ExponentialBackoff.cpp

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//===- llvm/Support/ExponentialBackoff.h ------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
 
#include "llvm/Support/ExponentialBackoff.h"
#include <thread>
 
using namespace llvm;
 
bool ExponentialBackoff::waitForNextAttempt() {
  auto Now = std::chrono::steady_clock::now();
  if (Now >= EndTime)
    return false;
 
  duration CurMaxWait = std::min(MinWait * CurrentMultiplier, MaxWait);
  std::uniform_int_distribution<uint64_t> Dist(MinWait.count(),
                                               CurMaxWait.count());
  // Use random_device directly instead of a PRNG as uniform_int_distribution
  // often only takes a few samples anyway.
  duration WaitDuration = std::min(duration(Dist(RandDev)), EndTime - Now);
  if (CurMaxWait < MaxWait)
    CurrentMultiplier *= 2;
  std::this_thread::sleep_for(WaitDuration);
  return true;
}