Code Spelunking: Teach Yourself How Rails Works

@jnraine Code spelunking teach yourself how Rails works

Jordan Raine @jnraine Vancouver, Canada

I’m STUCK

<?php require( dirname(__FILE__) . '/db-config.php' ); $connection = connect_to_database($db_user, $db_password);
$post = $connection->query("SELECT * FROM posts WHERE slug = '%".$_SLUG."%';"); ?> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> <?php require( dirname(__FILE__) . '/head.php' ); ?> <body> <h1><?php $post["title"]; ?></h1> <div class="content"> <?php $post["body"]; ?> </div> </body> <?php require( dirname(__FILE__) . '/footer.php' ); ?> </html>

I’m STUCK

How you spend your time

Measuring Program Comprehension A Large-Scale Field Study with Professionals Xin
Xia , Lingfeng Bao, David Lo , Zhenchang Xing, Ahmed E. Hassan, and Shanping Li Published 30 July 2017 ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ ̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉̉ *

78 developers 2 companies 3,148 working hours

Comprehension Other Editing Navigation

Comprehension & Navigation Other Editing

Average Percentage of Time Spent by Developers 0% 25% 50%
75% 100% Comprehension  & Navigation Editing Other 82% 5% 13%

No comments or insufficient comments Meaningless classes/methods/variable names Large number
of LOC in a class/method Inconsistent coding styles Lack of documentation, ambiguous requirements Unfamiliarity with business logic Query reﬁnement, browsing a number of search results Navigating inheritance hierarchies Many third-party libraries Poor IDE support for code navigation Switching between editor/IDE and browser

1. Write code that is easier to use and change
2. Improve our ability to ﬁnd answers future you you

The more experience someone had, the less time they spent
on program comprehension.

How you spend your time Obstacles

Rails is big

$ rails new blog ! " 77 gems >250k LOC
12 core gems 75k LOC How this was calculated: https://gist.github.com/jnraine/b0f7bb5a4a5b10ff07274389e2de83ad

Rails is complex

ActionController::Base.ancestors.count # => 65 ActiveRecord::Base.ancestors.count # => 67

Post.new.save super super super

Rails is magic

define_method "#{callback}_action" do |*names, &blk| _insert_callbacks(names, blk) do |name, options|
set_callback(:process_action, callback, name, options) end end

%w{ Symbol Slash Dot }.each do |t| class_eval <<-eoruby, __FILE__,
__LINE__ + 1 class #{t} < Terminal; def type; :#{t.upcase}; end end eoruby end

Rails isn’t your codebase

How you spend your time Obstacles Code Spelunking

1. Ask a question 2. Start with what you know
3. Only read relevant code

What’s the difference between try and try!?

What’s the difference between try and try!? $ rails c
Loading development environment (Rails 6.0.0) >> "something".length => 9 >> nil.length NoMethodError: undefined method `length' for nil:NilClass

What’s the difference between try and try!? >> "something".try(:length) =>
9 >> nil.try(:length) => nil

try(:length) try!(:length) "something" 9 9 nil nil nil What’s the
difference between try and try!? >> "something".try!(:length) => 9 >> nil.try!(:length) => nil

difference between try and try!? >> "something".try!(:length)

Method Introspection

difference between try and try!? >> "something".try!(:length)

# dog.rb class Dog def name "Foxley" end def good_boy?
true end end

>> Dog.new.methods

>> Dog.new.methods =>[:good_boy?, :name, :to_json, :deep_dup, :acts_like?, :html_safe?, :w ith_options,
:duplicable?, :blank?, :present?, :presence, :to_yaml, :as _json, :instance_values, :instance_variable_names, :in?, :to_param, :pr esence_in, :to_query, :pretty_print_cycle, :pretty_print_instance_varia bles, :pretty_print, :pretty_print_inspect, :try, :try!, :require_or_lo ad, :load_dependency, :unloadable, :instance_variable_defined?, :remove _instance_variable, :instance_of?, :kind_of?, :is_a?, :tap, :instance_v ariable_get, :instance_variable_set, :protected_methods, :instance_vari ables, :private_methods, :method, :public_method, :public_send, :single ton_method, :define_singleton_method, :class_eval, :pretty_inspect, :ex tend, :to_enum, :enum_for, :<=>, :===, :=~, :! ~, :gem, :eql?, :respond_to?, :byebug, :remote_byebug, :debugger, :free ze, :inspect, :object_id, :send, :to_s, :display, :class, :nil?, :hash, :dup, :singleton_class, :clone, :then, :itself, :yield_self, :untaint, :taint, :tainted?, :trust, :untrust, :untrusted?, :singleton_methods, : frozen?, :methods, :public_methods, :equal?, :!, :==, :instance_exec, :

>> Dog.new.methods - Object.new.methods

>> Dog.new.methods - Object.new.methods => [:good_boy?, :name]

>> Dog.new.methods.grep /instance/

>> Dog.new.methods.grep /instance/ => [:instance_values, :instance_variable_names, :pretty_print_instance_variables, :instance_variable_defined?, :remove_instance_variable, :instance_of?,
:instance_variable_get, :instance_variable_set, :instance_variables, :instance_exec, :instance_eval]

>> dog = Dog.new => #<Dog:0x00007fedbe85ba48> >> dog.method(:name) => #<Method:
Dog#name> >> dog.method(:name).source_location => ["/spelunking/app/models/dog.rb", 2]

Dog#name> >> dog.method(:name).source_location => ["/spelunking/app/models/dog.rb", 2] >> dog.method(:name).source

Dog#name> >> dog.method(:name).source_location => ["/spelunking/app/models/dog.rb", 2] >> dog.method(:name).source ! gem “method_source”

Dog#name> >> dog.method(:name).source_location => ["/spelunking/app/models/dog.rb", 2] >> dog.method(:name).source => " def name\n \”Foxley\"\n end\n"

Dog#name> >> dog.method(:name).source_location => ["/spelunking/app/models/dog.rb", 2] >> dog.method(:name).source => " def name\n \”Foxley\"\n end\n" >> dog.method(:name).source.display def name “Foxley" end => nil

