一文详解分布式缓存（附代码）

原創

2020-09-18 15:03

\n /// 1.采用虚拟节点方式 2.节点总数可以自定义 3.每个物理节点的虚拟节点数可以自定义\n ///

\n public class ConsistentHash\n {\n //哈希环的虚拟节点信息\n public class VirtualNode\n {\n public string VirtualNodeName { get; set; }\n public NodeInfo Node { get; set; }\n }\n\n //添加元素删除元素时候的锁，来保证线程安全，或者采用读写锁也可以\n private readonly object objLock = new object();\n\n //虚拟环节点的总数量，默认为100\n int ringNodeCount;\n //每个物理节点对应的虚拟节点数量\n int virtualNodeNumber;\n //哈希环，这里用数组来存储\n public VirtualNode[] nodes = null;\n public ConsistentHash(int _ringNodeCount = 100, int _virtualNodeNumber = 3)\n {\n if (_ringNodeCount <= 0 || _virtualNodeNumber <= 0)\n {\n throw new Exception(\"_ringNodeCount和_virtualNodeNumber 必须大于0\");\n }\n this.ringNodeCount = _ringNodeCount;\n this.virtualNodeNumber = _virtualNodeNumber;\n nodes = new VirtualNode[_ringNodeCount];\n }\n //根据一致性哈希key 获取node信息,查找操作请业务方自行处理超时问题，因为多线程环境下，环的node可能全被清除\n public NodeInfo GetNode(string key)\n {\n var ringStartIndex = Math.Abs(GetKeyHashCode(key) % ringNodeCount);\n var vNode = FindNodeFromIndex(ringStartIndex);\n return vNode == null ? null : vNode.Node;\n }\n //虚拟环添加一个物理节点\n public void AddNode(NodeInfo newNode)\n {\n var nodeName = newNode.NodeName;\n int virtualNodeIndex = 0;\n lock (objLock)\n {\n //把物理节点转化为虚拟节点\n while (virtualNodeIndex < virtualNodeNumber)\n {\n var vNodeName = $\"{nodeName}#{virtualNodeIndex}\";\n var findStartIndex = Math.Abs(GetKeyHashCode(vNodeName) % ringNodeCount);\n var emptyIndex = FindEmptyNodeFromIndex(findStartIndex);\n if (emptyIndex < 0)\n {\n // 已经超出设置的最大节点数\n break;\n }\n nodes[emptyIndex] = new VirtualNode() { VirtualNodeName = vNodeName, Node = newNode };\n virtualNodeIndex++;\n \n }\n }\n }\n //删除一个虚拟节点\n public void RemoveNode(NodeInfo node)\n {\n var nodeName = node.NodeName;\n int virtualNodeIndex = 0;\n List lstRemoveNodeName = new List();\n while (virtualNodeIndex < virtualNodeNumber)\n {\n lstRemoveNodeName.Add($\"{nodeName}#{virtualNodeIndex}\");\n virtualNodeIndex++;\n }\n //从索引为0的位置循环一遍，把所有的虚拟节点都删除\n int startFindIndex = 0;\n lock (objLock)\n {\n while (startFindIndex < nodes.Length)\n {\n if (nodes[startFindIndex] != null && lstRemoveNodeName.Contains(nodes[startFindIndex].VirtualNodeName))\n {\n nodes[startFindIndex] = null;\n }\n startFindIndex++;\n }\n }\n\n }\n\n\n //哈希环获取哈希值的方法，因为系统自带的gethashcode，重启服务就变了\n protected virtual int GetKeyHashCode(string key)\n {\n var sh = new SHA1Managed();\n byte[] data = sh.ComputeHash(Encoding.Unicode.GetBytes(key));\n return BitConverter.ToInt32(data, 0);\n\n }\n\n #region 私有方法\n //从虚拟环的某个位置查找第一个node\n private VirtualNode FindNodeFromIndex(int startIndex)\n {\n if (nodes == null || nodes.Length <= 0)\n {\n return null;\n }\n VirtualNode node = null;\n while (node == null)\n {\n startIndex = GetNextIndex(startIndex);\n node = nodes[startIndex];\n }\n return node;\n }\n //从虚拟环的某个位置开始查找空位置\n private int FindEmptyNodeFromIndex(int startIndex)\n {\n\n while (true)\n {\n if (nodes[startIndex] == null)\n {\n return startIndex;\n }\n var nextIndex = GetNextIndex(startIndex);\n //如果索引回到原地，说明找了一圈，虚拟环节点已经满了，不会添加\n if (nextIndex == startIndex)\n {\n return -1;\n }\n startIndex = nextIndex;\n }\n }\n //获取一个位置的下一个位置索引\n private int GetNextIndex(int preIndex)\n {\n int nextIndex = 0;\n //如果查找的位置到了环的末尾，则从0位置开始查找\n if (preIndex != nodes.Length - 1)\n {\n nextIndex = preIndex + 1;\n }\n return nextIndex;\n }\n #endregion\n }\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"heading","attrs":{"align":null,"level":4},"content":[{"type":"link","attrs":{"href":"#测试生成的节点","title":null}},{"type":"text","text":"测试生成的节点"}]},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":" ConsistentHash h = new ConsistentHash(200, 5);\n h.AddNode(new Server() { IP = \"192.168.1.1\" });\n h.AddNode(new Server() { IP = \"192.168.1.2\" });\n