puppeteer: Notify the puppeteers when puppets enter or leave instances

7 files changed, 122 insertions, 19 deletions

diff --git a/lib/lkn/core/entity.ex b/lib/lkn/core/entity.ex
index 7e7a2a6..715970a 100644
--- a/lib/lkn/core/entity.ex
+++ b/lib/lkn/core/entity.ex
@@ -72,6 +72,7 @@ defmodule Lkn.Core.Entity do
   `Lkn.Core.Puppet` or a `Lkn.Core.Map`.
   """
   @type k :: Lkn.Core.Map.k | Lkn.Core.Puppet.k
+  @type digest :: term
 
   @typedoc """
   The third argument of the `start_link/3` function which is passed to
@@ -86,6 +87,8 @@ defmodule Lkn.Core.Entity do
   """
   @callback init_properties(init_args) :: %{prop => value}
 
+  @callback digest(entity :: %{prop => value}) :: digest
+
   defmacro __using__(components: comps) do
     quote location: :keep do
       use Supervisor
@@ -94,6 +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))
 
         sys = Enum.map(unquote(comps), &(&1.specs().system()))
 
@@ -109,6 +113,16 @@ defmodule Lkn.Core.Entity do
   end
 
   @doc """
+  Compute a digest which hopefully describes the entity
+  """
+  @spec digest(entity_key :: k) :: digest
+  def digest(entity_key) do
+    Option.some(di) = Lkn.Core.Entity.read(entity_key, :make_digest)
+
+    Lkn.Core.Properties.compute(entity_key, di)
+  end
+
+  @doc """
   Starts an Entity process linked to the current process.
   """
   @spec start_link(module, k, init_args) :: Supervisor.on_start
diff --git a/lib/lkn/core/instance.ex b/lib/lkn/core/instance.ex
index 8c175fb..ef16d96 100644
--- a/lib/lkn/core/instance.ex
+++ b/lib/lkn/core/instance.ex
@@ -207,6 +207,16 @@ defmodule Lkn.Core.Instance do
   """
   @spec register_puppet(k, Puppet.k) :: :ok
   def register_puppet(instance_key, puppet_key) do
+    # get a digest of the puppet and send it to the puppeteer
+    notify_puppeteers(instance_key, &Lkn.Core.Puppeteer.puppet_enter(
+          &1,
+          instance_key,
+          puppet_key,
+          Lkn.Core.Entity.digest(puppet_key)
+        )
+    )
+
+    # try registering the puppet to each system
     sys_map = Entity.systems(puppet_key)
 
     _ = Enum.map(sys_map, fn sys ->
@@ -232,6 +242,7 @@ defmodule Lkn.Core.Instance do
   """
   @spec unregister_puppet(k, Puppet.k) :: :ok
   def unregister_puppet(instance_key, puppet_key) do
+    # unregister the pupet from each systems
     sys_map = Entity.systems(puppet_key)
 
     _ = Enum.map(sys_map, fn sys ->
@@ -242,6 +253,14 @@ defmodule Lkn.Core.Instance do
       end
     end)
 
+    # notify the puppeteers
+    notify_puppeteers(instance_key, &Lkn.Core.Puppeteer.puppet_leave(
+          &1,
+          instance_key,
+          puppet_key
+        )
+    )
+
     :ok
   end
 
@@ -309,4 +328,12 @@ defmodule Lkn.Core.Instance do
   def handle_cast({:unregister_puppeteer, puppeteer_key}, state) do
     {:noreply, State.unregister_puppeteer(state, puppeteer_key)}
   end
+
+  def notify_puppeteers(instance_key, notif) do
+    Registry.dispatch(Lkn.Core.Notifier, Name.notify_group(instance_key), fn entries ->
+      for {_, key} <- entries do
+        notif.(key)
+      end
+    end)
+  end
 end
diff --git a/lib/lkn/core/properties.ex b/lib/lkn/core/properties.ex
index 241407c..d8e2d0a 100644
--- a/lib/lkn/core/properties.ex
+++ b/lib/lkn/core/properties.ex
@@ -37,4 +37,9 @@ defmodule Lkn.Core.Properties do
   def write(entity_key, prop, v) do
     Agent.update(Lkn.Core.Name.properties(entity_key), &Map.put(&1, prop, v))
   end
+
+  @spec compute(Lkn.Core.Entity.k, (%{Lkn.Core.Entity.prop => Lkn.Core.Entity.value} -> any)) :: any
+  def compute(entity_key, function) do
+    Agent.get(Lkn.Core.Name.properties(entity_key), function)
+  end
 end
diff --git a/lib/lkn/core/puppeteer.ex b/lib/lkn/core/puppeteer.ex
index 521e256..9150c2a 100644
--- a/lib/lkn/core/puppeteer.ex
+++ b/lib/lkn/core/puppeteer.ex
@@ -41,15 +41,27 @@ defmodule Lkn.Core.Puppeteer do
 
