Merge branch 'master' into treewip

* master: (27 commits)
  move digest cache on to the DetailsKey object
  remove object `hash` cache
  [ci skip] fix suggested change-replace 'an' with 'the in Rails engine guide'
  Missing documentation about hash algorithm option for MessageVerifier [ci skip]
  set `skip_listen` option to dummy appplication
  Fix the language in engines guide
  Add accidentally removed `#` [ci skip]
  fields_for_style needs to test for AC::Parameters
  Fix indentation for code block in changelog
  Remove accidentally duplicated change log title [ci skip]
  partially revert 69009f4473637a44ade26d954ef5ddea6ff903f2
  Remove needless `case_insensitive_comparison` in mysql2 adapter
  modify to `error` also abort when specify fail fast option
  Implement ActionController::Parameters#inspect
  remove unused method
  Remove unused Journey code
  Add Action Cable CHANGELOG in release notes [ci skip]
  Show proper error message when a non-relation object is passed to AR::Relation#or
  Fix semantics of test names for finish option in batches_test
  Fix typo
  ...

Conflicts:
	actionview/lib/action_view/digestor.rb

4 files changed, 33 insertions, 13 deletions

diff --git a/actionview/lib/action_view/digestor.rb b/actionview/lib/action_view/digestor.rb
index ad6c65c436..07600f2092 100644
--- a/actionview/lib/action_view/digestor.rb
+++ b/actionview/lib/action_view/digestor.rb
@@ -4,13 +4,11 @@ require 'monitor'
 
 module ActionView
   class Digestor
-    cattr_reader(:cache)
-    @@cache          = Concurrent::Map.new
     @@digest_mutex   = Mutex.new
 
     class PerRequestDigestCacheExpiry < Struct.new(:app) # :nodoc:
       def call(env)
-        ActionView::Digestor.cache.clear
+        ActionView::LookupContext::DetailsKey.clear
         app.call(env)
       end
     end
@@ -24,13 +22,13 @@ module ActionView
       # * <tt>partial</tt>  - Specifies whether the template is a partial
       def digest(name:, finder:, dependencies: [])
         dependencies ||= []
-        cache_key = ([ name, finder.details_key.hash ].compact + dependencies).join('.')
+        cache_key = ([ name ].compact + dependencies).join('.')
 
         # this is a correctly done double-checked locking idiom
         # (Concurrent::Map's lookups have volatile semantics)
-        @@cache[cache_key] || @@digest_mutex.synchronize do
-          @@cache.fetch(cache_key) do # re-check under lock
-            @@cache[cache_key] = tree(name, finder, dependencies).digest
+        finder.digest_cache[cache_key] || @@digest_mutex.synchronize do
+          finder.digest_cache.fetch(cache_key) do # re-check under lock
+            finder.digest_cache[cache_key] = tree(name, finder, dependencies).digest
           end
         end
       end
@@ -50,6 +48,7 @@ module ActionView
           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)
diff --git a/actionview/lib/action_view/lookup_context.rb b/actionview/lib/action_view/lookup_context.rb
index 126f289f55..86afedaa2d 100644
--- a/actionview/lib/action_view/lookup_context.rb
+++ b/actionview/lib/action_view/lookup_context.rb
@@ -55,9 +55,7 @@ module ActionView
 
     class DetailsKey #:nodoc:
       alias :eql? :equal?
-      alias :object_hash :hash
 
-      attr_reader :hash
       @details_keys = Concurrent::Map.new
 
       def self.get(details)
@@ -72,8 +70,16 @@ module ActionView
         @details_keys.clear
       end
 
+      def self.empty?; @details_keys.empty?; end
+
+      def self.digest_caches
+        @details_keys.values.map(&:digest_cache)
+      end
+
+      attr_reader :digest_cache
+
       def initialize
-        @hash = object_hash
+        @digest_cache = Concurrent::Map.new
       end
     end
 
@@ -200,6 +206,10 @@ module ActionView
       self.view_paths = view_paths
     end
 
+    def digest_cache
+      details_key.digest_cache
+    end
+
     def initialize_details(target, details)
       registered_details.each do |k|
         target[k] = details[k] || Accessors::DEFAULT_PROCS[k].call
diff --git a/actionview/test/fixtures/digestor/messages/peek.html.erb b/actionview/test/fixtures/digestor/messages/peek.html.erb
new file mode 100644
index 0000000000..84885ab0bc
--- /dev/null
+++ b/actionview/test/fixtures/digestor/messages/peek.html.erb
@@ -0,0 +1,2 @@
+<%# Template Dependency: messages/message %>
+<%= render "comments/comments" %>
diff --git a/actionview/test/template/digestor_test.rb b/actionview/test/template/digestor_test.rb
index 37c94d8831..6384aac46e 100644
--- a/actionview/test/template/digestor_test.rb
+++ b/actionview/test/template/digestor_test.rb
@@ -33,7 +33,6 @@ class TemplateDigestorTest < ActionView::TestCase
   def teardown
     Dir.chdir @cwd
     FileUtils.rm_r @tmp_dir
-    ActionView::Digestor.cache.clear
   end
 
   def test_top_level_change_reflected
@@ -130,6 +129,16 @@ class TemplateDigestorTest < ActionView::TestCase
     end
   end
 
+  def test_getting_of_singly_nested_dependencies
+    singly_nested_dependencies = ["messages/header", "messages/form", "messages/message", "events/event", "comments/comment"]
+    assert_equal singly_nested_dependencies, nested_dependencies('messages/edit')
+  end
+
+  def test_getting_of_doubly_nested_dependencies
+    doubly_nested = [{"comments/comments"=>["comments/comment"]}, "messages/message"]
+    assert_equal doubly_nested, nested_dependencies('messages/peek')
+  end
+
   def test_nested_template_directory
     assert_digest_difference("messages/show") do
       change_template("messages/actions/_move")
@@ -296,12 +305,12 @@ class TemplateDigestorTest < ActionView::TestCase
 
     def assert_digest_difference(template_name, options = {})
       previous_digest = digest(template_name, options)
-      ActionView::Digestor.cache.clear
+      finder.digest_cache.clear
 
       yield
 
       assert_not_equal previous_digest, digest(template_name, options), "digest didn't change"
-      ActionView::Digestor.cache.clear
+      finder.digest_cache.clear
     end
 
     def digest(template_name, options = {})