php教程|php手册
Yii,多数据库,主从,读写,分离,方法
php教程-php手册
Yii框架数据库多数据库、主从、读写分离 实现,功能描述:
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1.实现主从数据库读写分离 主库：写 从库(可多个)：读
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2.主数据库无法连接时 可设置从数据库是否 可写
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3.所有从数据库无法连接时 可设置主数据库是否 可读
4.如果从数据库连接失败 可设置N秒内不再连接
利用yii扩展实现,代码如下:
array(* db=>array(* connectionString=>mysql://,* slaves=>array(*array(connectionString=>mysql://),*array(connectionString=>mysql://),* )* )* )* */public $slaves = array();/*** * 从数据库状态 false 则只用主数据库* @var bool $enableSlave* */public $enableSlave = true;/*** @var slavesWrite 紧急情况主数据库无法连接 切换从服务器（读写）.*/public $slavesWrite = false;/*** @var masterRead 紧急情况从主数据库无法连接 切换从住服务器（读写）.*/public $masterRead = false;/*** @var _slave*/private $_slave;/*** @var _disableWrite 从服务器（只读）.*/private $_disableWrite = true;/**** 重写 createCommand 方法,1.开启从库 2.存在从库 3.当前不处于一个事务中 4.从库读数据* @param string $sql* @return CDbCommand* */public function createCommand($sql = null) { if ($this->enableSlave && !emptyempty($this->slaves) && is_string($sql) && !$this->getCurrentTransaction() && self::isReadOperation($sql) && ($slave = $this->getSlave()) ) { return $slave->createCommand($sql); } else { if (!$this->masterRead) { if ($this->_disableWrite && !self::isReadOperation($sql)) {throw new CDbException("Master db server is not available now!Disallow write operation on slave server!"); } } return parent::createCommand($sql); }}/*** 获得从服务器连接资源* @return CDbConnection* */public function getSlave() { if (!isset($this->_slave)) { shuffle($this->slaves); foreach ($this->slaves as $slaveConfig) { if ($this->_isDeadServer($slaveConfig[connectionString])) {continue; } if (!isset($slaveConfig[class]))$slaveConfig[class] = CDbConnection; $slaveConfig[autoConnect] = false; try {if ($slave = Yii::createComponent($slaveConfig)) { Yii::app()->setComponent(dbslave, $slave); $slave->setAttribute(PDO::ATTR_TIMEOUT, $this->timeout); $slave->setAttribute(PDO::MYSQL_ATTR_USE_BUFFERED_QUERY, true); $slave->setActive(true); $this->_slave = $slave; break;} } catch (Exception $e) {$this->_markDeadServer($slaveConfig[connectionString]);Yii::log("Slave database connection failed!ntConnection string:{$slaveConfig[connectionString]}", warning);continue; } } if (!isset($this->_slave)) { $this->_slave = null; $this->enableSlave = false; } } return $this->_slave;}public function setActive($value) { if ($value != $this->getActive()) { if ($value) { try {if ($this->_isDeadServer($this->connectionString)) { throw new CDbException(Master db server is already dead!);}//PDO::ATTR_TIMEOUT must set before pdo instance create$this->setAttribute(PDO::ATTR_TIMEOUT, $this->timeout);$this->open(); } catch (Exception $e) {$this->_markDeadServer($this->connectionString);$slave = $this->getSlave();Yii::log($e->getMessage(), CLogger::LEVEL_ERROR, exception.CDbException);if ($slave) { $this->connectionString = $slave->connectionString; $this->username = $slave->username; $this->password = $slave->password; if ($this->slavesWrite) { $this->_disableWrite = false; } $this->open();} else { //Slave also unavailable if ($this->masterRead) { $this->connectionString = $this->connectionString; $this->username = $this->username; $this->password = $this->password; $this->open(); } else { throw new CDbException(Yii::t(yii, CDbConnection failed to open the DB connection.), (int) $e->getCode(), $e->errorInfo); }} } } else { $this->close(); } }}/*** 检测读操作 sql 语句* * 关键字： SELECT,DECRIBE,SHOW ...* 写操作:UPDATE,INSERT,DELETE ...* */public static function isReadOperation($sql) { $sql = substr(ltrim($sql), 0, 10); $sql = str_ireplace(array(SELECT, SHOW, DESCRIBE, PRAGMA), ^O^, $sql); //^O^,magic smile return strpos($sql, ^O^) === 0;}/*** 检测从服务器是否被标记 失败.*/private function _isDeadServer($c) { $cache = Yii::app()->{$this->cacheID}; if ($cache && $cache->get(DeadServer:: . $c) == 1) { return true; } return false;}/*** 标记失败的slaves.*/private function _markDeadServer($c) { $cache = Yii::app()->{$this->cacheID}; if ($cache) { $cache->set(DeadServer:: . $c, 1, $this->markDeadSeconds); }} }
main.php配置:components 数组中,代码如下:
代码如下:
db=>array( class=>application.extensions.DbConnectionMan,//扩展路径 connectionString => mysql:host=192.168.1.128;dbname=db_xcpt,//主数据库 写 emulatePrepare => true, username => oot, password => oot, charset => utf8, ablePrefix => xcpt_, //表前缀 enableSlave=>true,//从数据库启用 urgencyWrite=>true,//紧急情况 主数据库无法连接 启用从数据库 写功能masterRead=>true,//紧急情况 从数据库无法连接 启用主数据库 读功能 slaves=>array(//从数据库 array( //slave1 connectionString=>mysql:host=localhost;dbname=db_xcpt, emulatePrepare => true, username=> oot, password=> oot, charset => utf8, ablePrefix => xcpt_, //表前缀 ), array( //slave2 connectionString=>mysql:host=localhost;dbname=db_xcpt, emulatePrepare => true, username=> oot, password=> oot, charset => utf8, ablePrefix => xcpt_, //表前缀 ),), ),
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