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/**
* Copyright (C) 2021-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#include "mongo/platform/basic.h"
#include "mongo/db/pipeline/document_source_change_stream_add_post_image.h"
#include "mongo/bson/simple_bsonelement_comparator.h"
#include "mongo/db/ops/write_ops_parsers.h"
#include "mongo/db/pipeline/change_stream_helpers_legacy.h"
#include "mongo/db/pipeline/document_source_change_stream_add_pre_image.h"
#include "mongo/db/update/update_driver.h"
namespace mongo {
constexpr StringData DocumentSourceChangeStreamAddPostImage::kStageName;
constexpr StringData DocumentSourceChangeStreamAddPostImage::kFullDocumentFieldName;
namespace {
REGISTER_INTERNAL_DOCUMENT_SOURCE(_internalChangeStreamAddPostImage,
LiteParsedDocumentSourceChangeStreamInternal::parse,
DocumentSourceChangeStreamAddPostImage::createFromBson,
true);
constexpr auto makePostImageNotFoundErrorMsg =
&DocumentSourceChangeStreamAddPreImage::makePreImageNotFoundErrorMsg;
Value assertFieldHasType(const Document& fullDoc, StringData fieldName, BSONType expectedType) {
auto val = fullDoc[fieldName];
uassert(40578,
str::stream() << "failed to look up post image after change: expected \"" << fieldName
<< "\" field to have type " << typeName(expectedType)
<< ", instead found type " << typeName(val.getType()) << ": "
<< val.toString() << ", full object: " << fullDoc.toString(),
val.getType() == expectedType);
return val;
}
} // namespace
boost::intrusive_ptr<DocumentSourceChangeStreamAddPostImage>
DocumentSourceChangeStreamAddPostImage::createFromBson(
const BSONElement elem, const boost::intrusive_ptr<ExpressionContext>& expCtx) {
uassert(5467608,
str::stream() << "the '" << kStageName << "' stage spec must be an object",
elem.type() == BSONType::Object);
auto parsedSpec = DocumentSourceChangeStreamAddPostImageSpec::parse(
IDLParserErrorContext("DocumentSourceChangeStreamAddPostImageSpec"), elem.Obj());
return new DocumentSourceChangeStreamAddPostImage(expCtx, parsedSpec.getFullDocument());
}
DocumentSource::GetNextResult DocumentSourceChangeStreamAddPostImage::doGetNext() {
auto input = pSource->getNext();
if (!input.isAdvanced()) {
return input;
}
auto opTypeVal = assertFieldHasType(
input.getDocument(), DocumentSourceChangeStream::kOperationTypeField, BSONType::String);
if (opTypeVal.getString() != DocumentSourceChangeStream::kUpdateOpType) {
return input;
}
// TODO SERVER-58584: remove the feature flag.
if (_fullDocumentMode != FullDocumentModeEnum::kUpdateLookup) {
tassert(5869000,
str::stream() << "Feature flag must be enabled for fullDocument: "
<< FullDocumentMode_serializer(_fullDocumentMode),
feature_flags::gFeatureFlagChangeStreamPreAndPostImages.isEnabled(
serverGlobalParams.featureCompatibility));
}
// Create a mutable output document from the input document.
MutableDocument output(input.releaseDocument());
const auto postImageDoc = (_fullDocumentMode == FullDocumentModeEnum::kUpdateLookup
? lookupLatestPostImage(output.peek())
: generatePostImage(output.peek()));
uassert(ErrorCodes::NoMatchingDocument,
str::stream() << "Change stream was configured to require a post-image for all update "
"events, but the post-image was not found for event: "
<< makePostImageNotFoundErrorMsg(output.peek()),
postImageDoc || _fullDocumentMode != FullDocumentModeEnum::kRequired);
// Even if no post-image was found, we have to populate the 'fullDocument' field.
output[kFullDocumentFieldName] = (postImageDoc ? Value(*postImageDoc) : Value(BSONNULL));
// Do not propagate the update modification and pre-image id information further.
output.remove(kRawOplogUpdateSpecFieldName);
output.remove(kPreImageIdFieldName);
return output.freeze();
}
NamespaceString DocumentSourceChangeStreamAddPostImage::assertValidNamespace(
const Document& inputDoc) const {
auto namespaceObject =
assertFieldHasType(inputDoc, DocumentSourceChangeStream::kNamespaceField, BSONType::Object)
.getDocument();
auto dbName = assertFieldHasType(namespaceObject, "db"_sd, BSONType::String);
auto collectionName = assertFieldHasType(namespaceObject, "coll"_sd, BSONType::String);
NamespaceString nss(pExpCtx->ns.tenantId(), dbName.getString(), collectionName.getString());
// Change streams on an entire database only need to verify that the database names match. If
// the database is 'admin', then this is a cluster-wide $changeStream and we are permitted to
// lookup into any namespace.
