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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.
*/
#define MONGO_LOGV2_DEFAULT_COMPONENT ::mongo::logv2::LogComponent::kCommand
#include "mongo/db/pipeline/change_stream_helpers_legacy.h"
#include "mongo/db/pipeline/document_source_change_stream_close_cursor.h"
#include "mongo/db/pipeline/document_source_change_stream_ensure_resume_token_present.h"
#include "mongo/db/pipeline/document_source_change_stream_oplog_match.h"
#include "mongo/db/pipeline/document_source_change_stream_topology_change.h"
#include "mongo/db/pipeline/document_source_change_stream_transform.h"
#include "mongo/db/pipeline/document_source_change_stream_unwind_transactions.h"
#include "mongo/db/pipeline/document_source_check_invalidate.h"
#include "mongo/db/pipeline/document_source_check_resume_token.h"
#include "mongo/db/pipeline/document_source_lookup_change_post_image.h"
#include "mongo/db/pipeline/document_source_lookup_change_pre_image.h"
#include "mongo/db/pipeline/document_source_update_on_add_shard.h"
#include "mongo/db/pipeline/expression.h"
namespace mongo {
namespace change_stream_legacy {
std::list<boost::intrusive_ptr<DocumentSource>> buildPipeline(
const boost::intrusive_ptr<ExpressionContext>& expCtx,
const DocumentSourceChangeStreamSpec spec,
BSONElement rawSpec) {
std::list<boost::intrusive_ptr<DocumentSource>> stages;
boost::intrusive_ptr<DocumentSource> resumeStage = nullptr;
boost::optional<ResumeTokenData> startAfterInvalidate;
bool showMigrationEvents = spec.getShowMigrationEvents();
uassert(31123,
"Change streams from mongos may not show migration events.",
!(expCtx->inMongos && showMigrationEvents));
auto resumeAfter = spec.getResumeAfter();
auto startAfter = spec.getStartAfter();
if (resumeAfter || startAfter) {
uassert(50865,
"Do not specify both 'resumeAfter' and 'startAfter' in a $changeStream stage",
!startAfter || !resumeAfter);
const ResumeToken token = resumeAfter ? resumeAfter.get() : startAfter.get();
const ResumeTokenData tokenData = token.getData();
// If resuming from an "invalidate" using "startAfter", pass along the resume token data to
// DocumentSourceCheckInvalidate to signify that another invalidate should not be generated.
if (startAfter && tokenData.fromInvalidate) {
startAfterInvalidate = tokenData;
}
uassert(ErrorCodes::InvalidResumeToken,
"Attempting to resume a change stream using 'resumeAfter' is not allowed from an "
"invalidate notification.",
!resumeAfter || !tokenData.fromInvalidate);
// If we are resuming a single-collection stream, the resume token should always contain a
// UUID unless the token is a high water mark.
uassert(ErrorCodes::InvalidResumeToken,
"Attempted to resume a single-collection stream, but the resume token does not "
"include a UUID.",
tokenData.uuid || !expCtx->isSingleNamespaceAggregation() ||
ResumeToken::isHighWaterMarkToken(tokenData));
// For a regular resume token, we must ensure that (1) all shards are capable of resuming
// from the given clusterTime, and (2) that we observe the resume token event in the stream
// before any event that would sort after it. High water mark tokens, however, do not refer
// to a specific event; we thus only need to check (1), similar to 'startAtOperationTime'.
if (expCtx->needsMerge || ResumeToken::isHighWaterMarkToken(tokenData)) {
resumeStage = DocumentSourceCheckResumability::create(expCtx, tokenData);
} else {
resumeStage = DocumentSourceEnsureResumeTokenPresent::create(expCtx, tokenData);
}
}
// If we do not have a 'resumeAfter' starting point, check for 'startAtOperationTime'.
if (auto startAtOperationTime = spec.getStartAtOperationTime()) {
uassert(40674,
"Only one type of resume option is allowed, but multiple were found.",
!resumeStage);
resumeStage = DocumentSourceCheckResumability::create(expCtx, *startAtOperationTime);
}
auto transformStage = DocumentSourceChangeStreamTransform::createFromBson(rawSpec, expCtx);
tassert(5467606,
"'DocumentSourceChangeStreamTransform' stage should populate "
"'initialPostBatchResumeToken' field",
!expCtx->initialPostBatchResumeToken.isEmpty());
// We must always build the DSOplogMatch stage even on mongoS, since our validation logic relies
// upon the fact that it is always the first stage in the pipeline.
stages.push_back(DocumentSourceOplogMatch::create(expCtx, showMigrationEvents));
stages.push_back(DocumentSourceChangeStreamUnwindTransaction::create(expCtx));
stages.push_back(transformStage);
const bool csOptFeatureFlag =
feature_flags::gFeatureFlagChangeStreamsOptimization.isEnabledAndIgnoreFCV();
// The 'DocumentSourceChangeStreamTopologyChange' only runs in a cluster, and will be dispatched
// by mongoS to the shards.
