SpringCloud中使用Apollo实现动态刷新

普通字段

在需要刷新的字段上使用@value注解即可,例如:

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@Value("${test.user.name}")
private String name;

@Value("${test.user.age}")
private Integer age;

@Value("${test.user.sex}")
private Boolean sex;

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K8S中搭建Apollo

环境准备

  • Rancher
  • k8s 1.20
  • Helm 3
  • MySQL数据库

添加Apollo Helm Chart仓库

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helm repo add apollo https://www.apolloconfig.com/charts
helm search repo apollo

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一致性Hash算法

算法实现

不带虚拟节点的实现

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import java.util.SortedMap;
import java.util.TreeMap;

/**
* 不带虚拟节点的一致性Hash算法
*/
public class ConsistentHashingWithoutVirtualNode {

//待添加入Hash环的服务器列表
private static String[] servers = {"192.168.0.0:111", "192.168.0.1:111",
"192.168.0.2:111", "192.168.0.3:111", "192.168.0.4:111"};

//key表示服务器的hash值,value表示服务器
private static SortedMap<Integer, String> sortedMap = new TreeMap<>();

//程序初始化,将所有的服务器放入sortedMap中
static {
for (int i = 0; i < servers.length; i++) {
String server = servers[i];
int hash = getHash(server);
System.out.println("[" + server + "]加入集合中, 其Hash值为" + hash);
sortedMap.put(hash, server);
}
System.out.println();
}

//得到应当路由到的结点
private static String getServer(String key) {
//得到该key的hash值
int hash = getHash(key);
//得到大于该Hash值的所有Map
SortedMap<Integer, String> subMap = sortedMap.tailMap(hash);
if (subMap.isEmpty()) {
//如果没有比该key的hash值大的,则从第一个node开始
Integer i = sortedMap.firstKey();
//返回对应的服务器
return sortedMap.get(i);
} else {
//第一个Key就是顺时针过去离node最近的那个结点
Integer i = subMap.firstKey();
//返回对应的服务器
return subMap.get(i);
}
}

//使用FNV1_32_HASH算法计算服务器的Hash值,这里不使用重写hashCode的方法,最终效果没区别
private static int getHash(String str) {
final int p = 16777619;
int hash = (int) 2166136261L;
for (int i = 0; i < str.length(); i++)
hash = (hash ^ str.charAt(i)) * p;
hash += hash << 13;
hash ^= hash >> 7;
hash += hash << 3;
hash ^= hash >> 17;
hash += hash << 5;

// 如果算出来的值为负数则取其绝对值
if (hash < 0)
hash = Math.abs(hash);
return hash;
}

public static void main(String[] args) {
String[] keys = {"太阳", "月亮", "星星"};
for (String key : keys)
System.out.println("[" + key + "]的hash值为" + getHash(key)
+ ", 被路由到结点[" + getServer(key) + "]");
}
}

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漏桶算法

实现

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import java.util.concurrent.TimeUnit;

/**
* @author <a href="mailto:wf2311@163.com">wf2311</a>
* @since 2021/4/25 11:52.
*/
public class LeakyBucketRateLimiter {
/**
* 桶的大小
*/
private final long bucket;

/**
* 桶的已用量
*/
private long used;

/**
* 桶的流出速率
*/
private final int rate;

/**
* 流出速率单位
*/
private final TimeUnit rateUnit;

/**
*
*/
private final int perMillisRadio;

/**
* 最新刷新时间
*/
private volatile long lastRefreshTime;

public static LeakyBucketRateLimiter create(long bucket, int rate, TimeUnit rateUnit) {
return new LeakyBucketRateLimiter(bucket, rate, rateUnit);
}

private LeakyBucketRateLimiter(long bucket, int rate, TimeUnit rateUnit) {
this.bucket = bucket;
this.rate = rate;
this.rateUnit = rateUnit;
this.perMillisRadio = convertMillisRadio();
}

private int convertMillisRadio() {
switch (rateUnit) {
case MILLISECONDS:
return 1;
case SECONDS:
return 1000;
case MINUTES:
return 1000 * 60;
case HOURS:
return 1000 * 60 * 60;
default:
throw new AssertionError();
}
}

private void refreshBucketUsed() {
long now = System.currentTimeMillis();
if (lastRefreshTime > 0) {
long n = (now - lastRefreshTime) / perMillisRadio;
used = Math.max(0, used - n * rate);
}
lastRefreshTime = now;
}

public boolean tryAcquire() {
return tryAcquire(1);
}

public synchronized boolean tryAcquire(int n) {
//刷新桶的使用量
refreshBucketUsed();
//如果桶未满,则获取成功
if (used + n <= bucket) {
used += n;
return true;
}
return false;
}

}

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Queue

总览

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Set

总览

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NavigableMap

总览

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SortedMap

总览

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TreeMap

总览

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渲染