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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/change_stream_filter_helpers.h"
#include "mongo/db/pipeline/document_source_change_stream_add_post_image.h"
#include "mongo/db/pipeline/document_source_change_stream_add_pre_image.h"
#include "mongo/db/pipeline/document_source_change_stream_check_invalidate.h"
#include "mongo/db/pipeline/document_source_change_stream_check_resumability.h"
#include "mongo/db/pipeline/document_source_change_stream_check_topology_change.h"
#include "mongo/db/pipeline/document_source_change_stream_ensure_resume_token_present.h"
#include "mongo/db/pipeline/document_source_change_stream_handle_topology_change.h"
#include "mongo/db/pipeline/document_source_change_stream_oplog_match.h"
#include "mongo/db/pipeline/document_source_change_stream_transform.h"
#include "mongo/db/pipeline/document_source_change_stream_unwind_transaction.h"
#include "mongo/db/pipeline/expression.h"
#include "mongo/s/grid.h"
namespace mongo {
namespace change_stream_legacy {
std::list<boost::intrusive_ptr<DocumentSource>> buildPipeline(
const boost::intrusive_ptr<ExpressionContext>& expCtx, DocumentSourceChangeStreamSpec spec) {
// The only case where we expect to build a legacy pipeline is if we are a shard which has
// received a $changeStream request from an older mongoS.
tassert(5565900,
"Unexpected {needsMerge:false} request for a legacy change stream pipeline",
expCtx->needsMerge);
std::list<boost::intrusive_ptr<DocumentSource>> stages;
const auto userRequestedResumePoint =
spec.getResumeAfter() || spec.getStartAfter() || spec.getStartAtOperationTime();
if (!userRequestedResumePoint) {
// Make sure we update the 'resumeAfter' in the 'spec' so that we serialize the
// correct resume token when sending it to the shards.
spec.setResumeAfter(ResumeToken::makeHighWaterMarkToken(
DocumentSourceChangeStream::getStartTimeForNewStream(expCtx)));
}
// Unfold the $changeStream into its constituent stages and add them to the pipeline.
stages.push_back(DocumentSourceChangeStreamOplogMatch::create(expCtx, spec));
stages.push_back(DocumentSourceChangeStreamUnwindTransaction::create(expCtx));
stages.push_back(DocumentSourceChangeStreamTransform::create(expCtx, spec));
tassert(5467606,
"'DocumentSourceChangeStreamTransform' stage should populate "
"'initialPostBatchResumeToken' field",
!expCtx->initialPostBatchResumeToken.isEmpty());
// 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(DocumentSourceChangeStreamCheckInvalidate::create(expCtx, spec));
// We must always check that the shard is capable of resuming from the specified point.
stages.push_back(DocumentSourceChangeStreamCheckResumability::create(expCtx, spec));
// If 'showExpandedEvents' is NOT set, add a filter that returns only classic change events.
if (!spec.getShowExpandedEvents()) {
stages.push_back(DocumentSourceMatch::create(
change_stream_filter::getMatchFilterForClassicOperationTypes(), expCtx));
}
return stages;
}
boost::optional<Document> legacyLookupPreImage(boost::intrusive_ptr<ExpressionContext> pExpCtx,
const Document& preImageId) {
// We need the oplog's UUID for lookup, so obtain the collection info via MongoProcessInterface.
auto localOplogInfo = pExpCtx->mongoProcessInterface->getCollectionOptions(
pExpCtx->opCtx, NamespaceString::kRsOplogNamespace);
// Extract the UUID from the collection information. We should always have a valid uuid here.
auto oplogUUID = invariantStatusOK(UUID::parse(localOplogInfo["uuid"]));
// Look up the pre-image oplog entry using the opTime as the query filter.
const auto opTime = repl::OpTime::parse(preImageId.toBson());
auto lookedUpDoc =
pExpCtx->mongoProcessInterface->lookupSingleDocument(pExpCtx,
NamespaceString::kRsOplogNamespace,
oplogUUID,
Document{opTime.asQuery()},
boost::none);
// Return boost::none to signify that we failed to find the pre-image.
