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, 7 insertions, 0 deletions

diff --git a/spec/models/concerns/routable_spec.rb b/spec/models/concerns/routable_spec.rb
index cff86afe768..cad705ee594 100644
--- a/spec/models/concerns/routable_spec.rb
+++ b/spec/models/concerns/routable_spec.rb
@@ -66,6 +66,13 @@ describe Group, 'Routable' do
       it { expect(described_class.find_by_full_path(group.to_param.upcase)).to eq(group) }
       it { expect(described_class.find_by_full_path(nested_group.to_param)).to eq(nested_group) }
       it { expect(described_class.find_by_full_path('unknown')).to eq(nil) }
+
+      it 'includes route information when loading a record' do
+        path = group.to_param
+        control_count = ActiveRecord::QueryRecorder.new { described_class.find_by_full_path(path) }.count
+
+        expect { described_class.find_by_full_path(path).route }.not_to exceed_all_query_limit(control_count)
+      end
     end
 
     context 'with redirect routes' do