Rename Orchestra to Notifications [#3321 state:resolved]

1 files changed, 103 insertions, 0 deletions

diff --git a/activesupport/lib/active_support/notifications.rb b/activesupport/lib/active_support/notifications.rb
new file mode 100644
index 0000000000..6335686196
--- /dev/null
+++ b/activesupport/lib/active_support/notifications.rb
@@ -0,0 +1,103 @@
+require 'thread'
+
+module ActiveSupport
+  # Notifications provides an instrumentation API for Ruby. To instrument an action
+  # in Ruby you just need to:
+  #
+  #   ActiveSupport::Notifications.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:
+  #
+  #   @listener = []
+  #   ActiveSupport::Notifications.register @listener
+  #
+  #   ActiveSupport::Notifications.instrument(:render, :extra => :information) do
+  #     render :text => "Foo"
+  #   end
+  #
+  #   event           #=> ActiveSupport::Notifications::Event
+  #   event.name      #=> :render
+  #   event.duration  #=> 10 (in miliseconds)
+  #   event.result    #=> "Foo"
+  #   event.payload   #=> { :extra => :information }
+  #
+  # Notifications 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::Notifications::Listener.
+  #
+  module Notifications
+    @stacked_events = Hash.new { |h,k| h[k] = [] }
+    @listeners = []
+
+    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)
+      @listeners.each { |s| s.push(event) }
+    end
+
+    def self.register(listener)
+      @listeners << listener
+    end
+
+    def self.unregister(listener)
+      @listeners.delete(listener)
+    end
+
+    class Event
+      attr_reader :name, :time, :duration, :parent, :thread_id, :payload
+      attr_accessor :result
+
+      def initialize(name, parent=nil, payload=nil)
+        @name      = name
+        @time      = Time.now
+        @thread_id = Thread.current.object_id
+        @parent    = parent
+        @payload   = payload
+      end
+
+      def finish!
+        @duration = 1000 * (Time.now.to_f - @time.to_f)
+      end
+    end
+
+    class Listener
+      attr_reader :mutex, :signaler, :thread
+
+      def initialize
+        @mutex, @signaler = Mutex.new, ConditionVariable.new
+        @stream = []
+        @thread = Thread.new do
+          loop do
+            (event = @stream.shift) ? consume(event) : wait
+          end
+        end
+      end
+
+      def wait
+        @mutex.synchronize do
+          @signaler.wait(@mutex)
+        end
+      end
+
+      def push(event)
+        @mutex.synchronize do
+          @stream.push(event)
+          @signaler.broadcast
+        end
+      end
+
+      def consume(event)
+        raise NotImplementedError
+      end
+    end
+  end
+end