From 6f9810e779b6fcb5d931665539fc95a5a29ebe93 Mon Sep 17 00:00:00 2001
From: Paul Rosania <paul.rosania@gmail.com>
Date: Thu, 28 Jan 2010 16:50:24 -0500
Subject: [PATCH] tsort-based dependency resolution for initializers

---
 activerecord/lib/active_record/railtie.rb          |    2 +-
 railties/lib/rails/initializable.rb                |   29 +++++--------
 .../application/initializers/frameworks_test.rb    |    2 +-
 railties/test/initializable_test.rb                |   43 +++++++++++++++++++-
 4 files changed, 55 insertions(+), 21 deletions(-)

diff --git a/activerecord/lib/active_record/railtie.rb b/activerecord/lib/active_record/railtie.rb
index 5e4ce34..e061ca5 100644
--- a/activerecord/lib/active_record/railtie.rb
+++ b/activerecord/lib/active_record/railtie.rb
@@ -47,7 +47,7 @@ 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 d91f678..730fd0f 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/test/application/initializers/frameworks_test.rb b/railties/test/application/initializers/frameworks_test.rb
index ea05232..a84b882 100644
--- a/railties/test/application/initializers/frameworks_test.rb
+++ b/railties/test/application/initializers/frameworks_test.rb
@@ -1,7 +1,7 @@
 require "isolation/abstract_unit"
 
 module ApplicationTests
-  class FrameworlsTest < Test::Unit::TestCase
+  class FrameworksTest < Test::Unit::TestCase
     include ActiveSupport::Testing::Isolation
 
     def setup
diff --git a/railties/test/initializable_test.rb b/railties/test/initializable_test.rb
index 0c7378c..3bce63f 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
 
@@ -120,6 +120,39 @@ module InitializableTests
       super + MoreInitializers.new.initializers
     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
-- 
1.6.4.2