llvm/lib/Support/ExponentialBackoff.cpp

   1 //===- llvm/Support/ExponentialBackoff.h ------------------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "llvm/Support/ExponentialBackoff.h"
  10 #include <thread>
  11
  12 using namespace llvm;
  13
  14 bool ExponentialBackoff::waitForNextAttempt() {
  15   auto Now = std::chrono::steady_clock::now();
  16   if (Now >= EndTime)
  17     return false;
  18
  19   duration CurMaxWait = std::min(MinWait * CurrentMultiplier, MaxWait);
  20   std::uniform_int_distribution<uint64_t> Dist(MinWait.count(),
  21                                                CurMaxWait.count());
  22   // Use random_device directly instead of a PRNG as uniform_int_distribution
  23   // often only takes a few samples anyway.
  24   duration WaitDuration = std::min(duration(Dist(RandDev)), EndTime - Now);
  25   if (CurMaxWait < MaxWait)
  26     CurrentMultiplier *= 2;
  27   std::this_thread::sleep_for(WaitDuration);
  28   return true;
  29 }