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。
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：
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();
}
}
}