libcruft-util/thread/ticketlock.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 "ticketlock.hpp"

using util::thread::ticketlock;


///////////////////////////////////////////////////////////////////////////////
ticketlock::ticketlock ():
    current (0),
    next (0)
{ }


///////////////////////////////////////////////////////////////////////////////
void
ticketlock::lock (void)
{
    auto self = next++;

    while (current != self)
        __asm__ volatile ("pause");
}


//-----------------------------------------------------------------------------
void
ticketlock::unlock (void)
{
    ++current;
}