Push cells source to the client on initial render (#875)

assets/js/cell/index.js

@@ -4,7 +4,6 @@ import Markdown from "./markdown";
 import { globalPubSub } from "../lib/pub_sub";
 import { md5Base64, smoothlyScrollToElement } from "../lib/utils";
 import scrollIntoView from "scroll-into-view-if-needed";
-import { loadLocalSettings } from "../lib/settings";
 
 /**
  * A hook managing a single cell.
@@ -14,7 +13,6 @@ import { loadLocalSettings } from "../lib/settings";
  *
  * Configuration:
  *
- *   * `data-focusable-id` - an identifier for the focus/insert navigation
  *   * `data-cell-id` - id of the cell being edited
  *   * `data-type` - type of the cell
  *   * `data-session-path` - root path to the current session
@@ -27,13 +25,38 @@ const Cell = {
       insertMode: false,
       // For text cells (markdown or elixir)
       liveEditor: null,
+      markdown: null,
       evaluationDigest: null,
     };
 
-    if (["markdown", "elixir"].includes(this.props.type)) {
-      this.pushEvent("cell_init", { cell_id: this.props.cellId }, (payload) => {
+    this.handleEvent(`cell_init:${this.props.cellId}`, (payload) => {
       const { source, revision, evaluation_digest } = payload;
 
+      // Setup markdown rendering
+      if (this.props.type === "markdown") {
+        const markdownContainer = this.el.querySelector(
+          `[data-element="markdown-container"]`
+        );
+        this.state.markdown = new Markdown(markdownContainer, source, {
+          baseUrl: this.props.sessionPath,
+          emptyText: "Empty markdown cell",
+        });
+      }
+
+      // Setup action handlers
+      if (this.props.type === "elixir") {
+        const amplifyButton = this.el.querySelector(
+          `[data-element="amplify-outputs-button"]`
+        );
+        amplifyButton.addEventListener("click", (event) => {
+          this.el.toggleAttribute("data-js-amplified");
+        });
+      }
+
+      // Setting up an editor takes relatively much synchronous time,
+      // so we postpone it, so that other immediate initializations
+      // are done first. This is relevant if there are a lot of cells
+      setTimeout(() => {
         const editorContainer = this.el.querySelector(
           `[data-element="editor-container"]`
         );
@@ -52,16 +75,6 @@ const Cell = {
           revision
         );
 
-        // Setup action handlers
-        if (this.props.type === "elixir") {
-          const amplifyButton = this.el.querySelector(
-            `[data-element="amplify-outputs-button"]`
-          );
-          amplifyButton.addEventListener("click", (event) => {
-            this.el.toggleAttribute("data-js-amplified");
-          });
-        }
-
         // Setup change indicator
         if (this.props.type === "elixir") {
           this.state.evaluationDigest = evaluation_digest;
@@ -97,19 +110,10 @@ const Cell = {
           });
         }
 
-        // Setup markdown rendering
+        // Setup markdown updates
         if (this.props.type === "markdown") {
-          const markdownContainer = this.el.querySelector(
-            `[data-element="markdown-container"]`
-          );
-          const baseUrl = this.props.sessionPath;
-          const markdown = new Markdown(markdownContainer, source, {
-            baseUrl,
-            emptyText: "Empty markdown cell",
-          });
-
           this.state.liveEditor.onChange((newSource) => {
-            markdown.setContent(newSource);
+            this.state.markdown.setContent(newSource);
           });
         }
 
@@ -135,8 +139,8 @@ const Cell = {
         this.state.liveEditor.onCursorSelectionChange((selection) => {
           broadcastSelection(this, selection);
         });
+      }, 0);
     });
-    }
 
     this._unsubscribeFromNavigationEvents = globalPubSub.subscribe(
       "navigation",

lib/livebook/session/data.ex

@@ -1165,10 +1165,12 @@ defmodule Livebook.Session.Data do
         Delta.transform(delta_ahead, transformed_new_delta, :left)
       end)
 
-    # Note: the session LV drops cell's source once it's no longer needed
+    # Note: the clients drop cell's source once it's no longer needed
     new_source =
-      Map.get(cell, :source) &&
-        JSInterop.apply_delta_to_string(transformed_new_delta, cell.source)
+      case cell.source do
+        :__pruned__ -> :__pruned__
+        source -> JSInterop.apply_delta_to_string(transformed_new_delta, source)
+      end
 
     data_actions
     |> set!(notebook: Notebook.update_cell(data.notebook, cell.id, &%{&1 | source: new_source}))

lib/livebook_web/live/session_live.ex

@@ -43,6 +43,7 @@ defmodule LivebookWeb.SessionLive do
          )
          |> assign_private(data: data)
          |> prune_outputs()
+         |> prune_cell_sources()
          |> allow_upload(:cell_image,
            accept: ~w(.jpg .jpeg .png .gif),
            max_entries: 1,
@@ -534,30 +535,6 @@ defmodule LivebookWeb.SessionLive do
     {:reply, payload, socket}
   end
 
