Abstract publishing, subscribing and instrumenting in Orchestra.

activesupport/lib/active_support/orchestra.rb

@@ -1,4 +1,5 @@
 require 'thread'
+require 'active_support/core_ext/module/delegation'
 
 module ActiveSupport
   # Orchestra provides an instrumentation API for Ruby. To instrument an action
@@ -31,22 +32,65 @@ module ActiveSupport
   module Orchestra
     mattr_accessor :queue
 
-    @stacked_events = Hash.new { |h,k| h[k] = [] }
+    class << self
+      delegate :instrument, :to => :instrumenter
 
-    def self.instrument(name, payload=nil)
-      stack = @stacked_events[Thread.current.object_id]
-      event = Event.new(name, stack.last, payload)
-      stack << event
-      event.result = yield
-      event
-    ensure
-      event.finish!
-      stack.delete(event)
-      queue.push(event)
+      def instrumenter
+        Thread.current[:orchestra_instrumeter] ||= Instrumenter.new(publisher)
+      end
+
+      def publisher
+        @publisher ||= Publisher.new(queue)
+      end
+
+      def subscribe(pattern=nil, &block)
+        Subscriber.new(queue).bind(pattern).subscribe(&block)
+      end
     end
 
-    def self.subscribe(pattern=nil, &block)
-      queue.subscribe(pattern, &block)
+    class Instrumenter
+      def initialize(publisher)
+        @publisher = publisher
+        @stack = []
+      end
+
+      def instrument(name, payload=nil)
+        event = Event.new(name, @stack.last, payload)
+        @stack << event
+        event.result = yield
+        event
+      ensure
+        event.finish!
+        @stack.pop
+        @publisher.publish(event)
+      end
+    end
+
+    class Publisher
+      def initialize(queue)
+        @queue = queue
+      end
+
+      def publish(event)
+        @queue.publish(event)
+      end
+    end
+
+    class Subscriber
+      def initialize(queue)
+        @queue = queue
+      end
+
+      def bind(pattern)
+        @pattern = pattern
+        self
+      end
+
+      def subscribe
+        @queue.subscribe(@pattern) do |event|
+          yield event
+        end
+      end
     end
 
     class Event
@@ -80,7 +124,7 @@ module ActiveSupport
         end
       end
 
-      def push(event)
+      def publish(event)
         @stream.push(event)
         @thread.run
       end