215 lines
8.1 KiB
Ruby
215 lines
8.1 KiB
Ruby
# frozen_string_literal: true
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module Banzai
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module Renderer
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# Convert a Markdown String into an HTML-safe String of HTML
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#
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# Note that while the returned HTML will have been sanitized of dangerous
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# HTML, it may post a risk of information leakage if it's not also passed
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# through `post_process`.
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#
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# Also note that the returned String is always HTML, not XHTML. Views
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# requiring XHTML, such as Atom feeds, need to call `post_process` on the
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# result, providing the appropriate `pipeline` option.
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#
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# text - Markdown String
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# context - Hash of context options passed to our HTML Pipeline
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#
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# Returns an HTML-safe String
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def self.render(text, context = {})
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cache_key = context.delete(:cache_key)
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cache_key = full_cache_key(cache_key, context[:pipeline])
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if cache_key
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Gitlab::Metrics.measure(:banzai_cached_render) do
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Rails.cache.fetch(cache_key) do
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cacheless_render(text, context)
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end
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end
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else
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cacheless_render(text, context)
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end
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end
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# Convert a Markdown-containing field on an object into an HTML-safe String
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# of HTML. This method is analogous to calling render(object.field), but it
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# can cache the rendered HTML in the object, rather than Redis.
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def self.render_field(object, field, context = {})
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unless object.respond_to?(:cached_markdown_fields)
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return cacheless_render_field(object, field, context)
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end
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object.refresh_markdown_cache! unless object.cached_html_up_to_date?(field)
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object.cached_html_for(field)
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end
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# Same as +render_field+, but without consulting or updating the cache field
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def self.cacheless_render_field(object, field, context = {})
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text = object.__send__(field) # rubocop:disable GitlabSecurity/PublicSend
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context = context.reverse_merge(object.banzai_render_context(field)) if object.respond_to?(:banzai_render_context)
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cacheless_render(text, context)
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end
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# Perform multiple render from an Array of Markdown String into an
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# Array of HTML-safe String of HTML.
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#
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# The redis cache is completely obviated if we receive a `:rendered` key in the
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# context, as it is assumed the item has been pre-rendered somewhere else and there
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# is no need to cache it.
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#
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# If no `:rendered` key is present in the context, as the rendered Markdown String
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# can be already cached, read all the data from the cache using
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# Rails.cache.read_multi operation. If the Markdown String is not in the cache
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# or it's not cacheable (no cache_key entry is provided in the context) the
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# Markdown String is rendered and stored in the cache so the next render call
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# gets the rendered HTML-safe String from the cache.
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#
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# For further explanation see #render method comments.
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#
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# texts_and_contexts - An Array of Hashes that contains the Markdown String (:text)
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# an options passed to our HTML Pipeline (:context)
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#
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# If on the :context you specify a :cache_key entry will be used to retrieve it
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# and cache the result of rendering the Markdown String.
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#
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# Returns an Array containing HTML-safe String instances.
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#
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# Example:
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# texts_and_contexts
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# => [{ text: '### Hello',
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# context: { cache_key: [note, :note] } }]
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def self.cache_collection_render(texts_and_contexts)
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items_collection = texts_and_contexts.each do |item|
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context = item[:context]
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if context.key?(:rendered)
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item[:rendered] = context.delete(:rendered)
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else
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# If the attribute didn't come in pre-rendered, let's prepare it for caching it in redis
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cache_key = full_cache_multi_key(context.delete(:cache_key), context[:pipeline])
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item[:cache_key] = cache_key if cache_key
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end
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end
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cacheable_items, non_cacheable_items = items_collection.group_by do |item|
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if item.key?(:rendered)
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# We're not really doing anything here as these don't need any processing, but leaving it just in case
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# as they could have a cache_key and we don't want them to be re-rendered
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:rendered
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elsif item.key?(:cache_key)
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:cacheable
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else
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:non_cacheable
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end
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end.values_at(:cacheable, :non_cacheable)
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items_in_cache = []
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items_not_in_cache = []
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if cacheable_items.present?
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items_in_cache = Rails.cache.read_multi(*cacheable_items.map { |item| item[:cache_key] })
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items_not_in_cache = cacheable_items.reject do |item|
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item[:rendered] = items_in_cache[item[:cache_key]]
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items_in_cache.key?(item[:cache_key])
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end
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end
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(items_not_in_cache + Array.wrap(non_cacheable_items)).each do |item|
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item[:rendered] = render(item[:text], item[:context])
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Rails.cache.write(item[:cache_key], item[:rendered]) if item[:cache_key]
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end
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items_collection.map { |item| item[:rendered] }
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end
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def self.render_result(text, context = {})
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text = Pipeline[:pre_process].to_html(text, context) if text
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Pipeline[context[:pipeline]].call(text, context)
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end
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# Perform post-processing on an HTML String
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#
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# This method is used to perform state-dependent changes to a String of
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# HTML, such as removing references that the current user doesn't have
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# permission to make (`ReferenceRedactorFilter`).
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#
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# html - String to process
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# context - Hash of options to customize output
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# :pipeline - Symbol pipeline type - for context transform only, defaults to :full
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# :project - Project
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# :user - User object
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# :post_process_pipeline - pipeline to use for post_processing - defaults to PostProcessPipeline
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#
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# Returns an HTML-safe String
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def self.post_process(html, context)
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context = Pipeline[context[:pipeline]].transform_context(context)
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# Use a passed class for the pipeline or default to PostProcessPipeline
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pipeline = context.delete(:post_process_pipeline) || ::Banzai::Pipeline::PostProcessPipeline
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if context[:xhtml]
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pipeline.to_document(html, context).to_html(save_with: Nokogiri::XML::Node::SaveOptions::AS_XHTML)
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else
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pipeline.to_html(html, context)
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end.html_safe
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end
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def self.cacheless_render(text, context = {})
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return text.to_s unless text.present?
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real_start = Gitlab::Metrics::System.monotonic_time
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cpu_start = Gitlab::Metrics::System.cpu_time
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result = render_result(text, context)
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output = result[:output]
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rendered = if output.respond_to?(:to_html)
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output.to_html
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else
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output.to_s
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end
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cpu_duration_histogram.observe({}, Gitlab::Metrics::System.cpu_time - cpu_start)
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real_duration_histogram.observe({}, Gitlab::Metrics::System.monotonic_time - real_start)
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rendered
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end
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def self.real_duration_histogram
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Gitlab::Metrics.histogram(
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:gitlab_banzai_cacheless_render_real_duration_seconds,
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'Duration of Banzai pipeline rendering in real time',
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{},
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[0.01, 0.01, 0.05, 0.1, 0.5, 1, 2, 5, 10.0, 50, 100]
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)
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end
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def self.cpu_duration_histogram
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Gitlab::Metrics.histogram(
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:gitlab_banzai_cacheless_render_cpu_duration_seconds,
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'Duration of Banzai pipeline rendering in cpu time',
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{},
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Gitlab::Metrics::EXECUTION_MEASUREMENT_BUCKETS
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)
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end
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def self.full_cache_key(cache_key, pipeline_name)
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return unless cache_key
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["banzai", *cache_key, pipeline_name || :full]
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end
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# To map Rails.cache.read_multi results we need to know the Rails.cache.expanded_key.
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# Other option will be to generate stringified keys on our side and don't delegate to Rails.cache.expanded_key
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# method.
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def self.full_cache_multi_key(cache_key, pipeline_name)
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return unless cache_key
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Rails.cache.__send__(:expanded_key, full_cache_key(cache_key, pipeline_name)) # rubocop:disable GitlabSecurity/PublicSend
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end
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end
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end
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