mutex.h

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/*
 * Copyright (C) 2026 Robin Gareus <robin@gareus.org>
 *
 * 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.
 */
 
#pragma once
 
#include <chrono>
#include <condition_variable>
#include <mutex>
 
#include "pbd/libpbd_visibility.h"
 
namespace PBD
{
 
class LIBPBD_API Mutex
{
public:
        enum LockFlags {
                Acquire,
                NotLock,
                TryLock
        };
        Mutex ();
 
        class Lock;
 
        void lock ()
        {
                _mutex.lock ();
        }
 
        bool trylock ()
        {
                return _mutex.try_lock ();
        }
 
        void unlock ()
        {
                _mutex.unlock ();
        }
 
private:
        friend class Cond;
        Mutex (Mutex const&)            = delete;
        Mutex& operator= (Mutex const&) = delete;
 
        std::mutex _mutex;
};
 
class LIBPBD_API Mutex::Lock
{
public:
        Lock (Mutex&, Mutex::LockFlags m = Acquire);
        ~Lock ();
 
        inline void acquire ()
        {
                _mutex.lock ();
                _locked = true;
        }
 
        inline bool try_acquire ()
        {
                _locked = _mutex.trylock ();
                return _locked;
        }
 
        inline void release ()
        {
                _mutex.unlock ();
                _locked = false;
        }
 
        inline bool locked () const
        {
                return _locked;
        }
 
private:
        Lock (Mutex::Lock const&)                   = delete;
        Mutex::Lock& operator= (Mutex::Lock const&) = delete;
 
        Mutex& _mutex;
        bool   _locked;
};
 
class Cond
{
public:
        Cond ();
 
        void signal ()
        {
                _cond.notify_one ();
        }
 
        void broadcast ()
        {
                _cond.notify_all ();
        }
 
        void wait (Mutex& mutex)
        {
                std::unique_lock m (mutex._mutex, std::adopt_lock);
                _cond.wait (m);
        }
 
        bool wait_for (Mutex& mutex, std::chrono::milliseconds const& rel_time)
        {
                std::unique_lock m (mutex._mutex, std::adopt_lock);
                return std::cv_status::no_timeout == _cond.wait_for (m, rel_time);
        }
 
private:
        Cond (Cond const&)            = delete;
        Cond& operator= (Cond const&) = delete;
 
        std::condition_variable _cond;
};
 
} // namespace PBD