uassert(40579,
str::stream() << "unexpected namespace during post image lookup: " << nss.ns()
<< ", expected " << pExpCtx->ns.ns(),
nss == pExpCtx->ns ||
(pExpCtx->isClusterAggregation() || pExpCtx->isDBAggregation(nss.db())));
return nss;
}
boost::optional<Document> DocumentSourceChangeStreamAddPostImage::generatePostImage(
const Document& updateOp) const {
// If the 'fullDocumentBeforeChange' is present and null, then we already tried and failed to
// look up a pre-image. We can't compute the post-image without it, so return early.
if (updateOp[kFullDocumentBeforeChangeFieldName].getType() == BSONType::jstNULL) {
return boost::none;
}
// Otherwise, obtain the pre-image from the information in the input document.
auto preImage = [&]() -> boost::optional<Document> {
// Check whether we have already looked up the pre-image document.
if (!updateOp[kFullDocumentBeforeChangeFieldName].missing()) {
return updateOp[kFullDocumentBeforeChangeFieldName].getDocument();
}
// Otherwise, we need to look it up ourselves. Extract the preImageId field.
auto preImageId = updateOp[kPreImageIdFieldName];
tassert(5869001,
"Missing both 'fullDocumentBeforeChange' and 'preImageId' fields",
!preImageId.missing());
// Use DSCSAddPreImage::lookupPreImage to retrieve the actual pre-image.
return DocumentSourceChangeStreamAddPreImage::lookupPreImage(pExpCtx,
preImageId.getDocument());
}();
// Return boost::none if pre-image is missing.
if (!preImage) {
return boost::none;
}
// Raw oplog update spec field must be provided for the update commands.
tassert(5869002,
"Raw oplog update spec was missing or invalid in change stream",
updateOp[kRawOplogUpdateSpecFieldName].isObject());
// Setup the UpdateDriver for performing the post-image computation.
UpdateDriver updateDriver(pExpCtx);
const auto rawOplogUpdateSpec = updateOp[kRawOplogUpdateSpecFieldName].getDocument().toBson();
const auto updateMod = write_ops::UpdateModification::parseFromOplogEntry(
rawOplogUpdateSpec, {false /* mustCheckExistenceForInsertOperations */});
// UpdateDriver only expects to apply a diff in the context of oplog application.
updateDriver.setFromOplogApplication(true);
updateDriver.parse(updateMod, {});
// Compute post-image.
mutablebson::Document postImage(preImage->toBson());
uassertStatusOK(updateDriver.update(pExpCtx->opCtx,
StringData(),
&postImage,
false /* validateForStorage */,
FieldRefSet(),
false /* isInsert */));
return Document(postImage.getObject());
}
boost::optional<Document> DocumentSourceChangeStreamAddPostImage::lookupLatestPostImage(
const Document& updateOp) const {
// Make sure we have a well-formed input.
auto nss = assertValidNamespace(updateOp);
auto documentKey = assertFieldHasType(updateOp,
DocumentSourceChangeStream::kDocumentKeyField,
BSONType::Object)
.getDocument();
// Extract the resume token data from the input event.
auto resumeTokenData =
ResumeToken::parse(updateOp[DocumentSourceChangeStream::kIdField].getDocument()).getData();
auto readConcern = BSON("level"
<< "majority"
<< "afterClusterTime" << resumeTokenData.clusterTime);
// Update lookup queries sent from mongoS to shards are allowed to use speculative majority
// reads. Even if the lookup itself succeeded, it may not have returned any results if the
// document was deleted in the time since the update op.
invariant(resumeTokenData.uuid);
return pExpCtx->mongoProcessInterface->lookupSingleDocument(
pExpCtx, nss, *resumeTokenData.uuid, documentKey, std::move(readConcern));
}
Value DocumentSourceChangeStreamAddPostImage::serialize(
boost::optional<ExplainOptions::Verbosity> explain) const {
return explain
? Value(Document{
{DocumentSourceChangeStream::kStageName,
Document{{"stage"_sd, kStageName},
{kFullDocumentFieldName, FullDocumentMode_serializer(_fullDocumentMode)}}}})
: Value(Document{{kStageName,
DocumentSourceChangeStreamAddPostImageSpec(_fullDocumentMode).toBSON()}});
}
} // namespace mongo
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