>> Post.create(title: "Code spelunking") >> Post.method(:create).source.display def create(attributes = nil,
&block) if attributes.is_a?(Array) attributes.collect { |attr| create(attr, &block) } else object = new(attributes, &block) object.save object end end => nil

>> Post.new.save

>> Post.new.save Post.new.save super super super

>> Post.new.save >> Post.new.method(:save)

>> Post.new.save >> Post.new.method(:save) => #<Method: ActiveRecord::Suppressor#save> >> ✅

>> Post.new.save >> Post.new.method(:save) => #<Method: ActiveRecord::Suppressor#save> >> Post.new.method(:save).super_method ✅

>> Post.new.save >> Post.new.method(:save) => #<Method: ActiveRecord::Suppressor#save> >> Post.new.method(:save).super_method =>
#<Method: ActiveRecord::Transactions#save> >> ✅ ✅

#<Method: ActiveRecord::Transactions#save> >> Post.new.method(:save).super_method.super_method ✅ ✅

#<Method: ActiveRecord::Transactions#save> >> Post.new.method(:save).super_method.super_method => #<Method: ActiveRecord::Validations#save> >> ✅ ✅ ✅

#<Method: ActiveRecord::Transactions#save> >> Post.new.method(:save).super_method.super_method => #<Method: ActiveRecord::Validations#save> >> Post.new.method(:save).super_method.super_method.super_method ✅ ✅ ✅

#<Method: ActiveRecord::Transactions#save> >> Post.new.method(:save).super_method.super_method => #<Method: ActiveRecord::Validations#save> >> Post.new.method(:save).super_method.super_method.super_method => #<Method: ActiveRecord::Persistence#save> >> ✅ ✅ ✅ ✅

#<Method: ActiveRecord::Transactions#save> >> Post.new.method(:save).super_method.super_method => #<Method: ActiveRecord::Validations#save> >> Post.new.method(:save).super_method.super_method.super_method => #<Method: ActiveRecord::Persistence#save> >> Post.new.method(:save).super_method.super_method.super_method.super_method ✅ ✅ ✅ ✅

#<Method: ActiveRecord::Transactions#save> >> Post.new.method(:save).super_method.super_method => #<Method: ActiveRecord::Validations#save> >> Post.new.method(:save).super_method.super_method.super_method => #<Method: ActiveRecord::Persistence#save> >> Post.new.method(:save).super_method.super_method.super_method.super_method => nil >> ✅ ✅ ✅ ✅

>> "something".method(:empty?).source MethodSource::SourceNotFoundError: Could not locate source for empty?! >>

>> "something".method(:empty?).source MethodSource::SourceNotFoundError: Could not locate source for empty?! >>
"something".method(:empty?).source_location => nil

difference between try and try!? >>

What’s the difference between try and try!? >> "something".method(:try).source.display

What’s the difference between try and try!? >> "something".method(:try).source.display def
try(method_name = nil, *args, &b) if method_name.nil? && block_given? if b.arity == 0 instance_eval(&b) else yield self end elsif respond_to?(method_name) public_send(method_name, *args, &b) end end => nil >>

def try(method_name = nil, *args, &b) if method_name.nil? && block_given?
if b.arity == 0 instance_eval(&b) else yield self end elsif respond_to?(method_name) public_send(method_name, *args, &b) end end

if b.arity == 0 instance_eval(&b) else yield self end elsif respond_to?(method_name) public_send(method_name, *args, &b) end end Only read relevant code

if b.arity == 0 instance_eval(&b) else yield self end elsif respond_to?(method_name) public_send(method_name, *args, &b) end end false

# ... elsif respond_to?(method_name) public_send(method_name, *args, &b) end end

try(method_name = nil, *args, &b) if method_name.nil? && block_given? if b.arity == 0 instance_eval(&b) else yield self end elsif respond_to?(method_name) public_send(method_name, *args, &b) end end => nil >>

try(method_name = nil, *args, &b) if method_name.nil? && block_given? if b.arity == 0 instance_eval(&b) else yield self end elsif respond_to?(method_name) public_send(method_name, *args, &b) end end => nil >> nil.method(:try).source.display def try(method_name = nil, *args) nil end => nil

def try(method_name = nil, *args) nil end

What’s the difference between try and try!? >>

What’s the difference between try and try!? >> “something".method(:try!).source.display

What’s the difference between try and try!? >> "something".method(:try!).source.display def
try!(method_name = nil, *args, &b) if method_name.nil? && block_given? if b.arity == 0 instance_eval(&b) else yield self end else public_send(method_name, *args, &b) end end => nil >>

def try!(method_name = nil, *args, &b) if method_name.nil? && block_given?
if b.arity == 0 instance_eval(&b) else yield self end else public_send(method_name, *args, &b) end end

if b.arity == 0 instance_eval(&b) else yield self end else public_send(method_name, *args, &b) end end false

if b.arity == 0 instance_eval(&b) else yield self end else public_send(method_name, *args, &b) end end

# ... else public_send(method_name, *args, &b) end end

# ... elsif respond_to?(method_name) public_send(method_name, *args, &b) end end def try!(method_name = nil, *args, &b) if method_name.nil? && block_given? # ... else public_send(method_name, *args, &b) end end

What’s the difference between try and try!? >>

What’s the difference between try and try!? >> "something".try(:lengthhhhh) =>
nil >>

What’s the difference between try and try!? >> "something".try(:lengthhhhh) =>
nil >> "something".try!(:lengthhhhh) NoMethodError: undefined method `lengthhhhh' for "something":String

try!(method_name = nil, *args, &b) if method_name.nil? && block_given? if b.arity == 0 instance_eval(&b) else yield self end else public_send(method_name, *args, &b) end end => nil >>

try!(method_name = nil, *args, &b) if method_name.nil? && block_given? if b.arity == 0 instance_eval(&b) else yield self end else public_send(method_name, *args, &b) end end => nil >> nil.method(:try!).source.display def try!(method_name = nil, *args) nil end => nil

def try!(method_name = nil, *args) nil end

def try(method_name = nil, *args) nil end def try!(method_name =
nil, *args) nil end

