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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.
*/
#pragma once
#include "mongo/db/sorter/in_mem_iterator.h"
#include "mongo/db/sorter/merge_iterator.h"
#include "mongo/db/sorter/sorted_file_writer.h"
#include "mongo/db/sorter/sorter.h"
namespace mongo::sorter {
/**
* A Sorter which may spill to disk if configured to do so. Each instance of this class will, if
* spilling is enabled, generate a file name and spill sorted data ranges to that file.
*/
template <typename Key, typename Value>
class SpillableSorter : public Sorter<Key, Value> {
public:
using Base = Sorter<Key, Value>;
using Data = typename Base::Data;
using Iterator = typename Base::Iterator;
using CompFn = typename Base::CompFn;
using Settings = typename Base::Settings;
using Base::_comp;
using Base::_done;
SpillableSorter(StringData name,
const Options& options,
const CompFn& comp,
const Settings& settings)
: SpillableSorter(options,
comp,
settings,
options.tempDir
? std::make_unique<File>(*options.tempDir + "/" + nextFileName(name))
: nullptr) {}
SpillableSorter(const Options& options,
const CompFn& comp,
const Settings& settings,
const std::string& fileName)
: SpillableSorter(
options, comp, settings, std::make_unique<File>(*options.tempDir + "/" + fileName)) {
invariant(!fileName.empty());
}
std::unique_ptr<Iterator> done(typename Iterator::ReturnPolicy returnPolicy) {
invariant(!std::exchange(_done, true));
if (_spilled.empty()) {
_sort();
return std::make_unique<InMemIterator<Key, Value>>(_data, returnPolicy);
}
_spill();
return std::make_unique<MergeIterator<Key, Value>>(_spilled, _options.limit, _comp);
}
size_t numSpills() const override {
return _spilled.size();
}
protected:
virtual void _sort() = 0;
void _spill() {
if (_data.empty()) {
return;
}
if (!_options.tempDir) {
// This error message only applies to sorts from user queries made through the find or
// aggregation commands. Other clients should suppress this error, either by allowing
// external sorting or by catching and throwing a more appropriate error.
uasserted(ErrorCodes::QueryExceededMemoryLimitNoDiskUseAllowed,
str::stream()
<< "Sort exceeded memory limit of " << _options.maxMemoryUsageBytes
<< " bytes, but did not opt in to external sorting.");
}
_sort();
_updateStateAfterSort();
SortedFileWriter<Key, Value> writer(_file.get(), _options.dbName, _settings);
for (size_t i = 0; i < _data.size(); i++) {
writer.addAlreadySorted(_data[i].first, _data[i].second);
}
_spilled.push_back(writer.done());
// Clear _data and release backing array's memory.
std::vector<Data>().swap(_data);
_memUsed = 0;
}
virtual void _updateStateAfterSort() {}
const Options _options;
const std::function<bool(const Data&, const Data&)> _less;
const Settings _settings;
std::vector<Data> _data;
std::unique_ptr<File> _file;
std::vector<std::unique_ptr<Iterator>> _spilled;
size_t _memUsed = 0;
private:
SpillableSorter(const Options& options,
const CompFn& comp,
const Settings& settings,
std::unique_ptr<File> file)
: Base(comp),
_options(options),
_less([comp](const Data& lhs, const Data& rhs) {
dassertCompIsSane(comp, lhs, rhs);
return comp(lhs, rhs) < 0;
}),
_settings(settings),
_file(std::move(file)) {}
};
} // namespace mongo::sorter
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