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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 <absl/container/flat_hash_map.h>
#include <absl/container/inlined_vector.h>
#include <memory>
#include <string>
#include <vector>
#include "mongo/bson/util/builder.h"
#include "mongo/db/exec/sbe/expressions/expression.h"
#include "mongo/db/exec/sbe/stages/hash_agg.h"
#include "mongo/db/exec/sbe/stages/plan_stats.h"
#include "mongo/db/exec/sbe/stages/stages.h"
#include "mongo/db/exec/sbe/values/slot.h"
#include "mongo/db/query/index_bounds.h"
#include "mongo/db/storage/index_entry_comparison.h"
#include "mongo/util/indexed_string_vector.h"
/**
* Contains a set of functions for shallow estimating the size of allocated on the heap objects
* in a given container. The functions do not take account of the size of the given container, only
* its values allocated on the heap.
* They are used to calculate compile-time size of an SBE tree.
*/
namespace mongo::sbe::size_estimator {
size_t estimate(const IndexBounds& indexBounds);
size_t estimate(const OrderedIntervalList& list);
size_t estimate(const Interval& interval);
size_t estimate(const IndexSeekPoint& indexSeekPoint);
inline size_t estimate(const std::unique_ptr<PlanStage>& planStage) {
return planStage->estimateCompileTimeSize();
}
inline size_t estimate(const std::unique_ptr<EExpression>& expr) {
return expr->estimateSize();
}
inline size_t estimate(value::TypeTags tag, value::Value val) {
size_t size = value::getApproximateSize(tag, val);
return std::max(static_cast<size_t>(0), size - sizeof(tag) - sizeof(val));
}
inline size_t estimate(const std::string& str) {
return sizeof(std::string::value_type) * str.capacity();
}
inline size_t estimate(const BSONObj& bson) {
return bson.objsize();
}
size_t estimate(const IndexBoundsChecker& checker);
// Calculate sizes of heap-allocated values only. Therefore, sizes of scalar values are always 0.
template <typename S, std::enable_if_t<std::is_scalar_v<S>, bool> = true>
inline size_t estimate(S) {
return 0;
}
inline size_t estimate(const StringData& str) {
return 0;
}
inline size_t estimate(const HashAggStage::AggExprPair& expr) {
size_t size = 0;
if (expr.init) {
size += expr.init->estimateSize();
}
size += expr.acc->estimateSize();
return size;
}
// Calculate the size of a SpecificStats's derived class.
// We need a template argument here rather than passing const SpecificStats&
// as we need to know the exact type to properly compute the size of the object.
template <typename S, std::enable_if_t<std::is_base_of_v<SpecificStats, S>, bool> = true>
inline size_t estimate(const S& stats) {
return stats.estimateObjectSizeInBytes() - sizeof(S);
}
template <typename A, typename B>
inline size_t estimate(const std::pair<A, B>& pair) {
return estimate(pair.first) + estimate(pair.second);
}
// Calculate the size of the inlined vector's elements.
template <typename T, size_t N, typename A>
size_t estimate(const absl::InlinedVector<T, N, A>& vector) {
size_t size = 0;
// Calculate size of the value only if the values are not inlined.
if (vector.capacity() > N) {
size += vector.capacity() * sizeof(T);
}
for (const auto& elem : vector) {
size += estimate(elem);
}
return size;
}
// Calculate the size of the vector's elements.
template <typename T, typename A>
size_t estimate(const std::vector<T, A>& vector) {
size_t size = vector.capacity() * sizeof(T);
for (const auto& elem : vector) {
size += estimate(elem);
}
return size;
}
// Overload of 'estimate' function for std::vector<bool> since
// the latter is often an optimized specialization of std::vector for bool
// and it might fail to match against ordinary 'size_t estimate(const std::vector<T, A>&)'.
inline size_t estimate(const std::vector<bool>& vec) {
return vec.capacity() * sizeof(bool);
}
template <typename T, typename A>
size_t estimateContainerOnly(const std::vector<T, A>& vector) {
return vector.capacity() * sizeof(T);
}
template <typename K, typename V, typename... Args>
size_t estimate(const absl::flat_hash_map<K, V, Args...>& map) {
// The estimation is based on the memory usage of absl::flat_hash_map
// documented in https://abseil.io/docs/cpp/guides/container:
// The container uses O((sizeof(std::pair<const K, V>) + 1) * bucket_count()) bytes.
// The tests with a custom allocator showed that actual memory usage was
// (sizeof(std::pair<const K, V>) + 1) * bucket_count() + C,
// where C was equal to 17 for non-empty containers on x64 platform
// and 0 for empty containers.
constexpr size_t kEstimatedConstantPayload = 17;
size_t bucketSize = sizeof(std::pair<const K, V>) + 1;
size_t size = map.bucket_count() * bucketSize;
size += map.empty() ? 0 : kEstimatedConstantPayload;
for (auto&& [key, val] : map) {
size += estimate(key);
size += estimate(val);
}
return size;
}
template <class BufferAllocator>
size_t estimate(const BasicBufBuilder<BufferAllocator>& ba) {
return static_cast<size_t>(ba.capacity());
}
inline size_t estimate(const value::MaterializedRow& row) {
size_t size = 0;
for (size_t idx = 0; idx < row.size(); ++idx) {
auto [tag, val] = row.getViewOfValue(idx);
size += estimate(tag, val);
}
return size;
}
inline size_t estimate(const IndexedStringVector& vec) {
size_t size = size_estimator::estimate(vec.getUnderlyingVector());
size += size_estimator::estimate(vec.getUnderlyingMap());
return size;
}
} // namespace mongo::sbe::size_estimator
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