if (csOptFeatureFlag && expCtx->inMongos) {
stages.push_back(DocumentSourceChangeStreamTopologyChange::create(expCtx));
}
// The resume stage must come after the check invalidate stage so that the former can determine
// whether the event that matches the resume token should be followed by an "invalidate" event.
stages.push_back(DocumentSourceCheckInvalidate::create(expCtx, startAfterInvalidate));
// The resume stage 'DocumentSourceCheckResumability' should come before the split point stage
// 'DocumentSourceUpdateOnAddShard'.
if (resumeStage &&
resumeStage->getSourceName() == DocumentSourceCheckResumability::kStageName) {
stages.push_back(resumeStage);
resumeStage.reset();
}
// If the pipeline is build on MongoS, then the stage 'DocumentSourceUpdateOnAddShard' acts as
// the split point for the pipline. All stages before this stages will run on shards and all
// stages after and inclusive of this stage will run on the MongoS.
if (expCtx->inMongos) {
stages.push_back(DocumentSourceUpdateOnAddShard::create(expCtx));
}
// This resume stage should be 'DocumentSourceEnsureResumeTokenPresent'.
if (resumeStage) {
stages.push_back(resumeStage);
}
if (!expCtx->needsMerge) {
if (!csOptFeatureFlag) {
// There should only be one close cursor stage. If we're on the shards and producing
// input to be merged, do not add a close cursor stage, since the mongos will already
// have one.
stages.push_back(DocumentSourceCloseCursor::create(expCtx));
}
// We only create a pre-image lookup stage on a non-merging mongoD. We place this stage here
// so that any $match stages which follow the $changeStream pipeline prefix may be able to
// skip ahead of the DSLPreImage stage. This allows a whole-db or whole-cluster stream to
// run on an instance where only some collections have pre-images enabled, so long as the
// user filters for only those namespaces.
// TODO SERVER-36941: figure out how to get this to work in a sharded cluster.
if (spec.getFullDocumentBeforeChange() != FullDocumentBeforeChangeModeEnum::kOff) {
invariant(!expCtx->inMongos);
stages.push_back(DocumentSourceLookupChangePreImage::create(expCtx, spec));
}
// There should be only one post-image lookup stage. If we're on the shards and producing
// input to be merged, the lookup is done on the mongos.
if (spec.getFullDocument() == FullDocumentModeEnum::kUpdateLookup) {
stages.push_back(DocumentSourceLookupChangePostImage::create(expCtx));
}
}
return stages;
}
} // namespace change_stream_legacy
Value DocumentSourceOplogMatch::serializeLegacy(
boost::optional<ExplainOptions::Verbosity> explain) const {
return explain ? Value(Document{{"$_internalOplogMatch"_sd, Document{}}}) : Value();
}
Value DocumentSourceChangeStreamTransform::serializeLegacy(
boost::optional<ExplainOptions::Verbosity> explain) const {
tassert(
5467607,
str::stream() << "At least one of 'resumeAfter', 'startAfter' or 'startAtOperationTime' "
"fields should be present to serialize "
<< DocumentSourceChangeStreamTransform::kStageName << " stage",
_changeStreamSpec.getResumeAfter() || _changeStreamSpec.getStartAtOperationTime() ||
_changeStreamSpec.getStartAfter());
return Value(Document{{getSourceName(), _changeStreamSpec.toBSON()}});
}
Value DocumentSourceCheckInvalidate::serializeLegacy(
boost::optional<ExplainOptions::Verbosity> explain) const {
// We only serialize this stage in the context of explain.
return explain ? Value(DOC(kStageName << Document())) : Value();
}
Value DocumentSourceCheckResumability::serializeLegacy(
boost::optional<ExplainOptions::Verbosity> explain) const {
// We only serialize this stage in the context of explain.
return explain ? Value(DOC(getSourceName()
<< DOC("resumeToken" << ResumeToken(_tokenFromClient).toDocument())))
: Value();
}
Value DocumentSourceChangeStreamUnwindTransaction::serializeLegacy(
boost::optional<ExplainOptions::Verbosity> explain) const {
if (explain) {
tassert(5543800, "nsRegex has not been initialized", _nsRegex != boost::none);
return Value(Document{{kStageName, Value(Document{{"nsRegex", _nsRegex->pattern()}})}});
}
return Value();
}
Value DocumentSourceLookupChangePreImage::serializeLegacy(
boost::optional<ExplainOptions::Verbosity> explain) const {
return (explain ? Value{Document{{kStageName, Document()}}} : Value());
}
Value DocumentSourceLookupChangePostImage::serializeLegacy(
boost::optional<ExplainOptions::Verbosity> explain) const {
return (explain ? Value{Document{{kStageName, Document()}}} : Value());
}
Value DocumentSourceChangeStreamTopologyChange::serializeLegacy(
boost::optional<ExplainOptions::Verbosity> explain) const {
return (explain ? Value{Document{{kStageName, Document()}}} : Value());
}
} // namespace mongo
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