Enhanced Rails Metal - the load order of metals can now be configured [#2057 state:resolved]

Signed-off-by: Joshua Peek <josh@joshpeek.com>

8 files changed, 105 insertions, 3 deletions

diff --git a/railties/lib/initializer.rb b/railties/lib/initializer.rb
index 24ce3e75ff..edea4e513a 100644
--- a/railties/lib/initializer.rb
+++ b/railties/lib/initializer.rb
@@ -559,6 +559,7 @@ Run `rake gems:install` to install the missing gems.
     end
 
     def initialize_metal
+      Rails::Rack::Metal.requested_metals = configuration.metals
       Rails::Rack::Metal.metal_paths += plugin_loader.engine_metal_paths
 
       configuration.middleware.insert_before(
@@ -715,6 +716,11 @@ Run `rake gems:install` to install the missing gems.
       @plugins = plugins.nil? ? nil : plugins.map { |p| p.to_sym }
     end
 
+    # The list of metals to load. If this is set to <tt>nil</tt>, all metals will
+    # be loaded in alphabetical order. If this is set to <tt>[]</tt>, no metals will
+    # be loaded. Otherwise metals will be loaded in the order specified
+    attr_accessor :metals
+
     # The path to the root of the plugins directory. By default, it is in
     # <tt>vendor/plugins</tt>.
     attr_accessor :plugin_paths
diff --git a/railties/lib/rails/rack/metal.rb b/railties/lib/rails/rack/metal.rb
index 8dac992ef2..bce59f4c78 100644
--- a/railties/lib/rails/rack/metal.rb
+++ b/railties/lib/rails/rack/metal.rb
@@ -8,16 +8,26 @@ module Rails
 
       cattr_accessor :metal_paths
       self.metal_paths = ["#{Rails.root}/app/metal"]
+      cattr_accessor :requested_metals
 
       def self.metals
         matcher = /#{Regexp.escape('/app/metal/')}(.*)\.rb\Z/
         metal_glob = metal_paths.map{ |base| "#{base}/**/*.rb" }
+        all_metals = {}
 
         Dir[*metal_glob].sort.map do |file|
-          path = file.match(matcher)[1]
-          require path
-          path.classify.constantize
+          file = file.match(matcher)[1]
+          all_metals[file.classify] = file
         end
+
+        load_list = requested_metals || all_metals.keys
+
+        load_list.map do |requested_metal|
+          if metal = all_metals[requested_metal]
+            require metal
+            requested_metal.constantize
+          end
+        end.compact
       end
 
