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/**
* Copyright (C) 2022-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 <random>
#include <vector>
#include "value_utils.h"
namespace mongo::ce {
class SBEValue;
// A simple histogram describing the distribution of values of each data type.
using DataTypeDistribution = std::map<value::TypeTags, double>;
/**
Describes the distribution of a dataset according to type and weight. Other ctor parameters
are used to describe the various data types which can be emitted and correspond to the fields
named similarly
*/
class DatasetDescriptor {
public:
DatasetDescriptor(const DataTypeDistribution& dataTypeDistribution,
size_t intNDV,
int minInt,
int maxInt,
size_t strNDV,
size_t minStrLen,
size_t maxStrLen,
std::shared_ptr<DatasetDescriptor> nestedDataDescriptor = nullptr,
double reuseScalarsRatio = 0,
size_t arrNDV = 0,
size_t minArrLen = 0,
size_t maxArrLen = 0);
// Generate a random dataset of 'nElems' according to the data distribution characteristics in
// this object.
std::vector<SBEValue> genRandomDataset(size_t nElems, DatasetDescriptor* parentDesc = nullptr);
private:
// Select a random value data type.
value::TypeTags getRandDataType() {
double key = _uniformRandProbability(_gen);
return (*_dataTypeDistribution.upper_bound(key)).second;
}
// Generate a random string with size 'len'.
std::string genRandomString(size_t len);
// Generate a random array with length determined uniformly between minArrLen and maxArrLen
std::vector<SBEValue> genRandomArray();
// Generate a set of random arrays that are chosen from when generating array data.
void fillRandomArraySet();
private:
using InternalDataTypeDistribution = std::map<double, value::TypeTags>;
/*
* General distribution charecteristics.
*/
// Pseudo-random generator.
std::mt19937_64 _gen;
// Random probabilities. Used to:
// - Select Value data types as random indexes in '_dataTypeDistribution'.
// - Select the source of values - either existing scalars or new.
std::uniform_real_distribution<double> _uniformRandProbability{0.0, 1.0};
// Distribution of different SBE data types. There will be %percent values of each type.
InternalDataTypeDistribution _dataTypeDistribution;
double _reuseScalarsRatio;
/*
* Integer data parameters.
*/
// Number of distinct integer values.
const size_t _intNDV;
// A set of integers to choose from while generating random integers.
std::vector<int> _intSet;
// Generator of random integers with uniform distribution.
std::uniform_int_distribution<int> _uniformIntDist;
// Generator of random indexes into the set of integers '_intSet'.
std::uniform_int_distribution<size_t> _uniformIntIdxDist;
/*
* String data parameters.
*/
// All strings draw characters from this alphabet.
static const std::string _alphabet;
// A set of random strings to choose from. In theory there can be duplicates, but this is very
// unlikely. We don't care much if there are a few duplicates anyway.
std::vector<std::string> _stringSet;
// Generator of random indexes into the set of characters '_alphabet'.
std::uniform_int_distribution<size_t> _uniformCharIdxDist{0, _alphabet.size() - 1};
// Generator of random indexes into the set of strings '_stringSet'.
std::uniform_int_distribution<size_t> _uniformStrIdxDist;
/*
* Array data parameters.
*/
// Number of distinct arrays.
// TODO: currently not used. The idea is to use it in the same way as arrays - pre-generate
// '_arrNDV' arrays, then select randomly from this initial set.
size_t _arrNDV;
// Set of arrays to pick from when generating random data.
std::vector<std::vector<SBEValue>> _arraySet;
// Generator of random array sizes.
std::uniform_int_distribution<size_t> _uniformArrSizeDist;
// Descriptor of the dataset within each array.
std::shared_ptr<DatasetDescriptor> _nestedDataDescriptor;
// Generator of random indexes into the set of arrays '_arraySet'.
std::uniform_int_distribution<size_t> _uniformArrIdxDist;
}; // namespace mongo::ce
/**
Generate a random string of length len.
* The alphabet is fixed as [0-9][a-z][A-Z]
* Characters are chosed uniformly from the alphabet
*/
auto genRandomString(size_t len, std::mt19937_64& gen, size_t seed);
/**
Generate a uniformly random set of elements consisting of string and ints in the
requested ratio
*/
std::vector<SBEValue> genRandomValueArray(size_t nElems,
double intRatio,
double strRatio,
size_t seed);
/**
Generate a set up values consisting of half scalars, and half arrays of length 10
Values contained in the result will be drawn from the input vector
*/
std::vector<SBEValue> genRandomValueArrayWithArrays(const std::vector<SBEValue>& input);
} // namespace mongo::ce
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