guard.cpp

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// Copyright (c) 2013-2025  Made to Order Software Corp.  All Rights Reserved
//
// https://snapwebsites.org/project/cppthread
// contact@m2osw.com
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License along
// with this program; if not, write to the Free Software Foundation, Inc.,
// 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 
// self
//
#include    "cppthread/guard.h"
 
#include    "cppthread/exception.h"
#include    "cppthread/log.h"
#include    "cppthread/mutex.h"
 
 
// last include
//
#include    <snapdev/poison.h>
 
 
 
namespace cppthread
{
 
 
 
guard::guard(mutex & m)
    : f_mutex(&m)
{
    if(f_mutex == nullptr)
    {
        // mutex is mandatory
        //
        throw logic_error("mutex missing in guard() constructor");
    }
    f_mutex->lock();
    f_locked = true;
}
 
 
guard::~guard()
{
    try
    {
        unlock();
    }
    catch(std::exception const & e)
    {
        // a log was already printed, we do not absolutely need another one
        log << log_level_t::fatal
            << "mutex::unlock() threw an exception while in the ~guard() function."
            << end;
        std::terminate();
    }
}
 
 
void guard::unlock(bool done)
{
    if(f_locked)
    {
        mutex * m(f_mutex);
        f_locked = false;
        if(done)
        {
            f_mutex = nullptr;
        }
        m->unlock();
    }
}
 
 
void guard::lock()
{
    if(f_mutex == nullptr)
    {
        return;
    }
 
    f_mutex->lock();
 
    if(f_locked)
    {
        f_mutex->unlock();
    }
    else
    {
        f_locked = true;
    }
}
 
 
bool guard::is_locked() const
{
    bool result(f_mutex != nullptr);
    if(result)
    {
        f_mutex->lock();
        result = f_locked;
        f_mutex->unlock();
    }
 
    return result;
}
 
 
 
 
} // namespace cppthread
// vim: ts=4 sw=4 et