feat: the fattest of fixes

lib/elevator/hall_orders.ex

@@ -225,6 +225,12 @@ defmodule Elevator.HallOrders do
     Enum.filter(order_map, fn {_, order_state} ->
       case order_state do
         {:handling, cost_map} ->
+          if Cost.min_alive_cost(cost_map, alive) == Communicator.my_id() do
+            Logger.debug(
+              "\nCost map: #{inspect(cost_map)}\nAlive: #{inspect(alive)}\nI (#{inspect(Communicator.my_id())}) am the one to serve"
+            )
+          end
+
           Cost.min_alive_cost(cost_map, alive) == Communicator.my_id()
 
         _ ->
@@ -236,7 +242,7 @@ defmodule Elevator.HallOrders do
 
   @type enum_orders ::
           Elevator.Types.hall_order_map()
-          | Enumerable.t({Elevator.Types.hall_order_key(), Elevator.Types.hall_order_value()})
+          | Enumerable.t({Elevator.Types.hall_order_key(), Elevator.Types.hall_order_state()})
   @spec orders_by_floor(enum_orders()) :: %{floor() => MapSet.t(hall_btn())}
   defp orders_by_floor(orders) do
     # Restructure order map to the format floor => MapSet(order)

lib/elevator/hall_orders/cost.ex

@@ -79,17 +79,21 @@ defmodule Elevator.HallOrders.Cost do
   def min_alive_cost(cost_map, alive_set) do
     alive_costs = Enum.filter(cost_map, fn {node, _} -> MapSet.member?(alive_set, node) end)
 
-    {min_node, _} =
-      Enum.min(
-        alive_costs,
-        fn {node1, cost1}, {node2, cost2} ->
-          cost1 < cost2 or (cost1 == cost2 and node1 < node2)
-        end,
-        # Fallback when no alive costs exist
-        fn -> {:nonode@nohost, :infinity} end
-      )
-
-    min_node
+    if Enum.count(alive_costs) != MapSet.size(alive_set) do
+      nil
+    else
+      {min_node, _} =
+        Enum.min(
+          alive_costs,
+          fn {node1, cost1}, {node2, cost2} ->
+            cost1 < cost2 or (cost1 == cost2 and node1 < node2)
+          end,
+          # Fallback when no alive costs exist
+          fn -> {:nonode@nohost, :infinity} end
+        )
+
+      min_node
+    end
   end
 
   @spec simulate_cost_until_served(combined_orders_t(), State.t(), {floor_t(), hall_btn_t()}) ::

lib/elevator/hall_orders/order.ex

@@ -32,10 +32,10 @@ defmodule Elevator.HallOrders.Order do
     new_order_state =
       case new_order_state do
         {:pending, barrier_set} ->
-          {:pending, MapSet.put(barrier_set, Node.self())}
+          {:pending, MapSet.put(barrier_set, Communicator.my_id())}
 
         {:arrived, barrier_set} ->
-          {:arrived, MapSet.put(barrier_set, Node.self())}
+          {:arrived, MapSet.put(barrier_set, Communicator.my_id())}
 
         _ ->
           new_order_state

scripts/hosts

@@ -3,6 +3,10 @@
 #
 # Lines starting with # and blank lines are ignored.
 
+9   student@10.100.23.19
+10  student@10.100.23.20
+11  student@10.100.23.21
+12  student@10.100.23.22
 16  student@10.100.23.26
 19  student@10.100.23.29
 21  student@10.100.23.172