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/**
* Copyright (C) 2017 MongoDB Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* 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
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* 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 GNU Affero General 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 <algorithm>
#include "mongo/s/query/router_stage_remove_metadata_fields.h"
#include "mongo/bson/bsonobjbuilder.h"
#include "mongo/db/pipeline/document.h"
namespace mongo {
RouterStageRemoveMetadataFields::RouterStageRemoveMetadataFields(
OperationContext* opCtx,
std::unique_ptr<RouterExecStage> child,
std::vector<StringData> metadataFields)
: RouterExecStage(opCtx, std::move(child)), _metaFields(std::move(metadataFields)) {
for (auto&& fieldName : _metaFields) {
invariant(fieldName[0] == '$'); // We use this information to optimize next().
}
}
StatusWith<ClusterQueryResult> RouterStageRemoveMetadataFields::next(
RouterExecStage::ExecContext execContext) {
auto childResult = getChildStage()->next(execContext);
if (!childResult.isOK() || !childResult.getValue().getResult()) {
return childResult;
}
BSONObjIterator iterator(*childResult.getValue().getResult());
// Find the first field that we need to remove.
while (iterator.more() && (*iterator).fieldName()[0] != '$' &&
std::find(_metaFields.begin(), _metaFields.end(), (*iterator).fieldNameStringData()) ==
_metaFields.end()) {
++iterator;
}
if (!iterator.more()) {
// We got all the way to the end without finding any fields to remove, just return the whole
// document.
return childResult;
}
// Copy everything up to the first metadata field.
const auto firstElementBufferStart =
childResult.getValue().getResult()->firstElement().rawdata();
auto endOfNonMetaFieldBuffer = (*iterator).rawdata();
BSONObjBuilder builder;
builder.bb().appendBuf(firstElementBufferStart,
endOfNonMetaFieldBuffer - firstElementBufferStart);
// Copy any remaining fields that are not metadata. We expect metadata fields are likely to be
// at the end of the document, so there is likely nothing else to copy.
while ((++iterator).more()) {
if (std::find(_metaFields.begin(), _metaFields.end(), (*iterator).fieldNameStringData()) ==
_metaFields.end()) {
builder.append(*iterator);
}
}
return {builder.obj()};
}
} // namespace mongo
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