Orchestra listeners have their own queue.

activesupport/lib/active_support/orchestra.rb

@@ -3,31 +3,41 @@ require 'active_support/core_ext/module/delegation'
 
 module ActiveSupport
   # Orchestra provides an instrumentation API for Ruby. To instrument an action
-  # in Ruby you just need to:
+  # in Ruby you just need to do:
   #
   #   ActiveSupport::Orchestra.instrument(:render, :extra => :information) do
   #     render :text => "Foo"
   #   end
   #
-  # Those actions are consumed by listeners. A listener is anything that responds
-  # to push. You can even register an array:
+  # You can consume those events and the information they provide by registering
+  # a subscriber. For instance, let's store all instrumented events in an array:
   #
-  #   @listener = []
-  #   ActiveSupport::Orchestra.register @listener
+  #   @events = []
+  #
+  #   ActiveSupport::Orchestra.subscribe do |event|
+  #     @events << event
+  #   end
   #
   #   ActiveSupport::Orchestra.instrument(:render, :extra => :information) do
   #     render :text => "Foo"
   #   end
   #
-  #   event           #=> ActiveSupport::Orchestra::Event
+  #   event = @events.first
+  #   event.class     #=> ActiveSupport::Orchestra::Event
   #   event.name      #=> :render
   #   event.duration  #=> 10 (in miliseconds)
   #   event.result    #=> "Foo"
   #   event.payload   #=> { :extra => :information }
   #
-  # Orchestra ships with a default listener implementation which puts events in
-  # a stream and consume them in a Thread. This implementation is thread safe
-  # and is available at ActiveSupport::Orchestra::Listener.
+  # When subscribing to Orchestra, you can pass a pattern, to only consume
+  # events that match the pattern:
+  #
+  #   ActiveSupport::Orchestra.subscribe(/render/) do |event|
+  #     @render_events << event
+  #   end
+  #
+  # Orchestra ships with a queue implementation that consumes and publish events
+  # to subscribers in a thread. You can use any queue implementation you want.
   #
   module Orchestra
     mattr_accessor :queue
@@ -108,37 +118,43 @@ module ActiveSupport
     #
     class LittleFanout
       def initialize
-        @listeners, @stream = [], []
-
-        @thread = Thread.new do
-          loop do
-            (event = @stream.shift) ? consume(event) : Thread.stop
-          end
-        end
+        @listeners, @stream = [], Queue.new
+        @thread = Thread.new { consume }
       end
 
       def publish(*event)
         @stream.push(event)
-        @thread.run
       end
 
       def subscribe(pattern=nil, &block)
         @listeners << Listener.new(pattern, &block)
       end
 
-      def consume(event)
-        @listeners.each { |l| l.publish(*event) }
+      def consume
+        while event = @stream.shift
+          @listeners.each { |l| l.publish(*event) }
+        end
       end
 
       class Listener
+        attr_reader :thread
+
         def initialize(pattern, &block)
           @pattern = pattern
           @subscriber = block
+          @queue = Queue.new
+          @thread = Thread.new { consume }
         end
 
         def publish(name, payload)
           unless @pattern && name.to_s !~ @pattern
-            @subscriber.call(name, payload)
+            @queue << [name, payload]
+          end
+        end
+
+        def consume
+          while event = @queue.shift
+            @subscriber.call(*event)
           end
         end
       end

activesupport/test/orchestra_test.rb

@@ -50,6 +50,8 @@ class OrchestraMainTest < Test::Unit::TestCase
       1 + 1
     end
 
+    sleep(0.1)
+
     assert_equal 1, @events.size
     assert_equal :awesome, @events.last.name
     assert_equal Hash[:payload => "orchestra"], @events.last.payload
@@ -58,18 +60,22 @@ class OrchestraMainTest < Test::Unit::TestCase
   def test_nested_events_can_be_instrumented
     ActiveSupport::Orchestra.instrument(:awesome, :payload => "orchestra") do
       ActiveSupport::Orchestra.instrument(:wot, :payload => "child") do
-        sleep(0.1)
+        1 + 1
       end
 
+      sleep(0.1)
+
       assert_equal 1, @events.size
       assert_equal :wot, @events.first.name
       assert_equal Hash[:payload => "child"], @events.first.payload
-      assert_in_delta 100, @events.first.duration, 30
     end
 
+    sleep(0.1)
+
     assert_equal 2, @events.size
     assert_equal :awesome, @events.last.name
     assert_equal Hash[:payload => "orchestra"], @events.last.payload
+    assert_in_delta 100, @events.last.duration, 70
   end
 
   def test_event_is_pushed_even_if_block_fails
@@ -77,6 +83,8 @@ class OrchestraMainTest < Test::Unit::TestCase
       raise "OMG"
     end rescue RuntimeError
 
+    sleep(0.1)
+
     assert_equal 1, @events.size
     assert_equal :awesome, @events.last.name
     assert_equal Hash[:payload => "orchestra"], @events.last.payload
@@ -89,7 +97,7 @@ class OrchestraMainTest < Test::Unit::TestCase
     ActiveSupport::Orchestra.instrument(:something){ 0 }
     ActiveSupport::Orchestra.instrument(:cache){ 10 }
 
-    sleep 0.1
+    sleep(0.1)
 
     assert_equal 1, @another.size
     assert_equal :cache, @another.first.name