h.AddNode(new Server() { IP = \"192.168.1.3\" });\n h.AddNode(new Server() { IP = \"192.168.1.4\" });\n h.AddNode(new Server() { IP = \"192.168.1.5\" });\n\n for (int i = 0; i < h.nodes.Length; i++)\n {\n if (h.nodes[i] != null)\n {\n Console.WriteLine($\"{i}===={h.nodes[i].VirtualNodeName}\");\n }\n }\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"输出结果(还算比较均匀)："}]},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":"2====192.168.1.3#4\n10====192.168.1.1#0\n15====192.168.1.3#3\n24====192.168.1.2#2\n29====192.168.1.3#2\n33====192.168.1.4#4\n64====192.168.1.5#1\n73====192.168.1.4#3\n75====192.168.1.2#0\n77====192.168.1.1#3\n85====192.168.1.1#4\n88====192.168.1.5#4\n117====192.168.1.4#1\n118====192.168.1.2#4\n137====192.168.1.1#1\n152====192.168.1.2#1\n157====192.168.1.5#2\n158====192.168.1.2#3\n159====192.168.1.3#0\n162====192.168.1.5#0\n165====192.168.1.1#2\n166====192.168.1.3#1\n177====192.168.1.5#3\n185====192.168.1.4#0\n196====192.168.1.4#2\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"heading","attrs":{"align":null,"level":4},"content":[{"type":"link","attrs":{"href":"#测试一下性能","title":null}},{"type":"text","text":"测试一下性能"}]},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":" Stopwatch w = new Stopwatch();\n w.Start();\n for (int i = 0; i < 100000; i++)\n {\n var aaa = h.GetNode(\"test1\");\n }\n w.Stop();\n Console.WriteLine(w.ElapsedMilliseconds);\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"输出结果（调用10万次耗时657毫秒）："}]},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":"657\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"heading","attrs":{"align":null,"level":4},"content":[{"type":"link","attrs":{"href":"#写在最后","title":null}},{"type":"text","text":"写在最后"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"以上代码实有优化空间"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"numberedlist","attrs":{"start":null,"normalizeStart":1},"content":[{"type":"listitem","content":[{"type":"paragraph","attrs":{"indent":0,"number":1,"align":null,"origin":null},"content":[{"type":"text","text":"哈希函数"}]}]},{"type":"listitem","content":[{"type":"paragraph","attrs":{"indent":0,"number":2,"align":null,"origin":null},"content":[{"type":"text","text":"很多for循环的临时变量有兴趣优化的同学可以留言哦!!"}]}]}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"blockquote","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"strong"}],"text":"更多精彩文章"}]},{"type":"bulletedlist","content":[{"type":"listitem","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"link","attrs":{"href":"https://mp.weixin.qq.com/mp/appmsgalbum?action=getalbum&album_id=1342955119549267969&__biz=MzIwNTc3OTAxOA==#wechat_redirect","title":null},"content":[{"type":"text","text":"分布式大并发系列"}]}]}]},{"type":"listitem","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"link","attrs":{"href":"https://mp.weixin.qq.com/mp/appmsgalbum?action=getalbum&album_id=1342959003139227648&__biz=MzIwNTc3OTAxOA==#wechat_redirect","title":null},"content":[{"type":"text","text":"架构设计系列"}]}]}]},{"type":"listitem","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"link","attrs":{"href":"https://mp.weixin.qq.com/mp/appmsgalbum?action=getalbum&album_id=1342962375443529728&__biz=MzIwNTc3OTAxOA==#wechat_redirect","title":null},"content":[{"type":"text","text":"趣学算法和数据结构系列"}]}]}]},{"type":"listitem","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"link","attrs":{"href":"https://mp.weixin.qq.com/mp/appmsgalbum?action=getalbum&album_id=1342964237798391808&__biz=MzIwNTc3OTAxOA==#wechat_redirect","title":null},"content":[{"type":"text","text":"设计模式系列"}]}]}]}]}]},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/f8/f8af5984765a267892bf1a1272272625.png","alt":"image","title":null,"style":null,"href":null,"fromPaste":true,"pastePass":true}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}}]}