Added on_worker_shutdown hook mechanism

lib/puma/cli.rb

@@ -99,6 +99,7 @@ module Puma
         :binds => [],
         :workers => 0,
         :daemon => false,
+		:before_worker_shutdown => [],
         :before_worker_boot => [],
         :after_worker_boot => []
       }
@@ -228,7 +229,7 @@ module Puma
 
         cfg = @config.dup
 
-        [ :logger, :before_worker_boot, :after_worker_boot, :on_restart ].each { |o| cfg.options.delete o }
+        [ :logger, :before_worker_shutdown, :before_worker_boot, :after_worker_boot, :on_restart ].each { |o| cfg.options.delete o }
 
         state["config"] = cfg
 

lib/puma/cluster.rb

@@ -216,6 +216,11 @@ module Puma
 
       server.run.join
 
+      # Invoke any worker shutdown hooks so they can prevent the worker
+	  # exiting until any background operations are completed
+      hooks = @options[:before_worker_shutdown]
+      hooks.each { |h| h.call(index) }
+
     ensure
       @worker_write.close
     end

lib/puma/configuration.rb

@@ -21,6 +21,7 @@ module Puma
       @options[:mode] ||= :http
       @options[:binds] ||= []
       @options[:on_restart] ||= []
+      @options[:before_worker_shutdown] ||= []
       @options[:before_worker_boot] ||= []
       @options[:after_worker_boot] ||= []
       @options[:worker_timeout] ||= DefaultWorkerTimeout
@@ -301,6 +302,17 @@ module Puma
         @options[:workers] = count.to_i
       end
 
+      # *Cluster mode only* Code to run immediately before a worker shuts
+	  # down (after it has finished processing HTTP requests). These hooks
+	  # can block if necessary to wait for background operations unknown
+	  # to puma to finish before the process terminates.
+      #
+      # This can be called multiple times to add hooks.
+      #
+      def on_worker_shutdown(&block)
+        @options[:before_worker_shutdown] << block
+      end
+
       # *Cluster mode only* Code to run when a worker boots to setup
       # the process before booting the app.
       #