xmemcached 动态增加节点
来源：程序员人生 发布时间：2015-01-26 08:51:21 阅读次数：3188次
1.介绍
支持所有的基于文本的协议和2进制memcached的基础协议，目前，包括获得/设置获得，添加删除添加替换、prepend、CAS、多得到/得到增加下降flush_all统计等。
2.依赖
如果是maven工程
<dependency>
<groupId>com.googlecode.xmemcached</groupId>
<artifactId>xmemcached</artifactId>
<version>${version}</version>
</dependency>
3.例子
MemcachedClient client=new XMemcachedClient("host",11211);
//store a value for one hour(synchronously).
client.set("key",3600,someObject);
//Retrieve a value.(synchronously).
Object someObject=client.get("key");
//Retrieve a value.(synchronously),operation timeout two seconds.
someObject=client.get("key",2000);
//Touch cache item ,update it's expire time to 10 seconds.
boolean success=client.touch("key",10);
//delete value
client.delete("key");
4.Weighted Server（节点权重）
设置 localhost:12000 的权重为1，设置 localhost:12001 的权重为3.
MemcachedClientBuilder builder = new XMemcachedClientBuilder(AddrUtil.getAddresses("localhost:12000 localhost:12001"),new int[]{1,3});
MemcachedClient memcachedClient=builder.build();
可以通过jmx动态改变权重
public interface XMemcachedClientMBean{
....
/**
* Set a memcached server's weight
*
* @param server
* @param weight
*/
public void setServerWeight(String server, int weight);
}
5. 获得所有key
MemcachedClient client=...
KeyIterator it=client.getKeyIterator(AddrUtil.getOneAddress("localhost:11211"));
while(it.hasNext())
{
String key=it.next();
}
6.SASL认证
Memcached客户端1.4.3支持SASL认证。2进制协议是有效的。xmemcached 1.2.5支持此功能。如果memcached服务器启用SASL使用CRAM-MD5或普通的机制，设置用户名为“cacheuser”和密码为“123456”，那末你可使用xmemcached这样：
MemcachedClientBuilder builder = new XMemcachedClientBuilder(
AddrUtil.getAddresses(server));
builder.addAuthInfo(AddrUtil.getOneAddress(server), AuthInfo
.typical("cacheuser", "password"));
// Must use binary protocol
builder.setCommandFactory(new BinaryCommandFactory());
MemcachedClient client=builder.build();
7.使用计数器来增加/减少。
您可使用增加/减少memcachedclient的方法来增加或减少计数器，但有1个计数器xmemcached封装增加/减少的方法，你可使用计数器就像AtomicLong：
Counter counter=client.getCounter("counter",0);
counter.incrementAndGet();
counter.decrementAndGet();
counter.addAndGet(-10);
8. 2进制协议。
MemcachedClientBuilder builder = new XMemcachedClientBuilder(AddrUtil.getAddresses("localhost:12000 localhost:12001"),new int[]{1,3});
builder.setCommandFactory(new BinaryCommandFactory());//use binary protocol
MemcachedClient memcachedClient=builder.build();
9.Kestrel
MemcachedClientBuilder builder = new XMemcachedClientBuilder(AddrUtil.getAddresses("localhost:12000 localhost:12001"),new int[]{1,3});
builder.setCommandFactory(new KestrelCommandFactory());
MemcachedClient memcachedClient=builder.build();
// 存储字符串
client.setPrimitiveAsString(true);
10.动态增加节点
MemcachedClient client=new XMemcachedClient(AddrUtil.getAddresses("server1:11211 server2:11211"));
//Add two new memcached nodes
client.addServer("server3:11211 server4:11211");
//Remove memcached servers
client.removeServer("server1:11211 server2:11211");
11.设置连接池
MemcachedClientBuilder builder = new XMemcachedClientBuilder(AddrUtil.getAddresses("localhost:12000"));
builder.setConnectionPoolSize(5); //set connection pool size to five
12 Cas操作
class CASThread extends Thread {
static final class IncrmentOperation implements CASOperation<Integer> {
/*
*Max repeat times.if repeat times is great than this value,
*xmemcached will throw a TimeoutException.
*/
@Override
public int getMaxTries() {
return Integer.MAX_VALUE;
}
//increase current value
@Override
public Integer getNewValue(long currentCAS, Integer currentValue) {
return currentValue + 1; // current value + 1
}
}
private XMemcachedClient mc;
private CountDownLatch cd;
public CASThread(XMemcachedClient mc, CountDownLatch cdl) {
super();
this.mc = mc;
this.cd = cdl;
}
public void run() {
try {
//do the cas operation
if (mc.cas("a", 0, new IncrmentOperation()))
this.cd.countDown();
} catch (Exception e) {
e.printStackTrace();
}
}
}
public class CASTest {
public static void main(String[] args) throws Exception {
if (args.length < 2) {
System.err.println("Usage:java CASTest [threadNum] [server]");
System.exit(1);
}
//threads num
int NUM = Integer.parseInt(args[0]);
XMemcachedClient mc = new XMemcachedClient(AddrUtil.getAddresses(args[1]));
//initial value is 0
mc.set("a", 0, 0);
CountDownLatch cdl = new CountDownLatch(NUM);
long start = System.currentTimeMillis();
//start NUM threads to increment the value
for (int i = 0; i < NUM; i++)
new CASThread(mc, cdl).start();
cdl.await();
System.out.println("test cas,timed:"
+ (System.currentTimeMillis() - start));
System.out.println("result=" + mc.get("a"));
mc.shutdown();
}
}
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