内存布局: 整个存储由: header + nodes + blocks 三部分构成,其中nodes由所有的node节点组成,blocks由所有的block元素构成 nodes即是由多阶hash打平而来,而blocks本来就是预先申请的大块存储 内存结构即最终磁盘组织结构,不需要额外转存,设计非常巧妙 如果再配合内存映射mmap简直完美,操作内存即是操作文件! 几个问题...
self.nodes = nodesself.ring = {}self.sortedKeys = []self.addNodes(nodes) #nodes是一个节点的列表,遍历列表逐个添加到hash环中def addNodes(self, nodes):if nodes:for node in nodes:# 和第一篇hash取模相同,我们使用sha1算法进行hash处理,然后强转intnodeHashResult = hashlib.sha1(node).hexdigest(...
} c.nodes[node] = true // add virtual node for i := 0; i < c.numOfVirtualNode; i++ { virtualKey := getVirtualKey(i, node) c.circle[virtualKey] = node c.hashSortedNodes = append(c.hashSortedNodes, virtualKey) } sort.Slice(c.hashSortedNodes, func(i, j int) bool { return...
hash(key)=10,nodes=5,hash(key)%nodes=0,命中0 redis节点 set hello world hash(key)=10,nodes=3,hash(key)%nodes=1,命中1 redis节点 get hello 结果发现每次同样key,在节点数变化后命中的节点不一样,导致造成大量的请求无法命中(访问正确的节点)从而导致缓存数据被重新加载,这样的结果就是重新hash做一次s...
*/publicvoidinitVirtual2RealRing(List<String>shards){this.shardNodes=shards;for(String node:shardNodes){for(int i=0;i<NODE_NUM;i++){long hashCode=hash("SHARD-"+node+"-NODE-"+i);virtualHash2RealNode.put(hashCode,node);}}}/**
* Hash nodes name */publicstaticfinalStringHASH_NODES="hash.nodes";/** * Hash arguments name */publicstaticfinalStringHASH_ARGUMENTS="hash.arguments";privatefinalConcurrentMap<String, ConsistentHashSelector<?>> selectors =newConcurrentHashMap<String, ConsistentHashSelector<?>>();@SuppressWarnings("...
for (T node : nodes) { add(node); } } public void add(T node) { for (int i = 0; i < numberOfReplicas; i++) { circle.put(hashFunction.hash(node.toString() + i), node); } } public void remove(T node) { for (int i = 0; i < numberOfReplicas; i++) { ...
With 100 replicas (“vnodes”) per server, the standard deviation of load is about 10%. Increasing the number of replicas to 1000 points per server reduces the standard deviation to ~3.2%. 当有100个虚拟节点时,哈希环法的映射结果的分布的标准差大约有 10%10%。 当虚拟节点增加到1000个时,这个...
* @param nodes * ,服务器节点 */publicConsistentHash(HashFunction hashFunction,int numberOfReplicas,Collection<T>nodes){this.hashFunction=hashFunction;this.numberOfReplicas=numberOfReplicas;for(T node:nodes){this.addNode(node);}}/** * 添加物理节点,每个node 会产生numberOfReplicas个虚拟节点,这些虚...
{// the number of replicasreplicaNumint// the total loads of all replicastotalLoadint64// the hash function for keyshashFuncfunc(keystring)uint64// the map of virtual nodes to hostshostMapmap[string]*Host// the map of hashed virtual nodes to host namereplicaHostMapmap[uint64]string// the...