mongo/jstests/replsets/initial_sync_commit_prepared_transaction.js

/**
 * Tests that initial sync successfully applies the commitTransaction oplog entry. To be able to
 * test this, we have to pause collection cloning and run commitTransaction so that the oplog entry
 * is applied during the oplog application phase of initial sync.
 *
 * @tags: [uses_transactions, uses_prepare_transaction]
 */

(function() {
    "use strict";

    load("jstests/libs/check_log.js");
    load("jstests/core/txns/libs/prepare_helpers.js");

    const replTest = new ReplSetTest({nodes: 2});
    replTest.startSet();

    const config = replTest.getReplSetConfig();
    // Increase the election timeout so that we do not accidentally trigger an election while the
    // secondary is restarting.
    config.settings = {"electionTimeoutMillis": 12 * 60 * 60 * 1000};
    replTest.initiate(config);

    const primary = replTest.getPrimary();
    let secondary = replTest.getSecondary();

    const dbName = "test";
    const collName = "initial_sync_commit_prepared_transaction";
    const testDB = primary.getDB(dbName);
    const testColl = testDB.getCollection(collName);

    assert.commandWorked(testColl.insert({_id: 1}));

    jsTestLog("Preparing a transaction that will be the oldest active transaction");

    // Prepare a transaction so that there is an active transaction with an oplog entry. The prepare
    // timestamp will become the beginFetchingTimestamp during initial sync.
    const session1 = primary.startSession({causalConsistency: false});
    const sessionDB1 = session1.getDatabase(dbName);
    const sessionColl1 = sessionDB1.getCollection(collName);
    session1.startTransaction();
    assert.commandWorked(sessionColl1.insert({_id: 2}));
    let prepareTimestamp1 = PrepareHelpers.prepareTransaction(session1);

    // Do another operation so that the beginFetchingTimestamp will be different from the
    // beginApplyingTimestamp.
    assert.commandWorked(testColl.insert({_id: 3}));

    jsTestLog("Restarting the secondary");

    // Restart the secondary with startClean set to true so that it goes through initial sync. Also
    // restart the node with a failpoint turned on that will pause initial sync after the secondary
    // has copied {_id: 1} and {_id: 3}. This way we can try to commit the prepared transaction
    // while initial sync is paused and know that its operations won't be copied during collection
    // cloning. Instead, the commitTransaction oplog entry must be applied during oplog application.
    replTest.stop(secondary,
                  // signal
                  undefined,
                  // Validation would encounter a prepare conflict on the open transaction.
                  {skipValidation: true});
    secondary = replTest.start(
        secondary,
        {
          startClean: true,
          setParameter: {
              'failpoint.initialSyncHangDuringCollectionClone': tojson(
                  {mode: 'alwaysOn', data: {namespace: testColl.getFullName(), numDocsToClone: 2}}),
              'numInitialSyncAttempts': 1
          }
        },
        true /* wait */);

    // Wait for failpoint to be reached so we know that collection cloning is paused.
    checkLog.contains(secondary, "initialSyncHangDuringCollectionClone fail point enabled");

    jsTestLog("Running operations while collection cloning is paused");

    // Commit a transaction on the sync source while collection cloning is paused so that we know
    // they must be applied during the oplog application stage of initial sync.
    assert.commandWorked(
        PrepareHelpers.commitTransactionAfterPrepareTS(session1, prepareTimestamp1));

    jsTestLog("Resuming initial sync");

    // Resume initial sync.
    assert.commandWorked(secondary.adminCommand(
        {configureFailPoint: "initialSyncHangDuringCollectionClone", mode: "off"}));

    // Wait for the secondary to complete initial sync.
    replTest.waitForState(secondary, ReplSetTest.State.SECONDARY);

    jsTestLog("Initial sync completed");

    // Make sure the transaction committed properly and is reflected after the initial sync.
    let res = secondary.getDB(dbName).getCollection(collName).findOne({_id: 2});
    assert.docEq(res, {_id: 2}, res);

    // Step up the secondary after initial sync is done and make sure we can successfully run
    // another transaction.
    replTest.stepUp(secondary);
    replTest.waitForState(secondary, ReplSetTest.State.PRIMARY);
    let newPrimary = replTest.getPrimary();
    const session2 = newPrimary.startSession({causalConsistency: false});
    const sessionDB2 = session2.getDatabase(dbName);
    const sessionColl2 = sessionDB2.getCollection(collName);
    session2.startTransaction();
    assert.commandWorked(sessionColl2.insert({_id: 4}));
    let prepareTimestamp2 = PrepareHelpers.prepareTransaction(session2);
    assert.commandWorked(
        PrepareHelpers.commitTransactionAfterPrepareTS(session2, prepareTimestamp2));
    res = newPrimary.getDB(dbName).getCollection(collName).findOne({_id: 4});
    assert.docEq(res, {_id: 4}, res);

    replTest.stopSet();
})();