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// Confirms that change streams only see committed operations for prepared transactions.
// @tags: [uses_transactions,uses_change_streams,requires_majority_read_concern,
// exclude_from_large_txns_due_to_change_streams]
(function() {
"use strict";
load("jstests/core/txns/libs/prepare_helpers.js"); // For PrepareHelpers.
const dbName = "test";
const collName = "change_stream_transaction";
/**
* Asserts that the expected operation type and documentKey are found on the change stream
* cursor. Returns the change stream document.
*/
function assertWriteVisible(cursor, operationType, documentKey) {
assert.soon(() => cursor.hasNext());
const changeDoc = cursor.next();
assert.eq(operationType, changeDoc.operationType, changeDoc);
assert.eq(documentKey, changeDoc.documentKey, changeDoc);
return changeDoc;
}
/**
* Asserts that the expected operation type and documentKey are found on the change stream
* cursor. Pushes the corresponding resume token and change stream document to an array.
*/
function assertWriteVisibleWithCapture(cursor, operationType, documentKey, changeList) {
const changeDoc = assertWriteVisible(cursor, operationType, documentKey);
changeList.push(changeDoc);
}
/**
* Asserts that there are no changes waiting on the change stream cursor.
*/
function assertNoChanges(cursor) {
assert(!cursor.hasNext(), () => {
return "Unexpected change set: " + tojson(cursor.toArray());
});
}
function runTest(conn) {
const db = conn.getDB(dbName);
const coll = db.getCollection(collName);
const unwatchedColl = db.getCollection(collName + "_unwatched");
let changeList = [];
// Collections must be created outside of any transaction.
assert.commandWorked(db.createCollection(coll.getName()));
assert.commandWorked(db.createCollection(unwatchedColl.getName()));
//
// Start transaction 1.
//
const session1 = db.getMongo().startSession();
const sessionDb1 = session1.getDatabase(dbName);
const sessionColl1 = sessionDb1[collName];
session1.startTransaction({readConcern: {level: "majority"}});
//
// Start transaction 2.
//
const session2 = db.getMongo().startSession();
const sessionDb2 = session2.getDatabase(dbName);
const sessionColl2 = sessionDb2[collName];
session2.startTransaction({readConcern: {level: "majority"}});
//
// Start transaction 3.
//
const session3 = db.getMongo().startSession();
const sessionDb3 = session3.getDatabase(dbName);
const sessionColl3 = sessionDb3[collName];
session3.startTransaction({readConcern: {level: "majority"}});
// Open a change stream on the test collection.
const changeStreamCursor = coll.watch();
// Insert a document and confirm that the change stream has it.
assert.commandWorked(coll.insert({_id: "no-txn-doc-1"}, {writeConcern: {w: "majority"}}));
assertWriteVisibleWithCapture(
changeStreamCursor, "insert", {_id: "no-txn-doc-1"}, changeList);
// Insert two documents under each transaction and confirm no change stream updates.
assert.commandWorked(sessionColl1.insert([{_id: "txn1-doc-1"}, {_id: "txn1-doc-2"}]));
assert.commandWorked(sessionColl2.insert([{_id: "txn2-doc-1"}, {_id: "txn2-doc-2"}]));
assertNoChanges(changeStreamCursor);
// Update one document under each transaction and confirm no change stream updates.
assert.commandWorked(sessionColl1.update({_id: "txn1-doc-1"}, {$set: {"updated": 1}}));
assert.commandWorked(sessionColl2.update({_id: "txn2-doc-1"}, {$set: {"updated": 1}}));
assertNoChanges(changeStreamCursor);
// Update and then remove the second doc under each transaction and confirm no change stream
// events are seen.
assert.commandWorked(
sessionColl1.update({_id: "txn1-doc-2"}, {$set: {"update-before-delete": 1}}));
assert.commandWorked(
sessionColl2.update({_id: "txn2-doc-2"}, {$set: {"update-before-delete": 1}}));
assert.commandWorked(sessionColl1.remove({_id: "txn1-doc-2"}));
assert.commandWorked(sessionColl2.remove({_id: "txn2-doc-2"}));
assertNoChanges(changeStreamCursor);
// Perform a write to the 'session1' transaction in a collection that is not being watched
// by 'changeStreamCursor'. We do not expect to see this write in the change stream either
// now or on commit.
