From c1eafc9a2c52c7e5182345dcad3072870bdb40da Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jonatan=20K=C5=82osko?= <jonatanklosko@gmail.com>
Date: Sun, 21 Feb 2021 19:17:14 +0100
Subject: [PATCH] Save notebook and notify clients when session is stopped
 (#45)

---
 lib/live_book/session.ex                   | 18 ++++++++++++++----
 lib/live_book/session_supervisor.ex        |  4 ++--
 lib/live_book_web/live/session_live.ex     |  7 +++++++
 test/live_book/session_supervisor_test.exs |  2 ++
 test/live_book/session_test.exs            | 22 ++++++++++++++++++++++
 5 files changed, 47 insertions(+), 6 deletions(-)

diff --git a/lib/live_book/session.ex b/lib/live_book/session.ex
index 9e22b787b..b414a508c 100644
--- a/lib/live_book/session.ex
+++ b/lib/live_book/session.ex
@@ -215,11 +215,14 @@ defmodule LiveBook.Session do
   end
 
   @doc """
-  Synchronously stops the server.
+  Asynchronously sends a close request to the server.
+
+  This results in saving the file and broadcasting
+  a :closed message to the session topic.
   """
-  @spec stop(id()) :: :ok
-  def stop(session_id) do
-    GenServer.stop(name(session_id))
+  @spec close(id()) :: :ok
+  def close(session_id) do
+    GenServer.cast(name(session_id), :close)
   end
 
   ## Callbacks
@@ -377,6 +380,13 @@ defmodule LiveBook.Session do
     {:noreply, maybe_save_notebook(state)}
   end
 
+  def handle_cast(:close, state) do
+    maybe_save_notebook(state)
+    broadcast_message(state.session_id, :session_closed)
+
+    {:stop, :shutdown, state}
+  end
+
   @impl true
   def handle_info({:DOWN, ref, :process, _, _}, %{runtime_monitor_ref: ref} = state) do
     broadcast_info(state.session_id, "runtime node terminated unexpectedly")
diff --git a/lib/live_book/session_supervisor.ex b/lib/live_book/session_supervisor.ex
index 31b84f52a..4e41eb032 100644
--- a/lib/live_book/session_supervisor.ex
+++ b/lib/live_book/session_supervisor.ex
@@ -50,13 +50,13 @@ defmodule LiveBook.SessionSupervisor do
   end
 
   @doc """
-  Synchronously stops a session process identified by the given id.
+  Asynchronously stops a session process identified by the given id.
 
   Broadcasts `{:session_delete, id}` message under the `"sessions"` topic.
   """
   @spec delete_session(Session.id()) :: :ok
   def delete_session(id) do
-    Session.stop(id)
+    Session.close(id)
     broadcast_sessions_message({:session_deleted, id})
     :ok
   end
diff --git a/lib/live_book_web/live/session_live.ex b/lib/live_book_web/live/session_live.ex
index d1019f1f5..0162aafd5 100644
--- a/lib/live_book_web/live/session_live.ex
+++ b/lib/live_book_web/live/session_live.ex
@@ -382,6 +382,13 @@ defmodule LiveBookWeb.SessionLive do
     {:noreply, put_flash(socket, :info, message)}
   end
 
+  def handle_info(:session_closed, socket) do
+    {:noreply,
+     socket
+     |> put_flash(:info, "Session has been closed")
+     |> push_redirect(to: Routes.home_path(socket, :page))}
+  end
+
   def handle_info(_message, socket), do: {:noreply, socket}
 
   defp after_operation(socket, _prev_socket, {:insert_section, _index, section_id}) do
diff --git a/test/live_book/session_supervisor_test.exs b/test/live_book/session_supervisor_test.exs
index d40122b03..ba1e58d0e 100644
--- a/test/live_book/session_supervisor_test.exs
+++ b/test/live_book/session_supervisor_test.exs
@@ -23,9 +23,11 @@ defmodule LiveBook.SessionSupervisorTest do
     test "stops the session process identified by the given id" do
       {:ok, id} = SessionSupervisor.create_session()
       {:ok, pid} = SessionSupervisor.get_session_pid(id)
+      ref = Process.monitor(pid)
 
       SessionSupervisor.delete_session(id)
 
+      assert_receive {:DOWN, ^ref, :process, _, _}
       refute has_child_with_pid?(SessionSupervisor, pid)
     end
 
diff --git a/test/live_book/session_test.exs b/test/live_book/session_test.exs
index 29d30f5bc..616d5763b 100644
--- a/test/live_book/session_test.exs
+++ b/test/live_book/session_test.exs
@@ -187,6 +187,28 @@ defmodule LiveBook.SessionTest do
     end
   end
 
+  describe "close/1" do
+    @tag :tmp_dir
+    test "saves the notebook and notifies subscribers once the session is closed",
+         %{session_id: session_id, tmp_dir: tmp_dir} do
+      path = Path.join(tmp_dir, "notebook.livemd")
+      Session.set_path(session_id, path)
+      # Perform a change, so the notebook is dirty
+      Session.set_notebook_name(session_id, "My notebook")
+
+      Phoenix.PubSub.subscribe(LiveBook.PubSub, "sessions:#{session_id}")
+
+      refute File.exists?(path)
+
+      Process.flag(:trap_exit, true)
+      Session.close(session_id)
+
+      assert_receive :session_closed
+      assert File.exists?(path)
+      assert File.read!(path) =~ "My notebook"
+    end
+  end
+
   describe "start_link/1" do
     @tag :tmp_dir
     test "fails if the given path is already in use", %{tmp_dir: tmp_dir} do