     quote do
       defmodule unquote(name) do
-        unquote(Specs.gen_server_from_specs(block, key_type, key_to_name, state_type))
+        unquote(Specs.gen_server_from_specs(
+              block,
+              key_type,
+              key_to_name,
+              state_type,
+              additional_args: [
+                quote do unquote(Specs.var_name("instance_key")) :: Lkn.Core.Instance.k end,
+              ]
+            )
+        )
 
         defmacro __using__(args) do
           plugin_clients = case args do
                              [do: use_block] ->
-                               Specs.gen_server_plugin_entry_point(use_block,
-                                                                   quote do Lkn.Core.Puppeteer.k end,
-                                                                   &(Lkn.Core.Name.puppeteer(&1)),
-                                                                   quote do Lkn.Core.Puppeteer.state end)
+                               Specs.gen_server_plugin_entry_point(
+                                 use_block,
+                                 quote do Lkn.Core.Puppeteer.k end,
+                                 &(Lkn.Core.Name.puppeteer(&1)),
+                                 [quote do unquote(Specs.var_name("instance_key")) :: Lkn.Core.Instance.k end],
+                                 quote do Lkn.Core.Puppeteer.state end
+                               )
                              _ ->
                                quote do
                                end
@@ -97,6 +109,24 @@ defmodule Lkn.Core.Puppeteer do
               {:ok, State.new(puppeteer_key, s)}
             end
 
+            def handle_cast({:puppet_enter, instance_key, puppet_key, digest}, state) do
+              if state.instance_key == Lkn.Prelude.Option.some(instance_key) do
+                s2 = puppet_enter(state.state, state.instance_key, puppet_key, digest)
+
+                {:noreply, %State{state|state: s2}}
+              else
+                {:noreply, state}
+              end
+            end
+            def handle_cast({:puppet_leave, instance_key, puppet_key}, state) do
+              if state.instance_key == Lkn.Prelude.Option.some(instance_key) do
+                s2 = puppet_leave(state.state, state.instance_key, puppet_key)
+
+                {:noreply, %State{state|state: s2}}
+              else
+                {:noreply, state}
+              end
+            end
             def handle_cast({:leave_instance, instance_key}, state) do
               if state.instance_key == Lkn.Prelude.Option.some(instance_key) do
                 s2 = leave_instance(state.state, instance_key)
@@ -109,13 +139,13 @@ defmodule Lkn.Core.Puppeteer do
               end
             end
             def handle_cast({:spec, {name, args}}, state) do
-              s = :erlang.apply(__MODULE__, name, [state.puppeteer_key|args]++[state.state])
+              s = :erlang.apply(__MODULE__, name, [state.puppeteer_key|args]++[state.instance_key, state.state])
 
               {:noreply, %State{state|state: s}}
             end
             def handle_cast({:plugin, {name, args}}, state) do
               name = String.to_atom(String.replace_suffix(Atom.to_string(name), "", "_plugin"))
-              s = :erlang.apply(__MODULE__, name, [state.puppeteer_key|args]++[state.state])
+              s = :erlang.apply(__MODULE__, name, [state.puppeteer_key|args]++[state.instance_key, state.state])
 
               {:noreply, %State{state|state: s}}
             end
@@ -147,6 +177,8 @@ defmodule Lkn.Core.Puppeteer do
 
   @callback init_state(init_args) :: {:ok, state}|:error
   @callback leave_instance(state, Instance.k) :: state
+  @callback puppet_enter(state, Lkn.Core.Instance.k, Lkn.Core.Puppet.k, Lkn.Core.Entity.digest) :: state
+  @callback puppet_leave(state, Lkn.Core.Instance.k, Lkn.Core.Puppet.k) :: state
 
