memcache/memcached/memcachedb 配置、安装
当你听到memcache与memcached时把它当做是一个东东就好了，尽管它们存在区别，但是这并不影响你对它们的运用及理解。
“Memcache”它是一个自由和开放源代码、高性能、分配的内存对象缓存系统，即该系统名称为“Memcache”;
“Memcached”它是该系统的主程序文件，以守护程序方式运行于一个或多个服务器中（分布式），随时接受客户端的连接操作，使用共享内存存取数据;
“Memcachedb”它是新浪2007年的项目，在Memcached的基础上开发出来了，它与Memcache不同的是它提供了数据持久化存储
首先，我们需要下载一个memcached安装程序，memcached版本很多，开源的东西我们一定要找一个持续更新的版本，很简单，有团队在维护升级。
我选择的版本是：beitmemcached，项目地址：http://code.google.com/p/beitmemcached/ 注：此链结为windows下memcached文程序安装文件及示例。
图中的两个文件分别为：上面的是客户端调用示例项目文件、下面的文件是Memcached主程序安装文件
然后，将memcached主程序文件安装到服务器上。
Windows下安装：
1.将上图中Memcached 1.2.5.zip解压缩到 D:\program files\memcached目录下（此目录自行定义）。
2.Ctrl+R，输入cmd，打开命令行窗口，转到D:\program files\memcached目录下。
3.memcached.exe -d install
4.memcached.exe -d start
如果你要卸载，执行下面的命令：
1.memcached.exe -d stop
2.memcached.exe -d uninstall
Linux（CentOS 5.x）下安装：
1. yum install gcc
2. cd /tmp
3. wget http://www.monkey.org/~provos/libevent-2.0.4-alpha.tar.gz 注：memcached 用到了 libevent 这个库用于 Socket 的处理，所以 还需要安装 libevent
4. tar zxvf libevent-2.0.4-alpha.tar.gz
5. cd libevent-2.0.4-alpha
6. ./configure -prefix=/usr/local/libevent
7. make
8. make install
9. cd ~
10. cd /tmp
11. http://memcached.googlecode.com/files/memcached-1.4.5.tar.gz
12. tar zxvf memcached-1.4.5.tar.gz
13. cd memcached-1.4.5
14. ./configure -prefix=/usr/local/memcached --with-libevent=/usr/local/libevent 注：安装memcached时需要指定libevent的安装位置
15. make
16. make install
17. export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/libevent/lib 注：将libevent的lib目录加入LD_LIBRARY_PATH里
18. vi /etc/sysconfig/iptables
19. 将下面这行加入进去
-A RH-Firewall-l-INPUT -p tcp -m tcp --dport 11211 -j ACCEPT 注：将memcached加入到防火墙允许访问规则中
20. service iptables restart 注：防火墙重启
21. /usr/local/memcached/bin/memcached -d 注：启动memcached
memcached启动参数描述：
-d ：启动一个守护进程，
-m：分配给Memcache使用的内存数量，单位是MB，默认是64MB，
-u ：运行Memcache的用户
-l ：监听的服务器IP地址
-p ：设置Memcache监听的端口，默认是11211 注：-p（p为小写）
-c ：设置最大并发连接数，默认是1024
-P ：设置保存Memcache的pid文件 注：-P（P为大写）
如果要结束Memcache进程，执行：kill cat pid文件路径
无论是在windows下还是在linux下安装都非常简单，使用起来也很简单。
如何往memcached中插入数据？如何来读取数据？示例代码如下：
代码
using
System;
using
System.Collections.Generic;
namespace
BeIT.MemCached {
class
Example {
public
static
void
Main(
string
[] args) {
//
---------------------
//
Setting up a client.
//
---------------------
Console.Out.WriteLine(
"
Setting up Memcached Client.
"
); MemcachedClient.Setup(
"
MyCache
"
,
new
string
[] {
"
localhost
"
});
//
It is possible to have several clients with different configurations:
//
If it is impossible to resolve the hosts, this method will throw an exception.
try
{ MemcachedClient.Setup(
"
MyOtherCache
"
,
new
string
[]{
"
server1.example.com:12345
"
,
"
server2.example.com:12345
"
}); }
catch
(Exception e) { Console.WriteLine(e.Message); }
//
Get the instance we just set up so we can use it. You can either store this reference yourself in
//
some field, or fetch it every time you need it, it doesn't really matter.
MemcachedClient cache
=
MemcachedClient.GetInstance(
"
MyCache
"
);
//
It is also possible to set up clients in the standard config file. Check the section "beitmemcached"
//
in the App.config file in this project and you will see that a client called "MyConfigFileCache" is defined.
MemcachedClient configFileCache
=
MemcachedClient.GetInstance(
"
MyConfigFileCache
"
);
//
Change client settings to values other than the default like this:
cache.SendReceiveTimeout
=
5000
; cache.ConnectTimeout
=
5000
; cache.MinPoolSize
=
1
; cache.MaxPoolSize
=
5
;
//
----------------
//
Using a client.
//
----------------
//
Set some items
Console.Out.WriteLine(
"
Storing some items.
