ScopedAccess.h

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/*
 * Copyright (C) 2012 by
 *   MetraLabs GmbH (MLAB), GERMANY
 * and
 *   Neuroinformatics and Cognitive Robotics Labs (NICR) at TU Ilmenau, GERMANY
 * All rights reserved.
 *
 * Contact: info@mira-project.org
 *
 * Commercial Usage:
 *   Licensees holding valid commercial licenses may use this file in
 *   accordance with the commercial license agreement provided with the
 *   software or, alternatively, in accordance with the terms contained in
 *   a written agreement between you and MLAB or NICR.
 *
 * GNU General Public License Usage:
 *   Alternatively, this file may be used under the terms of the GNU
 *   General Public License version 3.0 as published by the Free Software
 *   Foundation and appearing in the file LICENSE.GPL3 included in the
 *   packaging of this file. Please review the following information to
 *   ensure the GNU General Public License version 3.0 requirements will be
 *   met: http://www.gnu.org/copyleft/gpl.html.
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 * IN NO EVENT SHALL "MLAB" OR "NICR" BE LIABLE TO ANY PARTY FOR DIRECT,
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 */

#ifndef _MIRA_SCOPEDACCESS_H_
#define _MIRA_SCOPEDACCESS_H_

#ifndef Q_MOC_RUN
#include <boost/noncopyable.hpp>
#include <boost/thread/mutex.hpp>
#endif

namespace mira {


template <typename Protectee>
class ScopedAccessBase : boost::noncopyable
{

public:

    ScopedAccessBase(Protectee* p) : mObject(p) {
        assert(mObject!=NULL);
    }

    ScopedAccessBase(ScopedAccessBase&& other) noexcept : mObject(NULL)
    {
        std::swap(mObject,other.mObject);
    }

    ScopedAccessBase& operator=(ScopedAccessBase&& other) noexcept
    {
        std::swap(mObject,other.mObject);
        return *this;
    }

public:

    Protectee* operator->() {
        return mObject;
    }

    const Protectee* operator->() const {
        return mObject;
    }

    Protectee& operator*() {
        return *mObject;
    }

    const Protectee& operator*() const {
        return *mObject;
    }

protected:
    Protectee* mObject;
};


template <typename Protectee, typename Mutex = void>
class ScopedAccess : public ScopedAccessBase<Protectee>
{
    typedef ScopedAccessBase<Protectee> Base;

public:

    ScopedAccess(Protectee* p, Mutex* m, bool lockedAlready = false)
            : Base(p), mMutex(m) {
        assert(mMutex!=NULL);
        if(!lockedAlready)
            mMutex->lock();
    }

    ~ScopedAccess() {
        // unlock the object when we go out of scope
        if (mMutex)
            mMutex->unlock();
    }

    ScopedAccess(ScopedAccess&& other) noexcept : Base(std::move(other)), mMutex(NULL)
    {
        std::swap(mMutex, other.mMutex);
    }

    ScopedAccess& operator=(ScopedAccess&& other) noexcept
    {
        Base::operator=(other);
        std::swap(mMutex, other.mMutex);
        return *this;
    }

protected:
    Mutex* mMutex;
};

template <typename Protectee>
class ScopedAccess<Protectee, void> : public ScopedAccessBase<Protectee>
{
    typedef ScopedAccessBase<Protectee> Base;

public:

    ScopedAccess(Protectee* p, bool lockedAlready = false) : Base(p) {
        if(!lockedAlready)
            this->mObject->lock();
    }

    ~ScopedAccess() {
        // unlock the object when we go out of scope
        if (this->mObject)
            this->mObject->unlock();
    }

    ScopedAccess(ScopedAccess&& other) noexcept : Base(std::move(other)) {}
    ScopedAccess& operator=(ScopedAccess&& other) noexcept { Base::operator=(other); }
};


template <typename T>
class ProtecteeMixin : public T, boost::noncopyable
{
public:

    void lock() {
        mMutex.lock();
    }

    void unlock() {
        mMutex.unlock();
    }

private:

    boost::mutex mMutex;
};


} // namespace

#endif