Add ability to get the root-router

lib/fluent/plugin_helper/event_emitter.rb

@@ -47,7 +47,11 @@ def event_emitter_used_actually?
 
       def event_emitter_router(label_name)
         if label_name
-          Engine.root_agent.find_label(label_name).event_router
+          if label_name == "@ROOT"
+            Engine.root_agent.event_router
+          else
+            Engine.root_agent.find_label(label_name).event_router
+          end
         elsif self.respond_to?(:as_secondary) && self.as_secondary
           if @primary_instance.has_router?
             @_event_emitter_lazy_init = true

lib/fluent/root_agent.rb

@@ -131,6 +131,7 @@ def configure(conf)
         end
         name = e.arg
         raise ConfigError, "Missing symbol argument on <label> directive" if name.empty?
+        raise ConfigError, "@ROOT for <label> is not permitted, reserved for getting root router" if name == '@ROOT'
 
         if name == ERROR_LABEL
           error_label_config = e

test/plugin_helper/test_event_emitter.rb

@@ -1,6 +1,7 @@
 require_relative '../helper'
 require 'fluent/plugin_helper/event_emitter'
 require 'fluent/plugin/base'
+require 'flexmock/test_unit'
 
 class EventEmitterTest < Test::Unit::TestCase
   setup do
@@ -48,4 +49,32 @@ class Dummy < Fluent::Plugin::TestBase
 
     d1.terminate
   end
+
+  test 'should not have event_emitter_router' do
+    d0 = Dummy0.new
+    assert !d0.respond_to?(:event_emitter_router)
+  end
+
+  test 'should have event_emitter_router' do
+    d = Dummy.new
+    assert d.respond_to?(:event_emitter_router)
+  end
+
+  test 'get router' do
+    router_mock = flexmock('mytest')
+    label_mock = flexmock('mylabel')
+    label_mock.should_receive(:event_router).twice.and_return(router_mock)
+    Fluent::Engine.root_agent.labels['@mytest'] = label_mock
+
+    d = Dummy.new
+    d.configure(config_element('ROOT', '', {'@label' => '@mytest'}))
+    router = d.event_emitter_router("@mytest")
+    assert_equal router_mock, router
+  end
+
+  test 'get root router' do
+    d = Dummy.new
+    router = d.event_emitter_router("@ROOT")
+    assert_equal Fluent::Engine.root_agent.event_router, router
+  end
 end

test/test_root_agent.rb

@@ -109,6 +109,34 @@ def configure_ra(conf_str)
       end
     end
 
+    test 'raises configuration error for label without name' do
+      conf = <<-EOC
+<label>
+  @type test_out
+</label>
+EOC
+      errmsg = "Missing symbol argument on <label> directive"
+      assert_raise Fluent::ConfigError.new(errmsg) do
+        configure_ra(conf)
+      end
+    end
+
+    test 'raises configuration error for <label @ROOT>' do
+      conf = <<-EOC
+<source>
+  @type test_in
+  @label @ROOT
+</source>
+<label @ROOT>
+  @type test_out
+</label>
+EOC
+      errmsg = "@ROOT for <label> is not permitted, reserved for getting root router"
+      assert_raise Fluent::ConfigError.new(errmsg) do
+        configure_ra(conf)
+      end
+    end
+
     test 'raises configuration error if there are not match sections in label section' do
       conf = <<-EOC
 <source>