For nil, they’re the same. For everything else, try! is
more strict. What’s the difference between try and try!? >> "something".try(:lengthhhhh) => nil >> "something".try!(:lengthhhhh) NoMethodError: undefined method `lengthhhhh' for "something":String >> nil.try(:lengthhhh) => nil >> nil.try!(:lengthhhh)

For nil, they’re the same. For everything else, try! is
more strict. What’s the difference between try and try!? >> "something".try(:lengthhhhh) => nil >> "something".try!(:lengthhhhh) NoMethodError: undefined method `lengthhhhh' for "something":String >> nil.try(:lengthhhh) => nil

1. Ask a question What’s the difference between try and
try!? 2. Start with what you know Look at try and try! code 3. Only read relevant code Skim 20 lines, read 6 lines

How you spend your time Obstacles Code Spelunking real work

We need a way to keep track of which request
enqueued a job. Can you ﬁgure out a way to add that?

class ApplicationController < ActionController::Base before_action do Current.request_id = request.id end
end

class ApplicationController < ActionController::Base before_action do Current.request_id = request.id end
end class ReportsController < ApplicationController def create ReportJob.perform_later # ... end end

class ApplicationJob < ActiveJob::Base attr_accessor :request_id end

class ApplicationJob < ActiveJob::Base attr_accessor :request_id end class ReportJob <
ApplicationJob queue_as :default def perform(*args) # ... puts "request_id: #{request_id.inspect}" end end

$ rails c Loading development environment (Rails 6.0.0) >>

$ rails c Loading development environment (Rails 6.0.0) >> Current.request_id
= "abcdef" => "abcdef" >>

= "abcdef" => "abcdef" >> ReportJob.perform_later >>

= "abcdef" => "abcdef" >> ReportJob.perform_later >> m, `$b .ss, $$: .,d$ `$$P,d$P' .,md$P"' ,$$$$$bmmd$$$P^' .d$$$$$$$$$$P' $$^' `"^$$$' ____ _ _ _ _ $: ,$$: / ___|(_) __| | ___| | _(_) __ _ `b :$$ \___ \| |/ _` |/ _ \ |/ / |/ _` | $$: ___) | | (_| | __/ <| | (_| | $$ |____/|_|\__,_|\___|_|\_\_|\__, | .d$$ |_|

= "abcdef" => "abcdef" >> ReportJob.perform_later >> m, `$b .ss, $$: .,d$ `$$P,d$P' .,md$P"' ,$$$$$bmmd$$$P^' .d$$$$$$$$$$P' $$^' `"^$$$' ____ _ _ _ _ $: ,$$: / ___|(_) __| | ___| | _(_) __ _ `b :$$ \___ \| |/ _` |/ _ \ |/ / |/ _` | $$: ___) | | (_| | __/ <| | (_| | $$ |____/|_|\__,_|\___|_|\_\_|\__, | .d$$ |_| ReportJob JID-123 INFO: start request_id: nil ReportJob JID-123 INFO: done

How do we add request_id to every job?

How do we add request_id to every job? $ rails
c Loading development environment (Rails 6.0.0) >>

c Loading development environment (Rails 6.0.0) >> ReportJob.method(:perform_later).source.display

c Loading development environment (Rails 6.0.0) >> ReportJob.method(:perform_later).source.display def perform_later(*args) job_or_instantiate(*args).enqueue end => nil >>

How do we add request_id to every job? >>

How do we add request_id to every job? >> ReportJob.job_or_instantiate

How do we add request_id to every job? >> ReportJob.job_or_instantiate.method(:enqueue).source.display

NoMethodError: private method `job_or_instantiate' called for ReportJob:Class from (pry):5:in `__pry__’ >>

NoMethodError: private method `job_or_instantiate' called for ReportJob:Class from (pry):5:in `__pry__’ >> ReportJob.send(:job_or_instantiate)

NoMethodError: private method `job_or_instantiate' called for ReportJob:Class from (pry):5:in `__pry__’ >> ReportJob.send(:job_or_instantiate).method(:enqueue).source.display

NoMethodError: private method `job_or_instantiate' called for ReportJob:Class from (pry):5:in `__pry__’ >> ReportJob.send(:job_or_instantiate).method(:enqueue).source.display def enqueue(options = {}) self.scheduled_at = options[:wait].seconds.from_now.to_f if options[:wait] self.scheduled_at = options[:wait_until].to_f if options[:wait_until] self.queue_name = self.class.queue_name_from_part(options[:queue]) if options[:queue] self.priority = options[:priority].to_i if options[:priority] successfully_enqueued = false run_callbacks :enqueue do if scheduled_at self.class.queue_adapter.enqueue_at self, scheduled_at else self.class.queue_adapter.enqueue self end successfully_enqueued = true end if successfully_enqueued self else if self.class.return_false_on_aborted_enqueue false else ActiveSupport::Deprecation.warn( "Rails 6.0 will return false when the enqueuing is aborted. Make sure your code doesn't depend on it" \ " returning the instance of the job and set `config.active_job.return_false_on_aborted_enqueue = true`" \ " to remove the deprecations." ) self end end end => nil

def enqueue(options = {}) self.scheduled_at = options[:wait].seconds.from_now.to_f if options[:wait] self.scheduled_at
= options[:wait_until].to_f if options[:wait_until] self.queue_name = self.class.queue_name_from_part(options[:queue]) if options[:queue] self.priority = options[:priority].to_i if options[:priority] successfully_enqueued = false run_callbacks :enqueue do if scheduled_at self.class.queue_adapter.enqueue_at self, scheduled_at else self.class.queue_adapter.enqueue self end successfully_enqueued = true end if successfully_enqueued self else if self.class.return_false_on_aborted_enqueue false else ActiveSupport::Deprecation.warn( "Rails 6.0 will return false when the enqueuing is aborted. Make sure your code doesn't depend on it" \ " returning the instance of the job and set `config.active_job.return_false_on_aborted_enqueue = true`" \ " to remove the deprecations." ) self end end end

