From 556cd39afd9a997980ec602edeb8087959764461 Mon Sep 17 00:00:00 2001
From: "byte[]" <byteslice@airmail.cc>
Date: Sun, 22 Dec 2019 18:42:07 -0500
Subject: [PATCH] more aggressive preloading

---
 lib/philomena/textile/renderer.ex              | 18 +++++++++++-------
 lib/philomena_web/comment_loader.ex            |  9 +++++++++
 .../controllers/image_controller.ex            |  8 ++++++--
 lib/philomena_web/image_loader.ex              |  8 +++++++-
 lib/philomena_web/plugs/advert_plug.ex         |  2 +-
 5 files changed, 34 insertions(+), 11 deletions(-)

diff --git a/lib/philomena/textile/renderer.ex b/lib/philomena/textile/renderer.ex
index 850cea46..c3d9fcf8 100644
--- a/lib/philomena/textile/renderer.ex
+++ b/lib/philomena/textile/renderer.ex
@@ -101,17 +101,21 @@ defmodule Philomena.Textile.Renderer do
   end
 
   defp find_images(text_segments) do
-    image_ids =
-      text_segments
-      |> Enum.flat_map(fn t ->
-        Regex.scan(~r|&gt;&gt;(\d+)|, t, capture: :all_but_first)
-        |> Enum.map(fn [first] -> String.to_integer(first) end)
-      end)
+    text_segments
+    |> Enum.flat_map(fn t ->
+      Regex.scan(~r|&gt;&gt;(\d+)|, t, capture: :all_but_first)
+      |> Enum.map(fn [first] -> String.to_integer(first) end)
+    end)
+    |> find_image_ids()
+  end
 
+  defp find_image_ids([]), do: %{}
+  defp find_image_ids(image_ids) do
     Image
     |> where([i], i.id in ^image_ids)
     |> where([i], i.hidden_from_users == false)
-    |> preload(:tags)
+    |> join(:left, [i], _ in assoc(i, :tags))
+    |> preload([_i, t], tags: t)
     |> Repo.all()
     |> Map.new(fn image -> {image.id, image} end)
   end
diff --git a/lib/philomena_web/comment_loader.ex b/lib/philomena_web/comment_loader.ex
index 542d9461..df034ef5 100644
--- a/lib/philomena_web/comment_loader.ex
+++ b/lib/philomena_web/comment_loader.ex
@@ -3,6 +3,15 @@ defmodule PhilomenaWeb.CommentLoader do
   alias Philomena.Repo
   import Ecto.Query
 
+  # More aggressive preloading skipped due to overhead
+  # from scrivener:
+  #
+  # |> join(:left, [c], _ in assoc(c, :image))
+  # |> join(:left, [c, _i], _ in assoc(c, :user))
+  # |> join(:left, [_c, _i, u], _ in assoc(u, :awards))
+  # |> join(:left, [_c, _i, _u, a], _ in assoc(a, :badge))
+  # |> preload([_c, i, u, a, b], [:deleted_by, image: i, user: {u, awards: {a, badge: b}}])
+
   def load_comments(conn, image) do
     pref = load_direction(conn.assigns.current_user)
 
diff --git a/lib/philomena_web/controllers/image_controller.ex b/lib/philomena_web/controllers/image_controller.ex
index 74eb8282..097eab42 100644
--- a/lib/philomena_web/controllers/image_controller.ex
+++ b/lib/philomena_web/controllers/image_controller.ex
@@ -147,8 +147,12 @@ defmodule PhilomenaWeb.ImageController do
       |> where(id: ^id)
       |> join(:inner_lateral, [i], _ in fragment("SELECT COUNT(*) FROM tag_changes t WHERE t.image_id = ?", i.id))
       |> join(:inner_lateral, [i, _], _ in fragment("SELECT COUNT(*) FROM source_changes s WHERE s.image_id = ?", i.id))
-      |> preload([:tags, :deleter, user: [awards: :badge]])
-      |> select([i, t, s], {i, t.count, s.count})
+      |> join(:left, [i, _tc, _sc], _ in assoc(i, :user))
+      |> join(:left, [_i, _tc, _sc, u], _ in assoc(u, :awards))
+      |> join(:left, [_i, _tc, _sc, _u, a], _ in assoc(a, :badge))
+      |> join(:left, [i, _tc, _sc, _u, _a, _b], _ in assoc(i, :tags))
+      |> preload([_i, _tc, _sc, u, a, b, t], [:deleter, tags: t, user: {u, awards: {a, badge: b}}])
+      |> select([i, tc, sc, _u], {i, tc.count, sc.count})
       |> Repo.one()
       |> case do
         nil ->
diff --git a/lib/philomena_web/image_loader.ex b/lib/philomena_web/image_loader.ex
index 6b4125a8..d8cf1211 100644
--- a/lib/philomena_web/image_loader.ex
+++ b/lib/philomena_web/image_loader.ex
@@ -20,7 +20,7 @@ defmodule PhilomenaWeb.ImageLoader do
     sort_queries = Keyword.get(options, :queries, [])
     sort_sorts   = Keyword.get(options, :sorts, [%{created_at: :desc}])
     pagination   = Keyword.get(options, :pagination, conn.assigns.image_pagination)
-    queryable    = Keyword.get(options, :queryable, Image |> preload(:tags))
+    queryable    = Keyword.get(options, :queryable, default_queryable())
 
     user    = conn.assigns.current_user
     filter  = conn.assigns.compiled_filter
@@ -126,4 +126,10 @@ defmodule PhilomenaWeb.ImageLoader do
     [{tag, description, dnp_entries}]
   end
   defp render_bodies(tags, _conn), do: tags
+
+  defp default_queryable do
+    Image
+    |> join(:left, [i], _ in assoc(i, :tags))
+    |> preload([_i, t], tags: t)
+  end
 end
diff --git a/lib/philomena_web/plugs/advert_plug.ex b/lib/philomena_web/plugs/advert_plug.ex
index 09246743..0b864c2b 100644
--- a/lib/philomena_web/plugs/advert_plug.ex
+++ b/lib/philomena_web/plugs/advert_plug.ex
@@ -24,4 +24,4 @@ defmodule PhilomenaWeb.AdvertPlug do
     do: true
   defp show_ads?(_user),
     do: true
-end
\ No newline at end of file
+end