       def initialize(app)
diff --git a/railties/test/fixtures/metal/multiplemetals/app/metal/metal_a.rb b/railties/test/fixtures/metal/multiplemetals/app/metal/metal_a.rb
new file mode 100644
index 0000000000..b8e7001351
--- /dev/null
+++ b/railties/test/fixtures/metal/multiplemetals/app/metal/metal_a.rb
@@ -0,0 +1,5 @@
+class MetalA < Rails::Rack::Metal
+  def self.call(env)
+    [200, { "Content-Type" => "text/html"}, "Hi"]
+  end
+end
diff --git a/railties/test/fixtures/metal/multiplemetals/app/metal/metal_b.rb b/railties/test/fixtures/metal/multiplemetals/app/metal/metal_b.rb
new file mode 100644
index 0000000000..adc2f45fcf
--- /dev/null
+++ b/railties/test/fixtures/metal/multiplemetals/app/metal/metal_b.rb
@@ -0,0 +1,5 @@
+class MetalB < Rails::Rack::Metal
+  def self.call(env)
+    [200, { "Content-Type" => "text/html"}, "Hi"]
+  end
+end
diff --git a/railties/test/fixtures/metal/singlemetal/app/metal/foo_metal.rb b/railties/test/fixtures/metal/singlemetal/app/metal/foo_metal.rb
new file mode 100644
index 0000000000..9ade2ce8e7
--- /dev/null
+++ b/railties/test/fixtures/metal/singlemetal/app/metal/foo_metal.rb
@@ -0,0 +1,5 @@
+class FooMetal < Rails::Rack::Metal
+  def self.call(env)
+    [200, { "Content-Type" => "text/html"}, "Hi"]
+  end
+end
diff --git a/railties/test/fixtures/metal/subfolders/app/metal/Folder/metal_a.rb b/railties/test/fixtures/metal/subfolders/app/metal/Folder/metal_a.rb
new file mode 100644
index 0000000000..71a5a62eb8
--- /dev/null
+++ b/railties/test/fixtures/metal/subfolders/app/metal/Folder/metal_a.rb
@@ -0,0 +1,7 @@
+module Folder
+  class MetalA < Rails::Rack::Metal
+    def self.call(env)
+      [200, { "Content-Type" => "text/html"}, "Hi"]
+    end
+  end
+end
diff --git a/railties/test/fixtures/metal/subfolders/app/metal/Folder/metal_b.rb b/railties/test/fixtures/metal/subfolders/app/metal/Folder/metal_b.rb
new file mode 100644
index 0000000000..430d7bfed6
--- /dev/null
+++ b/railties/test/fixtures/metal/subfolders/app/metal/Folder/metal_b.rb
@@ -0,0 +1,7 @@
+module Folder
+  class MetalB < Rails::Rack::Metal
+    def self.call(env)
+      [200, { "Content-Type" => "text/html"}, "Hi"]
+    end
+  end
+end
diff --git a/railties/test/metal_test.rb b/railties/test/metal_test.rb
new file mode 100644
index 0000000000..cff231ed00
--- /dev/null
+++ b/railties/test/metal_test.rb
@@ -0,0 +1,57 @@
+require 'abstract_unit'
+require 'initializer'
+
+class MetalTest < Test::Unit::TestCase
+  def test_metals_should_return_list_of_found_metal_apps
+    use_appdir("singlemetal") do
+      assert_equal(["FooMetal"], found_metals_as_string_array)
+    end
+  end
+
+  def test_metals_should_return_alphabetical_list_of_found_metal_apps
+    use_appdir("multiplemetals") do
+      assert_equal(["MetalA", "MetalB"], found_metals_as_string_array)
+    end
+  end
+
+  def test_metals_load_order_should_be_overriden_by_requested_metals
+    use_appdir("multiplemetals") do
+      Rails::Rack::Metal.requested_metals = ["MetalB", "MetalA"]
+      assert_equal(["MetalB", "MetalA"], found_metals_as_string_array)
+    end
+  end
+
+  def test_metals_not_listed_should_not_load
+    use_appdir("multiplemetals") do
+      Rails::Rack::Metal.requested_metals = ["MetalB"]
+      assert_equal(["MetalB"], found_metals_as_string_array)
+    end
+  end
+p
+  def test_metal_finding_should_work_with_subfolders
+    use_appdir("subfolders") do
+      assert_equal(["Folder::MetalA", "Folder::MetalB"], found_metals_as_string_array)
+    end
+  end
+
+  def test_metal_finding_with_requested_metals_should_work_with_subfolders
+    use_appdir("subfolders") do
+      Rails::Rack::Metal.requested_metals = ["Folder::MetalB"]
+      assert_equal(["Folder::MetalB"], found_metals_as_string_array)
+    end
+  end
+
+  private
+
+  def use_appdir(root)
+    dir = "#{File.dirname(__FILE__)}/fixtures/metal/#{root}"
+    Rails::Rack::Metal.metal_paths = ["#{dir}/app/metal"]
+    Rails::Rack::Metal.requested_metals = nil
+    $LOAD_PATH << "#{dir}/app/metal"
+    yield
+  end
+
+  def found_metals_as_string_array
+    Rails::Rack::Metal.metals.map { |m| m.to_s }
+  end
+end