class RedisCache {public $servers = array();  //真实服务器private $_servers = array();    //虚拟节点const SERVER_REPLICAS = 10000; //服务器副本数量，提高一致性哈希算法的数据分布均匀程度public function __construct( $servers ){$this->servers = $servers;//Redis虚拟节点哈希表foreach ($this->servers as $k => $server) {for ($i = 0; $i < self::SERVER_REPLICAS; $i++) {$hash = crc32($server['host'] . '#' .$server['port'] . '#'. $i);$this->_servers[$hash] = $k;}}ksort($this->_servers);// something else...}
}

class RedisCache {public $servers = array();  //真实服务器private $_servers = array();    //虚拟节点private $_serverKeys = array();private $_badServers = array(); // 故障服务器列表private $_count = 0;const SERVER_REPLICAS = 10000; //服务器副本数量，提高一致性哈希算法的数据分布均匀程度public function __construct( $servers ){$this->servers = $servers;$this->_count = count($this-> servers);//Redis虚拟节点哈希表foreach ($this ->servers as $k => $server) {for ($i = 0; $i < self::SERVER_REPLICAS; $i++) {$hash = crc32($server[ 'host'] . '#' .$server['port'] . '#'. $i);$this->_servers [$hash] = $k;}}ksort( $this->_servers );$this->_serverKeys = array_keys($this-> _servers);}/*** 使用一致性哈希分派服务器，附加故障检测及转移功能*/    private function getRedis($key){$hash = crc32($key);$slen = $this->_count * self:: SERVER_REPLICAS;// 快速定位虚拟节点$sid = $hash > $this->_serverKeys [$slen-1] ? 0 : $this->quickSearch($this->_serverKeys, $hash, 0, $slen);$conn = false;$i = 0;do {$n = $this->_servers [$this->_serverKeys[$sid]];!in_array($n, $this->_badServers ) && $conn = $this->getRedisConnect($n);$sid = ($sid + 1) % $slen;} while (!$conn && $i++ < $slen);return $conn ? $conn : new Redis();}/*** 二分法快速查找*/private function quickSearch($stack, $find, $start, $length) {if ($length == 1) {return $start;}else if ($length == 2) {return $find <= $stack[$start] ? $start : ($start +1);}$mid = intval($length / 2);if ($find <= $stack[$start + $mid - 1]) {return $this->quickSearch($stack, $find, $start, $mid);}else {return $this->quickSearch($stack, $find, $start+$mid, $length-$mid);}}private function getRedisConnect($n=0){static $REDIS = array();if (!$REDIS[$n]){$REDIS[$n] = new Redis();try{$ret = $REDIS[$n]->pconnect( $this->servers [$n]['host'], $this->servers [$n]['port']);if (!$ret) {unset($REDIS[$n]);$this->_badServers [] = $n;return false;}} catch(Exception $e){unset($REDIS[$n]);$this->_badServers [] = $n;return false;}}return $REDIS[$n];}public function getValue($key){try{$getValue = $this->getRedis($key)->get($key);} catch(Exception $e){$getValue = null;}return $getValue;}public function setValue($key,$value,$expire){if($expire == 0){try{$ret = $this->getRedis($key)->set($key, $value);} catch(Exception $e){$ret = false;}} else{try{$ret = $this->getRedis($key)->setex($key, $expire, $value);} catch(Exception $e){$ret = false;}}return $ret;}public function deleteValue($key){return $this->getRedis($key)->delete($key);}public function flushValues(){//TODOreturn true;}
}// Usage:
$redis_servers = array(array('host'       => '10.0.0.1','port'       => 6379,),array('host'       => '10.0.0.2','port'       => 6379,),array('host'       => '10.0.0.3','port'       => 6379,),array('host'       => '10.0.0.3','port'       => 6928,),
);$redisCache = new RedisCache($redis_servers);
$testKey = 'test_key';
$testValue = 'test_value_object';
$redisCache->setValue($testKey, $testValue, 3600);
$value = $redisCache->getValue($testKey);