这篇文章主要介绍了yii实现多数据库主从读写分离的方法,通过针对yii数据库类的扩展实现多数据库主从读写的分离功能,是非常实用的技巧,需要的朋友可以参考下
本文实例讲述了yii实现多数据库主从读写分离的方法。分享给大家供大家参考。具体分析如下：
yii框架数据库多数据库、主从、读写分离 实现,功能描述:
1.实现主从数据库读写分离 主库：写 从库(可多个)：读
2.主数据库无法连接时 可设置从数据库是否 可写
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:
代码如下:
<?php
/**
* 主数据库 写 从数据库（可多个）读
* 实现主从数据库 读写分离 主服务器无法连接 从服务器可切换写功能
* 从务器无法连接 主服务器可切换读功
* by lmt
* */
class dbconnectionman extends cdbconnection {
public $timeout = 10; //连接超时时间
public $markdeadseconds = 600; //如果从数据库连接失败 600秒内不再连接
//用 cache 作为缓存全局标记
public $cacheid = 'cache';
/**
* @var array $slaves.slave database connection(read) config array.
* 配置符合 cdbconnection.
* @example
* 'components'=>array(
* 'db'=>array(
* 'connectionstring'=>'mysql://<master>',
* 'slaves'=>array(
* array('connectionstring'=>'mysql://<slave01>'),
* array('connectionstring'=>'mysql://<slave02>'),
* )
* )
* )
* */
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' => 'root',
'password' => 'root',
'charset' => 'utf8',
'tableprefix' => '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'=>'root',
'password'=>'root',
'charset' => 'utf8',
'tableprefix' => 'xcpt_', //表前缀
),
array( //slave2
'connectionstring'=>'mysql:host=localhost;dbname=db_xcpt',
'emulateprepare' => true,
'username'=>'root',
'password'=>'root',
'charset' => 'utf8',
'tableprefix' => 'xcpt_', //表前缀
),
),
),