Adds a throttle notifier to throttle any notifier

lib/exception_notifier.rb

@@ -10,6 +10,7 @@ module ExceptionNotifier
   autoload :HipchatNotifier, 'exception_notifier/hipchat_notifier'
   autoload :WebhookNotifier, 'exception_notifier/webhook_notifier'
   autoload :IrcNotifier, 'exception_notifier/irc_notifier'
+  autoload :ThrottleNotifier, 'exception_notifier/throttle_notifier'
 
   class UndefinedNotifierError < StandardError; end
 
@@ -74,6 +75,12 @@ def clear_ignore_conditions!
       @@ignores.clear
     end
 
+    def create_notifier(name, options)
+      notifier_classname = "#{name}_notifier".camelize
+      notifier_class = ExceptionNotifier.const_get(notifier_classname)
+      notifier_class.new(options)
+    end
+
     private
     def ignored?(exception, options)
       @@ignores.any?{ |condition| condition.call(exception, options) }
@@ -95,10 +102,7 @@ def fire_notification(notifier_name, exception, options)
     end
 
     def create_and_register_notifier(name, options)
-      notifier_classname = "#{name}_notifier".camelize
-      notifier_class = ExceptionNotifier.const_get(notifier_classname)
-      notifier = notifier_class.new(options)
-      register_exception_notifier(name, notifier)
+      register_exception_notifier(name, create_notifier(name, options))
     rescue NameError => e
       raise UndefinedNotifierError, "No notifier named '#{name}' was found. Please, revise your configuration options. Cause: #{e.message}"
     end

lib/exception_notifier/throttle_notifier.rb

@@ -0,0 +1,23 @@
+module ExceptionNotifier
+  class ThrottleNotifier
+    def initialize options={}
+      @notifier = ExceptionNotifier.create_notifier(options[:notifier], options[:notifier_options] || {})
+      @max_notifications_per_hour = 3
+      @past_exceptions = Hash.new {|h,k| h[k] = []}
+    end
+
+    def call(exception, options={})
+      key = exception.class.to_s.each_byte.reduce(&:+)
+
+      past_times = @past_exceptions[key]
+      past_times.reject! {|t| (Time.now - t) >= 3600}
+      past_times << Time.now
+
+      if past_times.size <= @max_notifications_per_hour
+        @notifier.call exception, options
+      else
+        ExceptionNotifier::logger.warn "An exception occurred (#{exception}) and the notifier #{@notifier} was throttled."
+      end
+    end
+  end
+end

test/exception_notifier/throttle_notifier_test.rb

@@ -0,0 +1,41 @@
+require 'test_helper'
+
+class ThrottleNotifierTest < ActiveSupport::TestCase
+  setup do
+    @throttle = ExceptionNotifier::ThrottleNotifier.new notifier: :email
+    @notifier = @throttle.instance_variable_get "@notifier"
+  end
+
+  test "should delegate to notifier by default" do
+    exception = Exception.new
+    options = {}
+    @notifier.expects(:call).with(exception, options)
+
+    @throttle.call exception, options
+  end
+
+  test "should stop delegating after three equivalent exceptions occur" do
+    exception = Exception.new
+    options = {}
+    @notifier.expects(:call).with(exception, options).times(3)
+    ExceptionNotifier::logger.expects(:warn).stubs(:warn)
+
+    4.times { @throttle.call exception, options }
+  end
+
+  test "should resume delegating after an hour has passed" do
+    Time.stubs(:now).returns(Time.new 2000,1,1,1)
+    exception = Exception.new
+    options = {}
+    @notifier.stubs(:call)
+    ExceptionNotifier::logger.expects(:warn).times(2).stubs(:warn)
+
+    4.times { @throttle.call exception, options }
+
+    Time.stubs(:now).returns(Time.new 2000,1,1,2)
+    @notifier.expects(:call).with(exception, options).times(3)
+
+    4.times { @throttle.call exception, options }
+  end
+end
+