-  def handle_event("cell_init", %{"cell_id" => cell_id}, socket) do
-    data = socket.private.data
-
-    case Notebook.fetch_cell_and_section(data.notebook, cell_id) do
-      {:ok, cell, _section} ->
-        info = data.cell_infos[cell.id]
-
-        payload = %{
-          source: cell.source,
-          revision: info.revision,
-          evaluation_digest: encode_digest(info.evaluation_digest)
-        }
-
-        # From this point on we don't need cell source in the LV,
-        # so we are going to drop it altogether
-        socket = remove_cell_source(socket, cell_id)
-
-        {:reply, payload, socket}
-
-      :error ->
-        {:noreply, socket}
-    end
-  end
-
   def handle_event("append_section", %{}, socket) do
     idx = length(socket.private.data.notebook.sections)
     Session.insert_section(socket.assigns.session.pid, idx)
@@ -1119,6 +1096,8 @@ defmodule LivebookWeb.SessionLive do
   end
 
   defp after_operation(socket, _prev_socket, {:insert_cell, client_pid, _, _, _, cell_id}) do
+    socket = prune_cell_sources(socket)
+
     if client_pid == self() do
       push_event(socket, "cell_inserted", %{cell_id: cell_id})
     else
@@ -1144,6 +1123,8 @@ defmodule LivebookWeb.SessionLive do
   end
 
   defp after_operation(socket, _prev_socket, {:restore_cell, client_pid, cell_id}) do
+    socket = prune_cell_sources(socket)
+
     if client_pid == self() do
       push_event(socket, "cell_restored", %{cell_id: cell_id})
     else
@@ -1249,12 +1230,6 @@ defmodule LivebookWeb.SessionLive do
   defp encode_digest(nil), do: nil
   defp encode_digest(digest), do: Base.encode64(digest)
 
-  defp remove_cell_source(socket, cell_id) do
-    update_in(socket.private.data.notebook, fn notebook ->
-      Notebook.update_cell(notebook, cell_id, &%{&1 | source: nil})
-    end)
-  end
-
   defp process_intellisense_response(
          %{range: %{from: from, to: to}} = response,
          {:details, line, _column}
@@ -1380,9 +1355,7 @@ defmodule LivebookWeb.SessionLive do
     %{
       id: cell.id,
       type: :elixir,
-      # Note: we need this during initial loading,
-      # at which point we still have the source
-      empty?: cell.source == "",
+      source_info: cell_source_info(cell, info),
       outputs: cell.outputs,
       validity_status: info.validity_status,
       evaluation_status: info.evaluation_status,
@@ -1395,13 +1368,25 @@ defmodule LivebookWeb.SessionLive do
     }
   end
 
-  defp cell_to_view(%Cell.Markdown{} = cell, _data) do
+  defp cell_to_view(%Cell.Markdown{} = cell, data) do
+    info = data.cell_infos[cell.id]
+
     %{
       id: cell.id,
       type: :markdown,
-      # Note: we need this during initial loading,
-      # at which point we still have the source
-      empty?: cell.source == ""
+      source_info: cell_source_info(cell, info)
+    }
+  end
+
+  defp cell_source_info(%{source: :__pruned__}, _info) do
+    :__pruned__
+  end
+
+  defp cell_source_info(cell, info) do
+    %{
+      source: cell.source,
+      revision: info.revision,
+      evaluation_digest: encode_digest(info.evaluation_digest)
     }
   end
 
@@ -1477,6 +1462,20 @@ defmodule LivebookWeb.SessionLive do
     )
   end
 
+  defp prune_cell_sources(%{private: %{data: data}} = socket) do
+    assign_private(
+      socket,
+      data:
+        update_in(
+          data.notebook,
+          &Notebook.update_cells(&1, fn
+            %{source: _} = cell -> %{cell | source: :__pruned__}
+            cell -> cell
+          end)
+        )
+    )
+  end
+
   # Changes that affect only a single cell are still likely to
   # have impact on dirtiness, so we need to always mirror it
   defp update_dirty_status(data_view, data) do

lib/livebook_web/live/session_live/cell_component.ex

@@ -1,6 +1,29 @@
 defmodule LivebookWeb.SessionLive.CellComponent do
   use LivebookWeb, :live_component
 
+  @impl true
+  def mount(socket) do
+    {:ok, assign(socket, initialized: false)}
+  end
+
+  @impl true
+  def update(assigns, socket) do
+    socket = assign(socket, assigns)
+
+    socket =
+      if not connected?(socket) or socket.assigns.initialized do
+        socket
+      else
+        %{id: id, source_info: info} = socket.assigns.cell_view
+
+        socket
+        |> push_event("cell_init:#{id}", info)
+        |> assign(initialized: true)
+      end
+
+    {:ok, socket}
+  end
+
   @impl true
   def render(assigns) do
     ~H"""
@@ -52,7 +75,7 @@ defmodule LivebookWeb.SessionLive.CellComponent do
         data-element="markdown-container"
         id={"markdown-container-#{@cell_view.id}"}
         phx-update="ignore">
-        <.content_placeholder bg_class="bg-gray-200" empty={@cell_view.empty?} />
+        <.content_placeholder bg_class="bg-gray-200" empty={empty?(@cell_view.source_info)} />
       </div>
     </.cell_body>
     """
@@ -214,7 +237,7 @@ defmodule LivebookWeb.SessionLive.CellComponent do
       <div id={"editor-#{@cell_view.id}"} phx-update="ignore">
         <div class="py-3 rounded-lg bg-editor" data-element="editor-container">
           <div class="px-8">
-            <.content_placeholder bg_class="bg-gray-500" empty={@cell_view.empty?} />
+            <.content_placeholder bg_class="bg-gray-500" empty={empty?(@cell_view.source_info)} />
           </div>
         </div>
       </div>
@@ -248,6 +271,9 @@ defmodule LivebookWeb.SessionLive.CellComponent do
     """
   end
 
+  defp empty?(%{source: ""} = _source_info), do: true
+  defp empty?(_source_info), do: false
+
   defp cell_status(%{cell_view: %{evaluation_status: :evaluating}} = assigns) do
     ~H"""
     <.status_indicator circle_class="bg-blue-500" animated_circle_class="bg-blue-400" change_indicator={true}>