<?php/** * 对服务器进行一致性hash分布算法 */class HashRing{ private $servers = array(); private $nodeList = array(); private $nodeHashList = array(); private $nodeTotalNum = 0; private $virtualNodeNum = 32; private $keyHash = ''; public function __construct($servers) { $this->servers = $servers; foreach ($servers as $server) { for ($i = 0; $i < $this->virtualNodeNum; $i++) { $this->nodeList[sprintf("%u", crc32($server.'-'.$i))] = array($server, $i); } } ksort($this->nodeList); $this->nodeHashList = array_keys($this->nodeList); } private function getNodeIndex($key) { $this->keyHash = sprintf("%u", crc32($key)); if ($this->keyHash > end($this->nodeHashList)) { $this->keyHash = $this->keyHash % end($this->nodeHashList); } if ($this->keyHash <= reset($this->nodeHashList)) { return 0; } $this->nodeTotalNum = count($this->nodeHashList); return $this->binaryChopIndex(0, $this->nodeTotalNum); } private function binaryChopIndex($l=0, $r=0) { if ($l < $r) { $avg = intval(($l+$r) / 2); if ($this->nodeHashList[$avg] == $this->keyHash) { return $avg; } elseif ($this->keyHash < $this->nodeHashList[$avg] && ($avg > 0)) { return $this->binaryChopIndex($l, $avg-1); } else { return $this->binaryChopIndex($avg+1, $r); } } else { return $l; } } public function getServersByKey($key, $num=1) { $index = $this->getNodeIndex($key); $server = $this->nodeList[$this->nodeHashList[$index]]; if ($num == 1) { return $server[0]; } if ($num >= count($this->servers)) { $num = count($this->servers); } $result = array($server[0]); for ($i=$index+1; true; $i++) { if ($i >= $this->nodeTotalNum) { $i = 0; } $nextServer = $this->nodeList[$this->nodeHashList[$i]]; if (!in_array($nextServer[0], $result)) { $result[] = $nextServer[0]; } if (count($result) == $num) { break; } } return $result; }}//示例$servers = array( '127.0.0.1:11211', '127.0.0.1:11212', '127.0.0.1:11213', '127.0.0.1:11214', '127.0.0.1:11215');$obj = new HashRing($servers);$servers = $obj->getServersByKey('testkey', 2);print_r($servers);echo "/n"; 
