llvm/libcxx/test/std/input.output/syncstream/osyncstream/thread/several_threads.pass.cpp

//===----------------------------------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//

// UNSUPPORTED: c++03, c++11, c++14, c++17
// UNSUPPORTED: no-localization
// UNSUPPORTED: no-threads
// UNSUPPORTED: libcpp-has-no-experimental-syncstream

// <syncstream>

// template <class charT, class traits, class Allocator>
// class basic_osyncstream;

// The test writes all elements in test_strings in a random order in ss. Every
// write is done by an osyncstream. This means the output is in random order,
// but the words should be written without interleaving. To increment the
// change of interleaving words are written one character at a time.

#include <cassert>
#include <chrono>
#include <mutex>
#include <sstream>
#include <string>
#include <syncstream>
#include <thread>
#include <unordered_set>
#include <vector>

#include "test_macros.h"

static std::ostringstream ss;

static std::unordered_multiset<std::string> test_strings = {
    "C++ ",
    "is ",
    "a ",
    "general-purpose ",
    "programming ",
    "language ",
    "created ",
    "by ",
    "Bjarne ",
    "Stroustrup ",
    "as ",
    "an ",
    "extension ",
    "of ",
    "the ",
    "C ",
    "programming ",
    "language, ",
    "or ",
    "C ",
    "with ",
    "Classes. ",
    "The ",
    "language ",
    "has ",
    "expanded ",
    "significantly ",
    "over ",
    "time, ",
    "and ",
    "modern ",
    "C++ ",
    "has ",
    "object-oriented, ",
    "generic, ",
    "and ",
    "functional ",
    "features ",
    "in ",
    "addition ",
    "to ",
    "facilities ",
    "for ",
    "low-level ",
    "memory ",
    "manipulation. ",
    "It ",
    "is ",
    "almost ",
    "always ",
    "implemented ",
    "as ",
    "a ",
    "compiled ",
    "language, ",
    "and ",
    "many ",
    "vendors ",
    "provide ",
    "C++ ",
    "compilers, ",
    "including ",
    "the ",
    "Free ",
    "Software ",
    "Foundation, ",
    "LLVM, ",
    "Microsoft, ",
    "Intel, ",
    "and ",
    "IBM, ",
    "so ",
    "it ",
    "is ",
    "available ",
    "on ",
    "many ",
    "platforms."};

void f(std::string text) {
  std::osyncstream out(ss);
  for (char c : text)
    out << c;
}

void test() {
  ss = std::basic_ostringstream<char>();
  std::vector<std::thread> threads;
  for (std::string const& word : test_strings)
    threads.push_back(std::thread(f, word));

  for (auto& thread : threads)
    thread.join();

  std::string output = ss.str();
  for (const std::string& word : test_strings)
    assert(output.find(word) != std::string::npos);
}

int main(int, char**) {
  // The more we test, the more likely we catch an error
  for (size_t i = 0; i < 1024; ++i)
    test();

  return 0;
}