1 files changed, 101 insertions, 0 deletions
diff --git a/activesupport/lib/active_support/notifications/fanout.rb b/activesupport/lib/active_support/notifications/fanout.rb
new file mode 100644
index 0000000000..bb07e4765c
--- /dev/null
+++ b/activesupport/lib/active_support/notifications/fanout.rb
@@ -0,0 +1,101 @@
+require 'thread'
+
+module ActiveSupport
+  module Notifications
+    # This is a default queue implementation that ships with Notifications. It
+    # consumes events in a thread and publish them to all registered subscribers.
+    #
+    class Fanout
+      def initialize(sync = false)
+        @subscriber_klass = sync ? Subscriber : AsyncSubscriber
+        @subscribers = []
+      end
+
+      def bind(pattern)
+        Binding.new(self, pattern)
+      end
+
+      def subscribe(pattern = nil, &block)
+        @subscribers << @subscriber_klass.new(pattern, &block)
+      end
+
+      def publish(*args)
+        @subscribers.each { |s| s.publish(*args) }
+      end
+
+      def wait
+        sleep(0.05) until @subscribers.all?(&:drained?)
+      end
+
+      # Used for internal implementation only.
+      class Binding #:nodoc:
+        def initialize(queue, pattern)
+          @queue = queue
+          @pattern =
+            case pattern
+            when Regexp, NilClass
+              pattern
+            else
+              /^#{Regexp.escape(pattern.to_s)}/
+            end
+        end
+
+        def subscribe(&block)
+          @queue.subscribe(@pattern, &block)
+        end
+      end
+
+      class Subscriber #:nodoc:
+        def initialize(pattern, &block)
+          @pattern = pattern
+          @block = block
+        end
+
+        def publish(*args)
+          push(*args) if matches?(args.first)
+        end
+
+        def drained?
+          true
+        end
+
+        private
+          def matches?(name)
+            !@pattern || @pattern =~ name.to_s
+          end
+
+          def push(*args)
+            @block.call(*args)
+          end
+      end
+
+      # Used for internal implementation only.
+      class AsyncSubscriber < Subscriber #:nodoc:
+        def initialize(pattern, &block)
+          super
+          @events = Queue.new
+          start_consumer
+        end
+
+        def drained?
+          @events.empty?
+        end
+
+        private
+          def start_consumer
+            Thread.new { consume }
+          end
+
+          def consume
+            while args = @events.shift
+              @block.call(*args)
+            end
+          end
+
+          def push(*args)
+            @events << args
+          end
+      end
+    end
+  end
+end