refcounter.h

/*
 *  Copyright (C) 2006  Helmut Grohne
 *
 *  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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#ifndef LIBMUTH_REFCOUNTER_H
#define LIBMUTH_REFCOUNTER_H

#include <assert.h>
#include "compiler.h"
#include "refcounter_decls.h"

inline void RefCounter::addWeakRef(WeakRefBase &wr) {
        WITHACQUIRED(this->datalock);
        this->notifier.insert(&wr);
        this->cond.notify();
}

inline void RefCounter::removeWeakRef(WeakRefBase &wr) {
        WITHACQUIRED(this->datalock);
        this->notifier.erase(&wr);
        this->cond.notify();
}

inline void RefCounter::notifyall() {
        /* datalock is acquired from ~RefCounter() */
        while(!this->notifier.empty()) {
                WeakRefBase *const t(*this->notifier.begin());
                if(likely(t->datalock.tryacquire())) {
                        this->notifier.erase(this->notifier.begin());
                        t->notify();
                        t->datalock.release();
                } else
                        this->cond.wait();
        }
}

inline RefCounter::~RefCounter() {
        /* datalock is acquired in decref. */
        this->notifyall();
        this->datalock.release();
}

inline RefCounter::RefCounter() : cond(datalock), refcount(0) {
}

inline void RefCounter::incref() {
        WITHACQUIRED(this->datalock);
        ++this->refcount;
}

inline void RefCounter::decref() {
        this->datalock.acquire();
        if(!--this->refcount)
                /* The destructor will release the lock. */
                delete this;
        else
                this->datalock.release();
}

template<class RC> inline Reference<RC>::Reference(RC *obj) : object(obj) {
        assert(this->object != NULL);
        this->object->incref();
}

template<class RC> inline Reference<RC>::Reference(const Reference &other)
                : object(other.object) {
        this->object->incref();
}

template<class RC> inline Reference<RC> &Reference<RC>::operator=(RC *obj) {
        assert(obj != NULL);
        obj->incref();
        this->object->decref();
        this->object = obj;
        return *this;
}

template<class RC> inline Reference<RC> &Reference<RC>::operator=(const
                Reference &other) {
        other.object->incref();
        this->object->decref();
        this->object = other.object;
        return *this;
}

template<class RC> inline bool Reference<RC>::operator==(const Reference
                &other) const {
        return this->object == other.object;
}

template<class RC> inline bool Reference<RC>::operator!=(const Reference
                &other) const {
        return this->object != other.object;
}

template<class RC> inline RC &Reference<RC>::operator*() const {
        return *this->object;
}

template<class RC> inline RC *Reference<RC>::operator->() const {
        return this->object;
}

template<class RC> inline Reference<RC>::~Reference() {
        this->object->decref();
}

inline WeakRefBase::WeakRefBase() {
}

template<class RC> void WeakReference<RC>::notify() {
        /* locked in RefCounter::notifyall */
        this->object = NULL;
}

template<class RC> inline WeakReference<RC>::WeakReference() : object(NULL) {
}

template<class RC> inline WeakReference<RC>::WeakReference(const WeakReference
                &other) : object(other.object) {
        if(this->object)
                this->object->addWeakRef(*this);
}

template<class RC> inline WeakReference<RC>::WeakReference(const Reference<RC>
                &other) : object(other.object) {
        assert(this->object != NULL);
        this->object->addWeakRef(*this);
}

template<class RC> inline WeakReference<RC>::WeakReference(RC *obj)
                : object(obj) {
        if(this->object)
                this->object->addWeakRef(*this);
}

template<class RC> inline WeakReference<RC> &WeakReference<RC>::operator=(const
                WeakReference &other) {
        WITHACQUIRED(this->datalock);
        if(likely(this->object != other.object)) {
                if(this->object)
                        this->object->removeWeakRef(*this);
                this->object = other.object;
                if(this->object)
                        this->object->addWeakRef(*this);
        }
        return *this;
}

template<class RC> inline WeakReference<RC> &WeakReference<RC>::operator=(const
                Reference<RC> &other) {
        WITHACQUIRED(this->datalock);
        if(likely(this->object != other.object)) {
                if(this->object)
                        this->object->removeWeakRef(*this);
                this->object = other.object;
                assert(this->object != NULL);
                this->object->addWeakRef(*this);
        }
        return *this;
}

template<class RC> inline bool WeakReference<RC>::operator==(const WeakReference
                &other) const {
        WITHACQUIRED(this->datalock);
        return this->object == other.object;
}

template<class RC> inline bool WeakReference<RC>::operator==(const Reference<RC>
                &other) const {
        WITHACQUIRED(this->datalock);
        return this->object == other.object;
}

template<class RC> inline bool WeakReference<RC>::operator!=(const WeakReference
                &other) const {
        WITHACQUIRED(this->datalock);
        return this->object != other.object;
}

template<class RC> inline bool WeakReference<RC>::operator!=(const Reference<RC>
                &other) const {
        WITHACQUIRED(this->datalock);
        return this->object != other.object;
}

template<class RC> inline Reference<RC> WeakReference<RC>::operator*() const {
        WITHACQUIRED(this->datalock);
        if(!this->object)
                throw NullPointerException();
        return Reference<RC>(this->object);
}

template<class RC> WeakReference<RC>::~WeakReference() {
        WITHACQUIRED(this->datalock);
        if(this->object)
                this->object->removeWeakRef(*this);
}

#endif

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