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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/pipeline/accumulator.h"
#include "mongo/db/pipeline/document_source.h"
#include "mongo/db/pipeline/expression.h"
#include "mongo/db/pipeline/window_function/window_function_sum.h"
namespace mongo {
class WindowFunctionAvg final : public RemovableSum {
public:
explicit WindowFunctionAvg(ExpressionContext* const expCtx) : RemovableSum(expCtx), _count(0) {
// Note that RemovableSum manages the memory usage tracker directly for calls to add/remove.
// Here we only add the members that this class holds.
_memUsageBytes += sizeof(long long);
}
static std::unique_ptr<WindowFunctionState> create(ExpressionContext* const expCtx) {
return std::make_unique<WindowFunctionAvg>(expCtx);
}
static Value getDefault() {
return Value(BSONNULL);
}
void add(Value value) final {
if (!value.numeric())
return;
RemovableSum::add(std::move(value));
_count++;
}
void remove(Value value) final {
if (!value.numeric())
return;
RemovableSum::remove(std::move(value));
_count--;
}
Value getValue() const final {
if (_count == 0) {
return getDefault();
}
Value sum = RemovableSum::getValue();
switch (sum.getType()) {
case NumberInt:
case NumberLong:
return Value(sum.coerceToDouble() / static_cast<double>(_count));
case NumberDouble: {
double internalSum = sum.getDouble();
if (std::isnan(internalSum) || std::isinf(internalSum)) {
return sum;
}
return Value(internalSum / static_cast<double>(_count));
}
case NumberDecimal: {
Decimal128 internalSum = sum.getDecimal();
if (internalSum.isNaN() || internalSum.isInfinite()) {
return sum;
}
return Value(internalSum.divide(Decimal128(_count)));
}
default:
MONGO_UNREACHABLE_TASSERT(5371301);
}
}
void reset() {
RemovableSum::reset();
_count = 0;
_memUsageBytes += sizeof(long long);
}
private:
long long _count;
};
} // namespace mongo
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