Crop big consolidated views (#5835)

* Crop big consolidated views

* number format

extra/lib/plausible/consolidated_view/cache.ex

@@ -12,6 +12,8 @@ defmodule Plausible.ConsolidatedView.Cache do
   use Plausible.Cache
 
   @cache_name :consolidated_views
+  @large_view_alert_threshold 12_000
+  @max_sites_per_view 14_000
 
   @impl true
   def name(), do: @cache_name
@@ -82,4 +84,21 @@ defmodule Plausible.ConsolidatedView.Cache do
       [{row.consolidated_view_id, row.site_ids} | acc]
     end)
   end
+
+  def get(key, opts) do
+    case super(key, opts) do
+      nil ->
+        []
+
+      site_ids when length(site_ids) > @large_view_alert_threshold ->
+        Sentry.capture_message("Consolidated View crop warning",
+          extra: %{sites: length(site_ids), key: key}
+        )
+
+        Enum.take(site_ids, @max_sites_per_view)
+
+      site_ids ->
+        site_ids
+    end
+  end
 end

test/plausible/consolidated_view/cache_test_sync.exs

@@ -0,0 +1,37 @@
+defmodule Plausible.CondolidatedView.CacheTestSync do
+  use Plausible.DataCase, async: false
+  use Plausible.Teams.Test
+
+  on_ee do
+    alias Plausible.ConsolidatedView.Cache
+
+    setup do
+      Sentry.put_config(:test_mode, true)
+
+      on_exit(fn ->
+        Sentry.put_config(:test_mode, false)
+      end)
+    end
+
+    test "big views get cropped up to 14k", %{test: test} do
+      assert :ok = Sentry.Test.start_collecting_sentry_reports()
+      {:ok, _pid} = start_test_cache(test)
+
+      Plausible.Cache.Adapter.put(test, "key", Enum.to_list(1..20_000))
+      site_ids = Cache.get("key", cache_name: test, force?: true)
+      assert length(site_ids) == 14_000
+
+      assert [
+               %{
+                 extra: %{key: "key", sites: 20_000},
+                 message: %{formatted: "Consolidated View crop warning"}
+               }
+             ] = Sentry.Test.pop_sentry_reports()
+    end
+  end
+
+  defp start_test_cache(cache_name) do
+    %{start: {m, f, a}} = Cache.child_spec(cache_name: cache_name)
+    apply(m, f, a)
+  end
+end