Optimize AS::Notifications to remember which subscribers don't match and not run them. This will allow notifications that are only useful in dev or testing to run efficiently in production.

2 files changed, 13 insertions, 4 deletions

diff --git a/activesupport/lib/active_support/notifications.rb b/activesupport/lib/active_support/notifications.rb
index fca2efd969..3f1fe64e9b 100644
--- a/activesupport/lib/active_support/notifications.rb
+++ b/activesupport/lib/active_support/notifications.rb
@@ -44,7 +44,7 @@ module ActiveSupport
 
     class << self
       attr_writer :notifier
-      delegate :publish, :subscribe, :to => :notifier
+      delegate :publish, :subscribe, :unsubscribe, :to => :notifier
       delegate :instrument, :to => :instrumenter
 
       def notifier
diff --git a/activesupport/lib/active_support/notifications/fanout.rb b/activesupport/lib/active_support/notifications/fanout.rb
index e08011e23f..cd60054862 100644
--- a/activesupport/lib/active_support/notifications/fanout.rb
+++ b/activesupport/lib/active_support/notifications/fanout.rb
@@ -5,6 +5,7 @@ module ActiveSupport
     class Fanout
       def initialize
         @subscribers = []
+        @listeners_for = {}
       end
 
       def bind(pattern)
@@ -12,16 +13,22 @@ module ActiveSupport
       end
 
       def subscribe(pattern = nil, &block)
+        @listeners_for.clear
         @subscribers << Subscriber.new(pattern, &block)
         @subscribers.last
       end
 
       def unsubscribe(subscriber)
         @subscribers.delete(subscriber)
+        @listeners_for.clear
       end
 
-      def publish(*args)
-        @subscribers.each { |s| s.publish(*args) }
+      def publish(name, *args)
+        if listeners = @listeners_for[name]
+          listeners.each { |s| s.publish(name, *args) }
+        else
+          @listeners_for[name] = @subscribers.select { |s| s.publish(name, *args) }
+        end
       end
 
       # This is a sync queue, so there is not waiting.
@@ -53,7 +60,9 @@ module ActiveSupport
         end
 
         def publish(*args)
-          push(*args) if matches?(args.first)
+          return unless matches?(args.first)
+          push(*args)
+          true
         end
 
         def drained?