require "concurrent/map" require "action_view/dependency_tracker" require "monitor" module ActionView class Digestor @@digest_mutex = Mutex.new module PerExecutionDigestCacheExpiry def self.before(target) ActionView::LookupContext::DetailsKey.clear end end class << self # Supported options: # # * name - Template name # * finder - An instance of ActionView::LookupContext # * dependencies - An array of dependent views def digest(name:, finder:, dependencies: []) dependencies ||= [] cache_key = [ name, finder.rendered_format, dependencies ].flatten.compact.join(".") # this is a correctly done double-checked locking idiom # (Concurrent::Map's lookups have volatile semantics) finder.digest_cache[cache_key] || @@digest_mutex.synchronize do finder.digest_cache.fetch(cache_key) do # re-check under lock partial = name.include?("/_") root = tree(name, finder, partial) dependencies.each do |injected_dep| root.children << Injected.new(injected_dep, nil, nil) end finder.digest_cache[cache_key] = root.digest(finder) end end end def logger ActionView::Base.logger || NullLogger end # Create a dependency tree for template named +name+. def tree(name, finder, partial = false, seen = {}) logical_name = name.gsub(%r|/_|, "/") options = {} options[:formats] = [finder.rendered_format] if finder.rendered_format if template = finder.disable_cache { finder.find_all(logical_name, [], partial, [], options).first } finder.rendered_format ||= template.formats.first if node = seen[template.identifier] # handle cycles in the tree node else node = seen[template.identifier] = Node.create(name, logical_name, template, partial) deps = DependencyTracker.find_dependencies(name, template, finder.view_paths) deps.uniq { |n| n.gsub(%r|/_|, "/") }.each do |dep_file| node.children << tree(dep_file, finder, true, seen) end node end else logger.error " '#{name}' file doesn't exist, so no dependencies" logger.error " Couldn't find template for digesting: #{name}" seen[name] ||= Missing.new(name, logical_name, nil) end end end class Node attr_reader :name, :logical_name, :template, :children def self.create(name, logical_name, template, partial) klass = partial ? Partial : Node klass.new(name, logical_name, template, []) end def initialize(name, logical_name, template, children = []) @name = name @logical_name = logical_name @template = template @children = children end def digest(finder, stack = []) Digest::MD5.hexdigest("#{template.source}-#{dependency_digest(finder, stack)}") end def dependency_digest(finder, stack) children.map do |node| if stack.include?(node) false else finder.digest_cache[node.name] ||= begin stack.push node node.digest(finder, stack).tap { stack.pop } end end end.join("-") end def to_dep_map children.any? ? { name => children.map(&:to_dep_map) } : name end end class Partial < Node; end class Missing < Node def digest(finder, _ = []) "" end end class Injected < Node def digest(finder, _ = []) name end end class NullLogger def self.debug(_); end def self.error(_); end end end end