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|
# frozen_string_literal: true
# This module takes care of updating cache columns for Markdown-containing
# fields. Use like this in the body of your class:
#
# include CacheMarkdownField
# cache_markdown_field :foo
# cache_markdown_field :bar
# cache_markdown_field :baz, pipeline: :single_line
# cache_markdown_field :baz, whitelisted: true
#
# Corresponding foo_html, bar_html and baz_html fields should exist.
module CacheMarkdownField
extend ActiveSupport::Concern
# Increment this number every time the renderer changes its output
CACHE_COMMONMARK_VERSION_START = 10
CACHE_COMMONMARK_VERSION = 15
# changes to these attributes cause the cache to be invalidates
INVALIDATED_BY = %w[author project].freeze
# Knows about the relationship between markdown and html field names, and
# stores the rendering contexts for the latter
class FieldData
def initialize
@data = {}
end
delegate :[], :[]=, to: :@data
def markdown_fields
@data.keys
end
def html_field(markdown_field)
"#{markdown_field}_html"
end
def html_fields
markdown_fields.map { |field| html_field(field) }
end
def html_fields_whitelisted
markdown_fields.each_with_object([]) do |field, fields|
if @data[field].fetch(:whitelisted, false)
fields << html_field(field)
end
end
end
end
def skip_project_check?
false
end
# Returns the default Banzai render context for the cached markdown field.
def banzai_render_context(field)
raise ArgumentError.new("Unknown field: #{field.inspect}") unless
cached_markdown_fields.markdown_fields.include?(field)
# Always include a project key, or Banzai complains
project = self.project if self.respond_to?(:project)
group = self.group if self.respond_to?(:group)
context = cached_markdown_fields[field].merge(project: project, group: group)
# Banzai is less strict about authors, so don't always have an author key
context[:author] = self.author if self.respond_to?(:author)
context[:markdown_engine] = :common_mark
context
end
# Update every column in a row if any one is invalidated, as we only store
# one version per row
def refresh_markdown_cache
options = { skip_project_check: skip_project_check? }
updates = cached_markdown_fields.markdown_fields.map do |markdown_field|
[
cached_markdown_fields.html_field(markdown_field),
Banzai::Renderer.cacheless_render_field(self, markdown_field, options)
]
end.to_h
updates['cached_markdown_version'] = latest_cached_markdown_version
updates.each {|html_field, data| write_attribute(html_field, data) }
end
def refresh_markdown_cache!
updates = refresh_markdown_cache
return unless persisted? && Gitlab::Database.read_write?
update_columns(updates)
end
def cached_html_up_to_date?(markdown_field)
html_field = cached_markdown_fields.html_field(markdown_field)
return false if cached_html_for(markdown_field).nil? && !__send__(markdown_field).nil? # rubocop:disable GitlabSecurity/PublicSend
markdown_changed = attribute_changed?(markdown_field) || false
html_changed = attribute_changed?(html_field) || false
latest_cached_markdown_version == cached_markdown_version &&
(html_changed || markdown_changed == html_changed)
end
def invalidated_markdown_cache?
cached_markdown_fields.html_fields.any? {|html_field| attribute_invalidated?(html_field) }
end
def attribute_invalidated?(attr)
__send__("#{attr}_invalidated?") # rubocop:disable GitlabSecurity/PublicSend
end
def cached_html_for(markdown_field)
raise ArgumentError.new("Unknown field: #{field}") unless
cached_markdown_fields.markdown_fields.include?(markdown_field)
__send__(cached_markdown_fields.html_field(markdown_field)) # rubocop:disable GitlabSecurity/PublicSend
end
def latest_cached_markdown_version
@latest_cached_markdown_version ||= (CacheMarkdownField::CACHE_COMMONMARK_VERSION << 16) | local_version
end
def local_version
# because local_markdown_version is stored in application_settings which
# uses cached_markdown_version too, we check explicitly to avoid
# endless loop
return local_markdown_version if has_attribute?(:local_markdown_version)
settings = Gitlab::CurrentSettings.current_application_settings
# Following migrations are not properly isolated and
# use real models (by calling .ghost method), in these migrations
# local_markdown_version attribute doesn't exist yet, so we
# use a default value:
# db/migrate/20170825104051_migrate_issues_to_ghost_user.rb
# db/migrate/20171114150259_merge_requests_author_id_foreign_key.rb
if settings.respond_to?(:local_markdown_version)
settings.local_markdown_version
else
0
end
end
included do
cattr_reader :cached_markdown_fields do
FieldData.new
end
# Always exclude _html fields from attributes (including serialization).
# They contain unredacted HTML, which would be a security issue
alias_method :attributes_before_markdown_cache, :attributes
def attributes
attrs = attributes_before_markdown_cache
html_fields = cached_markdown_fields.html_fields
whitelisted = cached_markdown_fields.html_fields_whitelisted
exclude_fields = html_fields - whitelisted
exclude_fields.each do |field|
attrs.delete(field)
end
if whitelisted.empty?
attrs.delete('cached_markdown_version')
end
attrs
end
# Using before_update here conflicts with elasticsearch-model somehow
before_create :refresh_markdown_cache, if: :invalidated_markdown_cache?
before_update :refresh_markdown_cache, if: :invalidated_markdown_cache?
end
class_methods do
private
# Specify that a field is markdown. Its rendered output will be cached in
# a corresponding _html field. Any custom rendering options may be provided
# as a context.
def cache_markdown_field(markdown_field, context = {})
cached_markdown_fields[markdown_field] = context
html_field = cached_markdown_fields.html_field(markdown_field)
invalidation_method = "#{html_field}_invalidated?".to_sym
# The HTML becomes invalid if any dependent fields change. For now, assume
# author and project invalidate the cache in all circumstances.
define_method(invalidation_method) do
changed_fields = changed_attributes.keys
invalidations = changed_fields & [markdown_field.to_s, *INVALIDATED_BY]
invalidations.delete(markdown_field.to_s) if changed_fields.include?("#{markdown_field}_html")
!invalidations.empty? || !cached_html_up_to_date?(markdown_field)
end
end
end
end
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