entity: Add stop/1 and stop/2 to kill an entity in a clean way

2 files changed, 52 insertions, 12 deletions

diff --git a/lib/lkn/core/entity.ex b/lib/lkn/core/entity.ex
index 715970a..c87b51d 100644
--- a/lib/lkn/core/entity.ex
+++ b/lib/lkn/core/entity.ex
@@ -86,8 +86,8 @@ defmodule Lkn.Core.Entity do
   This map is used by
   """
   @callback init_properties(init_args) :: %{prop => value}
-
   @callback digest(entity :: %{prop => value}) :: digest
+  @callback destroy(key :: k, entity :: %{prop => value}, reason :: term) :: any
 
   defmacro __using__(components: comps) do
     quote location: :keep do
@@ -97,7 +97,7 @@ defmodule Lkn.Core.Entity do
 
       def init(key: entity_key, args: args) do
         props = init_properties(args)
-        props = Map.put(props, :make_digest, & __MODULE__.digest(&1))
+        props = Map.put(props, :module, __MODULE__)
 
         sys = Enum.map(unquote(comps), &(&1.specs().system()))
 
@@ -117,9 +117,9 @@ defmodule Lkn.Core.Entity do
   """
   @spec digest(entity_key :: k) :: digest
   def digest(entity_key) do
-    Option.some(di) = Lkn.Core.Entity.read(entity_key, :make_digest)
+    Option.some(mod) = Lkn.Core.Entity.read(entity_key, :module)
 
-    Lkn.Core.Properties.compute(entity_key, di)
+    Lkn.Core.Properties.compute(entity_key, &mod.digest(&1))
   end
 
   @doc """
@@ -152,4 +152,18 @@ defmodule Lkn.Core.Entity do
   def read(key, prop) do
     Lkn.Core.Properties.read(key, prop)
   end
+
+  @doc """
+  Stop the given Entity
+
+  This
+  """
+  def stop(key, reason \\ :normal) do
+    # clean up
+    Option.some(mod) = Lkn.Core.Entity.read(key, :module)
+    Lkn.Core.Properties.compute(key, &mod.destroy(key, &1, reason))
+
+    # and exit
+    Supervisor.stop(Name.entity(key), reason)
+  end
 end
diff --git a/test/core_test.exs b/test/core_test.exs
index 0e95c6b..a2e08e7 100644
--- a/test/core_test.exs
+++ b/test/core_test.exs
@@ -49,13 +49,25 @@ defmodule Lkn.Core.Test do
   test "spawning entity" do
     entity_key = UUID.uuid4()
 
-    {:ok, _} = Test.Entity.start_link(entity_key, name: "lkn", level: 4)
+    {:ok, _} = Test.Entity.start_link(entity_key, name: "lkn", level: 4, owner: self())
+  end
+
+  test "spawning then stoping entity" do
+    entity_key = UUID.uuid4()
+
+    {:ok, _} = Test.Entity.start_link(entity_key, name: "lkn", level: 4, owner: self())
+    Lkn.Core.Entity.stop(entity_key)
+
+    receive do
+      {:destroyed, key, :normal} -> assert key == entity_key
+      after 100 -> assert false
+    end
   end
 
   test "has component" do
     entity_key = UUID.uuid4()
 
-    {:ok, _} = Test.Entity.start_link(entity_key, name: "lkn", level: 4)
+    {:ok, _} = Test.Entity.start_link(entity_key, name: "lkn", level: 4, owner: self())
 
     assert Lkn.Core.Entity.has_component?(entity_key, Test.System)
     assert !Lkn.Core.Entity.has_component?(entity_key, Test.NoSystem)
@@ -64,7 +76,7 @@ defmodule Lkn.Core.Test do
   test "spawning entity and read level" do
     entity_key = UUID.uuid4()
 
-    {:ok, _} = Test.Entity.start_link(entity_key, name: "lkn", level: 4)
+    {:ok, _} = Test.Entity.start_link(entity_key, name: "lkn", level: 4, owner: self())
     Option.some(4) = Lkn.Core.Entity.read(entity_key, :level)
   end
 
@@ -100,7 +112,7 @@ defmodule Lkn.Core.Test do
     entity_key = UUID.uuid4()
     ghost_key = UUID.uuid4()
 
-    {:ok, _} = Test.Entity.start_link(entity_key, name: "lkn", level: 4)
+    {:ok, _} = Test.Entity.start_link(entity_key, name: "lkn", level: 4, owner: self())
     {:ok, _} = Test.Ghost.start_link(ghost_key)
 
     0 = Lkn.Core.System.population_size(instance_key, Test.System)
@@ -142,7 +154,7 @@ defmodule Lkn.Core.Test do
 
     entity_key = UUID.uuid4()
 
-    {:ok, _} = Test.Entity.start_link(entity_key, name: "lkn", level: 4)
+    {:ok, _} = Test.Entity.start_link(entity_key, name: "lkn", level: 4, owner: self())
 
     Lkn.Core.Instance.register_puppet(instance_key, entity_key)
 
@@ -385,6 +397,10 @@ defmap Test.Map do
   def digest(_props) do
     %{}
   end
+
+  def destroy(_key, _props, _reason) do
+    :ok
+  end
 end
 
 ######################################################################
@@ -407,17 +423,23 @@ end
 defpuppet Test.Entity do
   @components [Test.Entity.Component]
 
-  def start_link(key, args = [name: _name, level: _level]) do
+  def start_link(key, args = [name: _name, level: _level, owner: _owner]) do
     Lkn.Core.Entity.start_link(__MODULE__, key, args)
   end
 
-  def init_properties(name: name, level: level) do
-    %{:name => name, :level => level}
+  def init_properties(name: name, level: level, owner: owner) do
+    %{:name => name, :level => level, :owner => owner}
   end
 
   def digest(props) do
     props
   end
+
+  def destroy(key, props, reason) do
+    target = Map.get(props, :owner)
+    send target, {:destroyed, key, reason}
+    :ok
+  end
 end
 
 defpuppet Test.Ghost do
@@ -434,6 +456,10 @@ defpuppet Test.Ghost do
   def digest(props) do
     props
   end
+
+  def destroy(_key, _props, _reason) do
+    :ok
+  end
 end
 
 ######################################################################