Keep memory usage state at the root on homepage (#1129)

* Keep memory usage state at the root on homepage

* Update lib/livebook/system_resources.ex

Co-authored-by: José Valim <jose.valim@dashbit.co>

Co-authored-by: José Valim <jose.valim@dashbit.co>

lib/livebook/settings.ex

@@ -13,7 +13,7 @@ defmodule Livebook.Settings do
   @doc """
   Returns the current autosave path.
   """
-  @spec autosave_path() :: String.t()
+  @spec autosave_path() :: String.t() | nil
   def autosave_path() do
     case storage().fetch_key(:settings, "global", :autosave_path) do
       {:ok, value} -> value

lib/livebook/system_resources.ex

@@ -46,13 +46,16 @@ defmodule Livebook.SystemResources do
 
   @impl true
   def handle_cast(:update, state) do
-    measure()
+    memory = measure()
+    Phoenix.PubSub.local_broadcast(Livebook.PubSub, "system_resources", {:memory_update, memory})
     {:noreply, state}
   end
 
   defp measure() do
-    memory = :memsup.get_system_memory_data()
-    :ets.insert(@name, {:memory, %{total: memory[:total_memory], free: memory[:free_memory]}})
+    memory_data = :memsup.get_system_memory_data()
+    memory = %{total: memory_data[:total_memory], free: memory_data[:free_memory]}
+    :ets.insert(@name, {:memory, memory})
+    memory
   end
 
   defp schedule() do

lib/livebook_web/live/home_live.ex

@@ -11,6 +11,7 @@ defmodule LivebookWeb.HomeLive do
   def mount(params, _session, socket) do
     if connected?(socket) do
       Phoenix.PubSub.subscribe(Livebook.PubSub, "tracker_sessions")
+      Phoenix.PubSub.subscribe(Livebook.PubSub, "system_resources")
     end
 
     sessions = Sessions.list_sessions()
@@ -113,7 +114,8 @@ defmodule LivebookWeb.HomeLive do
           <div id="running-sessions" class="py-12" role="region" aria-label="running sessions">
             <.live_component module={LivebookWeb.HomeLive.SessionListComponent}
               id="session-list"
-              sessions={@sessions}/>
+              sessions={@sessions}
+              memory={@memory} />
           </div>
         </div>
       </div>
@@ -335,6 +337,10 @@ defmodule LivebookWeb.HomeLive do
     {:noreply, socket}
   end
 
+  def handle_info({:memory_update, memory}, socket) do
+    {:noreply, assign(socket, memory: memory)}
+  end
+
   defp files(sessions) do
     Enum.map(sessions, & &1.file)
   end

lib/livebook_web/live/home_live/close_session_component.ex

@@ -33,7 +33,6 @@ defmodule LivebookWeb.HomeLive.CloseSessionComponent do
   @impl true
   def handle_event("close", %{}, socket) do
     Livebook.Session.close(socket.assigns.session.pid)
-    SessionListComponent.refresh_memory_info()
     {:noreply, push_patch(socket, to: socket.assigns.return_to, replace: true)}
   end
 end

lib/livebook_web/live/home_live/edit_sessions_component.ex

@@ -54,7 +54,6 @@ defmodule LivebookWeb.HomeLive.EditSessionsComponent do
     |> Enum.map(& &1.pid)
     |> Livebook.Session.close()
 
-    SessionListComponent.refresh_memory_info()
     {:noreply, push_patch(socket, to: socket.assigns.return_to, replace: true)}
   end
 
@@ -64,7 +63,6 @@ defmodule LivebookWeb.HomeLive.EditSessionsComponent do
     |> Enum.map(& &1.pid)
     |> Livebook.Session.disconnect_runtime()
 
-    SessionListComponent.refresh_memory_info()
     {:noreply, push_patch(socket, to: socket.assigns.return_to, replace: true)}
   end
 

lib/livebook_web/live/home_live/session_list_component.ex

@@ -12,10 +12,6 @@ defmodule LivebookWeb.HomeLive.SessionListComponent do
   end
 
   @impl true
-  def update(%{memory_timestamp: ts}, socket) do
-    {:ok, assign(socket, :memory_timestamp, ts)}
-  end
-
   def update(assigns, socket) do
     {sessions, assigns} = Map.pop!(assigns, :sessions)
 
@@ -30,11 +26,7 @@ defmodule LivebookWeb.HomeLive.SessionListComponent do
     socket =
       socket
       |> assign(assigns)
-      |> assign(
-        sessions: sessions,
-        show_autosave_note?: show_autosave_note?,
-        memory_timestamp: System.os_time()
-      )
+      |> assign(sessions: sessions, show_autosave_note?: show_autosave_note?)
 
     {:ok, socket}
   end
@@ -50,7 +42,7 @@ defmodule LivebookWeb.HomeLive.SessionListComponent do
           </h2>
         </div>
         <div class="flex flex-row">
-          <.memory_info memory_timestamp={@memory_timestamp} />
+          <.memory_info memory={@memory} />
           <%= if @sessions != [] do %>
             <.edit_sessions sessions={@sessions} socket={@socket}/>
           <% end %>
@@ -191,7 +183,7 @@ defmodule LivebookWeb.HomeLive.SessionListComponent do
   end
 
   defp memory_info(assigns) do
-    %{free: free, total: total} = Livebook.SystemResources.memory()
+    %{free: free, total: total} = assigns.memory
     used = total - free
     percentage = Float.round(used / total * 100, 2)
     assigns = assign(assigns, free: free, used: used, total: total, percentage: percentage)
@@ -291,7 +283,6 @@ defmodule LivebookWeb.HomeLive.SessionListComponent do
   def handle_event("disconnect_runtime", %{"id" => session_id}, socket) do
     session = Enum.find(socket.assigns.sessions, &(&1.id == session_id))
     Session.disconnect_runtime(session.pid)
-    refresh_memory_info()
     {:noreply, socket}
   end
 
@@ -300,10 +291,6 @@ defmodule LivebookWeb.HomeLive.SessionListComponent do
     time_words <> " ago"
   end
 
-  def refresh_memory_info do
-    send_update(__MODULE__, memory_timestamp: System.os_time(), id: "session-list")
-  end
-
   def toggle_edit(:on) do
     JS.remove_class("hidden", to: "[data-el-bulk-edit-member]")
     |> JS.add_class("hidden", to: "#toggle-edit")