The Web Server Latency Challenge
As databases grow, calculating page layouts on the server on every request degrades web performance. While client-side Single Page Applications are emerging, server-side frameworks must optimize page compilation speeds.
The upcoming release of Ruby on Rails 4.0 addresses this by standardizing cache patterns and page transitions.
Valuable Note: The goal of Rails 4 is keeping rendering times sub-second by caching HTML fragments aggressively, avoiding database lookups entirely.
Russian Doll Caching and Key-Based Invalidation
Rails 4 formalizes Russian Doll Caching—nesting cached fragments inside one another:
- ◆Visual Layout: A dashboard view caches a list of items, and each item caches its own details.
- ◆Invalidation: If a child item is updated, its cache key updates. This invalidates the parent container cache automatically using timestamps.
| Cache Level | Cache Key Pattern | Scope |
|---|---|---|
| Parent Grid | views/users-list-20130125 | Wraps the entire loop. |
| Child Card | views/user-card-id-12-20130124 | Wraps individual elements. |
Implementing Key-Based Caching
<%# Nested fragment caching in Rails 4.0 views %>
<% cache @project do %>
<div class="project-header">
<h2><%= @project.title %></h2>
</div>
<div class="tasks">
<% @project.tasks.each do |task| %>
<% cache task do %>
<p><%= task.description %></p>
<% end %>
<% end %>
</div>
<% end %>Turbolinks
To speed up client navigation, Turbolinks intercepts anchor link clicks. Instead of full page reloads, it fetches pages via AJAX and replaces the HTML <body> element dynamically, keeping CSS and JavaScript assets in memory.