= options[:wait_until].to_f if options[:wait_until] self.queue_name = self.class.queue_name_from_part(options[:queue]) if options[:queue] self.priority = options[:priority].to_i if options[:priority] successfully_enqueued = false run_callbacks :enqueue do if scheduled_at self.class.queue_adapter.enqueue_at self, scheduled_at else self.class.queue_adapter.enqueue self end successfully_enqueued = true end if successfully_enqueued self else if self.class.return_false_on_aborted_enqueue false else ActiveSupport::Deprecation.warn( "Rails 6.0 will return false when the enqueuing is aborted. Make sure your code doesn't depend on it" \ " returning the instance of the job and set `config.active_job.return_false_on_aborted_enqueue = true`" \ " to remove the deprecations." ) self end end end 1 2 3

= options[:wait_until].to_f if options[:wait_until] self.queue_name = self.class.queue_name_from_part(options[:queue]) if options[:queue] self.priority = options[:priority].to_i if options[:priority] successfully_enqueued = false run_callbacks :enqueue do if scheduled_at self.class.queue_adapter.enqueue_at self, scheduled_at else self.class.queue_adapter.enqueue self end successfully_enqueued = true end if successfully_enqueued self else if self.class.return_false_on_aborted_enqueue false else ActiveSupport::Deprecation.warn( "Rails 6.0 will return false when the enqueuing is aborted. Make sure your code doesn't depend on it" \ " returning the instance of the job and set `config.active_job.return_false_on_aborted_enqueue = true`" \ " to remove the deprecations." ) self end end end 1 2 3 1 self.scheduled_at = options[:wait].seconds.from_now.to_f if options[:wait] self.scheduled_at = options[:wait_until].to_f if options[:wait_until] self.queue_name = self.class.queue_name_from_part(options[:queue]) if options[:queue] self.priority = options[:priority].to_i if options[:priority] successfully_enqueued = false 1. Variable assignment

= options[:wait_until].to_f if options[:wait_until] self.queue_name = self.class.queue_name_from_part(options[:queue]) if options[:queue] self.priority = options[:priority].to_i if options[:priority] successfully_enqueued = false run_callbacks :enqueue do if scheduled_at self.class.queue_adapter.enqueue_at self, scheduled_at else self.class.queue_adapter.enqueue self end successfully_enqueued = true end if successfully_enqueued self else if self.class.return_false_on_aborted_enqueue false else ActiveSupport::Deprecation.warn( "Rails 6.0 will return false when the enqueuing is aborted. Make sure your code doesn't depend on it" \ " returning the instance of the job and set `config.active_job.return_false_on_aborted_enqueue = true`" \ " to remove the deprecations." ) self end end end 2 3 1

def enqueue(options = {}) # ... run_callbacks :enqueue do if
scheduled_at self.class.queue_adapter.enqueue_at self, scheduled_at else self.class.queue_adapter.enqueue self end successfully_enqueued = true end if successfully_enqueued self else if self.class.return_false_on_aborted_enqueue false else ActiveSupport::Deprecation.warn( "Rails 6.0 will return false when the enqueuing is aborted. Make sure your code doesn't depend on it" \ " returning the instance of the job and set `config.active_job.return_false_on_aborted_enqueue = true`" \ " to remove the deprecations." ) self end end end 1 2 3

scheduled_at self.class.queue_adapter.enqueue_at self, scheduled_at else self.class.queue_adapter.enqueue self end successfully_enqueued = true end if successfully_enqueued self else if self.class.return_false_on_aborted_enqueue false else ActiveSupport::Deprecation.warn( "Rails 6.0 will return false when the enqueuing is aborted. Make sure your code doesn't depend on it" \ " returning the instance of the job and set `config.active_job.return_false_on_aborted_enqueue = true`" \ " to remove the deprecations." ) self end end end 2 3

scheduled_at self.class.queue_adapter.enqueue_at self, scheduled_at else self.class.queue_adapter.enqueue self end successfully_enqueued = true end if successfully_enqueued self else if self.class.return_false_on_aborted_enqueue false else ActiveSupport::Deprecation.warn( "Rails 6.0 will return false when the enqueuing is aborted. Make sure your code doesn't depend on it" \ " returning the instance of the job and set `config.active_job.return_false_on_aborted_enqueue = true`" \ " to remove the deprecations." ) self end end end 2 3 2 2. Method with a block run_callbacks :enqueue do if scheduled_at self.class.queue_adapter.enqueue_at self, scheduled_at else self.class.queue_adapter.enqueue self end successfully_enqueued = true end

3. Conditional if successfully_enqueued self else if self.class.return_false_on_aborted_enqueue false else
ActiveSupport::Deprecation.warn( "Rails 6.0 will return false when the enqueuing is aborted. Make sure your code " returning the instance of the job and set `config.active_job.return_false_on_ " to remove the deprecations." ) self end end

if successfully_enqueued self else if self.class.return_false_on_aborted_enqueue false else ActiveSupport::Deprecation.warn( "Rails
6.0 will return false when the enqueuing is aborted. Make sure your code " returning the instance of the job and set `config.active_job.return_false_on_ " to remove the deprecations." ) self end end 3. Conditional

scheduled_at self.class.queue_adapter.enqueue_at self, scheduled_at else self.class.queue_adapter.enqueue self end successfully_enqueued = true end # ... end 2 3

scheduled_at self.class.queue_adapter.enqueue_at self, scheduled_at else self.class.queue_adapter.enqueue self end successfully_enqueued = true end # ... end 2

scheduled_at # ... else self.class.queue_adapter.enqueue self end successfully_enqueued = true end # ... end 2

How do we add request_id to every job? >> ReportJob.queue_adapter

How do we add request_id to every job? >> ReportJob.queue_adapter.method(:enqueue).source.display

How do we add request_id to every job? >> ReportJob.queue_adapter.method(:enqueue).source.display
def enqueue(job) #:nodoc: # Sidekiq::Client does not support symbols as keys job.provider_job_id = Sidekiq::Client.push \ "class" => JobWrapper, "wrapped" => job.class.to_s, "queue" => job.queue_name, "args" => [ job.serialize ] end => nil

