module Banzai module Renderer module_function # Convert a Markdown String into an HTML-safe String of HTML # # Note that while the returned HTML will have been sanitized of dangerous # HTML, it may post a risk of information leakage if it's not also passed # through `post_process`. # # Also note that the returned String is always HTML, not XHTML. Views # requiring XHTML, such as Atom feeds, need to call `post_process` on the # result, providing the appropriate `pipeline` option. # # text - Markdown String # context - Hash of context options passed to our HTML Pipeline # # Returns an HTML-safe String def render(text, context = {}) cache_key = context.delete(:cache_key) cache_key = full_cache_key(cache_key, context[:pipeline]) if cache_key Gitlab::Metrics.measure(:banzai_cached_render) do Rails.cache.fetch(cache_key) do cacheless_render(text, context) end end else cacheless_render(text, context) end end # Convert a Markdown-containing field on an object into an HTML-safe String # of HTML. This method is analogous to calling render(object.field), but it # can cache the rendered HTML in the object, rather than Redis. # # The context to use is learned from the passed-in object by calling # #banzai_render_context(field), and cannot be changed. Use #render, passing # it the field text, if a custom rendering is needed. The generated context # is returned along with the HTML. def render_field(object, field) html_field = object.markdown_cache_field_for(field) html = object.__send__(html_field) return html if html.present? html = cacheless_render_field(object, field) update_object(object, html_field, html) unless object.new_record? || object.destroyed? html end # Same as +render_field+, but without consulting or updating the cache field def cacheless_render_field(object, field) text = object.__send__(field) context = object.banzai_render_context(field) cacheless_render(text, context) end # Perform multiple render from an Array of Markdown String into an # Array of HTML-safe String of HTML. # # As the rendered Markdown String can be already cached read all the data # from the cache using Rails.cache.read_multi operation. If the Markdown String # is not in the cache or it's not cacheable (no cache_key entry is provided in # the context) the Markdown String is rendered and stored in the cache so the # next render call gets the rendered HTML-safe String from the cache. # # For further explanation see #render method comments. # # texts_and_contexts - An Array of Hashes that contains the Markdown String (:text) # an options passed to our HTML Pipeline (:context) # # If on the :context you specify a :cache_key entry will be used to retrieve it # and cache the result of rendering the Markdown String. # # Returns an Array containing HTML-safe String instances. # # Example: # texts_and_contexts # => [{ text: '### Hello', # context: { cache_key: [note, :note] } }] def cache_collection_render(texts_and_contexts) items_collection = texts_and_contexts.each_with_index do |item, index| context = item[:context] cache_key = full_cache_multi_key(context.delete(:cache_key), context[:pipeline]) item[:cache_key] = cache_key if cache_key end cacheable_items, non_cacheable_items = items_collection.partition { |item| item.key?(:cache_key) } items_in_cache = [] items_not_in_cache = [] unless cacheable_items.empty? items_in_cache = Rails.cache.read_multi(*cacheable_items.map { |item| item[:cache_key] }) items_not_in_cache = cacheable_items.reject do |item| item[:rendered] = items_in_cache[item[:cache_key]] items_in_cache.key?(item[:cache_key]) end end (items_not_in_cache + non_cacheable_items).each do |item| item[:rendered] = render(item[:text], item[:context]) Rails.cache.write(item[:cache_key], item[:rendered]) if item[:cache_key] end items_collection.map { |item| item[:rendered] } end def render_result(text, context = {}) text = Pipeline[:pre_process].to_html(text, context) if text Pipeline[context[:pipeline]].call(text, context) end # Perform post-processing on an HTML String # # This method is used to perform state-dependent changes to a String of # HTML, such as removing references that the current user doesn't have # permission to make (`RedactorFilter`). # # html - String to process # context - Hash of options to customize output # :pipeline - Symbol pipeline type # :project - Project # :user - User object # # Returns an HTML-safe String def post_process(html, context) context = Pipeline[context[:pipeline]].transform_context(context) pipeline = Pipeline[:post_process] if context[:xhtml] pipeline.to_document(html, context).to_html(save_with: Nokogiri::XML::Node::SaveOptions::AS_XHTML) else pipeline.to_html(html, context) end.html_safe end def cacheless_render(text, context = {}) Gitlab::Metrics.measure(:banzai_cacheless_render) do result = render_result(text, context) output = result[:output] if output.respond_to?(:to_html) output.to_html else output.to_s end end end def full_cache_key(cache_key, pipeline_name) return unless cache_key ["banzai", *cache_key, pipeline_name || :full] end # To map Rails.cache.read_multi results we need to know the Rails.cache.expanded_key. # Other option will be to generate stringified keys on our side and don't delegate to Rails.cache.expanded_key # method. def full_cache_multi_key(cache_key, pipeline_name) return unless cache_key Rails.cache.send(:expanded_key, full_cache_key(cache_key, pipeline_name)) end def update_object(object, html_field, html) object.update_column(html_field, html) end end end