   @spec leave_instance(k, Instance.k) :: :ok
   def leave_instance(puppeteer_key, instance_key) do
@@ -157,4 +189,12 @@ defmodule Lkn.Core.Puppeteer do
   def find_instance(puppeteer_key, map_key) do
     GenServer.call(Name.puppeteer(puppeteer_key), {:find_instance, map_key})
   end
+
+  def puppet_enter(puppeteer_key, instance_key, puppet_key, digest) do
+    GenServer.cast(Name.puppeteer(puppeteer_key), {:puppet_enter, instance_key, puppet_key, digest})
+  end
+
+  def puppet_leave(puppeteer_key, instance_key, puppet_key) do
+    GenServer.cast(Name.puppeteer(puppeteer_key), {:puppet_leave, instance_key, puppet_key})
+  end
 end
diff --git a/lib/lkn/core/specs.ex b/lib/lkn/core/specs.ex
index eb0cb37..986b29a 100644
--- a/lib/lkn/core/specs.ex
+++ b/lib/lkn/core/specs.ex
@@ -33,7 +33,7 @@ defmodule Lkn.Core.Specs do
         end))
   end
 
-  def gen_server_plugin_entry_point(block, key_type, key_to_name, state_type) do
+  def gen_server_plugin_entry_point(block, key_type, key_to_name, additional_args, state_type) do
     block = case block do
               {:__block__, _, x} -> x
               x -> [x]
@@ -46,7 +46,7 @@ defmodule Lkn.Core.Specs do
     plugin = quote do :plugin end
 
     casts_client = Enum.map(casts, &(cast_client(plugin, var_name("key"), key_type, key_to_name, &1)))
-    casts_behaviour = Enum.map(casts, &(cast_server(&1, var_name("key"), key_type, [], state_type, "_plugin")))
+    casts_behaviour = Enum.map(casts, &(cast_server(&1, var_name("key"), key_type, additional_args, state_type, "_plugin")))
 
     quote do
       unquote(casts_client)
@@ -141,9 +141,10 @@ defmodule Lkn.Core.Specs do
     name = String.to_atom(String.replace_suffix(Atom.to_string(name), "", impl_suffix))
 
     arglistcl_type = [{:::, [], [key_name, key_type]}
-                      |Enum.map(cast.fun.arguments, &({:::, [], [&1.name, &1.type]}))] ++ additional_args ++ [
-      {:::, [], [{:state, [], nil}, state_type]}
-    ]
+                      |Enum.map(cast.fun.arguments, &({:::, [], [&1.name, &1.type]}))]
+      ++ additional_args ++ [
+        {:::, [], [{:state, [], nil}, state_type]}
+      ]
     arglistcl = [key_name
                  |Enum.map(cast.fun.arguments, &(&1.name))] ++
       Enum.map(additional_args, &(case &1 do
diff --git a/lib/lkn/core/system.ex b/lib/lkn/core/system.ex
index f17fb65..53ca6c7 100644
--- a/lib/lkn/core/system.ex
+++ b/lib/lkn/core/system.ex
@@ -173,11 +173,7 @@ defmodule Lkn.Core.System do
 
     @spec notify(t, any) :: :ok
     def notify(state, notif) do
-      Registry.dispatch(Lkn.Core.Notifier, Name.notify_group(state.instance_key), fn entries ->
-        for {_, key} <- entries do
-          notif.(key)
-        end
-      end)
+      Lkn.Core.Instance.notify_puppeteers(state.instance_key, notif)
     end
   end
 
diff --git a/test/core_test.exs b/test/core_test.exs
index 50039a0..0e95c6b 100644
--- a/test/core_test.exs
+++ b/test/core_test.exs
@@ -381,6 +381,10 @@ defmap Test.Map do
         %{:limit => 2}
     end
   end
+
+  def digest(_props) do
+    %{}
+  end
 end
 
 ######################################################################
@@ -410,6 +414,10 @@ defpuppet Test.Entity do
   def init_properties(name: name, level: level) do
     %{:name => name, :level => level}
   end
+
+  def digest(props) do
+    props
+  end
 end
 
 defpuppet Test.Ghost do
@@ -420,7 +428,11 @@ defpuppet Test.Ghost do
   end
 
   def init_properties([]) do
-    %{:name => "ghost", :level => 0}
+    %{}
+  end
+
+  def digest(props) do
+    props
   end
 end
 
@@ -450,12 +462,20 @@ defmodule Test.Puppeteer do
     {:ok, s}
   end
 
+  def puppet_enter(state, _instance_key, _puppet_key, _digest) do
+    state
+  end
+
+  def puppet_leave(state, _instance_key, _puppet_key) do
+    state
+  end
+
   def leave_instance(target, _instance_key) do
     send(target, :kick)
     target
   end
 
-  def emit(_puppeteer_key, msg, target) do
+  def emit(_puppeteer_key, msg, instance_key, target) do
     send target, msg
     target
   end