How do we add request_id to every job? >> ReportJob.new

How do we add request_id to every job? >> ReportJob.new.method(:serialize).source.display

def serialize { "job_class" => self.class.name, "job_id" => job_id, "provider_job_id" => provider_job_id, "queue_name" => queue_name, "priority" => priority, "arguments" => serialize_arguments_if_needed(arguments), "executions" => executions, "exception_executions" => exception_executions, "locale" => I18n.locale.to_s, "timezone" => Time.zone.try(:name), "enqueued_at" => Time.now.utc.iso8601 } end => nil >>

def serialize { "job_class" => self.class.name, "job_id" => job_id, "provider_job_id" => provider_job_id, "queue_name" => queue_name, "priority" => priority, "arguments" => serialize_arguments_if_needed(arguments), "executions" => executions, "exception_executions" => exception_executions, "locale" => I18n.locale.to_s, "timezone" => Time.zone.try(:name), "enqueued_at" => Time.now.utc.iso8601 } end => nil >> “request_id” => Current.request_id

class ApplicationJob < ActiveJob::Base # ... end

class ApplicationJob < ActiveJob::Base # ... def serialize end end

class ApplicationJob < ActiveJob::Base # ... def serialize super end
end

class ApplicationJob < ActiveJob::Base # ... def serialize super.merge("request_id" =>
Current.request_id) end end

How do we add request_id to every job? >> Current.request_id
= "abcdef" => "abcdef" >>

= "abcdef" => "abcdef" >> ReportJob.new

= "abcdef" => "abcdef" >> ReportJob.new.serialize

= "abcdef" => "abcdef" >> ReportJob.new.serialize["request_id"]

= "abcdef" => "abcdef" >> ReportJob.new.serialize["request_id"] => "abcdef" >>

>> How do we add request_id to every job?

>> Current.request_id = "abcdef" => "abcdef" How do we add
request_id to every job?

>> Current.request_id = "abcdef" => "abcdef" >> ReportJob.perform_later >> How
do we add request_id to every job?

>> Current.request_id = "abcdef" => "abcdef" >> ReportJob.perform_later >> m,
`$b .ss, $$: .,d$ `$$P,d$P' .,md$P"' ,$$$$$bmmd$$$P^' .d$$$$$$$$$$P' $$^' `"^$$$' ____ _ _ _ _ $: ,$$: / ___|(_) __| | ___| | _(_) __ _ `b :$$ \___ \| |/ _` |/ _ \ |/ / |/ _` | $$: ___) | | (_| | __/ <| | (_| | $$ |____/|_|\__,_|\___|_|\_\_|\__, | .d$$ |_| How do we add request_id to every job?

`$b .ss, $$: .,d$ `$$P,d$P' .,md$P"' ,$$$$$bmmd$$$P^' .d$$$$$$$$$$P' $$^' `"^$$$' ____ _ _ _ _ $: ,$$: / ___|(_) __| | ___| | _(_) __ _ `b :$$ \___ \| |/ _` |/ _ \ |/ / |/ _` | $$: ___) | | (_| | __/ <| | (_| | $$ |____/|_|\__,_|\___|_|\_\_|\__, | .d$$ |_| ReportJob JID-123 INFO: start request_id: nil ReportJob JID-123 INFO: done How do we add request_id to every job?

ReportJob.perform_later .job_or_instantiate #enqueue queue_adapter.enqueue job.serialize Sidekiq::Client.push

ActiveJob #enqueue #perform_later #serialize #perform ?

>> exit $ How do we add request_id to every
job?

>> exit $ bundle open How do we add request_id
to every job?

>> exit $ bundle open activejob How do we add

>> exit $ bundle open activejob To open a bundled
gem, set $EDITOR or $BUNDLER_EDITOR $ How do we add request_id to every job?

gem, set $EDITOR or $BUNDLER_EDITOR $ export EDITOR="subl -w" # Sublime Text, or $ How do we add request_id to every job?

gem, set $EDITOR or $BUNDLER_EDITOR $ export EDITOR="subl -w" # Sublime Text, or $ export EDITOR="code -w" # VS Code, or $ How do we add request_id to every job?

gem, set $EDITOR or $BUNDLER_EDITOR $ export EDITOR="subl -w" # Sublime Text, or $ export EDITOR="code -w" # VS Code, or $ export EDITOR="vim" # vim, or whatever you use $ How do we add request_id to every job?

gem, set $EDITOR or $BUNDLER_EDITOR $ export EDITOR="subl -w" # Sublime Text, or $ export EDITOR="code -w" # VS Code, or $ export EDITOR="vim" # vim, or whatever you use $ bundle open activejob How do we add request_id to every job?

module ActiveJob module QueueAdapters class SidekiqAdapter def enqueue(job) #:nodoc: #
Sidekiq::Client does not support symbols as keys job.provider_job_id = Sidekiq::Client.push \ "class" => JobWrapper, "wrapped" => job.class.to_s, "queue" => job.queue_name, "args" => [ job.serialize ] end def enqueue_at(job, timestamp) #:nodoc: job.provider_job_id = Sidekiq::Client.push \ "class" => JobWrapper, "wrapped" => job.class.to_s, "queue" => job.queue_name, "args" => [ job.serialize ], "at" => timestamp end class JobWrapper #:nodoc: include Sidekiq::Worker def perform(job_data) Base.execute job_data.merge("provider_job_id" => jid) end end end end end

Sidekiq::Client does not support symbols as keys job.provider_job_id = Sidekiq::Client.push \ "class" => JobWrapper, "wrapped" => job.class.to_s, "queue" => job.queue_name, "args" => [ job.serialize ] end def enqueue_at(job, timestamp) #:nodoc: job.provider_job_id = Sidekiq::Client.push \ "class" => JobWrapper, "wrapped" => job.class.to_s, "queue" => job.queue_name, "args" => [ job.serialize ], "at" => timestamp end class JobWrapper #:nodoc: include Sidekiq::Worker def perform(job_data) Base.execute job_data.merge("provider_job_id" => jid) end end end end end 1 2 3

