/**
 * Tests that a DDL op (drop collection) begun after a prepared transaction fails during shutdown.
 * Sets up a prepared transaction, starts drop collection in a parallel shell, attempts to wait for
 * the drop collection operation to enqueue a lock request waiting behind the transaction, then
 * shuts down the server. On restarting, we expect to find the collection was not dropped, that
 * there is no way for a DDL op to slip through and succeed after transaction resources (locks) are
 * cleared away during shutdown.
 *
 * This is an attempt to test that DDL ops cannot succeed AFTER transaction state (including locks)
 * is cleared during shutdown. However, a lot goes on during shutdown and the DDL op probably gets
 * interrupted well before the transaction state is cleared: either during shutdown's repl
 * stepdown attempt or as soon as operations get interrupted for shutdown (which occurs before
 * transaction state is cleared).
 *
 * @tags: [requires_persistence, uses_prepare_transaction, uses_transactions]
 */

(function() {
"use strict";

load("jstests/core/txns/libs/prepare_helpers.js");
load("jstests/libs/parallel_shell_helpers.js");
load('jstests/libs/test_background_ops.js');

const rst = new ReplSetTest({nodes: 1});
rst.startSet();
rst.initiate();

const dbName = "test";
const collName = "ddl_op_behind_prepared_transaction_fails_in_shutdown";
let primary = rst.getPrimary();
const testDB = primary.getDB(dbName);
const testColl = testDB.getCollection(collName);
const txnDoc = {
    _id: 100
};

jsTest.log("Creating a collection '" + collName + "' with data in it...");
assert.commandWorked(testDB.createCollection(collName, {writeConcern: {w: "majority"}}));
let bulk = testColl.initializeUnorderedBulkOp();
for (let i = 0; i < 2; ++i) {
    bulk.insert({_id: i});
}
assert.commandWorked(bulk.execute());

jsTest.log("Setting up a prepared transaction...");
const session = primary.startSession();
const sessionDB = session.getDatabase(dbName);
const sessionColl = sessionDB.getCollection(collName);
session.startTransaction();
assert.commandWorked(sessionColl.insert(txnDoc));
const prepareTimestamp = PrepareHelpers.prepareTransaction(session);

function runDropCollection(dbName, collName) {
    jsTest.log("Dropping collection in parallel shell...");
    // 'db' is defined in the parallel shell 'startParallelShell' will spin up.
    const res = db.getSiblingDB(dbName).runCommand({drop: collName});
    assert.commandFailedWithCode(
        res,
        [ErrorCodes.InterruptedAtShutdown, ErrorCodes.InterruptedDueToReplStateChange],
        "parallel shell drop cmd completed in an unexpected way: " + tojson(res));
    jsTest.log("Done dropping collection in parallel shell");
}

// Use a failpoint to wait for the drop operation to get as close as possible to a lock request
// before we release it and wait 1 second more for it to hopefully have time to enqueue a lock
// request. It takes a while for the parallel shell to start up, establish a connection with the
// server for the drop operation, etc., and we do not want to interrupt it earlier than lock
// acquisition with the shutdown signal.
//
// This is best-effort, not deterministic, since we cannot place a fail point directly in the
// locking code as that would hang everything rather than just drop.
assert.commandWorked(primary.adminCommand(
    {configureFailPoint: 'hangDropCollectionBeforeLockAcquisition', mode: 'alwaysOn'}));
let joinDropCollection;
try {
    jsTest.log("Starting a parallel shell to concurrently run drop collection...");
    joinDropCollection =
        startParallelShell(funWithArgs(runDropCollection, dbName, collName), primary.port);

    jsTest.log("Waiting for drop collection to block behind the prepared transaction...");
    checkLog.contains(primary,
                      "Hanging drop collection before lock acquisition while fail point is set");
} finally {
    assert.commandWorked(primary.adminCommand(
        {configureFailPoint: 'hangDropCollectionBeforeLockAcquisition', mode: 'off'}));
}
sleep(1 * 1000);

jsTest.log("Restarting the mongod...");
// Skip validation because it requires a lock that the prepared transaction is blocking.
rst.stop(primary, undefined, {skipValidation: true});
rst.start(primary, {}, true /*restart*/);
primary = rst.getPrimary();

joinDropCollection();

const numDocs = primary.getDB(dbName).getCollection(collName).find().length();
// We expect two documents because the third is in an uncommitted transaction and not visible.
assert.eq(
    2,
    numDocs,
    "Expected '" + collName + "' to find 2 documents, found " + numDocs +
        ". Drop collection may have succeeded during shutdown while a transaction was in the " +
        "prepared state.");

// We will check that the prepared transaction is still active as expected, since we are here.
assert.commandFailedWithCode(primary.getDB(dbName).runCommand({
    find: collName,
    filter: txnDoc,
    readConcern: {afterClusterTime: prepareTimestamp},
    maxTimeMS: 5000
}),
                             ErrorCodes.MaxTimeMSExpired);

// Skip validation because it requires a lock that the prepared transaction is blocking.
rst.stopSet(true /*use default exit signal*/, false /*forRestart*/, {skipValidation: true});
})();