Level up our echo serverv0.3.0

This should enable upgrade process to retain connections

*   Replace our simple task supervisor with a custom `simple_one_for_one`
    supervisor

*   Upgrade our echo server to use a `GenServer` behaviour

5 files changed, 43 insertions, 19 deletions

diff --git a/lib/octochat/acceptor.ex b/lib/octochat/acceptor.ex
index 5730ee4..28d14be 100644
--- a/lib/octochat/acceptor.ex
+++ b/lib/octochat/acceptor.ex
@@ -14,11 +14,7 @@ defmodule Octochat.Acceptor do
 
   defp loop_acceptor(socket) do
     {:ok, client} = :gen_tcp.accept(socket)
-    {:ok, pid} = Task.Supervisor.start_child(
-      Octochat.TaskSupervisor,
-      Octochat.Echo,
-      :serve,
-      [client])
+    {:ok, pid} = Octochat.ServerSupervisor.start_server(client)
     :ok = :gen_tcp.controlling_process(client, pid)
     loop_acceptor(socket)
   end
diff --git a/lib/octochat/server_supervisor.ex b/lib/octochat/server_supervisor.ex
new file mode 100644
index 0000000..d412ca5
--- /dev/null
+++ b/lib/octochat/server_supervisor.ex
@@ -0,0 +1,24 @@
+defmodule Octochat.ServerSupervisor do
+  @moduledoc """
+  Simple One-for-One Supervisor for socket connections
+  """
+
+  use Supervisor
+
+  def start_link() do
+    Supervisor.start_link(__MODULE__, :ok, name: __MODULE__)
+  end
+
+  def init(:ok) do
+    children = [
+      worker(Octochat.Echo, [], restart: :temporary)
+    ]
+
+    supervise(children, strategy: :simple_one_for_one)
+  end
+
+  def start_server(socket) do
+    Supervisor.start_child(__MODULE__, [socket])
+  end
+
+end
diff --git a/lib/octochat/servers/echo.ex b/lib/octochat/servers/echo.ex
index da04876..bea9864 100644
--- a/lib/octochat/servers/echo.ex
+++ b/lib/octochat/servers/echo.ex
@@ -2,23 +2,27 @@ defmodule Octochat.Echo do
   @moduledoc """
   Octochat Echo server
   """
+  use GenServer
   require Logger
 
-  def serve(socket) do
-    socket
-      |> read_line()
-      |> write_line!(socket)
+  def start_link(socket) do
+    GenServer.start_link(__MODULE__, socket)
+  end
 
-    serve(socket)
+  def init(socket) do
+    :ok = :inet.setopts(socket, active: true)
+    {:ok, %{socket: socket}}
+  end
+
+  def handle_info({:tcp, _, msg}, state = %{socket: socket}) do
+    msg
+      |> write_line!(socket)
+    {:noreply, state}
   end
 
-  defp read_line(socket) do
-    case :gen_tcp.recv(socket, 0) do
-      {:ok, line} -> line
-      {:error, reason} ->
-        Logger.error(reason)
-        Process.exit(self, :normal)
-    end
+  def handle_info({:tcp_closed, _}, state) do
+    Logger.info("#{__MODULE__}: Connection closing")
+    {:stop, :normal, %{}}
   end
 
   defp write_line!(line, socket) do
diff --git a/lib/octochat/supervisor.ex b/lib/octochat/supervisor.ex
index d551628..9882942 100644
--- a/lib/octochat/supervisor.ex
+++ b/lib/octochat/supervisor.ex
@@ -11,7 +11,7 @@ defmodule Octochat.Supervisor do
 
   def init(_) do
     children = [
-      supervisor(Task.Supervisor, [[name: Octochat.TaskSupervisor]]),
+      supervisor(Octochat.ServerSupervisor, []),
       worker(Task, [Octochat.Acceptor, :accept, []])
     ]
 
diff --git a/mix.exs b/mix.exs
index b504c69..a5bd07f 100644
--- a/mix.exs
+++ b/mix.exs
@@ -5,7 +5,7 @@ defmodule Octochat.Mixfile do
     [app: :octochat,
      description: "Demo Application for How Swapping Code",
      package: package(),
-     version: "0.2.1",
+     version: "0.3.0",
      elixir: "~> 1.3",
      build_embedded: Mix.env == :prod,
      start_permanent: Mix.env == :prod,