Sidekiq::Client does not support symbols as keys job.provider_job_id = Sidekiq::Client.push \ "class" => JobWrapper, "wrapped" => job.class.to_s, "queue" => job.queue_name, "args" => [ job.serialize ] end def enqueue_at(job, timestamp) #:nodoc: job.provider_job_id = Sidekiq::Client.push \ "class" => JobWrapper, "wrapped" => job.class.to_s, "queue" => job.queue_name, "args" => [ job.serialize ], "at" => timestamp end class JobWrapper #:nodoc: include Sidekiq::Worker def perform(job_data) Base.execute job_data.merge("provider_job_id" => jid) end end end end end 1 2 3 def enqueue(job) #:nodoc: # Sidekiq::Client does not support symbols as keys job.provider_job_id = Sidekiq::Client.push \ "class" => JobWrapper, "wrapped" => job.class.to_s, "queue" => job.queue_name, "args" => [ job.serialize ] end 1. enqueue method

Sidekiq::Client does not support symbols as keys job.provider_job_id = Sidekiq::Client.push \ "class" => JobWrapper, "wrapped" => job.class.to_s, "queue" => job.queue_name, "args" => [ job.serialize ] end def enqueue_at(job, timestamp) #:nodoc: job.provider_job_id = Sidekiq::Client.push \ "class" => JobWrapper, "wrapped" => job.class.to_s, "queue" => job.queue_name, "args" => [ job.serialize ], "at" => timestamp end class JobWrapper #:nodoc: include Sidekiq::Worker def perform(job_data) Base.execute job_data.merge("provider_job_id" => jid) end end end end end 1 2 3

module ActiveJob module QueueAdapters class SidekiqAdapter # ... def enqueue_at(job,
timestamp) #:nodoc: job.provider_job_id = Sidekiq::Client.push \ "class" => JobWrapper, "wrapped" => job.class.to_s, "queue" => job.queue_name, "args" => [ job.serialize ], "at" => timestamp end class JobWrapper #:nodoc: include Sidekiq::Worker def perform(job_data) Base.execute job_data.merge("provider_job_id" => jid) end end end end end 1 2 3

timestamp) #:nodoc: job.provider_job_id = Sidekiq::Client.push \ "class" => JobWrapper, "wrapped" => job.class.to_s, "queue" => job.queue_name, "args" => [ job.serialize ], "at" => timestamp end class JobWrapper #:nodoc: include Sidekiq::Worker def perform(job_data) Base.execute job_data.merge("provider_job_id" => jid) end end end end end 2 3

Sidekiq::Client does not support symbols as keys job.provider_job_id = Sidekiq::Client.push \ "class" => JobWrapper, "wrapped" => job.class.to_s, "queue" => job.queue_name, "args" => [ job.serialize ] end def enqueue_at(job, timestamp) #:nodoc: job.provider_job_id = Sidekiq::Client.push \ "class" => JobWrapper, "wrapped" => job.class.to_s, "queue" => job.queue_name, "args" => [ job.serialize ], "at" => timestamp end class JobWrapper #:nodoc: include Sidekiq::Worker def perform(job_data) Base.execute job_data.merge("provider_job_id" => jid) end end end end end 1 2 3 def enqueue_at(job, timestamp) #:nodoc: job.provider_job_id = Sidekiq::Client.push \ "class" => JobWrapper, "wrapped" => job.class.to_s, "queue" => job.queue_name, "args" => [ job.serialize ], "at" => timestamp end 2. enqueue_at method

timestamp) #:nodoc: job.provider_job_id = Sidekiq::Client.push \ "class" => JobWrapper, "wrapped" => job.class.to_s, "queue" => job.queue_name, "args" => [ job.serialize ], "at" => timestamp end class JobWrapper #:nodoc: include Sidekiq::Worker def perform(job_data) Base.execute job_data.merge("provider_job_id" => jid) end end end end end 2 3

module ActiveJob module QueueAdapters class SidekiqAdapter # ... # ...
class JobWrapper #:nodoc: include Sidekiq::Worker def perform(job_data) Base.execute job_data.merge("provider_job_id" => jid) end end end end end 2 3

module ActiveJob module QueueAdapters class SidekiqAdapter # ... class JobWrapper
#:nodoc: include Sidekiq::Worker def perform(job_data) Base.execute job_data.merge("provider_job_id" => jid) end end end end end 3

module ActiveJob module QueueAdapters class SidekiqAdapter # ... class JobWrapper
#:nodoc: include Sidekiq::Worker def perform(job_data) byebug Base.execute job_data.merge("provider_job_id" => jid) end end end end end 3

$ rails c Loading development environment (Rails 6.0.0) >> How

= "abcdef" => "abcdef" >> How do we add request_id to every job?

= "abcdef" => "abcdef" >> ReportJob.perform_later >> How do we add request_id to every job?

= "abcdef" => "abcdef" >> ReportJob.perform_later >> How do we add request_id to every job? m, `$b .ss, $$: .,d$ `$$P,d$P' .,md$P"' ,$$$$$bmmd$$$P^' .d$$$$$$$$$$P' $$^' `"^$$$' ____ _ _ _ _ $: ,$$: / ___|(_) __| | ___| | _(_) __ _ `b :$$ \___ \| |/ _` |/ _ \ |/ / |/ _` | $$: ___) | | (_| | __/ <| | (_| | $$ |____/|_|\__,_|\___|_|\_\_|\__, | .d$$ |_| ReportJob JID-123 INFO: start

= "abcdef" => "abcdef" >> ReportJob.perform_later >> How do we add request_id to every job? m, `$b .ss, $$: .,d$ `$$P,d$P' .,md$P"' ,$$$$$bmmd$$$P^' .d$$$$$$$$$$P' $$^' `"^$$$' ____ _ _ _ _ $: ,$$: / ___|(_) __| | ___| | _(_) __ _ `b :$$ \___ \| |/ _` |/ _ \ |/ / |/ _` | $$: ___) | | (_| | __/ <| | (_| | $$ |____/|_|\__,_|\___|_|\_\_|\__, | .d$$ |_| ReportJob JID-123 INFO: start  [26, 35] in activejob-6.0.0.beta3/lib/active_job/queue_adapters/sidekiq_adapter.rb 26: class JobWrapper #:nodoc: 27: include Sidekiq::Worker 28: 29: def perform(job_data) 30: byebug => 31: Base.execute job_data.merge("provider_job_id" => jid) 32: end 33: end 34: end 35: end (byebug)

