
    ********************************
    add - m2  True
    get - m2  test
     replace - m1  True
    get - m1  new1
    True
    True
      - m  []
      - m  {'mt2': 2, 'mt1': '1'}
    True
      - m  10
      - m  7
    True
      - m  1
      - m  1
    [({u'lru_maintainer_juggles': u'35766', ....)]
    [({'1': {'age_warm': '0', 'number_warm': '0', ....}})]

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python memcache详解

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