Laravel数据库读写分离配置的方法

来源：jb51　　时间：2019/10/14 9:38:49　　对本文有异议

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;
 }
 }
 
 ...
}