Class: Locomotive::Steam::Middlewares::Cache

Inherits:
ThreadSafe
  • Object
show all
Includes:
Locomotive::Steam::Middlewares::Concerns::Helpers
Defined in:
lib/locomotive/steam/middlewares/cache.rb

Constant Summary collapse

CACHEABLE_RESPONSE_CODES = 
[200, 301, 404, 410].freeze
CACHEABLE_REQUEST_METHODS = 
%w(GET HEAD).freeze
DEFAULT_CACHE_CONTROL = 
'max-age=0, s-maxage=3600, public, must-revalidate'.freeze
DEFAULT_CACHE_VARY = 
'Accept-Language'.freeze
NO_CACHE_CONTROL = 
'max-age=0, private, must-revalidate'.freeze

Constants included from Locomotive::Steam::Middlewares::Concerns::Helpers

Locomotive::Steam::Middlewares::Concerns::Helpers::CACHE_HEADERS, Locomotive::Steam::Middlewares::Concerns::Helpers::HTML_CONTENT_TYPE, Locomotive::Steam::Middlewares::Concerns::Helpers::HTML_MIME_TYPES

Instance Attribute Summary

Attributes inherited from ThreadSafe

#env

Instance Method Summary collapse

Methods included from Locomotive::Steam::Middlewares::Concerns::Helpers

#html?, #inject_cookies, #json?, #log, #make_local_path, #modify_path, #mounted_on, #redirect_to, #render_response

Methods inherited from ThreadSafe

#call, #decorate_entry, #default_liquid_context, #default_locale, #liquid_assigns, #live_editing?, #locale, #locales, #merge_with_params, #next, #page, #params, #path, #repositories, #request, #services, #session, #site

Instance Method Details

#_call ⇒ Object 



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# File 'lib/locomotive/steam/middlewares/cache.rb', line 18

def _call
  if cacheable?
    key = cache_key

    # TODO: only for debugging
    # log("HTTP keys: #{env.select { |key, _| key.starts_with?('HTTP_') }}".light_blue)

    # Test if the ETag or Last Modified has been modified. If not, return a 304 response
    if stale?(key)
      render_response(nil, 304, nil)
      return
    end

    # we have to tell the CDN (or any proxy) what the expiration & validation strategy are
    env['steam.cache_control']        = cache_control
    env['steam.cache_vary']           = cache_vary
    env['steam.cache_etag']           = key
    env['steam.cache_last_modified']  = site.last_modified_at.httpdate

    # retrieve the response from the cache.
    # This is useful if no CDN is being used.
    code, headers, _ = response = fetch_cached_response(key)

    unless CACHEABLE_RESPONSE_CODES.include?(code.to_i)
      env['steam.cache_control'] = headers['Cache-Control'] = NO_CACHE_CONTROL
      env['steam.cache_vary'] = headers['Vary'] = nil
    end

    # we don't want to render twice the page
    @next_response = response
  else
    env['steam.cache_control']  = NO_CACHE_CONTROL
  end
end