[IMP] *: optimise loading of home page

Fix outstanding query to make a positive `state` filtering, instead of
negative, matching 3b52b1aace8674259812a76b1566260937dbcacb.

Also manually create a map of stagings (grouped by branch) sharing a
single prefetch set.

For odoo the mergebot home page has 12 branches in the odoo project
and 8 in spreadsheet, 6 stagings each. This means 120 queries to
retrieve all the heads (Odoo stagings have 5 heads and spreadsheet
have 1, but that seems immaterial).

By fixing `_compute_statuses` and creating a single prefetch set for
all stagings of all branches we can fetch all the commits in a single
query instead of 120.

forwardport/data/views.xml

@@ -10,8 +10,7 @@
         <xpath expr="//div[@id='alerts']" position="inside">
             <t t-if="env['runbot_merge.pull_requests'].check_access_rights('read', False)">
                 <t t-set="outstanding" t-value="env['runbot_merge.pull_requests'].search_count([
-                    ('source_id', '!=', False),
-                    ('state', 'not in', ['merged', 'closed']),
+                    ('state', 'in', ['opened', 'validated', 'approved', 'ready', 'error']),
                     ('source_id.merge_date', '&lt;', datetime.datetime.now() - relativedelta(days=3)),
                 ])"/>
                 <div t-if="outstanding != 0" class="alert col-md-12 alert-warning mb-0">

runbot_merge/controllers/dashboard.py

@@ -13,8 +13,25 @@ LIMIT = 20
 class MergebotDashboard(Controller):
     @route('/runbot_merge', auth="public", type="http", website=True, sitemap=True)
     def dashboard(self):
+        projects = request.env['runbot_merge.project'].with_context(active_test=False).sudo().search([])
+        stagings = {
+            branch: projects.env['runbot_merge.stagings'].search([
+                ('target', '=', branch.id)], order='staged_at desc', limit=6)
+            for project in projects
+            for branch in project.branch_ids
+            if branch.active
+        }
+        prefetch_set = list({
+            id
+            for stagings in stagings.values()
+            for id in stagings.ids
+        })
+        for st in stagings.values():
+            st._prefetch_ids = prefetch_set
+
         return request.render('runbot_merge.dashboard', {
-            'projects': request.env['runbot_merge.project'].with_context(active_test=False).sudo().search([]),
+            'projects': projects,
+            'stagings_map': stagings,
         })
 
     @route('/runbot_merge/<int:branch_id>', auth='public', type='http', website=True, sitemap=False)

runbot_merge/models/pull_requests.py

@@ -1813,12 +1813,25 @@ class Stagings(models.Model):
         (repo, context, state, url)
         """
         Commits = self.env['runbot_merge.commit']
+        heads = {
+            head: repo
+            for st in self
+            for repo, head in json.loads(st.heads).items()
+            if not repo.endswith('^')
+        }
+        all_heads = Commits.search([('sha', 'in', list(heads))])
+        commits_map = {commit.sha: commit.id for commit in all_heads}
+
         for st in self:
-            heads = {
-                head: repo for repo, head in json.loads(st.heads).items()
-                if not repo.endswith('^')
-            }
-            commits = st.head_ids = Commits.search([('sha', 'in', list(heads.keys()))])
+            commits = st.head_ids = Commits._browse(
+                self.env,
+                tuple(
+                    commits_map[h]
+                    for repo, h in json.loads(st.heads).items()
+                    if not repo.endswith('^')
+                ),
+                all_heads._prefetch_ids
+            )
             if st.statuses_cache:
                 st.statuses = json.loads(st.statuses_cache)
                 continue

runbot_merge/views/templates.xml

@@ -72,7 +72,7 @@
         <t t-call="website.layout">
             <div id="wrap"><div class="container-fluid">
                 <t t-call="runbot_merge.alerts"/>
-                <section t-foreach="projects.with_context(active_test=False)" t-as="project" class="row">
+                <section t-foreach="projects" t-as="project" class="row">
                     <h1 class="col-md-12"><t t-esc="project.name"/></h1>
                     <div class="col-md-12">
                         key:
@@ -154,7 +154,7 @@
     <template id="stagings" name="mergebot branch stagings">
         <t t-set="repo_statuses" t-value="branch.project_id.repo_ids.having_branch(branch).status_ids"/>
         <ul class="list-unstyled stagings">
-            <t t-foreach="branch.env['runbot_merge.stagings'].search([('target', '=', branch.id)], order='staged_at desc', limit=6)" t-as="staging">
+            <t t-foreach="stagings_map[branch]" t-as="staging">
                 <t t-set="success" t-value="staging.state == 'success'"/>
                 <t t-set="failure" t-value="staging.state == 'failure'"/>
                 <t t-set="pending" t-value="staging.active and (not staging.state or staging.state == 'pending')"/>