tsort-based dependency resolution for initializers

Signed-off-by: Jeremy Kemper <jeremy@bitsweat.net>

5 files changed, 56 insertions, 22 deletions

diff --git a/activerecord/lib/active_record/railtie.rb b/activerecord/lib/active_record/railtie.rb
index dc80ac4b30..30da494d57 100644
--- a/activerecord/lib/active_record/railtie.rb
+++ b/activerecord/lib/active_record/railtie.rb
@@ -50,7 +50,7 @@ module ActiveRecord
     end
 
     # Setup database middleware after initializers have run
-    initializer "active_record.initialize_database_middleware" do |app|
+    initializer "active_record.initialize_database_middleware", :after => "action_controller.set_configs" do |app|
       middleware = app.config.middleware
       if middleware.include?("ActiveRecord::SessionStore")
         middleware.insert_before "ActiveRecord::SessionStore", ActiveRecord::ConnectionAdapters::ConnectionManagement
diff --git a/railties/lib/rails/initializable.rb b/railties/lib/rails/initializable.rb
index d91f67823f..9a82e051e7 100644
--- a/railties/lib/rails/initializable.rb
+++ b/railties/lib/rails/initializable.rb
@@ -1,3 +1,5 @@
+require 'tsort'
+
 module Rails
   module Initializable
     def self.included(base)
@@ -30,29 +32,21 @@ module Rails
     end
 
     class Collection < Array
+      include TSort
+
+      alias :tsort_each_node :each
+      def tsort_each_child(initializer, &block)
+        select { |i| i.before == initializer.name || i.name == initializer.after }.each(&block)
+      end
+
       def initialize(initializers = [])
-        super()
-        initializers.each do |initializer|
-          if initializer.before
-            index = index_for(initializer.before)
-          elsif initializer.after
-            index = index_for(initializer.after)
-            index += 1 if index
-          else
-            index = length
-          end
-          insert(index || -1, initializer)
-        end
+        super(initializers)
+        replace(tsort)
       end
 
       def +(other)
         Collection.new(to_a + other.to_a)
       end
-
-      def index_for(name)
-        initializer = find { |i| i.name == name }
-        initializer && index(initializer)
-      end
     end
 
     def run_initializers(*args)
@@ -87,6 +81,7 @@ module Rails
 
       def initializer(name, opts = {}, &blk)
         raise ArgumentError, "A block must be passed when defining an initializer" unless blk
+        opts[:after] ||= initializers.last.name unless initializers.empty? || initializers.find { |i| i.name == opts[:before] }
         initializers << Initializer.new(name, nil, opts, &blk)
       end
 
diff --git a/railties/lib/rails/plugin.rb b/railties/lib/rails/plugin.rb
index 881c97f02d..64d03e7599 100644
--- a/railties/lib/rails/plugin.rb
+++ b/railties/lib/rails/plugin.rb
@@ -43,7 +43,7 @@ module Rails
       @config ||= Engine::Configuration.new
     end
 
-    initializer :load_init_rb do |app|
+    initializer :load_init_rb, :before => :load_application_initializers do |app|
       file   = Dir["#{root}/{rails/init,init}.rb"].first
       config = app.config
       eval(File.read(file), binding, file) if file && File.file?(file)
diff --git a/railties/test/initializable_test.rb b/railties/test/initializable_test.rb
index 0c7378cb64..6a7e4dcc25 100644
--- a/railties/test/initializable_test.rb
+++ b/railties/test/initializable_test.rb
@@ -50,7 +50,7 @@ module InitializableTests
       $arr << 3
     end
 
-    initializer :four, :after => :one do
+    initializer :four, :after => :one, :before => :two do
       $arr << 4
     end
   end
@@ -97,7 +97,7 @@ module InitializableTests
         $arr << 3
       end
 
-      initializer :terminate, :after => :first do
+      initializer :terminate, :after => :first, :before => :startup do
         $arr << two
       end
 
@@ -121,6 +121,39 @@ module InitializableTests
     end
   end
 
+  module Interdependent
+    class PluginA
+      include Rails::Initializable
+
+      initializer "plugin_a.startup" do
+        $arr << 1
+      end
+
+      initializer "plugin_a.terminate" do
+        $arr << 4
+      end
+    end
+
+    class PluginB
+      include Rails::Initializable
+
+      initializer "plugin_b.startup", :after => "plugin_a.startup" do
+        $arr << 2
+      end
+
+      initializer "plugin_b.terminate", :before => "plugin_a.terminate" do
+        $arr << 3
+      end
+    end
+
+    class Application
+      include Rails::Initializable
+      def self.initializers
+        PluginB.initializers + PluginA.initializers
+      end
+    end
+  end
+
   class Basic < ActiveSupport::TestCase
     include ActiveSupport::Testing::Isolation
 
@@ -174,6 +207,12 @@ module InitializableTests
       Child.run_initializers
       assert_equal [5, 3, 1, 4, 2], $arr
     end
+
+    test "handles dependencies introduced before all initializers are loaded" do
+      $arr = []
+      Interdependent::Application.run_initializers
+      assert_equal [1, 2, 3, 4], $arr
+    end
   end
 
   class InstanceTest < ActiveSupport::TestCase
diff --git a/railties/test/railties/plugin_test.rb b/railties/test/railties/plugin_test.rb
index 997b692e49..09b859dcdd 100644
--- a/railties/test/railties/plugin_test.rb
+++ b/railties/test/railties/plugin_test.rb
@@ -47,7 +47,7 @@ module RailtiesTest
       assert_equal :debug, LEVEL
     end
 
-    test "plugin_init_is_ran_before_application_ones" do
+    test "plugin_init_is_run_before_application_ones" do
       plugin "foo", "$foo = true" do |plugin|
         plugin.write "lib/foo.rb", "module Foo; end"
       end