From c660f506eede74cdd3a53ab10b7ac82b8cc9b492 Mon Sep 17 00:00:00 2001
From: Pierre Tardy <tardyp@gmail.com>
Date: Thu, 27 Aug 2020 21:46:28 +0200
Subject: [PATCH] Fix bad fieldMapping in change data endpoint

This resulted in 100%CPU for large installs as the data filtered manually by python

Correct the test so that the actual fieldMapping is tested
---
 master/buildbot/data/changes.py                  | 2 +-
 master/buildbot/newsfragments/datachanges.bugfix | 1 +
 master/buildbot/test/unit/test_db_changes.py     | 3 ++-
 3 files changed, 4 insertions(+), 2 deletions(-)
 create mode 100644 master/buildbot/newsfragments/datachanges.bugfix

diff --git a/master/buildbot/data/changes.py b/master/buildbot/data/changes.py
index e36f26a0a3b..cb42951ef76 100644
--- a/master/buildbot/data/changes.py
+++ b/master/buildbot/data/changes.py
@@ -41,7 +41,7 @@ def _fixChange(self, change):
             del change['sourcestampid']
         return change
     fieldMapping = {
-        'changeid': 'changes.id',
+        'changeid': 'changes.changeid',
     }
 
 
diff --git a/master/buildbot/newsfragments/datachanges.bugfix b/master/buildbot/newsfragments/datachanges.bugfix
new file mode 100644
index 00000000000..ba5cdd004f2
--- /dev/null
+++ b/master/buildbot/newsfragments/datachanges.bugfix
@@ -0,0 +1 @@
+fix 100% CPU on large installs when looking using the changes api (:issue:`5504`)
diff --git a/master/buildbot/test/unit/test_db_changes.py b/master/buildbot/test/unit/test_db_changes.py
index 93a4f890763..54d95ae119c 100644
--- a/master/buildbot/test/unit/test_db_changes.py
+++ b/master/buildbot/test/unit/test_db_changes.py
@@ -19,6 +19,7 @@
 from twisted.trial import unittest
 
 from buildbot.data import resultspec
+from buildbot.data.changes import FixerMixin
 from buildbot.db import builds
 from buildbot.db import changes
 from buildbot.db import sourcestamps
@@ -277,7 +278,7 @@ def insert7Changes(self):
     def test_getChanges_subset(self):
         yield self.insert7Changes()
         rs = resultspec.ResultSpec(order=['-changeid'], limit=5)
-        rs.fieldMapping = {'changeid': 'changes.changeid'}
+        rs.fieldMapping = FixerMixin.fieldMapping
         changes = yield self.db.changes.getChanges(resultSpec=rs)
         changeids = [c['changeid'] for c in changes]
         self.assertEqual(changeids, [10, 11, 12, 13, 14])