Laravel数据库读写分离配置

Laravel数据库读写分离配置

原文地址：http://blog.onlywan.cc/14847498744910.html

###配置范例

'mysql' => [
'driver'   => 'mysql',
'write'    => [
'host' => '192.168.1.180',
],
'read'     => [
['host' => '192.168.1.182'],
['host' => '192.168.1.179'],
],
...
]

或

'mysql' => [
'driver'   => 'mysql',
'write'    => [
'host' => '192.168.1.180',
],
'read'     => [
'host' => ［
'192.168.1.182',
'192.168.1.179'
],
],
...
]

扩展配置范例

'mysql' => [
'driver'   => 'mysql',
'write'    => [
'host'      => '192.168.1.180',
'username'  => 'write',
'password'   => 'write',
],
'read'     => [
[
'host' => '192.168.1.182',
'username'  => 'read1',
'password'   => 'read1',
],
[
'host' => '192.168.1.179',
'username'  => 'read2',
'password'   => 'read2',
],
],
...
]

或者

'mysql' => [
'driver'   => 'mysql',
'write'    => [
'host'      => '192.168.1.180',
'username'  => 'write',
'password'   => 'write',
],
'read'     => [
'host' => ［
'192.168.1.179',
'192.168.1.182',
],
'username'  => 'read',
'password'   => 'read',
],
...
]

公司数据库架构为一主多从，从库访问地址为唯一地址，该处方便负载均衡及扩展从库。所以最终线上采用的配置

'mysql' => [
'driver'   => 'mysql',
'write'    => [
'host'      => '192.168.1.180',
'username'  => 'write',
'password'   => 'write',
],
'read'     => [
'host' => '192.168.1.179'
'username'  => 'read',
'password'   => 'read',
],
...
]

###代码分析
授人以鱼不如授人以渔，之所以配置如此灵活的原因，以及如何查找到这些配置方式。主要通过查找代码，分析代码；相关代码都在下面粘出，这里就不做解释了，代码能说明一切；

路径：vendor/laravel/framework/src/Illuminate/Database/Connectors/ConnectionFactory.php

代码：

class ConnectionFactory
{
...

/**
* Get the read configuration for a read / write connection.
*
* @param  array  $config
* @return array
*/
protected function getReadConfig(array $config)
{
$readConfig = $this->getReadWriteConfig($config, 'read');

if (isset($readConfig['host']) && is_array($readConfig['host'])) {
$readConfig['host'] = count($readConfig['host']) > 1
? $readConfig['host'][array_rand($readConfig['host'])]
: $readConfig['host'][0];
}

return $this->mergeReadWriteConfig($config, $readConfig);
}

...

/**
* Get a read / write level configuration.
*
* @param  array   $config
* @param  string  $type
* @return array
*/
protected function getReadWriteConfig(array $config, $type)
{
if (isset($config[$type][0])) {
return $config[$type][array_rand($config[$type])];
}

return $config[$type];
}

...

/**
* Merge a configuration for a read / write connection.
*
* @param  array  $config
* @param  array  $merge
* @return array
*/
protected function mergeReadWriteConfig(array $config, array $merge)
{
return Arr::except(array_merge($config, $merge), ['read', 'write']);
}

...
}

class Arr
{
...

/**
* Get all of the given array except for a specified array of items.
*
* @param  array  $array
* @param  array|string  $keys
* @return array
*/
public static function except($array, $keys)
{
static::forget($array, $keys);

return $array;
}

...

/**
* Remove one or many array items from a given array using "dot" notation.
*
* @param  array  $array
* @param  array|string  $keys
* @return void
*/
public static function forget(&$array, $keys)
{
$original = &$array;

$keys = (array) $keys;

if (count($keys) === 0) {
return;
}

foreach ($keys as $key) {
$parts = explode('.', $key);

while (count($parts) > 1) {
$part = array_shift($parts);

if (isset($array[$part]) && is_array($array[$part])) {
$array = &$array[$part];
} else {
$parts = [];
}
}

unset($array[array_shift($parts)]);

// clean up after each pass
$array = &$original;
}
}

...
}