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