1*0fca6ea1SDimitry Andric //===- llvm/Support/ExponentialBackoff.h ------------------------*- C++ -*-===// 2*0fca6ea1SDimitry Andric // 3*0fca6ea1SDimitry Andric // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4*0fca6ea1SDimitry Andric // See https://llvm.org/LICENSE.txt for license information. 5*0fca6ea1SDimitry Andric // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6*0fca6ea1SDimitry Andric // 7*0fca6ea1SDimitry Andric //===----------------------------------------------------------------------===// 8*0fca6ea1SDimitry Andric 9*0fca6ea1SDimitry Andric #include "llvm/Support/ExponentialBackoff.h" 10*0fca6ea1SDimitry Andric #include <thread> 11*0fca6ea1SDimitry Andric 12*0fca6ea1SDimitry Andric using namespace llvm; 13*0fca6ea1SDimitry Andric waitForNextAttempt()14*0fca6ea1SDimitry Andricbool ExponentialBackoff::waitForNextAttempt() { 15*0fca6ea1SDimitry Andric auto Now = std::chrono::steady_clock::now(); 16*0fca6ea1SDimitry Andric if (Now >= EndTime) 17*0fca6ea1SDimitry Andric return false; 18*0fca6ea1SDimitry Andric 19*0fca6ea1SDimitry Andric duration CurMaxWait = std::min(MinWait * CurrentMultiplier, MaxWait); 20*0fca6ea1SDimitry Andric std::uniform_int_distribution<uint64_t> Dist(MinWait.count(), 21*0fca6ea1SDimitry Andric CurMaxWait.count()); 22*0fca6ea1SDimitry Andric // Use random_device directly instead of a PRNG as uniform_int_distribution 23*0fca6ea1SDimitry Andric // often only takes a few samples anyway. 24*0fca6ea1SDimitry Andric duration WaitDuration = std::min(duration(Dist(RandDev)), EndTime - Now); 25*0fca6ea1SDimitry Andric if (CurMaxWait < MaxWait) 26*0fca6ea1SDimitry Andric CurrentMultiplier *= 2; 27*0fca6ea1SDimitry Andric std::this_thread::sleep_for(WaitDuration); 28*0fca6ea1SDimitry Andric return true; 29*0fca6ea1SDimitry Andric } 30