本文实例讲述了Memcached缓存系统的介绍、安装以及应用方法。分享给大家供大家参考，具体如下：
一. memcached 是什么?
memcached is a high-performance, distributed memory object caching system, generic in nature, but intended for use in speeding up dynamic web applications by alleviating database load.
memcached是一个高性能的、分布式内存对象缓存系统，应用广泛。 通过缓存数据库查询结果，减少数据库访问次数，以提高动态Web应用的速度、 提高可扩展性。
它可以应对任意多个连接，使用非阻塞的网络IO。由于它的工作机制是在内存中开辟一块空间，然后建立一个HashTable，Memcached自管理这些HashTable。还使用内置的内存块分配和哈希表算法，确保虚拟内存不会过来捣乱。
Memcached 官方网站：http://www.danga.com/memcached
二. memcached 的安装：
注：memcached 用到了libevent这个库用于Socket的处理，所以还需要安装libevent.官网：http://www.monkey.org/~provos/libevent/
1. 先安装libevent：
[root@localhost software]# tar zxvf libevent-1.4.11-stable.tar.gz [root@localhost libevent-1.4.11-stable]# ./configure �Cprefix=/usr [root@localhost libevent-1.4.11-stable]# make [root@localhost libevent-1.4.11-stable]# make install
2. 测试libevent是否安装成功
[root@localhost libevent-1.4.11-stable]# ls -al /usr/lib | grep libevent lrwxrwxrwx 1 root root 22 07-10 13:10 libevent-1.1a.so.1 -> libevent-1.1a.so.1.0.2 -rwxr-xr-x 1 root root 31596 2007-01-07 libevent-1.1a.so.1.0.2 lrwxrwxrwx 1 root root 21 07-21 03:33 libevent-1.4.so.2 -> libevent-1.4.so.2.1.3 -rwxr-xr-x 1 root root 308088 07-21 03:33 libevent-1.4.so.2.1.3 -rw-r--r-- 1 root root 394474 07-21 03:33 libevent.a lrwxrwxrwx 1 root root 26 07-21 03:33 libevent_core-1.4.so.2 -> libevent_core-1.4.so.2.1.3 -rwxr-xr-x 1 root root 109490 07-21 03:33 libevent_core-1.4.so.2.1.3 -rw-r--r-- 1 root root 148742 07-21 03:33 libevent_core.a -rwxr-xr-x 1 root root 866 07-21 03:33 libevent_core.la lrwxrwxrwx 1 root root 26 07-21 03:33 libevent_core.so -> libevent_core-1.4.so.2.1.3 lrwxrwxrwx 1 root root 27 07-21 03:33 libevent_extra-1.4.so.2 -> libevent_extra-1.4.so.2.1.3 -rwxr-xr-x 1 root root 246870 07-21 03:33 libevent_extra-1.4.so.2.1.3 -rw-r--r-- 1 root root 307370 07-21 03:33 libevent_extra.a -rwxr-xr-x 1 root root 873 07-21 03:33 libevent_extra.la lrwxrwxrwx 1 root root 27 07-21 03:33 libevent_extra.so -> libevent_extra-1.4.so.2.1.3 -rwxr-xr-x 1 root root 831 07-21 03:33 libevent.la lrwxrwxrwx 1 root root 21 07-21 03:33 libevent.so -> libevent-1.4.so.2.1.3
安装OK。
3. 安装memcached，同时需要安装中指定libevent的安装位置
[root@localhost software]# tar zxvf memcached-1.4.0.tar.gz [root@localhost memcached-1.4.0]# ./configure �Cwith-libevent=/usr [root@localhost memcached-1.4.0]# make [root@localhost memcached-1.4.0]# make intall
4. 测试是否成功安装memcached
[root@localhost memcached-1.4.0]# ls -al /usr/local/bin | grep memcached -rwxr-xr-x 1 root root 188225 07-21 03:35 memcached
