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// Tests resuming change streams on sharded collections.
//
// @tags: [
// requires_majority_read_concern,
// uses_change_streams,
// ]
(function() {
"use strict";
load('jstests/replsets/rslib.js'); // For getLatestOp.
load('jstests/libs/change_stream_util.js'); // For ChangeStreamTest.
const oplogSize = 1; // size in MB
const st = new ShardingTest({
shards: 2,
rs: {
nodes: 1,
oplogSize: oplogSize,
enableMajorityReadConcern: '',
// Use the noop writer with a higher frequency for periodic noops to speed up the test.
setParameter: {periodicNoopIntervalSecs: 1, writePeriodicNoops: true}
}
});
const mongosDB = st.s0.getDB(jsTestName());
const mongosColl = mongosDB[jsTestName()];
let cst = new ChangeStreamTest(mongosDB);
function testResume(mongosColl, collToWatch) {
mongosColl.drop();
// Enable sharding on the test DB and ensure its primary is st.shard0.shardName.
assert.commandWorked(mongosDB.adminCommand({enableSharding: mongosDB.getName()}));
st.ensurePrimaryShard(mongosDB.getName(), st.rs0.getURL());
// Shard the test collection on _id.
assert.commandWorked(
mongosDB.adminCommand({shardCollection: mongosColl.getFullName(), key: {_id: 1}}));
// Split the collection into 2 chunks: [MinKey, 0), [0, MaxKey].
assert.commandWorked(
mongosDB.adminCommand({split: mongosColl.getFullName(), middle: {_id: 0}}));
// Move the [0, MaxKey] chunk to st.shard1.shardName.
assert.commandWorked(mongosDB.adminCommand(
{moveChunk: mongosColl.getFullName(), find: {_id: 1}, to: st.rs1.getURL()}));
// Write a document to each chunk.
assert.commandWorked(mongosColl.insert({_id: -1}, {writeConcern: {w: "majority"}}));
assert.commandWorked(mongosColl.insert({_id: 1}, {writeConcern: {w: "majority"}}));
let changeStream = cst.startWatchingChanges(
{pipeline: [{$changeStream: {}}], collection: collToWatch, includeToken: true});
// We awaited the replication of the first writes, so the change stream shouldn't return
// them.
assert.commandWorked(mongosColl.update({_id: -1}, {$set: {updated: true}}));
// Record current time to resume a change stream later in the test.
const resumeTimeFirstUpdate = mongosDB.runCommand({hello: 1}).$clusterTime.clusterTime;
assert.commandWorked(mongosColl.update({_id: 1}, {$set: {updated: true}}));
// Test that we see the two writes, and remember their resume tokens.
let next = cst.getOneChange(changeStream);
assert.eq(next.operationType, "update");
assert.eq(next.documentKey._id, -1);
const resumeTokenFromFirstUpdateOnShard0 = next._id;
next = cst.getOneChange(changeStream);
assert.eq(next.operationType, "update");
assert.eq(next.documentKey._id, 1);
const resumeTokenFromFirstUpdateOnShard1 = next._id;
// Write some additional documents, then test that it's possible to resume after the first
// update.
assert.commandWorked(mongosColl.insert({_id: -2}, {writeConcern: {w: "majority"}}));
assert.commandWorked(mongosColl.insert({_id: 2}, {writeConcern: {w: "majority"}}));
changeStream = cst.startWatchingChanges({
pipeline: [{$changeStream: {resumeAfter: resumeTokenFromFirstUpdateOnShard0}}],
collection: collToWatch
});
for (let nextExpectedId of [1, -2, 2]) {
assert.eq(cst.getOneChange(changeStream).documentKey._id, nextExpectedId);
}
// Test that the stream can't resume if the resume token is no longer present in the oplog.
// Roll over the entire oplog on the shard with the resume token for the first update.
const shardWithResumeToken = st.rs1.getPrimary(); // Resume from shard 1.
const mostRecentOplogEntry = getLatestOp(shardWithResumeToken);
assert.neq(mostRecentOplogEntry, null);
const largeStr = new Array(4 * 1024 * oplogSize).join('abcdefghi');
let i = 0;
function oplogIsRolledOver() {
// The oplog has rolled over if the op that used to be newest is now older than the
// oplog's current oldest entry. Said another way, the oplog is rolled over when
// everything in the oplog is newer than what used to be the newest entry.
