[IMP] website: perf - prefetch menus when serving a page

If we are rendering a page, the menus will most likely be rendered as well.
Note that even in a 403 case when the page is found but is not visible, the
menus will also be shown on the 403 page.

Fetching the menus before accessing the requested page will prefetch that page
as well in one go if that page is in the menus, without any costs for the pages
not in the menus.

There is a tradeoff for 'non-layout' pages, which only occurs in advanced
technical cases:
1. Create a page with specific extension as name suffix (page.css) in which
   case the page will be bootstraped accordingly, without call to layout.
2. Remove the call to layout in HTML editor or backend
3. Remove the call to submenus template in HTML editor or backend
For those cases, the menus will be prefetched for no reason.

Note that homepage '/' is rendered through a controller, same logic is applied
there.

task-2211013

addons/website/controllers/main.py

@@ -68,6 +68,9 @@ class Website(Home):
 
     @http.route('/', type='http', auth="public", website=True, sitemap=True)
     def index(self, **kw):
+        # prefetch all menus (it will prefetch website.page too)
+        top_menu = request.website.menu_id
+
         homepage = request.website.homepage_id
         if homepage and (homepage.sudo().is_visible or request.env.user.has_group('base.group_user')) and homepage.url != '/':
             return request.env['ir.http'].reroute(homepage.url)
@@ -76,7 +79,6 @@ class Website(Home):
         if website_page:
             return website_page
         else:
-            top_menu = request.website.menu_id
             first_menu = top_menu and top_menu.child_id and top_menu.child_id.filtered(lambda menu: menu.is_visible)
             if first_menu and first_menu[0].url not in ('/', '', '#') and (not (first_menu[0].url.startswith(('/?', '/#', ' ')))):
                 return request.redirect(first_menu[0].url)

addons/website/models/ir_http.py

@@ -239,6 +239,9 @@ class Http(models.AbstractModel):
         published_domain = page_domain
         # specific page first
         page = request.env['website.page'].sudo().search(published_domain, order='website_id asc', limit=1)
+        if page:
+            # prefetch all menus (it will prefetch website.page too)
+            request.website.menu_id
         if page and (request.website.is_publisher() or page.is_visible):
             _, ext = os.path.splitext(req_page)
             return request.render(page.get_view_identifier(), {

addons/website/tests/test_performance.py

@@ -77,25 +77,25 @@ class TestWebsitePerformance(UtilPerf):
 
     def test_10_perf_sql_queries_page(self):
         # standard untracked website.page
-        self.assertEqual(self._get_url_hot_query(self.page.url), 14)
+        self.assertEqual(self._get_url_hot_query(self.page.url), 12)
         self.menu.unlink()
         self.assertEqual(self._get_url_hot_query(self.page.url), 14)
 
     def test_15_perf_sql_queries_page(self):
         # standard tracked website.page
         self.page.track = True
-        self.assertEqual(self._get_url_hot_query(self.page.url), 22)
+        self.assertEqual(self._get_url_hot_query(self.page.url), 20)
         self.menu.unlink()
         self.assertEqual(self._get_url_hot_query(self.page.url), 22)
 
     def test_20_perf_sql_queries_homepage(self):
         # homepage "/" has its own controller
-        self.assertEqual(self._get_url_hot_query('/'), 21)
+        self.assertEqual(self._get_url_hot_query('/'), 19)
 
     def test_30_perf_sql_queries_page_no_layout(self):
         # website.page with no call to layout templates
         self.page.arch = '<div>I am a blank page</div>'
-        self.assertEqual(self._get_url_hot_query(self.page.url), 8)
+        self.assertEqual(self._get_url_hot_query(self.page.url), 10)
 
     def test_40_perf_sql_queries_page_multi_level_menu(self):
         # menu structure should not impact SQL requests
@@ -113,7 +113,7 @@ class TestWebsitePerformance(UtilPerf):
         menu_bb.parent_id = menu_b
         menu_aa.parent_id = menu_a
 
-        self.assertEqual(self._get_url_hot_query(self.page.url), 14)
+        self.assertEqual(self._get_url_hot_query(self.page.url), 12)
 
     def test_50_perf_sql_web_content(self):
         # assets route /web/content/..