Preload routes informationab-routable-nplus1

This fixes a high frequency N+1 issue:

`RoutableActions#find_routable!` is used across many controllers to
retrieve e.g. the Project or Namespace by path. The `#find_routable!`
method calls `#ensure_canonical_path` which in turn retrieves
`#full_path` from the given Routable.

This in turn triggers a lookup on `routes`, leading to a high frequency
of these queries:

```sql
SELECT  "routes".* FROM "routes" WHERE "routes"."source_id" = $1 AND
"routes"."source_type" = $2 LIMIT $3
```

This is unnecessary as we already join `routes` in
`Routable#find_by_full_path` anyways.

1 files changed, 2 insertions, 2 deletions

diff --git a/app/models/concerns/routable.rb b/app/models/concerns/routable.rb
index 3a486632800..07d22641a0a 100644
--- a/app/models/concerns/routable.rb
+++ b/app/models/concerns/routable.rb
@@ -38,7 +38,7 @@ module Routable
       if Feature.enabled?(:routable_two_step_lookup)
         # Case sensitive match first (it's cheaper and the usual case)
         # If we didn't have an exact match, we perform a case insensitive search
-        found = joins(:route).find_by(routes: { path: path }) || where_full_path_in([path]).take
+        found = includes(:route).find_by(routes: { path: path }) || where_full_path_in([path]).take
       else
         order_sql = Arel.sql("(CASE WHEN routes.path = #{connection.quote(path)} THEN 0 ELSE 1 END)")
         found = where_full_path_in([path]).reorder(order_sql).take
@@ -67,7 +67,7 @@ module Routable
         "(LOWER(routes.path) = LOWER(#{connection.quote(path)}))"
       end
 
-      joins(:route).where(wheres.join(' OR '))
+      includes(:route).where(wheres.join(' OR ')).references(:routes)
     end
 
     # Temporary instrumentation of method calls