assert.commandWorked(
sessionDb1[unwatchedColl.getName()].insert({_id: "txn1-doc-unwatched-collection"}));
assertNoChanges(changeStreamCursor);
// Perform a write to the 'session3' transaction in a collection that is not being watched
// by 'changeStreamCursor'. We do not expect to see this write in the change stream either
// now or on commit.
assert.commandWorked(
sessionDb3[unwatchedColl.getName()].insert({_id: "txn3-doc-unwatched-collection"}));
assertNoChanges(changeStreamCursor);
// Perform a write outside of a transaction and confirm that the change stream sees only
// this write.
assert.commandWorked(coll.insert({_id: "no-txn-doc-2"}, {writeConcern: {w: "majority"}}));
assertWriteVisibleWithCapture(
changeStreamCursor, "insert", {_id: "no-txn-doc-2"}, changeList);
assertNoChanges(changeStreamCursor);
let prepareTimestampTxn1;
prepareTimestampTxn1 = PrepareHelpers.prepareTransaction(session1);
assertNoChanges(changeStreamCursor);
// TODO SERVER-39036: Change writeConcern to majority. Prior to this ticket a majority write
// will block on a prepared transaction. We should also be able to move the check for
// document existence prior to the transaction commit with this change.
// Perform a write at writeConcern w: local.
assert.commandWorked(coll.insert({_id: "no-txn-doc-3"}, {writeConcern: {w: 1}}));
//
// Commit first transaction and confirm expected changes.
//
assert.commandWorked(PrepareHelpers.commitTransaction(session1, prepareTimestampTxn1));
assertWriteVisibleWithCapture(
changeStreamCursor, "insert", {_id: "no-txn-doc-3"}, changeList);
assertWriteVisibleWithCapture(
changeStreamCursor, "insert", {_id: "txn1-doc-1"}, changeList);
assertWriteVisibleWithCapture(
changeStreamCursor, "insert", {_id: "txn1-doc-2"}, changeList);
assertWriteVisibleWithCapture(
changeStreamCursor, "update", {_id: "txn1-doc-1"}, changeList);
assertWriteVisibleWithCapture(
changeStreamCursor, "update", {_id: "txn1-doc-2"}, changeList);
assertWriteVisibleWithCapture(
changeStreamCursor, "delete", {_id: "txn1-doc-2"}, changeList);
assertNoChanges(changeStreamCursor);
// Transition the second transaction to prepared. We skip capturing the prepare
// timestamp it is not required for abortTransaction_forTesting().
PrepareHelpers.prepareTransaction(session2);
assertNoChanges(changeStreamCursor);
// TODO SERVER-39036: Change writeConcern to majority. Prior to this ticket a majority write
// will block on a prepared transaction. We should also be able to move the check for
// document existence prior to the transaction abort with this change.
// Perform a write at writeConcern w: local.
assert.commandWorked(coll.insert({_id: "no-txn-doc-4"}, {writeConcern: {w: 1}}));
//
// Abort second transaction.
//
assert.commandWorked(session2.abortTransaction_forTesting());
assertWriteVisibleWithCapture(
changeStreamCursor, "insert", {_id: "no-txn-doc-4"}, changeList);
assertNoChanges(changeStreamCursor);
changeStreamCursor.close();
// Test that change stream resume returns the expected set of documents at each point
// captured by this test.
for (let i = 0; i < changeList.length; ++i) {
const resumeCursor = coll.watch([], {startAfter: changeList[i]._id});
for (let x = (i + 1); x < changeList.length; ++x) {
const expectedChangeDoc = changeList[x];
assertWriteVisible(
resumeCursor, expectedChangeDoc.operationType, expectedChangeDoc.documentKey);
}
assertNoChanges(resumeCursor);
resumeCursor.close();
}
//
// Prepare and commit the third transaction and confirm that there are no visible changes.
//
let prepareTimestampTxn3;
prepareTimestampTxn3 = PrepareHelpers.prepareTransaction(session3);
assertNoChanges(changeStreamCursor);
assert.commandWorked(PrepareHelpers.commitTransaction(session3, prepareTimestampTxn3));
assertNoChanges(changeStreamCursor);
assert.commandWorked(db.dropDatabase());
}
const rst = new ReplSetTest({nodes: 1});
rst.startSet();
rst.initiate();
runTest(rst.getPrimary());
rst.stopSet();
})();
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