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Diffstat (limited to 'actionview/lib/action_view/digestor.rb')
-rw-r--r-- | actionview/lib/action_view/digestor.rb | 122 |
1 files changed, 122 insertions, 0 deletions
diff --git a/actionview/lib/action_view/digestor.rb b/actionview/lib/action_view/digestor.rb new file mode 100644 index 0000000000..72d79735ae --- /dev/null +++ b/actionview/lib/action_view/digestor.rb @@ -0,0 +1,122 @@ +require 'thread_safe' +require 'action_view/dependency_tracker' +require 'monitor' + +module ActionView + class Digestor + cattr_reader(:cache) + @@cache = ThreadSafe::Cache.new + @@digest_monitor = Monitor.new + + class << self + # Supported options: + # + # * <tt>name</tt> - Template name + # * <tt>finder</tt> - An instance of ActionView::LookupContext + # * <tt>dependencies</tt> - An array of dependent views + # * <tt>partial</tt> - Specifies whether the template is a partial + def digest(options) + options.assert_valid_keys(:name, :finder, :dependencies, :partial) + + cache_key = ([ options[:name], options[:finder].details_key.hash ].compact + Array.wrap(options[:dependencies])).join('.') + + # this is a correctly done double-checked locking idiom + # (ThreadSafe::Cache's lookups have volatile semantics) + @@cache[cache_key] || @@digest_monitor.synchronize do + @@cache.fetch(cache_key) do # re-check under lock + compute_and_store_digest(cache_key, options) + end + end + end + + private + def compute_and_store_digest(cache_key, options) # called under @@digest_monitor lock + klass = if options[:partial] || options[:name].include?("/_") + # Prevent re-entry or else recursive templates will blow the stack. + # There is no need to worry about other threads seeing the +false+ value, + # as they will then have to wait for this thread to let go of the @@digest_monitor lock. + pre_stored = @@cache.put_if_absent(cache_key, false).nil? # put_if_absent returns nil on insertion + PartialDigestor + else + Digestor + end + + digest = klass.new(options).digest + # Store the actual digest if config.cache_template_loading is true + @@cache[cache_key] = stored_digest = digest if ActionView::Resolver.caching? + digest + ensure + # something went wrong or ActionView::Resolver.caching? is false, make sure not to corrupt the @@cache + @@cache.delete_pair(cache_key, false) if pre_stored && !stored_digest + end + end + + attr_reader :name, :finder, :options + + def initialize(options) + @name, @finder = options.values_at(:name, :finder) + @options = options.except(:name, :finder) + end + + def digest + Digest::MD5.hexdigest("#{source}-#{dependency_digest}").tap do |digest| + logger.try :info, " Cache digest for #{template.inspect}: #{digest}" + end + rescue ActionView::MissingTemplate + logger.try :error, " Couldn't find template for digesting: #{name}" + '' + end + + def dependencies + DependencyTracker.find_dependencies(name, template) + rescue ActionView::MissingTemplate + [] # File doesn't exist, so no dependencies + end + + def nested_dependencies + dependencies.collect do |dependency| + dependencies = PartialDigestor.new(name: dependency, finder: finder).nested_dependencies + dependencies.any? ? { dependency => dependencies } : dependency + end + end + + private + def logger + ActionView::Base.logger + end + + def logical_name + name.gsub(%r|/_|, "/") + end + + def partial? + false + end + + def template + @template ||= finder.disable_cache { finder.find(logical_name, [], partial?) } + end + + def source + template.source + end + + def dependency_digest + template_digests = dependencies.collect do |template_name| + Digestor.digest(name: template_name, finder: finder, partial: true) + end + + (template_digests + injected_dependencies).join("-") + end + + def injected_dependencies + Array.wrap(options[:dependencies]) + end + end + + class PartialDigestor < Digestor # :nodoc: + def partial? + true + end + end +end |