第五周 - 命题作业

var crc32 = (function () {  function utf8encode(str) {    var utf8CharCodes = [];    for (var i = 0, len = str.length, c; i < len; ++i) {      c = str.charCodeAt(i);      if (c < 128) {        utf8CharCodes.push(c);      } else if (c < 2048) {        utf8CharCodes.push((c >> 6) | 192, (c & 63) | 128);      } else {        utf8CharCodes.push((c >> 12) | 224, ((c >> 6) & 63) | 128, (c & 63) | 128);      }    }    return utf8CharCodes;  }
  var cachedCrcTable = null;  function buildCRCTable() {    var table = [];    for (var i = 0, j, crc; i < 256; ++i) {      crc = i;      j = 8;      while (j--) {        if ((crc & 1) == 1) {          crc = (crc >>> 1) ^ 0xEDB88320;        } else {          crc >>>= 1;        }      }      table[i] = crc >>> 0;    }    return table;  }
  function getCrcTable() {    if (!cachedCrcTable) {      cachedCrcTable = buildCRCTable();    }    return cachedCrcTable;  }



  return function (str) {    var utf8CharCodes = utf8encode(str),      crc = -1,      crcTable = getCrcTable();    for (var i = 0, len = utf8CharCodes.length, y; i < len; ++i) {      y = (crc ^ utf8CharCodes[i]) & 0xFF;      crc = (crc >>> 8) ^ crcTable[y];    }    return (crc ^ -1) >>> 0;  };})();



function getPlaceholderCount(strSource) {  //统计字符串中包含{}或{xxXX}的个数  var thisCount = 0;  strSource.replace(/\{[xX]+\}|\{\}/g, function (m, i) {    //m为找到的{xx}元素、i为索引    thisCount++;  });  return thisCount;}



class consistenHashing {  constructor(nodes = [], replicas = 5) {    this.nodes = nodes    this.replicas = replicas    this.ring = {}    this.sortedKey = []    this.addNode(nodes)  }



  addNode(node) {    for (let i = 0; i < this.replicas; i++) {      let hashKey = Math.abs(crc32(`${node}_vnode_${i}`).toString())      this.ring[hashKey] = node      this.sortedKey.concat(hashKey)    }    this.sortedKey.sort()  }



  addNodes(nodes) {    if (nodes.length > 0) {      this.nodes.forEach(node => {        this.addNode(node)      })    }  }



  removeNodes(nodes = []) {    if (nodes.length > 0) {      nodes.forEach(node => {        for (let i = 0; i < this.replicas; i++) {          let hashKey = Math.abs(crc32(`${node}_vnode_${i}`).toString())          delete this.ring[hashKey]        }      })    }  }



  getNode(key) {    let hashKey = Math.abs(crc32(`${key}`).toString())    let i = 0;    for (; i < this.sortedKey.length; i++) {      if (hashKey < nodehash) {        return this.ring[nodehash]      } else {        continue      }      // constole.log(`${i} Keyhash:${keyhash} Nodehash:${nodehash}`)    }    if (i == this.sortedKey.length) return this.ring[this.sortedKey[0]]  }  }



defalutServices = [  '192.168.1.1:1',  '192.168.1.1:2',  '192.168.1.1:3',  '192.168.1.1:4',  '192.168.1.1:5',  '192.168.1.1:6',]



const ch = new consistenHashing(defalutServices)