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// Copyright 2016 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef REMOTING_BASE_RUNNING_SAMPLES_H_
#define REMOTING_BASE_RUNNING_SAMPLES_H_
#include <stddef.h>
#include <stdint.h>
#include "base/containers/circular_deque.h"
#include "base/sequence_checker.h"
#include "base/thread_annotations.h"
namespace remoting {
// Calculates the maximum or average of the most recent N recorded samples.
// This is typically used to smooth out random variation in point samples
// over bandwidth, frame rate, etc.
class RunningSamples {
public:
// Constructs a running sample helper that stores |window_size| most
// recent samples.
explicit RunningSamples(int window_size);
RunningSamples(const RunningSamples&) = delete;
RunningSamples& operator=(const RunningSamples&) = delete;
virtual ~RunningSamples();
// Records a point sample.
void Record(int64_t value);
// Returns the average over up to |window_size| of the most recent samples.
// 0 if no sample available
double Average() const;
// Returns the max over up to |window_size| of the most recent samples.
// 0 if no sample available
int64_t Max() const;
// Whether there is at least one record.
bool IsEmpty() const;
private:
// Stores the desired window size, as size_t to avoid casting when comparing
// with the size of |data_points_|.
const size_t window_size_;
// Stores the |window_size| most recently recorded samples.
base::circular_deque<int64_t> data_points_
GUARDED_BY_CONTEXT(sequence_checker_);
// Holds the sum of the samples in |data_points_|.
int64_t sum_ GUARDED_BY_CONTEXT(sequence_checker_) = 0;
SEQUENCE_CHECKER(sequence_checker_);
};
} // namespace remoting
#endif // REMOTING_BASE_RUNNING_SAMPLES_H_
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