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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/query/canonical_query_encoder.h"
namespace mongo {
/**
* Represents the "key" used in the PlanCache mapping from query shape -> query plan.
*/
class PlanCacheKey {
public:
PlanCacheKey(CanonicalQuery::QueryShapeString shapeString, std::string indexabilityString) {
_lengthOfQueryShape = shapeString.size();
_key = std::move(shapeString);
_key += indexabilityString;
}
CanonicalQuery::QueryShapeString getQueryShape() const {
return std::string(_key, 0, _lengthOfQueryShape);
}
StringData getQueryShapeStringData() const {
return StringData(_key.c_str(), _lengthOfQueryShape);
}
/**
* Return the 'indexability discriminators', that is, the plan cache key component after the
* stable key, but before the boolean indicating whether we are using the classic engine.
*/
StringData getIndexabilityDiscriminators() const {
return StringData(_key.c_str() + _lengthOfQueryShape, _key.size() - _lengthOfQueryShape);
}
StringData stringData() const {
return _key;
}
const std::string& toString() const {
return _key;
}
bool operator==(const PlanCacheKey& other) const {
return other._key == _key && other._lengthOfQueryShape == _lengthOfQueryShape;
}
bool operator!=(const PlanCacheKey& other) const {
return !(*this == other);
}
uint32_t queryHash() const {
return canonical_query_encoder::computeHash(getQueryShapeStringData());
}
uint32_t planCacheKeyHash() const {
return canonical_query_encoder::computeHash(stringData());
}
private:
// Key is broken into two parts:
// <query shape key> | <indexability discriminators>
std::string _key;
// How long the "query shape" is.
size_t _lengthOfQueryShape;
};
std::ostream& operator<<(std::ostream& stream, const PlanCacheKey& key);
StringBuilder& operator<<(StringBuilder& builder, const PlanCacheKey& key);
class PlanCacheKeyHasher {
public:
std::size_t operator()(const PlanCacheKey& k) const {
return std::hash<std::string>{}(k.toString());
}
};
} // namespace mongo
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