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/**
* Copyright (C) 2018-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/s/query/router_stage_pipeline.h"
#include "mongo/db/pipeline/document_source.h"
#include "mongo/db/pipeline/document_source_change_stream.h"
#include "mongo/db/pipeline/document_source_list_local_sessions.h"
#include "mongo/db/pipeline/expression_context.h"
#include "mongo/s/query/document_source_merge_cursors.h"
namespace mongo {
RouterStagePipeline::RouterStagePipeline(std::unique_ptr<Pipeline, PipelineDeleter> mergePipeline)
: RouterExecStage(mergePipeline->getContext()->opCtx),
_mergePipeline(std::move(mergePipeline)) {
invariant(!_mergePipeline->getSources().empty());
_mergeCursorsStage =
dynamic_cast<DocumentSourceMergeCursors*>(_mergePipeline->getSources().front().get());
}
StatusWith<ClusterQueryResult> RouterStagePipeline::next(RouterExecStage::ExecContext execContext) {
if (_mergeCursorsStage) {
_mergeCursorsStage->setExecContext(execContext);
}
// Pipeline::getNext will return a boost::optional<Document> or boost::none if EOF.
if (auto result = _mergePipeline->getNext()) {
return _validateAndConvertToBSON(*result);
}
// If we reach this point, we have hit EOF.
if (!_mergePipeline->getContext()->isTailableAwaitData()) {
_mergePipeline.get_deleter().dismissDisposal();
_mergePipeline->dispose(getOpCtx());
}
return {ClusterQueryResult()};
}
void RouterStagePipeline::doReattachToOperationContext() {
_mergePipeline->reattachToOperationContext(getOpCtx());
}
void RouterStagePipeline::doDetachFromOperationContext() {
_mergePipeline->detachFromOperationContext();
}
void RouterStagePipeline::kill(OperationContext* opCtx) {
_mergePipeline.get_deleter().dismissDisposal();
_mergePipeline->dispose(opCtx);
}
std::size_t RouterStagePipeline::getNumRemotes() const {
if (_mergeCursorsStage) {
return _mergeCursorsStage->getNumRemotes();
}
return 0;
}
BSONObj RouterStagePipeline::getPostBatchResumeToken() const {
auto pbrt = _mergeCursorsStage ? _mergeCursorsStage->getHighWaterMark() : BSONObj();
return pbrt.isEmpty() ? pbrt : _setPostBatchResumeTokenUUID(pbrt);
}
BSONObj RouterStagePipeline::_setPostBatchResumeTokenUUID(BSONObj pbrt) const {
// If the PBRT does not match the sort key of the latest document, it is a high water mark.
const bool isHighWaterMark = !pbrt.binaryEqual(_latestSortKey);
// If this stream is on a single collection and the token is a high water mark, then it may have
// come from a shard that does not have the collection. If so, we must fill in the correct UUID.
if (isHighWaterMark && _mergePipeline->getContext()->uuid) {
auto tokenData = ResumeToken::parse(pbrt).getData();
// Check whether the UUID is missing before regenerating the token.
if (!tokenData.uuid) {
invariant(tokenData.tokenType == ResumeTokenData::kHighWaterMarkToken);
tokenData.uuid = _mergePipeline->getContext()->uuid;
pbrt = ResumeToken(tokenData).toDocument().toBson();
}
}
return pbrt;
}
BSONObj RouterStagePipeline::_validateAndConvertToBSON(const Document& event) {
// If this is not a change stream pipeline, we have nothing to do except return the BSONObj.
if (!_mergePipeline->getContext()->isTailableAwaitData()) {
return event.toBson();
}
// Confirm that the document _id field matches the original resume token in the sort key field.
auto eventBSON = event.toBson();
auto resumeToken = event.getSortKeyMetaField();
auto idField = eventBSON.getObjectField("_id");
invariant(!resumeToken.isEmpty());
uassert(51060,
str::stream() << "Encountered an event whose _id field, which contains the resume "
"token, was modified by the pipeline. Modifying the _id field of an "
"event makes it impossible to resume the stream from that point. Only "
"transformations that retain the unmodified _id field are allowed. "
"Expected: "
<< BSON("_id" << resumeToken)
<< " but found: "
<< (eventBSON["_id"] ? BSON("_id" << eventBSON["_id"]) : BSONObj()),
idField.binaryEqual(resumeToken));
// Record the latest resume token for later comparison, then return the event in BSONObj form.
_latestSortKey = resumeToken;
return eventBSON;
}
bool RouterStagePipeline::remotesExhausted() {
return !_mergeCursorsStage || _mergeCursorsStage->remotesExhausted();
}
Status RouterStagePipeline::doSetAwaitDataTimeout(Milliseconds awaitDataTimeout) {
invariant(_mergeCursorsStage,
"The only cursors which should be tailable are those with remote cursors.");
return _mergeCursorsStage->setAwaitDataTimeout(awaitDataTimeout);
}
} // namespace mongo
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