请分析memcached源码memcached.c中的conn_waiting,conn_read,conn_parse_cmd,conn_nread,conn_write,conn_mwrite函数，并画出它们之间的UML类图

好的，我可以为您分析一下 memcached.c 中的这几个函数，并画出它们之间的 UML 类图。

1. conn_waiting()：这个函数用于等待客户端连接，并将连接加入到连接队列中。其 UML 类图如下所示：

+----------------+        +-------------------+
|     conn_t     |        |     conn_queue    |
+----------------+        +-------------------+
| event          |        | head: conn_t*      |
| sfd            |        | tail: conn_t*      |
| state          |        | lock: pthread_mutex_t |
| rbuf           |        +-------------------+
| wbuf           |
| rbuf_size      |
| wbuf_size      |
| rbytes         |
| wbytes         |
| cmd            |
| cmd_len        |
| key            |
| key_len        |
| opaque         |
| next           |
| prev           |
+----------------+
        ^
        |
        |
+-------------------+
|    conn_waiting   |
+-------------------+
| queue: conn_queue |
+-------------------+

2. conn_read()：这个函数用于从客户端连接中读取请求数据。其 UML 类图如下所示：

+----------------+        +-------------------+
|     conn_t     |        |     conn_queue    |
+----------------+        +-------------------+
| event          |        | head: conn_t*      |
| sfd            |        | tail: conn_t*      |
| state          |        | lock: pthread_mutex_t |
| rbuf           |        +-------------------+
| wbuf           |
| rbuf_size      |
| wbuf_size      |
| rbytes         |
| wbytes         |
| cmd            |
| cmd_len        |
| key            |
| key_len        |
| opaque         |
| next           |
| prev           |
+----------------+
        ^
        |
        |
+----------------+
|    conn_read   |
+----------------+

3. conn_parse_cmd()：这个函数用于解析客户端请求数据。其 UML 类图如下所示：

+----------------+        +-------------------+
|     conn_t     |        |     conn_queue    |
+----------------+        +-------------------+
| event          |        | head: conn_t*      |
| sfd            |        | tail: conn_t*      |
| state          |        | lock: pthread_mutex_t |
| rbuf           |        +-------------------+
| wbuf           |
| rbuf_size      |
| wbuf_size      |
| rbytes         |
| wbytes         |
| cmd            |
| cmd_len        |
| key            |
| key_len        |
| opaque         |
| next           |
| prev           |
+----------------+
        ^
        |
        |
+-------------------+
|   conn_parse_cmd  |
+-------------------+

4. conn_nread()：这个函数用于从客户端连接中读取指定数量的数据。其 UML 类图如下所示：

+----------------+        +-------------------+
|     conn_t     |        |     conn_queue    |
+----------------+        +-------------------+
| event          |        | head: conn_t*      |
| sfd            |        | tail: conn_t*      |
| state          |        | lock: pthread_mutex_t |
| rbuf           |        +-------------------+
| wbuf           |
| rbuf_size      |
| wbuf_size      |
| rbytes         |
| wbytes         |
| cmd            |
| cmd_len        |
| key            |
| key_len        |
| opaque         |
| next           |
| prev           |
+----------------+
        ^
        |
        |
+----------------+
|    conn_nread   |
+----------------+

5. conn_write()：这个函数用于向客户端连接写入响应数据。其 UML 类图如下所示：

+----------------+        +-------------------+
|     conn_t     |        |     conn_queue    |
+----------------+        +-------------------+
| event          |        | head: conn_t*      |
| sfd            |        | tail: conn_t*      |
| state          |        | lock: pthread_mutex_t |
| rbuf           |        +-------------------+
| wbuf           |
| rbuf_size      |
| wbuf_size      |
| rbytes         |
| wbytes         |
| cmd            |
| cmd_len        |
| key            |
| key_len        |
| opaque         |
| next           |
| prev           |
+----------------+
        ^
        |
        |
+----------------+
|    conn_write  |
+----------------+

6. conn_mwrite()：这个函数用于向客户端连接写入多个响应数据。其 UML 类图如下所示：

+----------------+        +-------------------+
|     conn_t     |        |     conn_queue    |
+----------------+        +-------------------+
| event          |        | head: conn_t*      |
| sfd            |        | tail: conn_t*      |
| state          |        | lock: pthread_mutex_t |
| rbuf           |        +-------------------+
| wbuf           |
| rbuf_size      |
| wbuf_size      |
| rbytes         |
| wbytes         |
| cmd            |
| cmd_len        |
| key            |
| key_len        |
| opaque         |
| next           |
| prev           |
+----------------+
        ^
        |
        |
+-------------------+
|   conn_mwrite     |
+-------------------+

以上就是这几个函数的 UML 类图。可以看出，它们都依赖于 conn_t 结构体，其中包含了客户端连接的状态、缓冲区、请求数据等信息。同时，它们之间也存在一定的关联，例如 conn_waiting() 函数会将连接加入到连接队列中，而 conn_read() 函数则会从连接队列中取出连接进行读取数据。