third_party/llvm-project/libcxx/test/std/thread/thread.mutex/thread.lock/thread.lock.shared/thread.lock.shared.locking/try_lock.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: no-threads
// UNSUPPORTED: c++03, c++11
//
// ALLOW_RETRIES: 2

// <shared_mutex>

// template <class Mutex> class shared_lock;

// bool try_lock();

#include <cassert>
#include <mutex>
#include <shared_mutex>
#include <system_error>

#include "test_macros.h"

bool try_lock_called = false;

struct mutex
{
    bool try_lock_shared()
    {
        try_lock_called = !try_lock_called;
        return try_lock_called;
    }
    void unlock_shared() {}
};

mutex m;

int main(int, char**)
{
    std::shared_lock<mutex> lk(m, std::defer_lock);
    assert(lk.try_lock() == true);
    assert(try_lock_called == true);
    assert(lk.owns_lock() == true);
#ifndef TEST_HAS_NO_EXCEPTIONS
    try
    {
        TEST_IGNORE_NODISCARD lk.try_lock();
        assert(false);
    }
    catch (std::system_error& e)
    {
        assert(e.code().value() == EDEADLK);
    }
#endif
    lk.unlock();
    assert(lk.try_lock() == false);
    assert(try_lock_called == false);
    assert(lk.owns_lock() == false);
    lk.release();
#ifndef TEST_HAS_NO_EXCEPTIONS
    try
    {
        TEST_IGNORE_NODISCARD lk.try_lock();
        assert(false);
    }
    catch (std::system_error& e)
    {
        assert(e.code().value() == EPERM);
    }
#endif

  return 0;
}