gocache
gocache: Distributed cache framework based on consistent hashing algorithm, only applicable to Go language novice learning projects
描述
gocache是一个基于Go语言实现的分布式缓存框架，参考了groupcache的设计，适合go语言、分布式初学者的开源项目。
特点
- gocache采用了2Q算法的方式读写缓存 2Q: A Low Overhead High Performance Buffer Management Replacement Algorithm
- gocache采用一致性哈希算法(虚拟节点)实现分布式储存
- gocache采用singleflight的方法预防缓存击穿
- 每个gocahe既具有客户端功能又具有服务端功能
- gocache具有Get/Delete操作，适合作为持久化数据源的分布式缓存
实验Demo
type dbSource map[string]float64
//模拟数据源
var dbsource = dbSource{
"apple": 6.90,
"pear": 18.20,
"grape": 15.40,
"banana": 11.0,
"watermelon": 30.0,
"melon": 35.0,
"strawberry": 66.40, //....
}
func main() {
group := gocache.NewGroup("price", 2<<5, 2<<4 , gocache.GetterFunction(
// 调用远程数据源
func(key string) ([]byte, error) {
log.Println("access dbsource", key)
if v, ok := dbsource[key]; ok {
return []byte(fmt.Sprintf("%.2f", v)), nil
}
return nil, fmt.Errorf("[dbsource] %s is not exist ", key)
}))
// 集群
addrs := []string{"http://localhost:8000", "http://localhost:8001", "http://localhost:8002", "http://localhost:8003"}
// 启动gocache
addr := localhost:8000
peers := gocache.NewHTTPPool("http://" + addr)
peers.Set(addrs...)
group.RegisterPeers(peers)
log.Println("gocache is runnning...", addr)
log.Fatal(http.ListenAndServe(addr, peers))
}分别启动4台主机，addr分别修改成 http://localhost:8000, http://localhost:8001, http://localhost:8002, http://localhost:8003。我们可以选取任意一台主机当作API主机， 因为每个gocahe既具有客户端功能又具有服务端功能。
现在访问8000端口主机寻找price命名组里的缓存pear：
curl http://localhost:8000/_gocache/price/pear结果：
# http://localhost:8000 结果：
2020/08/13 21:55:24 gocache is runnning... localhost:8000
2020/08/13 21:57:09 [Server http://localhost:8000] GET /_gocache/price/pear
2020/08/13 21:57:09 [Server http://localhost:8000] Pick peer http://localhost:8003
# http://localhost:8003 结果：
2020/08/13 21:55:24 gocache is runnning... localhost:8003
2020/08/13 21:57:09 [Server http://localhost:8003] GET /_gocache/price/pear
2020/08/13 21:57:09 access dbsource pear
2020/08/13 21:57:09 [Group price] Add cache,key is pear
可以明显的看出8000端口主机通过一致性哈希算法定位到8003端口主机，8003端口主机的该缓存为空，于是访问本地数据源，将缓存添加至8003端口主机中。
再次访问8002端口主机寻找price命名组里的缓存pear：
curl http://localhost:8002/_gocache/price/pear结果：
# http://localhost:8002 结果：
2020/08/13 22:01:52 [Server http://localhost:8002] GET /_gocache/price/pear
2020/08/13 22:01:52 [Server http://localhost:8002] Pick peer http://localhost:8003
# http://localhost:8003 结果
2020/08/13 22:01:52 [Server http://localhost:8003] GET /_gocache/price/pear
2020/08/13 22:01:52 [Group price] Hit cache,key is pear
当8003端口主机宕机，再次访问8002端口主机寻找price命名组里的缓存pear
结果：
# http://localhost:8002 结果：
2020/08/13 22:04:24 [Server http://localhost:8002] GET /_gocache/price/pear
2020/08/13 22:04:24 [Server http://localhost:8002] Pick peer http://localhost:8003
2020/08/13 22:04:27 [Group] Failed to get from peer price
2020/08/13 22:04:27 access dbsource pear
2020/08/13 22:04:27 [Group price] Add cache,key is pear
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