數據緩存中的依賴關系 - jacson－IT工程師數位筆記本

文章出處

1、緩存文件依賴

1  $cache = \YII::$app->cache;
2         $dependency = new \yii\caching\FileDependency(['fileName'=>'hw.txt']);
3         $cache->add('file_key','hello world',3000,$dependency);
4         var_dump($cache->get('file_key'));

當hw.txt文件中的內容出現變化，則該緩存過期

2、表達式依賴：

1 $cache = \YII::$app->cache;
2         $dependency = new \yii\caching\ExpressionDependency(['expression'=>'\YII::$app->request->get("name")']);
3         $cache->add('expression_key','hello world',3000,$dependency);
4         var_dump($cache->get('expression_key'));

當 ['expression'=>'\YII::$app->request->get("name")'] 中獲得的name的值發生了變化，則緩存過期

3、DB依賴

1 $cache=\YII::$app->cache;
2         $dependency = new \yii\caching\DbDependency(
3             ['sql'=>'SELECT count(*) FROM yii.order']
4         );
5         $cache->add('db_key','hello_world',3000,$dependency);
6         var_dump($cache->get('db_key'));