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Module: ActionView::CollectionCaching

Do not use. This module is for internal use only.
Relationships & Source Files
Extension / Inclusion / Inheritance Descendants
Included In:
CollectionRenderer, ObjectRenderer, PartialRenderer
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
self, ::ActiveSupport::Concern
Defined in: actionview/lib/action_view/renderer/partial_renderer/collection_caching.rb

Class Method Summary

::ActiveSupport::Concern - Extended

class_methods

Define class methods from given block.
included

Evaluate given block in context of base class, so that you can write class macros here.
prepended

Evaluate given block in context of base class, so that you can write class macros here.
append_features, prepend_features

Instance Attribute Summary

Instance Method Summary

DSL Calls

included

[ GitHub ] 


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# File 'actionview/lib/action_view/renderer/partial_renderer/collection_caching.rb', line 9

included do
  # Fallback cache store if Action View is used without Rails.
  # Otherwise overridden in Railtie to use Rails.cache.
  mattr_accessor :collection_cache, default: ActiveSupport::Cache::MemoryStore.new
end

Instance Attribute Details

#callable_cache_key? ⇒ Boolean (readonly, private)

[ GitHub ] 

  


# File 'actionview/lib/action_view/renderer/partial_renderer/collection_caching.rb', line 54



def callable_cache_key?
  @options[:cached].respond_to?(:call)
end


  







Instance Method Details



  

    #cache_collection_render(instrumentation_payload, view, template, collection)   (private)
  

  [ GitHub ]


  

  


# File 'actionview/lib/action_view/renderer/partial_renderer/collection_caching.rb', line 20



def cache_collection_render(instrumentation_payload, view, template, collection)
  return yield(collection) unless will_cache?(@options, view)

  collection_iterator = collection

  # Result is a hash with the key represents the
  # key used for cache lookup and the value is the item
  # on which the partial is being rendered
  keyed_collection, ordered_keys = collection_by_cache_keys(view, template, collection)

  # Pull all partials from cache
  # Result is a hash, key matches the entry in
  # `keyed_collection` where the cache was retrieved and the
  # value is the value that was present in the cache
  cached_partials = collection_cache.read_multi(*keyed_collection.keys)
  instrumentation_payload[:cache_hits] = cached_partials.size

  # Extract the items for the keys that are not found
  collection = keyed_collection.reject { |key, _| cached_partials.key?(key) }.values

  rendered_partials = collection.empty? ? [] : yield(collection_iterator.from_collection(collection))

  index = 0
  keyed_partials = fetch_or_cache_partial(cached_partials, template, order_by: keyed_collection.each_key) do
    # This block is called once
    # for every cache miss while preserving order.
    rendered_partials[index].tap { index += 1 }
  end

  ordered_keys.map do |key|
    keyed_partials[key]
  end
end


  








  

    #collection_by_cache_keys(view, template, collection)   (private)
  

  [ GitHub ]


  

  


# File 'actionview/lib/action_view/renderer/partial_renderer/collection_caching.rb', line 58



def collection_by_cache_keys(view, template, collection)
  seed = callable_cache_key? ? @options[:cached] : ->(i) { i }

  digest_path = view.digest_path_from_template(template)
  collection.preload! if callable_cache_key?

  collection.each_with_object([{}, []]) do |item, (hash, ordered_keys)|
    key = expanded_cache_key(seed.call(item), view, template, digest_path)
    ordered_keys << key
    hash[key] = item
  end
end


  








  

    #expanded_cache_key(key, view, template, digest_path)   (private)
  

  [ GitHub ]


  

  


# File 'actionview/lib/action_view/renderer/partial_renderer/collection_caching.rb', line 71



def expanded_cache_key(key, view, template, digest_path)
  key = view.combined_fragment_cache_key(view.cache_fragment_name(key, digest_path: digest_path))
  key.frozen? ? key.dup : key # #read_multi & #write may require mutability, Dalli 2.6.0.
end


  








  

    #fetch_or_cache_partial(cached_partials, template, order_by:)   (private)
  



  

    

order_by is an enumerable object containing keys of the cache, all keys are  passed in whether found already or not.



cached_partials is a hash. If the value exists it represents the rendered partial from the cache otherwise Hash#fetch will take the value of its block.



This method expects a block that will return the rendered partial. An example is to render all results for each element that was not found in the cache and store it as an array. Order it so that the first empty cache element in cached_partials corresponds to the first element in rendered_partials.



If the partial is not already cached it will also be written back to the underlying cache store.


  



  [ GitHub ]


  

  


# File 'actionview/lib/action_view/renderer/partial_renderer/collection_caching.rb', line 91



def fetch_or_cache_partial(cached_partials, template, order_by:)
  entries_to_write = {}

  keyed_partials = order_by.index_with do |cache_key|
    if content = cached_partials[cache_key]
      build_rendered_template(content, template)
    else
      rendered_partial = yield
      body = rendered_partial.body

      # We want to cache buffers as raw strings. This both improve performance and
      # avoid creating forward compatibility issues with the internal representation
      # of these two types.
      if body.is_a?(ActionView::OutputBuffer) || body.is_a?(ActiveSupport::SafeBuffer)
        body = body.to_str
      end

      entries_to_write[cache_key] = body
      rendered_partial
    end
  end

  unless entries_to_write.empty?
    collection_cache.write_multi(entries_to_write)
  end

  keyed_partials
end


  








  

    #will_cache?(options, view)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'actionview/lib/action_view/renderer/partial_renderer/collection_caching.rb', line 16



def will_cache?(options, view)
  options[:cached] && view.controller.respond_to?(:perform_caching) && view.controller.perform_caching
end