actor: minor supervision example improvements

Author: pitr-ch

doc/actor/supervision_tree.in.rb

@@ -1,7 +1,7 @@
 
 class Master < Concurrent::Actor::RestartingContext
   def initialize
-    # for listener to be child of master
+    # create listener a supervised child of master
     @listener = Listener.spawn(name: 'listener1', supervise: true)
   end
 
@@ -17,7 +17,7 @@ def on_message(msg)
     end
   end
 
-  # TODO turn this into Behaviour and make it default part of RestartingContext
+  # TODO this should be a part of a behaviour, it ensures that children are restarted/paused etc. when theirs parents are
   def on_event(event)
     event_name, _ = event
     case event_name
@@ -50,12 +50,15 @@ def on_message(msg)
 master   = Master.spawn(name: 'master', supervise: true)
 listener = master.ask!(:listener)
 listener.ask!(:number)
+# crash the listener which is supervised by master, it's restarted automatically reporting a different number
+listener.tell(:crash)
+listener.ask!(:number)
 
 master << :crash
 
 sleep 0.1
 
-# ask for listener again, old one is terminated
+# ask for listener again, old one is terminated with master and replaced with new one
 listener.ask!(:terminated?)
 listener = master.ask!(:listener)
 listener.ask!(:number)

doc/actor/supervision_tree.out.rb

@@ -48,22 +48,26 @@ def on_message(msg)
 end 
 
 master   = Master.spawn(name: 'master', supervise: true)
-    # => #<Concurrent::Actor::Reference:0x7ff3aa0d1380 /master (Master)>
+    # => #<Concurrent::Actor::Reference:0x7fd443366568 /master (Master)>
 listener = master.ask!(:listener)
-    # => #<Concurrent::Actor::Reference:0x7ff3aa8776e8 /master/listener1 (Listener)>
-listener.ask!(:number)                             # => 73
+    # => #<Concurrent::Actor::Reference:0x7fd44335cf68 /master/listener1 (Listener)>
+listener.ask!(:number)                             # => 20
+
+listener.tell(:crash)
+    # => #<Concurrent::Actor::Reference:0x7fd44335cf68 /master/listener1 (Listener)>
+listener.ask!(:number)                             # => 41
 
 master << :crash
-    # => #<Concurrent::Actor::Reference:0x7ff3aa0d1380 /master (Master)>
+    # => #<Concurrent::Actor::Reference:0x7fd443366568 /master (Master)>
 
-sleep 0.1                                          # => 1
+sleep 0.1                                          # => 0
 
 # ask for listener again, old one is terminated
 listener.ask!(:terminated?)                        # => true
 listener = master.ask!(:listener)
-    # => #<Concurrent::Actor::Reference:0x7ff3ab147110 /master/listener1 (Listener)>
-listener.ask!(:number)                             # => 48
+    # => #<Concurrent::Actor::Reference:0x7fd4433357b0 /master/listener1 (Listener)>
+listener.ask!(:number)                             # => 12
 
-master.ask!(:terminate!)                           # => [true, true]
+master.ask!(:terminate!)                           # => [[true], true]
 
 sleep 0.1                                          # => 0