mirror of
https://github.com/mozilla/gecko-dev.git
synced 2024-11-27 14:52:16 +00:00
94 lines
2.3 KiB
C++
94 lines
2.3 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
|
|
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
|
|
/* This Source Code Form is subject to the terms of the Mozilla Public
|
|
* License, v. 2.0. If a copy of the MPL was not distributed with this
|
|
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
|
|
|
|
/* Calculate the rolling mean of a series of values. */
|
|
|
|
#ifndef mozilla_RollingMean_h_
|
|
#define mozilla_RollingMean_h_
|
|
|
|
#include "mozilla/Assertions.h"
|
|
#include "mozilla/Vector.h"
|
|
|
|
#include <stddef.h>
|
|
#include <type_traits>
|
|
|
|
namespace mozilla {
|
|
|
|
/**
|
|
* RollingMean<T> calculates a rolling mean of the values it is given. It
|
|
* accumulates the total as values are added and removed. The second type
|
|
* argument S specifies the type of the total. This may need to be a bigger
|
|
* type in order to maintain that the sum of all values in the average doesn't
|
|
* exceed the maximum input value.
|
|
*
|
|
* WARNING: Float types are not supported due to rounding errors.
|
|
*/
|
|
template <typename T, typename S>
|
|
class RollingMean {
|
|
private:
|
|
size_t mInsertIndex;
|
|
size_t mMaxValues;
|
|
Vector<T> mValues;
|
|
S mTotal;
|
|
|
|
public:
|
|
static_assert(!std::is_floating_point_v<T>,
|
|
"floating-point types are unsupported due to rounding "
|
|
"errors");
|
|
|
|
explicit RollingMean(size_t aMaxValues)
|
|
: mInsertIndex(0), mMaxValues(aMaxValues), mTotal(0) {
|
|
MOZ_ASSERT(aMaxValues > 0);
|
|
}
|
|
|
|
RollingMean& operator=(RollingMean&& aOther) = default;
|
|
|
|
/**
|
|
* Insert a value into the rolling mean.
|
|
*/
|
|
bool insert(T aValue) {
|
|
MOZ_ASSERT(mValues.length() <= mMaxValues);
|
|
|
|
if (mValues.length() == mMaxValues) {
|
|
mTotal = mTotal - mValues[mInsertIndex] + aValue;
|
|
mValues[mInsertIndex] = aValue;
|
|
} else {
|
|
if (!mValues.append(aValue)) {
|
|
return false;
|
|
}
|
|
mTotal = mTotal + aValue;
|
|
}
|
|
|
|
mInsertIndex = (mInsertIndex + 1) % mMaxValues;
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* Calculate the rolling mean.
|
|
*/
|
|
T mean() const {
|
|
MOZ_ASSERT(!empty());
|
|
return T(mTotal / int64_t(mValues.length()));
|
|
}
|
|
|
|
bool empty() const { return mValues.empty(); }
|
|
|
|
/**
|
|
* Remove all values from the rolling mean.
|
|
*/
|
|
void clear() {
|
|
mValues.clear();
|
|
mInsertIndex = 0;
|
|
mTotal = T(0);
|
|
}
|
|
|
|
size_t maxValues() const { return mMaxValues; }
|
|
};
|
|
|
|
} // namespace mozilla
|
|
|
|
#endif // mozilla_RollingMean_h_
|