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/**
* Test that read-only transactions are executed speculatively, and that once they are committed
* with a majority write concern, the data read is indeed majority-committed.
*
* @tags: [uses_transactions, requires_majority_read_concern]
*/
(function() {
"use strict";
load("jstests/libs/write_concern_util.js"); // For stopServerReplication
const dbName = "test";
const collName = "speculative_read_transaction";
const rst = new ReplSetTest({name: collName, nodes: [{}, {rsConfig: {priority: 0}}]});
rst.startSet();
rst.initiate();
const primary = rst.getPrimary();
const secondary = rst.getSecondary();
const testDB = primary.getDB(dbName);
const coll = testDB[collName];
function runTest(sessionOptions) {
testDB.runCommand({drop: collName, writeConcern: {w: "majority"}});
// Do an initial write so we have something to update.
assert.commandWorked(coll.insert([{_id: 0, x: 0}], {w: "majority"}));
rst.awaitLastOpCommitted();
// Stop replication on the secondary so the majority commit never moves forward.
stopServerReplication(secondary);
// Do a local update in another client.
// The transaction should see this, due to speculative behavior.
const otherclient = new Mongo(primary.host);
assert.commandWorked(otherclient.getDB(dbName)[collName].update({_id: 0}, {x: 1}, {w: 1}));
// Initiate a session on the primary.
const session = testDB.getMongo().startSession(sessionOptions);
const sessionDb = session.getDatabase(dbName);
const sessionColl = sessionDb.getCollection(collName);
// Abort does not wait for write concern.
jsTestLog("Starting majority-abort transaction");
session.startTransaction({readConcern: {level: "snapshot"}, writeConcern: {w: "majority"}});
assert.eq(sessionColl.findOne({_id: 0}), {_id: 0, x: 1});
assert.commandWorked(session.abortTransaction_forTesting());
// This transaction should complete because it does not use majority write concern.
jsTestLog("Starting non-majority commit transaction");
session.startTransaction({readConcern: {level: "snapshot"}, writeConcern: {w: 1}});
assert.eq(sessionColl.findOne({_id: 0}), {_id: 0, x: 1});
assert.commandWorked(session.commitTransaction_forTesting());
// This transaction should not complete because it uses snapshot read concern, majority
// write concern and the commit point is not advancing.
jsTestLog("Starting majority-commit snapshot-read transaction");
session.startTransaction(
{readConcern: {level: "snapshot"}, writeConcern: {w: "majority", wtimeout: 5000}});
assert.eq(sessionColl.findOne({_id: 0}), {_id: 0, x: 1});
assert.commandFailedWithCode(session.commitTransaction_forTesting(),
ErrorCodes.WriteConcernFailed);
// Allow the majority commit point to advance to allow the failed write concern to clear.
restartServerReplication(secondary);
rst.awaitReplication();
stopServerReplication(secondary);
// Do another local update from another client
assert.commandWorked(otherclient.getDB(dbName)[collName].update({_id: 0}, {x: 2}, {w: 1}));
// This transaction should not complete because it uses local read concern upconverted to
// snapshot.
// TODO(SERVER-34881): Once default read concern is speculative majority, local read
// concern should not wait for the majority commit point to advance.
jsTestLog("Starting majority-commit local-read transaction");
session.startTransaction(
{readConcern: {level: "local"}, writeConcern: {w: "majority", wtimeout: 5000}});
assert.eq(sessionColl.findOne({_id: 0}), {_id: 0, x: 2});
assert.commandFailedWithCode(session.commitTransaction_forTesting(),
ErrorCodes.WriteConcernFailed);
// Allow the majority commit point to advance to allow the failed write concern to clear.
restartServerReplication(secondary);
rst.awaitReplication();
stopServerReplication(secondary);
// Do another local update from another client
assert.commandWorked(otherclient.getDB(dbName)[collName].update({_id: 0}, {x: 3}, {w: 1}));
// This transaction should not complete because it uses majority read concern, majority
// write concern, and the commit point is not advancing.
jsTestLog("Starting majority-commit majority-read transaction");
session.startTransaction(
{readConcern: {level: "majority"}, writeConcern: {w: "majority", wtimeout: 5000}});
assert.eq(sessionColl.findOne({_id: 0}), {_id: 0, x: 3});
assert.commandFailedWithCode(session.commitTransaction_forTesting(),
ErrorCodes.WriteConcernFailed);
// Restart server replication to allow majority commit point to advance.
restartServerReplication(secondary);
session.endSession();
}
runTest({causalConsistency: false});
runTest({causalConsistency: true});
rst.stopSet();
}());
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