Take live stream snapshot periodically

lib/asciinema/streaming/live_stream.ex

@@ -23,6 +23,7 @@ defmodule Asciinema.Streaming.LiveStream do
     field :peak_viewer_count, :integer
     field :buffer_time, :float
     field :parser, :string
+    field :snapshot, Asciinema.Ecto.Type.JsonArray
 
     timestamps()
 

lib/asciinema/streaming/live_stream_server.ex

@@ -1,5 +1,6 @@
 defmodule Asciinema.Streaming.LiveStreamServer do
   use GenServer, restart: :transient
+  alias Asciinema.Recordings.Snapshot
   alias Asciinema.Streaming.ViewerTracker
   alias Asciinema.{Colors, PubSub, Streaming, Vt}
   require Logger
@@ -169,7 +170,8 @@ defmodule Asciinema.Streaming.LiveStreamServer do
           Streaming.update_live_stream(state.stream,
             current_viewer_count: state.viewer_count,
             cols: cols,
-            rows: rows
+            rows: rows,
+            snapshot: generate_snapshot(state.vt)
           )
 
         nil ->
@@ -265,4 +267,12 @@ defmodule Asciinema.Streaming.LiveStreamServer do
       theme_palette: Enum.join(Enum.slice(colors, 2..-1), ":")
     ]
   end
+
+  defp generate_snapshot(vt) do
+    {:ok, {lines, cursor}} = Vt.dump_screen(vt)
+
+    {lines, cursor}
+    |> Snapshot.new()
+    |> Snapshot.unwrap()
+  end
 end

lib/asciinema_web/controllers/recording_svg.ex

@@ -422,6 +422,4 @@ defmodule AsciinemaWeb.RecordingSVG do
     |> Snapshot.new()
     |> Snapshot.crop(cols, rows)
   end
-
-  defp snapshot(_, _), do: Snapshot.new([])
 end

priv/repo/migrations/20240421122804_add_snapshot_to_live_streams.exs

@@ -0,0 +1,9 @@
+defmodule Asciinema.Repo.Migrations.AddSnapshotToLiveStreams do
+  use Ecto.Migration
+
+  def change do
+    alter table(:live_streams) do
+      add :snapshot, :text
+    end
+  end
+end