Move Supervisor methods around to prepare for async supervisor

That won't run a loop for supervise, it'll just start the processes and
the maintenance task.

Author: rosa

lib/solid_queue/processes/callbacks.rb

@@ -8,12 +8,5 @@ module Callbacks
       extend ActiveModel::Callbacks
       define_model_callbacks :boot, :shutdown
     end
-
-    private
-      def boot
-      end
-
-      def shutdown
-      end
   end
 end

lib/solid_queue/processes/poller.rb

@@ -39,6 +39,9 @@ def poll
         raise NotImplementedError
       end
 
+      def shutdown
+      end
+
       def with_polling_volume
         if SolidQueue.silence_polling? && ActiveRecord::Base.logger
           ActiveRecord::Base.logger.silence { yield }

lib/solid_queue/supervisor.rb

@@ -18,18 +18,12 @@ def initialize(configuration)
     end
 
     def start
-      run_callbacks(:boot) { boot }
+      boot
 
       start_processes
       launch_maintenance_task
 
-      loop do
-        break if stopped?
-
-        supervise
-      end
-    ensure
-      run_callbacks(:shutdown) { shutdown }
+      supervise
     end
 
     def stop
@@ -40,8 +34,10 @@ def stop
       attr_reader :configuration
 
       def boot
-        @stopped = false
-        sync_std_streams
+        run_callbacks(:boot) do
+          @stopped = false
+          sync_std_streams
+        end
       end
 
       def start_processes
@@ -53,15 +49,16 @@ def stopped?
       end
 
       def supervise
-        raise NotImplementedError
       end
 
       def start_process(configured_process)
         raise NotImplementedError
       end
 
       def shutdown
-        stop_maintenance_task
+        run_callbacks(:shutdown) do
+          stop_maintenance_task
+        end
       end
 
       def sync_std_streams

lib/solid_queue/supervisor/fork_supervisor.rb

@@ -17,13 +17,19 @@ def kind
       attr_reader :forks
 
       def supervise
-        procline "supervising #{forks.keys.join(", ")}"
-        process_signal_queue
+        loop do
+          break if stopped?
+
+          procline "supervising #{forks.keys.join(", ")}"
+          process_signal_queue
 
-        unless stopped?
-          reap_and_replace_terminated_forks
-          interruptible_sleep(1.second)
+          unless stopped?
+            reap_and_replace_terminated_forks
+            interruptible_sleep(1.second)
+          end
         end
+      ensure
+        shutdown
       end
 
       def start_process(configured_process)