安装OK。
三. 如何启动 memcached 服务：
只需要启动一个 memcached 监护进程，监护进程不需要配置文件，只要在命令行里面加三四个参数就可以了:
-d： (run as a daemon) 选项是启动一个守护进程
-m：(max memory to use for items in megabytes (default: 64 MB))是分配给Memcache使用的内存数量，单位是MB，我这里是100MB，
-u：(assume identity of
-l：(interface to listen on)是监听的服务器IP地址，如果有多个地址的话，这里指定了服务器的IP地址127.0.0.1，
-p：是设置Memcache监听的端口，这里设置了11211，最好是1024以上的端口，
-c：选项是最大运行的并发连接数，默认是1024，这里设置了256，根据服务器的负载量来设定，
-P：(save PID in
注：也可以启动多个守护进程，不过端口不能重复。
四. 安装 Memcached 的PHP扩展：
在PHP中使用Memcached，有两种方式：
一种是安装PHP的memcached扩展。该扩展是用c写的，效率较高，需要在服务器上安装。
另外一种则是直接使用客户端的php-memcached-client类库。
下面是使用PECL中Memcache的专用扩展，因为毕竟是用C写的，效率高，而且安装部署起来也比较方便。
1. 在 http://pecl.php.net/package/memcache 选择相应想要下载的memcache版本。我下载的是:memcache-2.2.5.tgz 版本。
2. 安装 memcache
[root@localhost software]# tar zxvf memcache-2.2.5.tgz [root@localhost software]# cd memcache-2.2.5 [root@localhost memcache-2.2.5]# /usr/bin/phpize [root@localhost memcache-2.2.5]# ./configure �Cenable-memcache �Cwith-php-config=/usr/bin/php-config �Cwith-zlib-dir [root@localhost memcache-2.2.5]# make [root@localhost memcache-2.2.5]# make install
这步会有类似这样的提示：Installing shared extensions: /usr/local/php/modules
3. 把/etc/php.ini中的
extension_dir = "./"
修改为：
extension_dir = "/usr/lib/php/modules"
4. 并添加： extension=memcache.so
也可执行以下shell命令，对php.ini文件的修改：
五. 安装C/C++ Memcached客户端库：libmemcached
下载：http://download.tangent.org/libmemcached-0.32.tar.gz
1. 安装 libmemcached
[root@localhost src]# tar zxvf libmemcached-0.32.tar.gz [root@localhost src]# cd libmemcached-0.32 [root@localhost libmemcached-0.32]# ./configure --prefix=/usr [root@localhost libmemcached-0.32]# make && make install
2. 检查安装结果
[root@localhost src]# ls /usr/lib/libmemcache* //库文件 [root@localhost src]# ls /usr/include/libmemcached/* //头文件 [root@localhost src]# ls /usr/bin/mem* //命令行工具
六. 应用：
1. 启动 memcache 服务
2. 重启 Web 服务器
[root@localhost bin]# service httpd restart
3. 创建 demo 测试程序
connect("127.0.0.1", 11211);
echo 'Memcache Version is:'.$mem->getVersion().'
';
//保存数据
$mem->set('key1', 'This is first memcache demo', 0, 60);
$val = $mem->get('key1');
echo "Get key1 value: ".$val."
"
//关闭连接
$mem->close();
?>
4. Memcached客户端与tokyotyrant DB操作访问
addServer('127.0.0.1:1978');
function microtime_float()
{
list($usec, $sec) = explode(" ", microtime());
return ((float)$usec + (float)$sec);
}
$time_start = microtime_float();
$data = 'abc123';
for($i = 0;$i <= 20000 ;$i++){
$key = (string) rand(1,100);
$memcache->set($key, $data);
}
for($i = 0;$i <= 20000 ;$i++){
$key = (string) rand(1,100);
echo $data = $memcache->get($key).'-'.$i.'
