ZeroTierOne/core/Meter.hpp
2020-06-05 13:04:37 -07:00

92 lines
2.4 KiB
C++

/*
* Copyright (c)2013-2020 ZeroTier, Inc.
*
* Use of this software is governed by the Business Source License included
* in the LICENSE.TXT file in the project's root directory.
*
* Change Date: 2024-01-01
*
* On the date above, in accordance with the Business Source License, use
* of this software will be governed by version 2.0 of the Apache License.
*/
/****/
#ifndef ZT_METER_HPP
#define ZT_METER_HPP
#include "Constants.hpp"
#include "Mutex.hpp"
#include <algorithm>
namespace ZeroTier {
/**
* Transfer rate and total transferred amount meter
*
* This class is lock-free and thread-safe.
*
* This maintains a set of buckets numbered according to the current time
* modulo TUNIT. Each bucket is incremented within that time window. When
* the time moves on to a new bucket, its old contents are added to a
* total accumulator and a new counter for that bucket starts.
*
* @tparam TUNIT Unit of time in milliseconds (default: 1000 for one second)
* @tparam LSIZE Log size in units of time (default: 10 for 10s worth of data)
*/
template<int64_t TUNIT = 1000, unsigned long LSIZE = 10>
class Meter
{
public:
/**
* Create and initialize a new meter
*
* @param now Start time
*/
ZT_INLINE Meter() noexcept
{}
/**
* Add a measurement
*
* @param now Current time
* @param count Count of items (usually bytes)
*/
ZT_INLINE void log(const int64_t now, uint64_t count) noexcept
{
// We log by choosing a log bucket based on the current time in units modulo
// the log size and then if it's a new bucket setting it or otherwise adding
// to it.
const unsigned long bucket = ((unsigned long)(now / TUNIT)) % LSIZE;
if (m_bucket.exchange(bucket) != bucket) {
m_totalExclCounts.fetch_add(m_counts[bucket].exchange(count));
} else {
m_counts[bucket].fetch_add(count);
}
}
/**
* Get rate per TUNIT time
*
* @param now Current time
* @param rate Result parameter: rate in count/TUNIT
* @param total Total count for life of object
*/
ZT_INLINE void rate(double &rate, uint64_t &total) const noexcept
{
total = 0;
for (unsigned long i = 0;i < LSIZE;++i)
total += m_counts[i].load();
rate = (double) total / (double) LSIZE;
total += m_totalExclCounts.load();
}
private:
std::atomic<uint64_t> m_counts[LSIZE];
std::atomic<uint64_t> m_totalExclCounts;
std::atomic<unsigned long> m_bucket;
};
} // namespace ZeroTier
#endif