test/std/thread/thread.condition/thread.condition.condvar/wait_pred.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: libcpp-has-no-threads

// <condition_variable>

// class condition_variable;

// template <class Predicate>
//   void wait(unique_lock<mutex>& lock, Predicate pred);

#include <condition_variable>
#include <mutex>
#include <thread>
#include <functional>
#include <cassert>

std::condition_variable cv;
std::mutex mut;

int test1 = 0;
int test2 = 0;

class Pred
{
    int& i_;
public:
    explicit Pred(int& i) : i_(i) {}

    bool operator()() {return i_ != 0;}
};

void f()
{
    std::unique_lock<std::mutex> lk(mut);
    assert(test2 == 0);
    test1 = 1;
    cv.notify_one();
    cv.wait(lk, Pred(test2));
    assert(test2 != 0);
}

int main(int, char**)
{
    std::unique_lock<std::mutex>lk(mut);
    std::thread t(f);
    assert(test1 == 0);
    while (test1 == 0)
        cv.wait(lk);
    assert(test1 != 0);
    test2 = 1;
    lk.unlock();
    cv.notify_one();
    t.join();

  return 0;
}