= "abcdef" => "abcdef" >> ReportJob.perform_later >> How do we add request_id to every job? [26, 35] in activejob-6.0.0.beta3/lib/active_job/queue_adapters/sidekiq_adapter.rb 26: class JobWrapper #:nodoc: 27: include Sidekiq::Worker 28: 29: def perform(job_data) 30: byebug => 31: Base.execute job_data.merge("provider_job_id" => jid) 32: end 33: end 34: end 35: end (byebug)

= "abcdef" => "abcdef" >> ReportJob.perform_later >> How do we add request_id to every job? [26, 35] in activejob-6.0.0.beta3/lib/active_job/queue_adapters/sidekiq_adapter.rb 26: class JobWrapper #:nodoc: 27: include Sidekiq::Worker 28: 29: def perform(job_data) 30: byebug => 31: Base.execute job_data.merge("provider_job_id" => jid) 32: end 33: end 34: end 35: end (byebug) job_data

= "abcdef" => "abcdef" >> ReportJob.perform_later >> How do we add request_id to every job? [26, 35] in activejob-6.0.0.beta3/lib/active_job/queue_adapters/sidekiq_adapter.rb 26: class JobWrapper #:nodoc: 27: include Sidekiq::Worker 28: 29: def perform(job_data) 30: byebug => 31: Base.execute job_data.merge("provider_job_id" => jid) 32: end 33: end 34: end 35: end (byebug) job_data { "job_class"=>"ReportJob", "job_id"=>"d13993c6-dd0f-4323-a1c3-544f2ed3b44a", "provider_job_id"=>nil, "queue_name"=>"default", "priority"=>nil,

= "abcdef" => "abcdef" >> ReportJob.perform_later >> How do we add request_id to every job? (byebug) job_data { "job_class"=>"ReportJob", "job_id"=>"d13993c6-dd0f-4323-a1c3-544f2ed3b44a", "provider_job_id"=>nil, "queue_name"=>"default", "priority"=>nil, "arguments"=>[], "executions"=>0, "exception_executions"=>{}, "locale"=>"en", "timezone"=>"UTC", "enqueued_at"=>"2019-04-26T01:11:19Z", "request_id"=>"abcdef" } (byebug)

= "abcdef" => "abcdef" >> ReportJob.perform_later >> How do we add request_id to every job? (byebug) job_data { "job_class"=>"ReportJob", "job_id"=>"d13993c6-dd0f-4323-a1c3-544f2ed3b44a", "provider_job_id"=>nil, "queue_name"=>"default", "priority"=>nil, "arguments"=>[], "executions"=>0, "exception_executions"=>{}, "locale"=>"en", "timezone"=>"UTC", "enqueued_at"=>"2019-04-26T01:11:19Z", "request_id"=>"abcdef" } (byebug) job_data["request_id"] "abcdef" (byebug)

= "abcdef" => "abcdef" >> ReportJob.perform_later >> How do we add request_id to every job? (byebug)

= "abcdef" => "abcdef" >> ReportJob.perform_later >> How do we add request_id to every job? (byebug) Base.method(:execute).source.display

= "abcdef" => "abcdef" >> ReportJob.perform_later >> How do we add request_id to every job? (byebug) Base.method(:execute).source.display def execute(job_data) #:nodoc: ActiveJob::Callbacks.run_callbacks(:execute) do job = deserialize(job_data) job.perform_now end end nil (byebug)

= "abcdef" => "abcdef" >> ReportJob.perform_later >> How do we add request_id to every job? (byebug) Base.method(:execute).source.display def execute(job_data) #:nodoc: ActiveJob::Callbacks.run_callbacks(:execute) do job = deserialize(job_data) job.perform_now end end nil (byebug) Base.method(:deserialize).source.display

= "abcdef" => "abcdef" >> ReportJob.perform_later >> How do we add request_id to every job? (byebug) Base.method(:execute).source.display def execute(job_data) #:nodoc: ActiveJob::Callbacks.run_callbacks(:execute) do job = deserialize(job_data) job.perform_now end end nil (byebug) Base.method(:deserialize).source.display def deserialize(job_data) job = job_data["job_class"].constantize.new job.deserialize(job_data) job end nil (byebug)

= "abcdef" => "abcdef" >> ReportJob.perform_later >> How do we add request_id to every job? (byebug) Base.method(:execute).source.display def execute(job_data) #:nodoc: ActiveJob::Callbacks.run_callbacks(:execute) do job = deserialize(job_data) job.perform_now end end nil (byebug) Base.method(:deserialize).source.display def deserialize(job_data) job = job_data["job_class"].constantize.new job.deserialize(job_data) job end nil (byebug) job_data["job_class"].constantize.new

= "abcdef" => "abcdef" >> ReportJob.perform_later >> How do we add request_id to every job? (byebug) Base.method(:execute).source.display def execute(job_data) #:nodoc: ActiveJob::Callbacks.run_callbacks(:execute) do job = deserialize(job_data) job.perform_now end end nil (byebug) Base.method(:deserialize).source.display def deserialize(job_data) job = job_data["job_class"].constantize.new job.deserialize(job_data) job end nil (byebug) job_data["job_class"].constantize.new.method(:deserialize).source.display

= "abcdef" => "abcdef" >> ReportJob.perform_later >> How do we add request_id to every job? (byebug) Base.method(:execute).source.display def execute(job_data) #:nodoc: ActiveJob::Callbacks.run_callbacks(:execute) do job = deserialize(job_data) job.perform_now end end nil (byebug) Base.method(:deserialize).source.display def deserialize(job_data) job = job_data["job_class"].constantize.new job.deserialize(job_data) job end nil (byebug) job_data["job_class"].constantize.new.method(:deserialize).source.display def deserialize(job_data) self.job_id = job_data["job_id"]

= "abcdef" => "abcdef" >> ReportJob.perform_later >> How do we add request_id to every job? (byebug) Base.method(:deserialize).source.display def deserialize(job_data) job = job_data["job_class"].constantize.new job.deserialize(job_data) job end nil (byebug) job_data["job_class"].constantize.new.method(:deserialize).source.display def deserialize(job_data) self.job_id = job_data["job_id"] self.provider_job_id = job_data["provider_job_id"] self.queue_name = job_data["queue_name"] self.priority = job_data["priority"] self.serialized_arguments = job_data["arguments"] self.executions = job_data["executions"] self.exception_executions = job_data["exception_executions"] self.locale = job_data["locale"] || I18n.locale.to_s self.timezone = job_data["timezone"] || Time.zone.try(:name)

