crc32 php abs,Memcache 分布式存储【一致性Hash】crc32

最新推荐文章于 2022-05-27 23:35:02 发布

转载最新推荐文章于 2022-05-27 23:35:02 发布 · 133 阅读

文章标签：

本文介绍了一个使用一致性哈希技术的MemcacheHash类，它通过CRC32哈希和虚拟节点管理，实现数据在多台物理服务器间的负载均衡。通过实例展示了单例模式下的一万次set/get操作对比单台Memcache的性能测试。

classmemcacheHash {private $_node = array();private $_nodeData = array();private $_keyNode = 0;private $_memcache = null;//每一个物理服务器生成虚拟节点个数 [注：节点数越多，cache分布的均匀性越好，同时set get操做时，也更耗资源，10台物理服务器，采用200较为合理]

private $_virtualNodeNum = 200;private function__construct() {/*放入配置文件*/

$config = 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');if (!$config) throw new Exception('Cache config NULL');foreach ($config as $key => $value) {for ($i = 0; $i < $this->_virtualNodeNum; $i++) {$this->_node[sprintf("%u", crc32($value . '_' . $i))] = $value . '_' . $i;

}

}ksort($this->_node);

}private function__clone(){}/**

* 单例，保证只有一个实例*/

static public functiongetInstance() {static $memcacheObj = null;if (!is_object($memcacheObj)) {$memcacheObj = newself();

}return $memcacheObj;

}/**

* 根据key作一致性hash后链接到一台物理memcache服务器

* @param string $key*/

private function _connectMemcache($key) {$this->_nodeData = array_keys($this->_node);$this->_keyNode = sprintf("%u", crc32($key));$nodeKey = $this->_findServerNode();//若是超出环，从头再用二分法查找一个最近的，而后环的头尾作判断，取最接近的节点

if ($this->_keyNode > end($this->_nodeData)) {$this->_keyNode -= end($this->_nodeData);$nodeKey2 = $this->_findServerNode();if (abs($nodeKey2 - $this->_keyNode) < abs($nodeKey - $this->_keyNode)) $nodeKey = $nodeKey2;

}list($config, $num) = explode('_', $this->_node[$nodeKey]);if (!$config) throw new Exception('Cache config Error');if (!isset($this->_memcache[$config])) {$this->_memcache[$config] = newMemcache;list($host, $port) = explode(':', $config);$this->_memcache[$config]->connect($host, $port);

}return $this->_memcache[$config];

}/**

* 采用二分法从虚拟memcache节点中查找最近的节点

* @param unknown_type $m

* @param unknown_type $b*/

private function _findServerNode($m = 0, $b = 0) {$total = count($this->_nodeData);if ($total != 0 && $b == 0) $b = $total - 1;if ($m < $b){$avg = intval(($m+$b) / 2);if ($this->_nodeData[$avg] == $this->_keyNode) return $this->_nodeData[$avg];elseif ($this->_keyNode < $this->_nodeData[$avg] && ($avg-1 >= 0)) return $this->_findServerNode($m, $avg-1);else return $this->_findServerNode($avg+1, $b);

}if (abs($this->_nodeData[$b] - $this->_keyNode) < abs($this->_nodeData[$m] - $this->_keyNode)) return $this->_nodeData[$b];else return $this->_nodeData[$m];

}public function set($key, $value, $expire = 0) {return $this->_connectMemcache($key)->set($key, json_encode($value), 0, $expire);

}//去重添加

public function add($key, $value, $expire = 0) {return $this->_connectMemcache($key)->add($key, json_encode($value), 0, $expire);

}public function get($key) {return json_decode($this->_connectMemcache($key)->get($key), true);

}public function delete($key) {return $this->_connectMemcache($key)->delete($key);

}

}$runData['BEGIN_TIME'] = microtime(true);//测试一万次set加get

for($i=0;$i<10000;$i++) {$key = md5(mt_rand());$b = memcacheHash::getInstance()->set($key, time(), 10);

}var_dump(number_format(microtime(true) - $runData['BEGIN_TIME'],6));//测试直接单台

$runData['BEGIN_TIME'] = microtime(true); $m= newMemcache;$m->connect('127.0.0.1', 11211);for($i=0;$i<10000;$i++) {$key = md5(mt_rand());$b = $m->set($key, time(), 0, 10);

}var_dump(number_format(microtime(true) - $runData['BEGIN_TIME'],6));