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/**
* Copyright (c) 2011 10gen 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.
*/
#pragma once
#include "mongo/platform/basic.h"
#include <boost/intrusive_ptr.hpp>
#include <boost/unordered_set.hpp>
#include <vector>
#include "mongo/bson/bsontypes.h"
#include "mongo/db/pipeline/value.h"
namespace mongo {
class Accumulator : public RefCountable {
public:
Accumulator() = default;
/** Process input and update internal state.
* merging should be true when processing outputs from getValue(true).
*/
void process(const Value& input, bool merging) {
processInternal(input, merging);
}
/** Marks the end of the evaluate() phase and return accumulated result.
* toBeMerged should be true when the outputs will be merged by process().
*/
virtual Value getValue(bool toBeMerged) const = 0;
/// The name of the op as used in a serialization of the pipeline.
virtual const char* getOpName() const = 0;
int memUsageForSorter() const {
dassert(_memUsageBytes != 0); // This would mean subclass didn't set it
return _memUsageBytes;
}
/// Reset this accumulator to a fresh state ready to receive input.
virtual void reset() = 0;
protected:
/// Update subclass's internal state based on input
virtual void processInternal(const Value& input, bool merging) = 0;
/// subclasses are expected to update this as necessary
int _memUsageBytes = 0;
};
class AccumulatorAddToSet final : public Accumulator {
public:
AccumulatorAddToSet();
void processInternal(const Value& input, bool merging) final;
Value getValue(bool toBeMerged) const final;
const char* getOpName() const final;
void reset() final;
static boost::intrusive_ptr<Accumulator> create();
private:
typedef boost::unordered_set<Value, Value::Hash> SetType;
SetType set;
};
class AccumulatorFirst final : public Accumulator {
public:
AccumulatorFirst();
void processInternal(const Value& input, bool merging) final;
Value getValue(bool toBeMerged) const final;
const char* getOpName() const final;
void reset() final;
static boost::intrusive_ptr<Accumulator> create();
private:
bool _haveFirst;
Value _first;
};
class AccumulatorLast final : public Accumulator {
public:
AccumulatorLast();
void processInternal(const Value& input, bool merging) final;
Value getValue(bool toBeMerged) const final;
const char* getOpName() const final;
void reset() final;
static boost::intrusive_ptr<Accumulator> create();
private:
Value _last;
};
class AccumulatorSum final : public Accumulator {
public:
AccumulatorSum();
void processInternal(const Value& input, bool merging) final;
Value getValue(bool toBeMerged) const final;
const char* getOpName() const final;
void reset() final;
static boost::intrusive_ptr<Accumulator> create();
private:
BSONType totalType;
long long longTotal;
double doubleTotal;
};
class AccumulatorMinMax final : public Accumulator {
public:
enum Sense : int {
MIN = 1,
MAX = -1, // Used to "scale" comparison.
};
explicit AccumulatorMinMax(Sense sense);
void processInternal(const Value& input, bool merging) final;
Value getValue(bool toBeMerged) const final;
const char* getOpName() const final;
void reset() final;
static boost::intrusive_ptr<Accumulator> createMin();
static boost::intrusive_ptr<Accumulator> createMax();
private:
Value _val;
const Sense _sense;
};
class AccumulatorPush final : public Accumulator {
public:
AccumulatorPush();
void processInternal(const Value& input, bool merging) final;
Value getValue(bool toBeMerged) const final;
const char* getOpName() const final;
void reset() final;
static boost::intrusive_ptr<Accumulator> create();
private:
std::vector<Value> vpValue;
};
class AccumulatorAvg final : public Accumulator {
public:
AccumulatorAvg();
void processInternal(const Value& input, bool merging) final;
Value getValue(bool toBeMerged) const final;
const char* getOpName() const final;
void reset() final;
static boost::intrusive_ptr<Accumulator> create();
private:
double _total;
long long _count;
};
class AccumulatorStdDev final : public Accumulator {
public:
explicit AccumulatorStdDev(bool isSamp);
void processInternal(const Value& input, bool merging) final;
Value getValue(bool toBeMerged) const final;
const char* getOpName() const final;
void reset() final;
static boost::intrusive_ptr<Accumulator> createSamp();
static boost::intrusive_ptr<Accumulator> createPop();
private:
const bool _isSamp;
long long _count;
double _mean;
double _m2; // Running sum of squares of delta from mean. Named to match algorithm.
};
}
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