"
); cache.Set(
"
mystring
"
,
"
The quick brown fox jumped over the lazy dog.
"
); cache.Set(
"
myarray
"
,
new
string
[]{
"
This is the first string.
"
,
"
This is the second string.
"
}); cache.Set(
"
myinteger
"
,
4711
); cache.Set(
"
mydate
"
,
new
DateTime(
2008
,
02
,
23
));
//
Use custom hash
cache.Set(
"
secondstring
"
,
"
Flygande b鋍kasiner s鰇a hwila p?mjuka tufvor
"
,
4711
);
//
Get a string
string
str
=
cache.Get(
"
mystring
"
)
as
string
;
if
(str
!=
null
) { Console.Out.WriteLine(
"
Fetched item with key: mystring, value:
"
+
str); }
//
Get an object
string
[] array
=
cache.Get(
"
myarray
"
)
as
string
[];
if
(array
!=
null
) { Console.Out.WriteLine(
"
Fetched items with key: myarray, value 1:
"
+
array[
0
]
+
"
, value 2:
"
+
array[
1
]); }
//
Get several values at once
object
[] result
=
cache.Get(
new
string
[]{
"
myinteger
"
,
"
mydate
"
});
if
(result[
0
]
!=
null
&&
result[
0
]
is
int
) { Console.Out.WriteLine(
"
Fetched item with key: myinteger, value:
"
+
(
int
)result[
0
]); }
if
(result[
1
]
!=
null
&&
result[
1
]
is
DateTime) { Console.Out.WriteLine(
"
Fetched item with key: mydate, value:
"
+
(DateTime)result[
1
]); } str
=
cache.Get(
"
secondstring
"
,
4711
)
as
string
;
if
(str
!=
null
) { Console.Out.WriteLine(
"
Fetched item with key and custom hash: secondstring, value:
"
+
str); }
//
Set a counter
Console.Out.WriteLine(
"
Setting an item for incrementing and decrementing.
"
); cache.SetCounter(
"
mycounter
"
,
9000
);
ulong
?
counter
=
cache.GetCounter(
"
mycounter
"
);
if
(counter.HasValue) { Console.Out.WriteLine(
"
Fetched mycounter, value:
"
+
counter.Value); }
//
Increment the counter
counter
=
cache.Increment(
"
mycounter
"
,
1
);
if
(counter.HasValue) { Console.Out.WriteLine(
"
Incremented mycounter with 1, new value:
"
+
counter.Value); }
//
Decrement the counter
counter
=
cache.Decrement(
"
mycounter
"
,
9000
);
if
(counter.HasValue) { Console.Out.WriteLine(
"
Decremented mycounter with 9000, new value:
"
+
counter.Value); }
//
Append and prepend
Console.Out.WriteLine(
"
Storing bar for append/prepend
"
); cache.Set(
"
foo
"
,
"
bar
"
); Console.Out.WriteLine(
"
Appending baz
"
); cache.Append(
"
foo
"
,
"
baz
"
); Console.Out.WriteLine(
"
Prepending foo
"
); cache.Prepend(
"
foo
"
,
"
foo
"
); Console.Out.WriteLine(
"
New value:
"
+
cache.Get(
"
foo
"
));
//
Cas
cache.Delete(
"
castest
"
); Console.Out.WriteLine(
"
Trying to CAS non-existant key castest:
"
+
cache.CheckAndSet(
"
castest
"
,
"
a
"
,
0
)); Console.Out.WriteLine(
"
Setting value for key: castest, value: a
"
); cache.Set(
"
castest
"
,
"
a
"
); Console.Out.WriteLine(
"
Trying to CAS key castest with the wrong unique:
"
+
cache.CheckAndSet(
"
castest
"
,
"
a
"
,
0
));
ulong
unique; cache.Gets(
"
castest
"
,
out
unique); Console.Out.WriteLine(
"
Getting cas unique for key castest:
"
+
unique); Console.Out.WriteLine(
"
Trying to CAS again with the above unique:
"
+
cache.CheckAndSet(
"
castest
"
,
"
b
"
, unique));
string
value
=
cache.Gets(
"
castest
"
,
out
unique)
as
string
; Console.Out.WriteLine(
"
New value:
"
+
value
+
"
, new unique:
"
+
unique); Console.Out.WriteLine(
"
Displaying the socketpool status:
"
);
foreach
(KeyValuePair
<
string
, Dictionary
<
string
,
string
>>
host
in
cache.Status()) { Console.Out.WriteLine(
"
Host:
"
+
host.Key);
foreach
(KeyValuePair
<
string
,
string
>
item
in
host.Value) { Console.Out.WriteLine(
"
\t
"
+
item.Key
+
"
:
"
+
item.Value); } Console.Out.WriteLine(); } Console.Out.WriteLine(); Console.Out.WriteLine(
"
Finished. Press enter to exit.
"
); Console.In.ReadLine(); } } }
注：memcached是以KEY-VALUE的方式进行数据存储的，KEY的大小限制：Key（max）<=250个字符；VALUE在存 储时有限制：Value（max）<= 1M；memcached默认过期时间：ExpiresTime（max）= 30（days）。