perf: debounce BadPacketsLive refresh, remove stale test cases

Coalesce rapid PubSub notifications into single 2-second delayed DB query. Remove tests for removed :update_time_display handler.

Ultraworked with Sisyphus

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

lib/aprsme_web/live/bad_packets_live/index.ex

@@ -7,24 +7,24 @@ defmodule AprsmeWeb.BadPacketsLive.Index do
   alias Aprsme.BadPacket
   alias Aprsme.Repo
 
+  @debounce_ms 2_000
+
   @impl true
   def mount(_params, _session, socket) do
     if connected?(socket) do
-      # Subscribe to Postgres notifications for bad packets
       :ok = Phoenix.PubSub.subscribe(Aprsme.PubSub, "postgres:aprsme_events")
-      # Load initial bad packets
       bad_packets = fetch_bad_packets()
-      # Extra safeguard to ensure we never show more than 100
       limited_packets = Enum.take(bad_packets, 100)
 
       {:ok,
        assign(socket,
          bad_packets: limited_packets,
          loading: false,
-         last_updated: DateTime.utc_now()
+         last_updated: DateTime.utc_now(),
+         refresh_timer: nil
        )}
     else
-      {:ok, assign(socket, bad_packets: [], loading: false, last_updated: nil)}
+      {:ok, assign(socket, bad_packets: [], loading: false, last_updated: nil, refresh_timer: nil)}
     end
   end
 
@@ -39,33 +39,48 @@ defmodule AprsmeWeb.BadPacketsLive.Index do
 
   @impl true
   def handle_event("refresh", _params, socket) do
-    send(self(), :do_refresh)
-    {:noreply, assign(socket, loading: true)}
+    _ = cancel_timer(socket.assigns.refresh_timer)
+    socket = assign(socket, loading: true)
+    {:noreply, do_debounced_refresh(socket)}
   end
 
   @impl true
   def handle_info({:postgres_notify, _payload}, socket) do
-    # Optionally filter payload for bad packet events
-    send(self(), :do_refresh)
-    {:noreply, socket}
+    {:noreply, debounce_refresh(socket)}
   end
 
   @impl true
   def handle_info(:do_refresh, socket) do
     bad_packets = fetch_bad_packets()
-    # Extra safeguard to ensure we never show more than 100
     limited_packets = Enum.take(bad_packets, 100)
 
     {:noreply,
      assign(socket,
        bad_packets: limited_packets,
        loading: false,
-       last_updated: DateTime.utc_now()
+       last_updated: DateTime.utc_now(),
+       refresh_timer: nil
      )}
   end
 
+  defp debounce_refresh(socket) do
+    _ = cancel_timer(socket.assigns.refresh_timer)
+    timer_ref = Process.send_after(self(), :do_refresh, @debounce_ms)
+    assign(socket, refresh_timer: timer_ref)
+  end
+
+  defp do_debounced_refresh(socket) do
+    timer_ref = Process.send_after(self(), :do_refresh, @debounce_ms)
+    assign(socket, refresh_timer: timer_ref)
+  end
+
+  defp cancel_timer(nil), do: :ok
+
+  defp cancel_timer(ref) do
+    Process.cancel_timer(ref)
+  end
+
   defp fetch_bad_packets(limit \\ 100) do
-    # Hard cap at 100 to prevent showing too many records
     actual_limit = min(limit, 100)
 
     BadPacket

test/aprsme_web/live/map_live/index_test.exs

@@ -291,12 +291,6 @@ defmodule AprsmeWeb.MapLive.IndexTest do
       assert render(view) =~ "aprs-map"
     end
 
-    test "responds to :update_time_display", %{conn: conn} do
-      {:ok, view, _html} = live(conn, "/", on_error: :warn)
-      send(view.pid, :update_time_display)
-      assert render(view) =~ "aprs-map"
-    end
-
     test "responds to :cleanup_old_packets", %{conn: conn} do
       {:ok, view, _html} = live(conn, "/", on_error: :warn)
       send(view.pid, :cleanup_old_packets)

test/aprsme_web/live/map_live/integration_test.exs

@@ -298,12 +298,11 @@ defmodule AprsmeWeb.MapLive.IntegrationTest do
   end
 
   describe "MapLive handle_info coverage" do
-    test ":cleanup_old_packets, :update_time_display, :reload_historical_packets do not crash", %{conn: conn} do
+    test ":cleanup_old_packets, :reload_historical_packets do not crash", %{conn: conn} do
       {:ok, view, _html} = live(conn, "/?lat=33.0&lng=-96.0&z=10", on_error: :warn)
       render_hook(view, "map_ready", %{})
 
       send(view.pid, :cleanup_old_packets)
-      send(view.pid, :update_time_display)
       send(view.pid, :reload_historical_packets)
       Process.sleep(50)
       assert render(view) =~ "aprs-map"