jack2/linux/JackLinuxFutex.h

/*
Copyright (C) 2004-2008 Grame
Copyright (C) 2016 Filipe Coelho

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

*/

#ifndef __JackLinuxFutex__
#define __JackLinuxFutex__

#include "JackSynchro.h"
#include "JackCompilerDeps.h"
#include <stddef.h>

namespace Jack
{

/*!
\brief Inter process synchronization using Linux futex.

 Based on the JackPosixSemaphore class.
 Adapted to work with linux futex to be as light as possible and also work in multiple architectures.

 Adds a new 'MakePrivate' function that makes the sync happen in the local process only,
 making it even faster for internal clients.
*/

class SERVER_EXPORT JackLinuxFutex : public detail::JackSynchro
{

    private:
        struct FutexData {
            int futex;         // futex, needs to be 1st member
            bool internal;     // current internal state
            bool wasInternal;  // initial internal state, only changes in allocate
            bool needsChange;  // change state on next wait call
            int externalCount; // how many external clients have connected
        };

        int fSharedMem;
        FutexData* fFutex;
        bool fPrivate;
        bool fPromiscuous;
        int fPromiscuousGid;

    protected:

        void BuildName(const char* name, const char* server_name, char* res, int size);

    public:

        JackLinuxFutex();

        bool Signal();
        bool SignalAll();
        bool Wait();
        bool TimedWait(long usec);

        bool Allocate(const char* name, const char* server_name, int value, bool internal = false);
        bool Connect(const char* name, const char* server_name);
        bool ConnectInput(const char* name, const char* server_name);
        bool ConnectOutput(const char* name, const char* server_name);
        bool Disconnect();
        void Destroy();

        void MakePrivate(bool priv);
};

} // end of namespace


#endif