SERVER-41207 Test committing prepared transactions after stepdown due to reconfig

3 files changed, 101 insertions, 0 deletions

diff --git a/jstests/replsets/libs/prepare_failover_due_to_reconfig.js b/jstests/replsets/libs/prepare_failover_due_to_reconfig.js
new file mode 100644
index 00000000000..cf5b4e58fd8
--- /dev/null
+++ b/jstests/replsets/libs/prepare_failover_due_to_reconfig.js
@@ -0,0 +1,72 @@
+"use strict";
+
+/**
+ * Library used to test that prepared transactions survive failovers due to reconfig.
+ */
+
+var testPrepareFailoverDueToReconfig = function(name, reconfigOnPrimary) {
+    load("jstests/core/txns/libs/prepare_helpers.js");
+
+    const dbName = "test";
+    const collName = name;
+
+    const rst = new ReplSetTest({name: name, nodes: 2});
+    const nodes = rst.nodeList();
+
+    rst.startSet();
+    rst.initiate({
+        "_id": name,
+        "members": [
+            {/* primary   */ "_id": 0, "host": nodes[0]},
+            {/* secondary */ "_id": 1, "host": nodes[1], "priority": 0}
+        ]
+    });
+
+    const primary = rst.getPrimary();
+    const secondary = rst.getSecondary();
+
+    const testDB = primary.getDB(dbName);
+    const testColl = testDB.getCollection(collName);
+
+    const oldDoc = {_id: 42, "is": "old"};
+    const newDoc = {_id: 42, "is": "new"};
+
+    // First create the collection.
+    assert.commandWorked(testColl.insert(oldDoc));
+
+    const session = primary.startSession();
+    const sessionDB = session.getDatabase(dbName);
+    const sessionColl = sessionDB.getCollection(collName);
+
+    session.startTransaction();
+    assert.commandWorked(sessionColl.update(oldDoc, newDoc));
+
+    // Prepare a transaction. This will be replicated to the secondary.
+    const prepareTimestamp = PrepareHelpers.prepareTransaction(session);
+
+    // Now reconfig to force a failover.
+    let config = rst.getReplSetConfigFromNode();
+
+    config.members[0].priority = 0;
+    config.members[1].priority = 1;
+    config.version++;
+
+    // Run the reconfig command on whichever node the caller targeted.
+    const reconfigTarget = reconfigOnPrimary ? primary : secondary;
+    assert.commandWorked(reconfigTarget.adminCommand({replSetReconfig: config, force: true}));
+    rst.waitForState(primary, ReplSetTest.State.SECONDARY);
+
+    // Wait for the old secondary to become the new primary.
+    const newPrimary = rst.getPrimary();
+    assert.neq(primary, newPrimary, "failover did not occur");
+
+    // Commit the prepared transaction on the new primary.
+    const newSession = new _DelegatingDriverSession(newPrimary, session);
+    assert.commandWorked(PrepareHelpers.commitTransaction(newSession, prepareTimestamp));
+
+    // Verify the effect of the transaction.
+    const doc = newPrimary.getDB(dbName).getCollection(collName).findOne({});
+    assert.docEq(newDoc, doc);
+
+    rst.stopSet();
+};
\ No newline at end of file
diff --git a/jstests/replsets/prepare_survives_primary_reconfig_failover.js b/jstests/replsets/prepare_survives_primary_reconfig_failover.js
new file mode 100644
index 00000000000..8db3322b796
--- /dev/null
+++ b/jstests/replsets/prepare_survives_primary_reconfig_failover.js
@@ -0,0 +1,14 @@
+/**
+ * Tests that prepared transactions can safely be committed after a failover due to reconfig. We
+ * issue the reconfig command directly against the primary in this test.
+ *
+ * @tags: [uses_transactions, uses_prepare_transaction]
+ */
+(function() {
+    "use strict";
+    load("jstests/replsets/libs/prepare_failover_due_to_reconfig.js");
+
+    let testName = "prepare_survives_primary_reconfig_failover";
+
+    testPrepareFailoverDueToReconfig(testName, /* reconfigOnPrimary */ true);
+})();
diff --git a/jstests/replsets/prepare_survives_reconfig_via_heartbeat_failover.js b/jstests/replsets/prepare_survives_reconfig_via_heartbeat_failover.js
new file mode 100644
index 00000000000..bf4a0c565a9
--- /dev/null
+++ b/jstests/replsets/prepare_survives_reconfig_via_heartbeat_failover.js
@@ -0,0 +1,15 @@
+/**
+ * Tests that prepared transactions can safely be committed after a failover due to reconfig. We
+ * issue the reconfig command against the secondary in this test, so that the primary can learn of
+ * the new config via a heartbeat from that secondary.
+ *
+ * @tags: [uses_transactions, uses_prepare_transaction]
+ */
+(function() {
+    "use strict";
+    load("jstests/replsets/libs/prepare_failover_due_to_reconfig.js");
+
+    let testName = "prepare_survives_reconfig_via_heartbeat_failover";
+
+    testPrepareFailoverDueToReconfig(testName, /* reconfigOnPrimary */ false);
+})();