backoff.h

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#pragma once

#include <algorithm>
#include <random>
#include <stdint.h>
#include <time.h>

struct Backoff {
 int64_t minAmount;
 int64_t maxAmount;
 int64_t current;
 int fails;
 std::mt19937_64 randGenerator;
 std::uniform_real_distribution<> randDistribution;

 double rand01() { return randDistribution(randGenerator); }

 Backoff(int64_t min, int64_t max)
 : minAmount(min)
 , maxAmount(max)
 , current(min)
 , fails(0)
 , randGenerator((uint64_t)time(0))
 {
 }

 void reset()
 {
 fails = 0;
 current = minAmount;
 }

 int64_t nextDelay()
 {
 ++fails;
 int64_t delay = (int64_t)((double)current * 2.0 * rand01());
 current = std::min(current + delay, maxAmount);
 return current;
 }
};