libcruft-util/test/thread/monitor.cpp

/*
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * Copyright 2018 Danny Robson <danny@nerdcruft.net>
 */

#include "tap.hpp"
#include "thread/monitor.hpp"
#include "thread/event.hpp"
#include "thread/semaphore.hpp"

#include <atomic>
#include <thread>


///////////////////////////////////////////////////////////////////////////////
// a single atomic integer wrapper that allows precise ordering of thread
// entrance and exit for exact testing of thread interleavings.
struct foo {
    foo ():
        enter (0),
        leave (0)
    { ; }

    void
    inc (void) {
        enter.acquire ();
        ++value;
        leave.release ();
    }

    std::atomic<int> value = 0;
    util::thread::semaphore enter;
    util::thread::semaphore leave;
};


///////////////////////////////////////////////////////////////////////////////
int
main ()
{
    util::TAP::logger tap;

    util::thread::monitor<foo> obj;
    const auto &value = obj->value;
    auto &enter = obj->enter;
    auto &leave = obj->leave;

    std::thread t1 ([&] () { obj->inc (); });
    std::thread t2 ([&] () { obj->inc (); });

    tap.expect_eq (value, 0, "wrapped class was left initialised");

    enter.release ();
    leave.acquire ();
    tap.expect_eq (value, 1, "only one thread had access");

    enter.release ();
    leave.acquire ();
    tap.expect_eq (value, 2, "second thread got access");

    t1.join ();
    t2.join ();

    return tap.status ();
}