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/**
* Test that change streams using speculative majority wait for the latest observed oplog timestamp
* to majority commit.
*
* If a change stream query returns a batch containing oplog entries no newer than timestamp T, the
* server may still report a high-water-mark postBatchResumeToken representing the latest majority
* committed oplog timestamp that it observed while scanning the oplog, which may be greater than T.
* A mongoS will use this PBRT as a guarantee that no new change events will occur at a lesser
* timestamp. This guarantee is only valid if the timestamp is actually majority committed, so we
* need to make sure that guarantee holds, even when using speculative majority.
*
* @tags: [uses_speculative_majority]
*/
(function() {
"use strict";
load("jstests/libs/write_concern_util.js"); // for [stop|restart]ServerReplication.
const name = "change_stream_speculative_majority_latest_oplog_timestamp";
const replTest = new ReplSetTest({
name: name,
nodes: [{}, {rsConfig: {priority: 0}}],
nodeOptions: {enableMajorityReadConcern: 'false'}
});
replTest.startSet();
replTest.initiate();
const dbName = name;
const collName = "coll";
const otherCollName = "coll_other";
const primary = replTest.getPrimary();
const secondary = replTest.getSecondary();
const primaryDB = primary.getDB(dbName);
const primaryColl = primaryDB[collName];
assert.commandWorked(primaryColl.insert({_id: 0}, {writeConcern: {w: "majority"}}));
let res = primaryDB.runCommand(
{aggregate: collName, pipeline: [{$changeStream: {}}], cursor: {}, maxTimeMS: 5000});
assert.commandWorked(res);
let cursorId = res.cursor.id;
// Insert a document on primary and let it majority commit.
assert.commandWorked(primaryColl.insert({_id: 1}, {writeConcern: {w: "majority"}}));
// Pause replication on the secondary so that further writes won't majority commit.
jsTestLog("Stopping replication to secondary.");
stopServerReplication(secondary);
// Receive the first change event.
res = primary.getDB(dbName).runCommand({getMore: cursorId, collection: collName});
let changes = res.cursor.nextBatch;
assert.eq(changes.length, 1);
assert.eq(changes[0]["fullDocument"], {_id: 1});
assert.eq(changes[0]["operationType"], "insert");
// Extract the postBatchResumeToken from the first batch.
const initialPostBatchResumeToken = res.cursor.postBatchResumeToken;
assert.neq(initialPostBatchResumeToken, undefined);
// Do a write on a collection that we are not watching changes for.
let otherWriteRes = primaryDB.runCommand({insert: otherCollName, documents: [{_id: 1}]});
let otherWriteOpTime = otherWriteRes.operationTime;
// Replication to the secondary is paused, so the write to 'otherCollName' cannot majority
// commit. A change stream getMore is expected to return the "latest oplog timestamp" which it
// scanned and this timestamp must be majority committed. So, this getMore should time out
// waiting for the previous write to majority commit, even though it's on a collection that is
// not being watched.
res = primary.getDB(dbName).runCommand(
{getMore: cursorId, collection: collName, maxTimeMS: 5000});
assert.commandFailedWithCode(res, ErrorCodes.MaxTimeMSExpired);
jsTestLog("Restarting replication to secondary.");
restartServerReplication(secondary);
replTest.awaitReplication();
// Now that writes can replicate again, the previous operation should have majority committed,
// making it safe to advance the postBatchResumeToken. Note that no further events are returned,
// indicating that the new PBRT is a high water mark generated at the latest oplog timestamp.
res = primary.getDB(dbName).runCommand(
{getMore: cursorId, collection: collName, maxTimeMS: 5000});
assert.commandWorked(res);
assert.eq(res.cursor.nextBatch, []);
assert.gt(bsonWoCompare(res.cursor.postBatchResumeToken, initialPostBatchResumeToken), 0);
replTest.stopSet();
})();
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