<?php/** * 一致性hahs实现类 * */class FlexiHash{/** * var int * 虚拟节点 */private $_replicas = 200;/** * 使用hash方法 */private $_hasher = null;/** * 真实节点计数器 * */private $_targetCount = 0;/** * 位置对应节点，用户lookup中根据位置确定要访问的节点 */private $_positionToTarget = array();/** * 节点对应位置，用于删除节点 */private $_targetToPositions = array();/** * 是否已排序 */private $_positionToTargetSorted = false;/** * @ $hasher hash方法 * @ $replicas 虚拟节点的个数 * * 确定要使用的hash方法和虚拟的节点数，虚拟节点越多，分布越均匀，但程序的分布式运算越慢 */public function __construct(FlexiHash_Hasher $hasher=null, $replicas = null){// hash方法$this->_hasher = $hasher?$hasher: new FlexiHash_Crc32Hasher();// 虚拟节点的个数if (!empty($replicas)){$this->_replicas = $replicas;}}/** * 增加节点，根据虚拟节点数，把节点分布到更多的虚拟位置上 */public function addTarget($target){if (isset($this->_targetToPositions[$target])) {throw new FlexiHash_Exception("Target $target already exists.");}$this->_targetToPositions[$target] = array();for ($i = 0; $i < $this->_replicas; $i++) {// 根据规定的方法hash$position = $this->_hasher->hash($target.$i);// 虚拟节点对应的真实的节点$this->_positionToTarget[$position] = $target;// 真实节点包含的虚拟节点$this->_targetToPositions[$target][] = $position;}$this->_positionToTargetSorted = false;// 真实节点个数$this->_targetCount++;return $this;}/** * 添加多个节点 * */public function addTargets($targets){foreach ($targets as $target){$this->addTarget($target);}return $this;}/** * 移除某个节点 * */public function removeTarget($target){if (!isset($this->_targetToPositions[$target])){throw new FlexiHash_Exception("target $target does not exist\n");}foreach($this->_targetToPositions[$target] as $position){unset($this->_positionToTarget[$position]);}unset($this->_targetToPositions[$target]);$this->_targetCount--;return $this;}/** * 获取所有节点 * */public function getAllTargets(){return array_keys($this->_targetToPositions);}/** * 根据key查找hash到的真实节点 * */public function lookup($resource){$targets = $this->lookupList($resource, 1);if (empty($targets)){throw new FlexiHash_Exception("no targets exist");}return $targets[0];}/** * 查找资源存在的节点 * * 描述:根据要求的数量，返回与$resource哈希后数值相等或比其大并且是最小的数值对应的节点，若不存在或数量不够，则从虚拟节点排序后的前一个或多个 */public function lookupList($resource, $requestedCount){if (!$requestedCount) {throw new FlexiHash_Exception('Invalid count requested');}if (empty($this->_positionToTarget)) {return array();}// 直接节点只有一个的时候if ($this->_targetCount == 1 ){return array_unique(array_values($this->_positionToTarget));}// 获取当前key进行hash后的值$resourcePosition = $this->_hasher->hash($resource);$results = array();$collect = false;$this->_sortPositionTargets();// 查找与$resourcePosition 相等或比其大并且是最小的数foreach($this->_positionToTarget as $key => $value){if (!$collect && $key > $resourcePosition){$collect = true;}if ($collect && !in_array($value, $results)){$results[] = $value;}// 找到$requestedCount 或个数与真实节点数量相同if (count($results) == $requestedCount || count($results) == $this->_targetCount){return $results;}}// 如数量不够或者未查到，则从第一个开始，将$results中不存在前$requestedCount-count($results)，设置为需要的节点foreach ($this->_positionToTarget as $key => $value){if (!in_array($value, $results)){$results[] = $value;}if (count($results) == $requestedCount || count($results) == $this->_targetCount){return $results;}}return $results;}/** * 根据虚拟节点进行排序 */private function _sortPositionTargets(){if (!$this->_positionToTargetSorted){ksort($this->_positionToTarget, SORT_REGULAR);$this->_positionToTargetSorted = true;}}}// end class/** * hash方式 */interface FlexiHash_Hasher{public function hash($string);}class FlexiHash_Crc32Hasher implements FlexiHash_Hasher{public function hash($string){return sprintf("%u",crc32($string));}}class FlexiHash_Md5Hasher implements FlexiHash_Hasher{public function hash($string){return substr(md5($string), 0, 8);}}class FlexiHash_Exception extends Exception{}$runData['BEGIN_TIME'] = microtime(true);$key="lihuibin";for($i=0;$i<10;$i++) {$targetsArray = array("127.0.0.1:11211","127.0.0.1:11212","127.0.0.1:11213","127.0.0.1:11214",#"127.0.0.1:11218");$flexiHashObj = new FlexiHash(new FlexiHash_Crc32Hasher(),1);$result = $flexiHashObj->addTargets($targetsArray);$key=$key."$i";$targets = $flexiHashObj->lookup($key);var_dump($targets);#$key = md5(mt_rand());#$targets = $flexiHashObj->lookup($key);#var_dump($targets);}echo "一致性hash:";var_dump(number_format(microtime(true) - $runData['BEGIN_TIME'],6));exit;$runData['BEGIN_TIME'] = microtime(true); $m= new Memcache;$m->connect('127.0.0.1', 11211); for($i=0;$i<10000;$i++) {$key = md5(mt_rand());$b = $m->set($key, time(), 0, 10);}echo "单台机器:";var_dump(number_format(microtime(true) - $runData['BEGIN_TIME'],6));?> |
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