list<intrusive_ptr<DocumentSource>> DocumentSourceChangeStream::createFromBson(
BSONElement elem, const intrusive_ptr<ExpressionContext>& expCtx) {
// TODO: Add sharding support here (SERVER-29141).
uassert(
40470, "The $changeStream stage is not supported on sharded systems.", !expCtx->inRouter);
uassert(40471,
"Only default collation is allowed when using a $changeStream stage.",
!expCtx->getCollator());
auto replCoord = repl::ReplicationCoordinator::get(expCtx->opCtx);
uassert(40573, "The $changeStream stage is only supported on replica sets", replCoord);
Timestamp startFrom = replCoord->getLastCommittedOpTime().getTimestamp();
intrusive_ptr<DocumentSourceCheckResumeToken> resumeStage = nullptr;
auto spec = DocumentSourceChangeStreamSpec::parse(IDLParserErrorContext("$changeStream"),
elem.embeddedObject());
if (auto resumeAfter = spec.getResumeAfter()) {
ResumeToken token = resumeAfter.get();
startFrom = token.getTimestamp();
DocumentSourceCheckResumeTokenSpec spec;
spec.setResumeToken(std::move(token));
resumeStage = DocumentSourceCheckResumeToken::create(expCtx, std::move(spec));
}
const bool changeStreamIsResuming = resumeStage != nullptr;
auto fullDocOption = spec.getFullDocument();
uassert(40575,
str::stream() << "unrecognized value for the 'fullDocument' option to the "
"$changeStream stage. Expected \"default\" or "
"\"updateLookup\", got \""
<< fullDocOption
<< "\"",
fullDocOption == "updateLookup"_sd || fullDocOption == "default"_sd);
const bool shouldLookupPostImage = (fullDocOption == "updateLookup"_sd);
auto oplogMatch = DocumentSourceOplogMatch::create(
buildMatchFilter(expCtx->ns, startFrom, changeStreamIsResuming), expCtx);
auto transformation = createTransformationStage(elem.embeddedObject(), expCtx);
list<intrusive_ptr<DocumentSource>> stages = {oplogMatch, transformation};
if (resumeStage) {
stages.push_back(resumeStage);
}
auto closeCursorSource = DocumentSourceCloseCursor::create(expCtx);
stages.push_back(closeCursorSource);
if (shouldLookupPostImage) {
stages.push_back(DocumentSourceLookupChangePostImage::create(expCtx));
}
return stages;
}
DocumentSourceChangeStreamTransform::DocumentSourceChangeStreamTransform(
const boost::intrusive_ptr<ExpressionContext>& expCtx,
const ServerGlobalParams::FeatureCompatibility::Version& fcv,
BSONObj changeStreamSpec)
: DocumentSource(expCtx),
_changeStreamSpec(changeStreamSpec.getOwned()),
_isIndependentOfAnyCollection(expCtx->ns.isCollectionlessAggregateNS()),
_fcv(fcv) {
_nsRegex.emplace(DocumentSourceChangeStream::getNsRegexForChangeStream(expCtx->ns));
auto spec = DocumentSourceChangeStreamSpec::parse(IDLParserErrorContext("$changeStream"),
_changeStreamSpec);
// If the change stream spec includes a resumeToken with a shard key, populate the document key
// cache with the field paths.
auto resumeAfter = spec.getResumeAfter();
auto startAfter = spec.getStartAfter();
if (resumeAfter || startAfter) {
ResumeToken token = resumeAfter ? resumeAfter.get() : startAfter.get();
ResumeTokenData tokenData = token.getData();
if (!tokenData.documentKey.missing() && tokenData.uuid) {
std::vector<FieldPath> docKeyFields;
auto docKey = tokenData.documentKey.getDocument();
auto iter = docKey.fieldIterator();
while (iter.more()) {
auto fieldPair = iter.next();
docKeyFields.push_back(fieldPair.first);
}
// If the document key from the resume token has more than one field, that means it
// includes the shard key and thus should never change.
auto isFinal = docKey.size() > 1;
_documentKeyCache[tokenData.uuid.get()] =
DocumentKeyCacheEntry({docKeyFields, isFinal});
}
}
}
list<intrusive_ptr<DocumentSource>> DocumentSourceChangeStream::createFromBson(
BSONElement elem, const intrusive_ptr<ExpressionContext>& expCtx) {
// TODO: Add sharding support here (SERVER-29141).
uassert(
40470, "The $changeStream stage is not supported on sharded systems.", !expCtx->inMongos);
uassert(40471,
"Only default collation is allowed when using a $changeStream stage.",
!expCtx->getCollator());
auto replCoord = repl::ReplicationCoordinator::get(expCtx->opCtx);
uassert(40573,
"The $changeStream stage is only supported on replica sets",
replCoord &&
replCoord->getReplicationMode() == repl::ReplicationCoordinator::Mode::modeReplSet);
Timestamp startFrom = replCoord->getMyLastAppliedOpTime().getTimestamp();
intrusive_ptr<DocumentSource> resumeStage = nullptr;
auto spec = DocumentSourceChangeStreamSpec::parse(IDLParserErrorContext("$changeStream"),
elem.embeddedObject());
if (auto resumeAfter = spec.getResumeAfter()) {
ResumeToken token = resumeAfter.get();
auto resumeNamespace = UUIDCatalog::get(expCtx->opCtx).lookupNSSByUUID(token.getUuid());
uassert(40615,
"The resume token UUID does not exist. Has the collection been dropped?",
!resumeNamespace.isEmpty());
startFrom = token.getTimestamp();
if (expCtx->needsMerge) {
DocumentSourceShardCheckResumabilitySpec spec;
spec.setResumeToken(std::move(token));
resumeStage = DocumentSourceShardCheckResumability::create(expCtx, std::move(spec));
} else {
DocumentSourceEnsureResumeTokenPresentSpec spec;
spec.setResumeToken(std::move(token));
resumeStage = DocumentSourceEnsureResumeTokenPresent::create(expCtx, std::move(spec));
}
}
const bool changeStreamIsResuming = resumeStage != nullptr;
auto fullDocOption = spec.getFullDocument();
uassert(40575,
str::stream() << "unrecognized value for the 'fullDocument' option to the "
"$changeStream stage. Expected \"default\" or "
"\"updateLookup\", got \""
<< fullDocOption
<< "\"",
fullDocOption == "updateLookup"_sd || fullDocOption == "default"_sd);
const bool shouldLookupPostImage = (fullDocOption == "updateLookup"_sd);
auto oplogMatch = DocumentSourceOplogMatch::create(
buildMatchFilter(expCtx->ns, startFrom, changeStreamIsResuming), expCtx);
auto transformation = createTransformationStage(elem.embeddedObject(), expCtx);
list<intrusive_ptr<DocumentSource>> stages = {oplogMatch, transformation};
if (resumeStage) {
stages.push_back(resumeStage);
}
auto closeCursorSource = DocumentSourceCloseCursor::create(expCtx);
stages.push_back(closeCursorSource);
if (shouldLookupPostImage) {
stages.push_back(DocumentSourceLookupChangePostImage::create(expCtx));
}
return stages;
}