1 files changed, 87 insertions, 0 deletions
diff --git a/jstests/replsets/update_commit_point_from_sync_source_ignores_term.js b/jstests/replsets/update_commit_point_from_sync_source_ignores_term.js
new file mode 100644
index 00000000000..7915dfd4b7b
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+++ b/jstests/replsets/update_commit_point_from_sync_source_ignores_term.js
@@ -0,0 +1,87 @@
+/**
+ * Tests that even if the sync source's lastOpCommitted is in a higher term than the node's
+ * lastApplied, the node can update its own lastOpCommitted to its lastApplied.
+ * @tags: [requires_majority_read_concern]
+ */
+(function() {
+    "use strict";
+
+    load("jstests/libs/write_concern_util.js");  // for [stop|restart]ServerReplication.
+
+    const dbName = "test";
+    const collName = "coll";
+
+    // Set up a ReplSetTest where nodes only sync one oplog entry at a time.
+    const rst = new ReplSetTest(
+        {nodes: 5, useBridge: true, nodeOptions: {setParameter: "bgSyncOplogFetcherBatchSize=1"}});
+    rst.startSet();
+    const config = rst.getReplSetConfig();
+    // Ban chaining and prevent elections.
+    config.settings = {chainingAllowed: false, electionTimeoutMillis: 12 * 60 * 60 * 1000};
+    rst.initiate(config);
+
+    const nodeA = rst.nodes[0];
+    const nodeB = rst.nodes[1];
+    const nodeC = rst.nodes[2];
+    const nodeD = rst.nodes[3];
+    const nodeE = rst.nodes[4];
+
+    jsTest.log("Node A is primary in term 1. Replicate a write to Node E that is not committed.");
+    assert.eq(nodeA, rst.getPrimary());
+    // Ensure Node E has a majority committed snapshot.
+    assert.commandWorked(nodeA.getDB(dbName)[collName].insert({_id: "dummy"}));
+    rst.awaitLastOpCommitted();
+    stopServerReplication([nodeB, nodeC, nodeD]);
+    assert.commandWorked(nodeA.getDB(dbName)[collName].insert({_id: "term 1, doc 1"}));
+    rst.awaitReplication(undefined, undefined, [nodeE]);
+    assert.eq(0,
+              nodeE.getDB(dbName)[collName]
+                  .find({_id: "term 1, doc 1"})
+                  .readConcern("majority")
+                  .itcount());
+
+    jsTest.log("Disconnect Node E. Perform a new write.");
+    nodeE.disconnect([nodeA, nodeB, nodeC, nodeD]);
+    restartServerReplication([nodeB, nodeC, nodeD]);
+    assert.commandWorked(nodeA.getDB(dbName)[collName].insert({_id: "term 1, doc 2"}));
+
+    jsTest.log("Step up Node B in term 2. Commit a new write.");
+    // Ensure Node B is caught up, so that it can become primary.
+    rst.awaitReplication(undefined, undefined, [nodeB]);
+    assert.commandWorked(nodeB.adminCommand({replSetStepUp: 1}));
+    rst.waitForState(nodeA, ReplSetTest.State.SECONDARY);
+    assert.eq(nodeB, rst.getPrimary());
+    assert.commandWorked(
+        nodeB.getDB(dbName)[collName].insert({_id: "term 2"}, {writeConcern: {w: "majority"}}));
+    // Node E might sync from Node A or Node B. Ensure they both have the new commit point.
+    rst.awaitLastOpCommitted(undefined, [nodeA]);
+
+    jsTest.log("Allow Node E to replicate the last write from term 1.");
+    // The stopReplProducerOnDocument failpoint ensures that Node E stops replicating before
+    // applying the document {msg: "new primary"}, which is the first document of term 2. This
+    // depends on the oplog fetcher batch size being 1.
+    assert.commandWorked(nodeE.adminCommand({
+        configureFailPoint: "stopReplProducerOnDocument",
+        mode: "alwaysOn",
+        data: {document: {msg: "new primary"}}
+    }));
+    nodeE.reconnect([nodeA, nodeB, nodeC, nodeD]);
+    assert.soon(() => {
+        return nodeE.getDB(dbName)[collName].find({_id: "term 1, doc 2"}).itcount() === 1;
+    });
+    assert.eq(0, nodeE.getDB(dbName)[collName].find({_id: "term 2"}).itcount());
+
+    jsTest.log("Node E now knows that its first write is majority committed.");
+    // It does not yet know that {_id: "term 1, doc 2"} is committed. Its last batch was {_id: "term
+    // 1, doc 2"}. The sync source's lastOpCommitted was in term 2, so Node E updated its
+    // lastOpCommitted to its lastApplied, which did not yet include {_id: "term 1, doc 2"}.
+    assert.eq(1,
+              nodeE.getDB(dbName)[collName]
+                  .find({_id: "term 1, doc 1"})
+                  .readConcern("majority")
+                  .itcount());
+
+    assert.commandWorked(
+        nodeE.adminCommand({configureFailPoint: "stopReplProducerOnDocument", mode: "off"}));
+    rst.stopSet();
+}());