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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/document_source_merge_cursors.h"
#include "mongo/db/pipeline/document_source_sort.h"
#include "mongo/db/query/find_common.h"
#include "mongo/s/grid.h"
#include "mongo/s/query/establish_cursors.h"
namespace mongo {
REGISTER_DOCUMENT_SOURCE(mergeCursors,
LiteParsedDocumentSourceDefault::parse,
DocumentSourceMergeCursors::createFromBson,
AllowedWithApiStrict::kInternal);
constexpr StringData DocumentSourceMergeCursors::kStageName;
DocumentSourceMergeCursors::DocumentSourceMergeCursors(
const boost::intrusive_ptr<ExpressionContext>& expCtx,
AsyncResultsMergerParams armParams,
boost::optional<BSONObj> ownedParamsSpec)
: DocumentSource(kStageName, expCtx),
_armParamsObj(std::move(ownedParamsSpec)),
_armParams(std::move(armParams)) {
// Populate the shard ids from the 'RemoteCursor'.
recordRemoteCursorShardIds(_armParams->getRemotes());
}
std::size_t DocumentSourceMergeCursors::getNumRemotes() const {
if (_armParams) {
return _armParams->getRemotes().size();
}
return _blockingResultsMerger->getNumRemotes();
}
BSONObj DocumentSourceMergeCursors::getHighWaterMark() {
if (!_blockingResultsMerger) {
populateMerger();
}
return _blockingResultsMerger->getHighWaterMark();
}
bool DocumentSourceMergeCursors::remotesExhausted() const {
if (_armParams) {
// We haven't started iteration yet.
return false;
}
return _blockingResultsMerger->remotesExhausted();
}
void DocumentSourceMergeCursors::populateMerger() {
invariant(!_blockingResultsMerger);
invariant(_armParams);
_blockingResultsMerger.emplace(
pExpCtx->opCtx,
std::move(*_armParams),
pExpCtx->mongoProcessInterface->taskExecutor,
// Assumes this is only called from the 'aggregate' or 'getMore' commands. The code which
// relies on this parameter does not distinguish/care about the difference so we simply
// always pass 'aggregate'.
pExpCtx->mongoProcessInterface->getResourceYielder("aggregate"_sd));
_armParams = boost::none;
// '_blockingResultsMerger' now owns the cursors.
_ownCursors = false;
}
std::unique_ptr<RouterStageMerge> DocumentSourceMergeCursors::convertToRouterStage() {
invariant(!_blockingResultsMerger, "Expected conversion to happen before execution");
return std::make_unique<RouterStageMerge>(
pExpCtx->opCtx, pExpCtx->mongoProcessInterface->taskExecutor, std::move(*_armParams));
}
DocumentSource::GetNextResult DocumentSourceMergeCursors::doGetNext() {
if (!_blockingResultsMerger) {
populateMerger();
}
auto next = uassertStatusOK(_blockingResultsMerger->next(pExpCtx->opCtx));
if (next.isEOF()) {
return GetNextResult::makeEOF();
}
return Document::fromBsonWithMetaData(*next.getResult());
}
Value DocumentSourceMergeCursors::serialize(SerializationOptions opts) const {
invariant(!_blockingResultsMerger);
invariant(_armParams);
return Value(Document{{kStageName, _armParams->toBSON(opts)}});
}
boost::intrusive_ptr<DocumentSource> DocumentSourceMergeCursors::createFromBson(
BSONElement elem, const boost::intrusive_ptr<ExpressionContext>& expCtx) {
uassert(17026,
"$mergeCursors stage expected an object as argument",
elem.type() == BSONType::Object);
auto ownedObj = elem.embeddedObject().getOwned();
auto armParams = AsyncResultsMergerParams::parse(
IDLParserContext(kStageName, false /*apiStrict*/, expCtx->ns.tenantId()), ownedObj);
return new DocumentSourceMergeCursors(expCtx, std::move(armParams), std::move(ownedObj));
}
boost::intrusive_ptr<DocumentSourceMergeCursors> DocumentSourceMergeCursors::create(
const boost::intrusive_ptr<ExpressionContext>& expCtx, AsyncResultsMergerParams params) {
return new DocumentSourceMergeCursors(expCtx, std::move(params));
}
void DocumentSourceMergeCursors::detachFromOperationContext() {
if (_blockingResultsMerger) {
_blockingResultsMerger->detachFromOperationContext();
}
}
void DocumentSourceMergeCursors::reattachToOperationContext(OperationContext* opCtx) {
if (_blockingResultsMerger) {
_blockingResultsMerger->reattachToOperationContext(opCtx);
}
}
void DocumentSourceMergeCursors::doDispose() {
if (_blockingResultsMerger) {
invariant(!_ownCursors);
_blockingResultsMerger->kill(pExpCtx->opCtx);
} else if (_ownCursors) {
populateMerger();
_blockingResultsMerger->kill(pExpCtx->opCtx);
}
}
void DocumentSourceMergeCursors::recordRemoteCursorShardIds(
const std::vector<RemoteCursor>& remoteCursors) {
for (const auto& remoteCursor : remoteCursors) {
tassert(5549103, "Encountered invalid shard ID", !remoteCursor.getShardId().empty());
_shardsWithCursors.emplace(remoteCursor.getShardId().toString());
}
}
} // namespace mongo
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