= "abcdef" => "abcdef" >> ReportJob.perform_later >> How do we add request_id to every job? (byebug) job_data["job_class"].constantize.new.method(:deserialize).source.display def deserialize(job_data) self.job_id = job_data["job_id"] self.provider_job_id = job_data["provider_job_id"] self.queue_name = job_data["queue_name"] self.priority = job_data["priority"] self.serialized_arguments = job_data["arguments"] self.executions = job_data["executions"] self.exception_executions = job_data["exception_executions"] self.locale = job_data["locale"] || I18n.locale.to_s self.timezone = job_data["timezone"] || Time.zone.try(:name) self.enqueued_at = job_data["enqueued_at"] end nil (byebug)

= "abcdef" => "abcdef" >> ReportJob.perform_later >> How do we add request_id to every job? (byebug) job_data["job_class"].constantize.new.method(:deserialize).source.display def deserialize(job_data) self.job_id = job_data["job_id"] self.provider_job_id = job_data["provider_job_id"] self.queue_name = job_data["queue_name"] self.priority = job_data["priority"] self.serialized_arguments = job_data["arguments"] self.executions = job_data["executions"] self.exception_executions = job_data["exception_executions"] self.locale = job_data["locale"] || I18n.locale.to_s self.timezone = job_data["timezone"] || Time.zone.try(:name) self.enqueued_at = job_data["enqueued_at"] end nil (byebug) self.request_id = job_data["request_id"]

Current.request_id) end end

Current.request_id) end def deserialize(job_data) end end

Current.request_id) end def deserialize(job_data) super end end

Current.request_id) end def deserialize(job_data) super self.request_id = job_data["request_id"] end end

>> Current.request_id = "abcdef" => "abcdef" How do we add

>> Current.request_id = "abcdef" => "abcdef" >> ReportJob.perform_later >> How

`$b .ss, $$: .,d$ `$$P,d$P' .,md$P"' ,$$$$$bmmd$$$P^' .d$$$$$$$$$$P' $$^' `"^$$$' ____ _ _ _ _ $: ,$$: / ___|(_) __| | ___| | _(_) __ _ `b :$$ \___ \| |/ _` |/ _ \ |/ / |/ _` | $$: ___) | | (_| | __/ <| | (_| | $$ |____/|_|\__,_|\___|_|\_\_|\__, | .d$$ |_| How do we add request_id to every job?

By adding it to serialization and deserialization. We add request_id
during serialization and set it during deserialization. >> Current.request_id = "abcdef" => "abcdef" >> ReportJob.perform_later >> m, `$b .ss, $$: .,d$ `$$P,d$P' .,md$P"' ,$$$$$bmmd$$$P^' .d$$$$$$$$$$P' $$^' `"^$$$' ____ _ _ _ _ $: ,$$: / ___|(_) __| | ___| | _(_) __ _ `b :$$ \___ \| |/ _` |/ _ \ |/ / |/ _` | $$: ___) | | (_| | __/ <| | (_| | $$ |____/|_|\__,_|\___|_|\_\_|\__, | .d$$ |_| ReportJob JID-123 INFO: start request_id: "abcdef" ReportJob JID-123 INFO: done How do we add request_id to every job?

By adding it to serialization and deserialization. >> Current.request_id =
"abcdef" => "abcdef" >> ReportJob.perform_later >> m, `$b .ss, $$: .,d$ `$$P,d$P' .,md$P"' ,$$$$$bmmd$$$P^' .d$$$$$$$$$$P' $$^' `"^$$$' ____ _ _ _ _ $: ,$$: / ___|(_) __| | ___| | _(_) __ _ `b :$$ \___ \| |/ _` |/ _ \ |/ / |/ _` | $$: ___) | | (_| | __/ <| | (_| | $$ |____/|_|\__,_|\___|_|\_\_|\__, | .d$$ |_| ReportJob JID-123 INFO: start request_id: "abcdef" ReportJob JID-123 INFO: done How do we add request_id to every job?

1. Ask a question How do we add request_id to
every job? 2. Start with what you know Look at perform_later. 3. Only read relevant code Skim 100 lines, read ~50 lines

https://github.com/deivid-rodriguez/byebug byebug

https://pryrepl.org/

https://pryrepl.org/ >> show-source "hello".empty? From: string.c (C Method): Owner: String
Visibility: public Number of lines: 7 static VALUE rb_str_empty(VALUE str) { if (RSTRING_LEN(str) == 0) return Qtrue; return Qfalse; }

Thanks. Jordan Raine @jnraine

• Donald Giannatti, Unsplash, https://unsplash.com/photos/OVLa83nRaLQ • Niklas Hamann, Unsplash, https://unsplash.com/photos/Pe4gh8a8mBY
• By The original uploader was Minghong at English Wikipedia. - Transferred from en.wikipedia to Commons by IngerAlHaosului using CommonsHelper., CC BY-SA 3.0, https://commons.wikimedia.org/ w/index.php?curid=8922606 • Andrew Buchanan, Unsplash, https://unsplash.com/photos/Csf7vDp-Whc • Majid Rangraz, Unsplash, https://unsplash.com/photos/IPMaxeoHXi4 • Rachel, Unsplash, https://unsplash.com/photos/GGlz-QSvL38 • Rohan Makhecha, Unsplash, https://unsplash.com/photos/5ﬂdl8eWIt0 • Eva Darron, Unsplash, https://unsplash.com/photos/oCdVtGFeDC0 • Mike Benna, Unsplash, https://unsplash.com/photos/5Cv3surFZM8 • Luc Tribolet, Unsplash, https://unsplash.com/photos/FQRxB1SimfI • Damian Zaleski, Unsplash, https://unsplash.com/photos/RYyr-k3Ysqg • Jennifer Regnier, Unsplash, https://unsplash.com/photos/sjP0USlCt10 Photo Credits

Code Spelunking: Teach Yourself How Rails Works

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