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edff3ff4d3
This provides a simple way to implement exponential backoff using a do
while loop.
Usage example (also see the change to LockFileManager.cpp):
```
ExponentialBackoff Backoff(10s);
do {
if (tryToDoSomething())
return ItWorked;
} while (Backoff.waitForNextAttempt());
return Timeout;
```
Abstracting this out of `LockFileManager` as the module build daemon
will need it.
30 lines
1.1 KiB
C++
30 lines
1.1 KiB
C++
//===- llvm/Support/ExponentialBackoff.h ------------------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Support/ExponentialBackoff.h"
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#include <thread>
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using namespace llvm;
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bool ExponentialBackoff::waitForNextAttempt() {
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auto Now = std::chrono::steady_clock::now();
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if (Now >= EndTime)
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return false;
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duration CurMaxWait = std::min(MinWait * CurrentMultiplier, MaxWait);
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std::uniform_int_distribution<uint64_t> Dist(MinWait.count(),
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CurMaxWait.count());
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// Use random_device directly instead of a PRNG as uniform_int_distribution
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// often only takes a few samples anyway.
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duration WaitDuration = std::min(duration(Dist(RandDev)), EndTime - Now);
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if (CurMaxWait < MaxWait)
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CurrentMultiplier *= 2;
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std::this_thread::sleep_for(WaitDuration);
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return true;
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}
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