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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/>.
*/
#include "mongo/pch.h"
#include "mongo/db/pipeline/accumulator.h"
#include "mongo/db/pipeline/document.h"
#include "mongo/db/pipeline/expression_context.h"
#include "mongo/db/pipeline/value.h"
namespace mongo {
namespace {
const char subTotalName[] = "subTotal";
const char countName[] = "count";
}
void AccumulatorAvg::processInternal(const Value& input, bool merging) {
if (!merging) {
Super::processInternal(input, merging);
}
else {
// We expect an object that contains both a subtotal and a count.
// This is what getValue(true) produced below.
verify(input.getType() == Object);
Value subTotal = input[subTotalName];
verify(!subTotal.missing());
doubleTotal += subTotal.getDouble();
Value subCount = input[countName];
verify(!subCount.missing());
count += subCount.getLong();
}
}
intrusive_ptr<Accumulator> AccumulatorAvg::create() {
return new AccumulatorAvg();
}
Value AccumulatorAvg::getValue(bool toBeMerged) const {
if (!toBeMerged) {
double avg = 0;
if (count)
avg = doubleTotal / static_cast<double>(count);
return Value(avg);
}
else {
MutableDocument out;
out.addField(subTotalName, Value(doubleTotal));
out.addField(countName, Value(count));
return Value(out.freeze());
}
}
AccumulatorAvg::AccumulatorAvg() {
// This is a fixed size Accumulator so we never need to update this
_memUsageBytes = sizeof(*this);
}
void AccumulatorAvg::reset() {
// All state is in parent
Super::reset();
}
const char *AccumulatorAvg::getOpName() const {
return "$avg";
}
}
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