From d370aed86df0489e8ff7ee308f4faefa54b57c05 Mon Sep 17 00:00:00 2001
From: "A. Jesse Jiryu Davis" <jesse@mongodb.com>
Date: Mon, 18 Mar 2019 08:53:15 -0400
Subject: SERVER-37255 Fix invariant when reconfig races with election

---
 jstests/replsets/reconfig_during_election.js | 49 ++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)
 create mode 100644 jstests/replsets/reconfig_during_election.js

(limited to 'jstests')

diff --git a/jstests/replsets/reconfig_during_election.js b/jstests/replsets/reconfig_during_election.js
new file mode 100644
index 00000000000..4f58b3cd477
--- /dev/null
+++ b/jstests/replsets/reconfig_during_election.js
@@ -0,0 +1,49 @@
+/**
+ * SERVER-37255: replSetReconfig runs on a node that is concurrently processing an election win.
+ */
+
+(function() {
+    "use strict";
+    load("jstests/replsets/libs/election_handoff.js");
+    load("jstests/libs/check_log.js");
+
+    const rst = ReplSetTest({nodes: 2});
+    const nodes = rst.startSet();
+    const config = rst.getReplSetConfig();
+    // Prevent elections and set heartbeat timeout >> electionHangsBeforeUpdateMemberState.
+    config.settings = {electionTimeoutMillis: 12 * 60 * 60 * 1000, heartbeatTimeoutSecs: 60 * 1000};
+    rst.initiate(config);
+
+    const incumbent = rst.getPrimary();
+    const candidate = rst.getSecondary();
+
+    jsTestLog("Step down");
+
+    assert.commandWorked(candidate.adminCommand({
+        configureFailPoint: "electionHangsBeforeUpdateMemberState",
+        mode: "alwaysOn",
+        data: {waitForMillis: 10 * 1000}
+    }));
+
+    // The incumbent sends replSetStepUp to the candidate for election handoff.
+    assert.adminCommandWorkedAllowingNetworkError(incumbent, {
+        replSetStepDown: ElectionHandoffTest.stepDownPeriodSecs,
+        secondaryCatchUpPeriodSecs: ElectionHandoffTest.stepDownPeriodSecs / 2
+    });
+
+    jsTestLog("Wait for candidate to win the election");
+
+    checkLog.contains(
+        candidate, "election succeeded - electionHangsBeforeUpdateMemberState fail point enabled");
+
+    jsTestLog("Try to interrupt it with a reconfig");
+
+    config.members[nodes.indexOf(candidate)].priority = 2;
+    config.version++;
+    assert.commandWorked(candidate.adminCommand({replSetReconfig: config, force: true}));
+
+    assert.commandWorked(candidate.adminCommand(
+        {configureFailPoint: "electionHangsBeforeUpdateMemberState", mode: "off"}));
+
+    rst.stopSet();
+})();
\ No newline at end of file
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