if (!lookedUpDoc) {
return boost::none;
}
// If we had an optime to look up, and we found an oplog entry with that timestamp, then we
// should always have a valid no-op entry containing a valid, non-empty pre-image document.
auto opLogEntry = uassertStatusOK(repl::OplogEntry::parse(lookedUpDoc->toBson()));
tassert(5868901,
"Oplog entry type must be a no-op",
opLogEntry.getOpType() == repl::OpTypeEnum::kNoop);
tassert(5868902,
"Oplog entry must contait a non-empty pre-image document",
!opLogEntry.getObject().isEmpty());
return Document{opLogEntry.getObject().getOwned()};
}
DocumentKeyCache::DocumentKeyCache(const boost::intrusive_ptr<ExpressionContext>& expCtx,
const ResumeTokenData& tokenData)
: _expCtx(expCtx) {
if (!tokenData.eventIdentifier.missing() && tokenData.uuid) {
auto docKey = tokenData.eventIdentifier.getDocument();
// Newly added events store their operationType and operationDescription as the
// eventIdentifier, not a documentKey.
if (docKey["_id"].missing()) {
return;
}
// Extract the list of documentKey fields from the resume token.
std::vector<FieldPath> docKeyFields;
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.
const bool isFinal = docKeyFields.size() > 1;
_cache[tokenData.uuid.get()] = std::make_pair(docKeyFields, isFinal);
}
}
Value DocumentKeyCache::getDocumentKeyForOplogInsert(Document oplogInsert) {
tassert(63860,
"Expected 'insert' oplog entry",
oplogInsert["op"].getType() == BSONType::String &&
oplogInsert["op"].getStringData() == "i"_sd);
auto nss = NamespaceString(oplogInsert["ns"].getStringData());
auto uuid = oplogInsert["ui"].getUuid();
// Extract the documentKey fields from the cache, or add them if not already present.
auto it = _cache.find(uuid);
if (it == _cache.end() || !it->second.second) {
auto docKeyFields = _collectDocumentKeyFieldsForHostedCollection(nss, uuid);
if (it == _cache.end() || docKeyFields.second) {
_cache[uuid] = docKeyFields;
}
}
// Extract the documentKey values from the inserted document.
return Value(document_path_support::extractPathsFromDoc(oplogInsert["o"].getDocument(),
_cache[uuid].first));
}
DocumentKeyCache::DocumentKeyCacheEntry
DocumentKeyCache::_collectDocumentKeyFieldsForHostedCollection(const NamespaceString& nss,
const UUID& uuid) const {
// If this is a replica set, nothing is sharded and never will be.
if (serverGlobalParams.clusterRole != ClusterRole::ShardServer) {
return {{"_id"}, true};
}
auto* const catalogCache = Grid::get(_expCtx->opCtx)->catalogCache();
auto swCM = catalogCache->getCollectionRoutingInfo(_expCtx->opCtx, nss);
if (swCM.isOK()) {
const auto& cm = swCM.getValue();
if (cm.isSharded() && cm.uuidMatches(uuid)) {
// Unpack the shard key. Collection is sharded so mark as final.
const auto& shardKeyPattern = cm.getShardKeyPattern().getKeyPatternFields();
return {_shardKeyToDocumentKeyFields(shardKeyPattern), true};
}
} else if (swCM != ErrorCodes::NamespaceNotFound) {
uassertStatusOK(std::move(swCM));
}
// An unsharded collection can still become sharded so is not final. If the uuid doesn't match
// the one stored in the ScopedCollectionDescription, this implies that the collection has been
// dropped and recreated as sharded. We don't know what the old document key fields might have
// been in this case so we return just _id.
return {{"_id"}, false};
}
std::vector<FieldPath> DocumentKeyCache::_shardKeyToDocumentKeyFields(
const std::vector<std::unique_ptr<FieldRef>>& keyPatternFields) const {
std::vector<FieldPath> result;
bool gotId = false;
for (auto& field : keyPatternFields) {
result.emplace_back(field->dottedField());
gotId |= (result.back().fullPath() == "_id");
}
if (!gotId) { // If not part of the shard key, "_id" comes last.
result.emplace_back("_id");
}
return result;
}
} // namespace change_stream_legacy
} // namespace mongo
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