HTTP Cache in Rails 4

Talk given during Paris.rb on November 5th, 2013

Transcript

1. HTTP cache in Rails 4
2. ccocchi EPITA MTI 2011 Rails 1.2 rabl-rails, libmemcached_store Scala, JS are also fine languages ccocch.io @ccocchi github.com/ccocchi
3. CaptainDash
4. Agenda What changed in Rails 4 HTTP cache in depth Benefits
6. Rails 3 Page caching Action caching Fragment caching
7. Rails 4 Page caching Action caching Fragment caching
8. There are only two hard things in Computer Science: cache invalidation and naming things.
9. HTTP cache and all those headers
10. max-age Client side Basic duration in seconds Cannot be expired by the server
11. Marty GET /posts max-age=3600 Rails
12. d e f s h o w e x p i r e s _ i n 3 . h o u r s , p u b l i c : t r u e e n d
13. ETag Entity Tag Response body signature Reduces network traffic
14. Marty GET /posts Etag: "5257d1fa-2a33" GET /posts If-None-Match: "5257d1fa-2a33" 304 Not Modified Rails
15. Activated by default in Rails via Rack::ETag middleware
16. d e f s h o w f r e s h _ w h e n @ p o s t , p u b l i c : t r u e # t h i s w i l l u s e a n M D 5 o f @ p o s t . c a c h e _ k e y e n d d e f s h o w f r e s h _ w h e n e t a g : " m y _ c u s t o m _ t a g " e n d
17. Using custom key instead of default ones can also reduce your app response time
18. Last-Modified Timestamp of last modification Reduces network traffic or/and application execution Well suited for REST applications
19. Marty GET /posts Last-Modified: Tue, 5 Nov 2013 19:45:26 +0000 GET /posts If-Modified-Since 304 Not Modified Rails
20. d e f s h o w f r e s h _ w h e n @ p o s t , p u b l i c : t r u e # t h i s w i l l u s e @ p o s t . u p d a t e d _ a t e n d d e f s h o w f r e s h _ w h e n l a s t _ m o d i f i e d : [ @ p o s t . u p d a t e d _ a t , @ p o s t . v e r i f i e d _ a t ] . m a x e n d
21. Are you fresh? d e f s h o w i f s t a l e ? ( l a s t _ m o d i f i e d : @ p o s t . p u b l i s h e d _ a t ) # s t a l e ? ( @ p o s t ) # T h i s b l o c k w i l l o n l y b e e x e c u t e d i f t h e r e q u e s t i s n o t f r e s h @ p o s t . s u p e r _ l o n g _ c a l l r e s p o n d _ w i t h @ p o s t e n d e n d
22. Private vs Public Cache-Control header
23. By default, all requests are private
24. If public, ALL proxies can cache this response
25. Use with caution
26. Benefits Hint: proxies
27. Simple, already included in HTTP and Rails
28. Cache is stored client side
29. Proxies handle HTTP caching
30. Use a combination of these mechanisms for maximum improvement (it is not always possible though)
31. max-age + ETag or max-age + Last-Modified
32. Proxy Rails Marty GET /posts GET /posts max-age + ETag max-age=3600 + Etag: "5257d1fa-2a33" Jennifer GET /posts < 3600 max-age + ETag GET /posts GET /posts + ETag From cache 304 Not Modified
33. Reverse proxies also handle HTTP caching
34. Reverse proxies can be what CDNs are to static content
35. Rev. Proxy Rails Marty GET /posts GET /posts max-age=3600 + Etag: "5257d1fa-2a33" max-age + ETag Jennifer GET /posts < 3600 max-age=3500 + Etag: "5257d1fa-2a33" GET /posts GET /posts + ETag From cache + max-age + ETag 304 Not Modified
36. TL;DR You surely are already using HTTP cache, learn how to use it at its best
37. ?