';
}
$time_end = microtime_float();
$time = $time_end - $time_start;
echo $time;
$memcache->close();
?>
5. C/C++ 与 Memcached 结合代码
#include#include #include #include int main(int argc, char *argv[]) { memcached_st *memc; memcached_return rc; memcached_server_st *servers; char value[8191]; //连接服务器 memc = memcached_create(NULL); servers = memcached_server_list_append(NULL, "127.0.0.1",11211, &rc); rc = memcached_server_push(memc, servers); memcached_server_free(servers); //存储数据 strcpy(value, "This is c first value"); rc = memcached_set(memc, "key1", 4, value, strlen(value), (time_t)180, (uint32_t)0); if (rc == MEMCACHED_SUCCESS) { printf("Save key:key1 data:/"%s/" success./n", value); } //获取数据 char return_key[MEMCACHED_MAX_KEY]; size_t return_key_length; char *return_value; size_t return_value_length; char *keys[]= {"key1"}; size_t key_length[]= {4}; uint32_t flags; rc = memcached_mget(memc, keys, key_length, 1); return_value = memcached_fetch(memc, return_key, &return_key_length, &return_value_length, &flags, &rc); if (rc == MEMCACHED_SUCCESS) { printf("Fetch key:%s data:%s/n", return_key, return_value); } //删除数据 rc = memcached_delete(memc, "key1", 4, (time_t)0); if (rc == MEMCACHED_SUCCESS) { printf("Delete Key key1 success./n"); } //释放内存 memcached_free(memc); return 0; }
编译源代码：
[root@localhost html]# gcc -o cmem cmem.c -lmemcached [root@localhost html]# ./cmem //执行 Save key:key1 data:"This is c first value" success. Fetch key:key1 data:This is c first value Delete Key key1 success.
6. C/C++ 与 Memcached 分布式结合代码
#include#include #include #include int main(int argc, char *argv[]) { memcached_st *memc; memcached_return rc; memcached_server_st *servers; char value[8191]; //connect multi server memc = memcached_create(NULL); servers = memcached_server_list_append(NULL, "localhost", 11211, &rc); servers = memcached_server_list_append(servers, "localhost", 11212, &rc); rc = memcached_server_push(memc, servers); memcached_server_free(servers); //Save multi data size_t i; char *keys[]= {"key1", "key2", "key3"}; size_t key_length[]= {4, 4, 4}; char *values[] = {"This is c first value", "This is c second value", "This is c third value"}; size_t val_length[]= {21, 22, 21}; for (i=0; i <3; i++) { rc = memcached_set(memc, keys[i], key_length[i], values[i], val_length[i], (time_t)180,(uint32_t)0); if (rc == MEMCACHED_SUCCESS) { printf("Save key:%s data:/"%s/" success./n", keys[i], values[i]); } } //Fetch multi data char return_key[MEMCACHED_MAX_KEY]; size_t return_key_length; char *return_value; size_t return_value_length; uint32_t flags; rc = memcached_mget(memc, keys, key_length, 3); while ((return_value = memcached_fetch(memc, return_key, &return_key_length, &return_value_length, &flags, &rc))) { if (rc == MEMCACHED_SUCCESS) { printf("Fetch key:%s data:%s/n", return_key, return_value); } } //Delete multi data for (i=0; i <3; i++) { rc = memcached_set(memc, keys[i], key_length[i], values[i], val_length[i], (time_t)180, (uint32_t)0); rc = memcached_delete(memc, keys[i], key_length[i], (time_t)0); if (rc == MEMCACHED_SUCCESS) { printf("Delete %s success/n", keys[i], values[i]); } } //free memcached_free(memc); return 0; }
编译源代码：
[root@localhost html]# gcc -o cmultmem cmultmem.c -lmemcached [root@localhost html]# ./cmultmem //执行 Save key:key1 data:"This is c first value" success. Save key:key2 data:"This is c second value" success. Save key:key3 data:"This is c third value" success. Fetch key:key2 data:This is c second value Fetch key:key3 data:This is c third value Fetch key:key1 data:This is c first value Delete key1 success Delete key2 success Delete key3 success
以上c/c++代码摘自：黑夜路人
7. 查看Memcache进程
[root@localhost html]# ps aux | grep memcached root 11382 0.0 0.7 55124 1896 ? Ssl 13:06 0:00 memcached -d -m 100 -u root -l 127.0.0.1 -p 11211 -c 256 -P /tmp/memcached.pid root 11395 0.0 0.2 3912 664 pts/1 R+ 13:08 0:00 grep memcached
8. 结束Memcache进程
[root@localhost html]# kill `cat /tmp/memcached.pid`
希望本文所述对大家memcached缓存程序设计有所帮助。