libcxx/test/std/thread/futures/futures.async/async_race.38682.pass.cpp

   1 //===----------------------------------------------------------------------===//
   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 // UNSUPPORTED: no-threads
  10 // UNSUPPORTED: c++03
  11
  12 // This test requires the fix for http://llvm.org/PR38682 (616ef1863fae). We mark the
  13 // test as UNSUPPORTED instead of XFAIL because the test doesn't fail consistently.
  14 // UNSUPPORTED: using-built-library-before-llvm-10
  15
  16 // This test is designed to cause and allow TSAN to detect a race condition
  17 // in std::async, as reported in https://llvm.org/PR38682.
  18
  19 #include <cassert>
  20 #include <functional>
  21 #include <future>
  22 #include <numeric>
  23 #include <vector>
  24
  25 #include "test_macros.h"
  26
  27
  28 static int worker(std::vector<int> const& data) {
  29   return std::accumulate(data.begin(), data.end(), 0);
  30 }
  31
  32 static int& worker_ref(int& i) { return i; }
  33
  34 static void worker_void() { }
  35
  36 int main(int, char**) {
  37   // future<T>
  38   {
  39     std::vector<int> const v{1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
  40     for (int i = 0; i != 20; ++i) {
  41       std::future<int> fut = std::async(std::launch::async, worker, v);
  42       int answer = fut.get();
  43       assert(answer == 55);
  44     }
  45   }
  46
  47   // future<T&>
  48   {
  49     for (int i = 0; i != 20; ++i) {
  50       std::future<int&> fut = std::async(std::launch::async, worker_ref, std::ref(i));
  51       int& answer = fut.get();
  52       assert(answer == i);
  53     }
  54   }
  55
  56   // future<void>
  57   {
  58     for (int i = 0; i != 20; ++i) {
  59       std::future<void> fut = std::async(std::launch::async, worker_void);
  60       fut.get();
  61     }
  62   }
  63
  64   return 0;
  65 }