return bsonWoCompare(
mostRecentOplogEntry.ts,
getFirstOplogEntry(shardWithResumeToken, {readConcern: "majority"}).ts) < 0;
}
while (!oplogIsRolledOver()) {
let idVal = 100 + (i++);
assert.commandWorked(
mongosColl.insert({_id: idVal, long_str: largeStr}, {writeConcern: {w: "majority"}}));
sleep(100);
}
ChangeStreamTest.assertChangeStreamThrowsCode({
db: mongosDB,
collName: collToWatch,
pipeline: [{$changeStream: {resumeAfter: resumeTokenFromFirstUpdateOnShard1}}],
expectedCode: ErrorCodes.ChangeStreamHistoryLost
});
ChangeStreamTest.assertChangeStreamThrowsCode({
db: mongosDB,
collName: collToWatch,
pipeline: [{$changeStream: {startAtOperationTime: resumeTimeFirstUpdate}}],
expectedCode: ErrorCodes.ChangeStreamHistoryLost
});
// Test that the change stream can't resume if the resume token *is* present in the oplog,
// but one of the shards has rolled over its oplog enough that it doesn't have a long enough
// history to resume. Since we just rolled over the oplog on shard 1, we know that
// 'resumeTokenFromFirstUpdateOnShard0' is still present on shard 0, but shard 1 doesn't
// have any changes earlier than that, so won't be able to resume.
ChangeStreamTest.assertChangeStreamThrowsCode({
db: mongosDB,
collName: collToWatch,
pipeline: [{$changeStream: {resumeAfter: resumeTokenFromFirstUpdateOnShard0}}],
expectedCode: ErrorCodes.ChangeStreamHistoryLost
});
// Drop the collection.
assert(mongosColl.drop());
// Shard the test collection on shardKey.
assert.commandWorked(
mongosDB.adminCommand({shardCollection: mongosColl.getFullName(), key: {shardKey: 1}}));
// Split the collection into 2 chunks: [MinKey, 50), [50, MaxKey].
assert.commandWorked(
mongosDB.adminCommand({split: mongosColl.getFullName(), middle: {shardKey: 50}}));
// Move the [50, MaxKey] chunk to st.shard1.shardName.
assert.commandWorked(mongosDB.adminCommand(
{moveChunk: mongosColl.getFullName(), find: {shardKey: 51}, to: st.rs1.getURL()}));
const numberOfDocs = 100;
// Insert test documents.
for (let counter = 0; counter < numberOfDocs / 5; ++counter) {
assert.commandWorked(mongosColl.insert({_id: "abcd" + counter, shardKey: counter * 5 + 0},
{writeConcern: {w: "majority"}}));
assert.commandWorked(mongosColl.insert({_id: "Abcd" + counter, shardKey: counter * 5 + 1},
{writeConcern: {w: "majority"}}));
assert.commandWorked(mongosColl.insert({_id: "aBcd" + counter, shardKey: counter * 5 + 2},
{writeConcern: {w: "majority"}}));
assert.commandWorked(mongosColl.insert({_id: "abCd" + counter, shardKey: counter * 5 + 3},
{writeConcern: {w: "majority"}}));
assert.commandWorked(mongosColl.insert({_id: "abcD" + counter, shardKey: counter * 5 + 4},
{writeConcern: {w: "majority"}}));
}
let allChangesCursor = cst.startWatchingChanges(
{pipeline: [{$changeStream: {}}], collection: collToWatch, includeToken: true});
// Perform the multi-update that will induce timestamp collisions
assert.commandWorked(mongosColl.update({}, {$set: {updated: true}}, {multi: true}));
// Loop over documents and open inner change streams resuming from a specified position.
// Note we skip the last document as it does not have the next document so we would
// hang indefinitely.
for (let counter = 0; counter < numberOfDocs - 1; ++counter) {
let next = cst.getOneChange(allChangesCursor);
const resumeToken = next._id;
const caseInsensitive = {locale: "en_US", strength: 2};
let resumedCaseInsensitiveCursor = cst.startWatchingChanges({
pipeline: [{$changeStream: {resumeAfter: resumeToken}}],
collection: collToWatch,
aggregateOptions: {collation: caseInsensitive}
});
cst.getOneChange(resumedCaseInsensitiveCursor);
}
}
// Test change stream on a single collection.
testResume(mongosColl, mongosColl.getName());
// Test change stream on all collections.
testResume(mongosColl, 1);
cst.cleanUp();
st.stop();
})();
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