Add lifecycle event registration support

lib/shoryuken.rb

@@ -26,7 +26,12 @@ module Shoryuken
     queues: [],
     aws: {},
     delay: 0,
-    timeout: 8
+    timeout: 8,
+    lifecycle_events: {
+      startup: [],
+      quiet: [],
+      shutdown: [],
+    }
   }
 
   @@queues = []
@@ -112,6 +117,20 @@ def on_stop(&block)
       @stop_callback = block
     end
 
+    # Register a block to run at a point in the Shoryuken lifecycle.
+    # :startup, :quiet or :shutdown are valid events.
+    #
+    #   Shoryuken.configure_server do |config|
+    #     config.on(:shutdown) do
+    #       puts "Goodbye cruel world!"
+    #     end
+    #   end
+    def on(event, &block)
+      raise ArgumentError, "Symbols only please: #{event}" unless event.is_a?(Symbol)
+      raise ArgumentError, "Invalid event name: #{event}" unless options[:lifecycle_events].key?(event)
+      options[:lifecycle_events][event] << block
+    end
+
     attr_reader :aws_initialization_callback,
                 :start_callback,
                 :stop_callback

lib/shoryuken/cli.rb

@@ -45,6 +45,8 @@ def run(args)
         callback.call
       end
 
+      fire_event(:startup)
+
       begin
         launcher.run
 
@@ -173,7 +175,7 @@ def handle_signal(sig)
         logger.info { 'Received USR1, will soft shutdown down' }
 
         launcher.stop
-
+        fire_event(:quiet, true)
         exit 0
       when 'TTIN'
         Thread.list.each do |thread|

lib/shoryuken/manager.rb

@@ -37,6 +37,8 @@ def stop(options = {})
           callback.call
         end
 
+        fire_event(:shutdown, true)
+
         @fetcher.terminate if @fetcher.alive?
 
         logger.info { "Shutting down #{@ready.size} quiet workers" }

lib/shoryuken/util.rb

@@ -12,6 +12,20 @@ def logger
       Shoryuken.logger
     end
 
+    def fire_event(event, reverse=false)
+      logger.info { "Firing '#{event}' lifecycle event" }
+      arr = Shoryuken.options[:lifecycle_events][event]
+      arr.reverse! if reverse
+      arr.each do |block|
+        begin
+          block.call
+        rescue => ex
+          logger.warn({ event: event })
+          logger.warn "#{ex.class.name}: #{ex.message}"
+        end
+      end
+    end
+
     def elapsed(started_at)
       # elapsed in ms
       (Time.now - started_at) * 1000