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<?php |
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/** |
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* @link http://www.tintsoft.com/ |
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* @copyright Copyright (c) 2012 TintSoft Technology Co. Ltd. |
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* @license http://www.tintsoft.com/license/ |
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*/ |
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namespace yuncms\base; |
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use yii\base\Component; |
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use yii\base\Exception; |
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/** |
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* Class Snowflake |
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* |
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* @author Tongle Xu <[email protected]> |
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* @since 3.0 |
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*/ |
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class Snowflake extends Component |
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{ |
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/** |
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* @var int 开始时间截 |
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*/ |
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public $epoch = 1414213562373; |
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/** |
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* @var int 工作机器ID(0~31) |
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*/ |
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public $workerId; |
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/** |
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* @var int 数据中心ID(0~31) |
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*/ |
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public $dataCenterId; |
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/** |
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* @var int 上次生成ID的时间截 |
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*/ |
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private $_lastTimestamp; |
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/** |
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* @var int 毫秒内序列(0~4095) |
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*/ |
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private $_sequence = 0; |
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const WORKER_BITS = 5; |
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const DATA_CENTER_BITS = 5; |
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const MAX_WORKER_ID = (-1 ^ (-1 << self::WORKER_BITS)); |
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const MAX_DATA_CENTER_ID = (-1 ^ (-1 << self::DATA_CENTER_BITS)); |
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const SEQUENCE_BITS = 12; |
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const WORKER_ID_SHIFT = self::SEQUENCE_BITS; |
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const DATA_CENTER_ID_SHIFT = self::SEQUENCE_BITS + self::WORKER_BITS; |
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const TIMESTAMP_LEFT_SHIFT = self::SEQUENCE_BITS + self::WORKER_BITS + self::DATA_CENTER_BITS; |
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const SEQUENCE_MASK = (-1 ^ (-1 << self::SEQUENCE_BITS)); |
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/** |
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* 初始化 |
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* @throws Exception |
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*/ |
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public function init() |
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{ |
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parent::init(); |
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if ($this->workerId > self::MAX_WORKER_ID || $this->workerId < 0) { |
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throw new Exception(sprintf("worker Id can't be greater than %d or less than 0",self::MAX_WORKER_ID)); |
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} |
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if ($this->dataCenterId > self::MAX_DATA_CENTER_ID || $this->dataCenterId < 0) { |
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throw new Exception(sprintf("dataCenterId can't be greater than %d or less than 0",self::MAX_DATA_CENTER_ID)); |
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} |
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} |
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/** |
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* 获得下一个ID (该方法是线程安全的) |
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* @return int |
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* @throws Exception |
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*/ |
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public function next() |
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{ |
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$timestamp = $this->milliTime(); |
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if ($timestamp < $this->_lastTimestamp) { |
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throw new Exception(sprintf("Clock moved backwards. Refusing to generate id for %d milliseconds", $this->_lastTimestamp - $timestamp)); |
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} |
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if ($this->_lastTimestamp == $timestamp) { |
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$this->_sequence = ($this->_sequence + 1) & self::SEQUENCE_MASK; |
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if ($this->_sequence == 0) { |
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$timestamp = $this->waitNextMilli($this->_lastTimestamp); |
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} |
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} else { |
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$this->_sequence = 0; |
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} |
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$this->_lastTimestamp = $timestamp; |
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return (($timestamp - $this->epoch) << self::TIMESTAMP_LEFT_SHIFT) |
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| ($this->dataCenterId << self::DATA_CENTER_ID_SHIFT) |
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| ($this->workerId << self::WORKER_ID_SHIFT) |
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| $this->_sequence; |
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} |
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/** |
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* 阻塞到下一个毫秒，直到获得新的时间戳 |
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* @param int $lastTimestamp 上次生成ID的时间截 |
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* @return int 当前时间戳 |
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*/ |
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protected function waitNextMilli($lastTimestamp) |
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{ |
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$timestamp = $this->milliTime(); |
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while ($timestamp <= $lastTimestamp) { |
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$timestamp = $this->milliTime(); |
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} |
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return $timestamp; |
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} |
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/** |
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* 返回以毫秒为单位的当前时间 |
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* @return int 当前时间(毫秒) |
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*/ |
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protected function milliTime() |
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{ |
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$microTime = microtime(); |
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$comps = explode(' ', $microTime); |
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// Note: Using a string here to prevent loss of precision |
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// in case of "overflow" (PHP converts it to a double) |
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return sprintf('%d%03d', $comps[1], $comps[0] * 1000); |
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} |
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} |
yuncms /
framework
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