From 6e1b4426698735a77b0db8b6ccd69ab37f05a0d8 Mon Sep 17 00:00:00 2001
From: Tristan Cacqueray <tdecacqu@redhat.com>
Date: Wed, 11 Jul 2018 02:50:51 +0000
Subject: [PATCH] timer: skip projects not using the pipeline

This change makes the timer driver skip projects that are not configured
to use the timer triggered pipeline. Timer operates on branch heads and
doesn't need speculative layouts to decide if it should be enqueued or not.
So it can be decided on cached data if it needs to run or not.

Change-Id: I410c0da5057727734ac82ce56cad75655a9ebc40
---
 .../notes/timer-optimization-a6babecaf1c7dab8.yaml   |  6 ++++++
 tests/fixtures/layouts/timer.yaml                    |  6 ++++++
 tests/unit/test_scheduler.py                         | 12 ++++++++++++
 zuul/driver/timer/__init__.py                        |  8 +++++++-
 4 files changed, 31 insertions(+), 1 deletion(-)
 create mode 100644 releasenotes/notes/timer-optimization-a6babecaf1c7dab8.yaml

diff --git a/releasenotes/notes/timer-optimization-a6babecaf1c7dab8.yaml b/releasenotes/notes/timer-optimization-a6babecaf1c7dab8.yaml
new file mode 100644
index 0000000000..d039664354
--- /dev/null
+++ b/releasenotes/notes/timer-optimization-a6babecaf1c7dab8.yaml
@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    The timer trigger does not enqueue an event for every branch of every
+    project anymore and it now only processes projects actually using the
+    pipeline triggered by a timer.
diff --git a/tests/fixtures/layouts/timer.yaml b/tests/fixtures/layouts/timer.yaml
index e9e9a170db..5aaa4ce9a5 100644
--- a/tests/fixtures/layouts/timer.yaml
+++ b/tests/fixtures/layouts/timer.yaml
@@ -39,6 +39,12 @@
           label: ubuntu-xenial
     run: playbooks/project-bitrot.yaml
 
+- project:
+    name: org/project1
+    check:
+      jobs:
+        - project-test1
+
 - project:
     name: org/project
     check:
diff --git a/tests/unit/test_scheduler.py b/tests/unit/test_scheduler.py
index 15f1ab0e32..158141b8d5 100755
--- a/tests/unit/test_scheduler.py
+++ b/tests/unit/test_scheduler.py
@@ -3375,6 +3375,18 @@ class TestScheduler(ZuulTestCase):
 
         self.assertEqual(len(self.builds), 2)
 
+        merge_count_project1 = 0
+        for job in self.gearman_server.jobs_history:
+            if job.name == b'merger:refstate':
+                args = job.arguments
+                if isinstance(args, bytes):
+                    args = args.decode('utf-8')
+                args = json.loads(args)
+                if args["items"][0]["project"] == "org/project1":
+                    merge_count_project1 += 1
+        self.assertEquals(merge_count_project1, 0,
+                          "project1 shouldn't have any refstate call")
+
         self.executor_server.hold_jobs_in_build = False
         # Stop queuing timer triggered jobs so that the assertions
         # below don't race against more jobs being queued.
diff --git a/zuul/driver/timer/__init__.py b/zuul/driver/timer/__init__.py
index 69cd508746..f3273425d1 100644
--- a/zuul/driver/timer/__init__.py
+++ b/zuul/driver/timer/__init__.py
@@ -79,7 +79,13 @@ class TimerDriver(Driver, TriggerInterface):
                     jobs.append(job)
 
     def _onTrigger(self, tenant, pipeline_name, timespec):
-        for project_name in tenant.layout.project_configs.keys():
+        for project_name, pcs in tenant.layout.project_configs.items():
+            # timer operates on branch heads and doesn't need speculative
+            # layouts to decide if it should be enqueued or not.
+            # So it can be decided on cached data if it needs to run or not.
+            if not [True for pc in pcs if pipeline_name in pc.pipelines]:
+                continue
+
             (trusted, project) = tenant.getProject(project_name)
             for branch in project.source.getProjectBranches(project, tenant):
                 event = TimerTriggerEvent()