// © 2016 and later: Unicode, Inc. and others.

// License & terms of use: http://www.unicode.org/copyright.html

/*

******************************************************************************

* Copyright (C) 2015, International Business Machines

* Corporation and others.  All Rights Reserved.

******************************************************************************

* sharedobject.cpp

*/

#include "sharedobject.h"

#include "mutex.h"

#include "uassert.h"

#include "umutex.h"

#include "unifiedcache.h"

U_NAMESPACE_BEGIN

SharedObject::~SharedObject() {}

UnifiedCacheBase::~UnifiedCacheBase() {}

void

SharedObject::addRef() const {

    umtx_atomic_inc(&hardRefCount);

}

// removeRef Decrement the reference count and delete if it is zero.

//           Note that SharedObjects with a non-null cachePtr are owned by the

//           unified cache, and the cache will be responsible for the actual deletion.

//           The deletion could be as soon as immediately following the

//           update to the reference count, if another thread is running

//           a cache eviction cycle concurrently.

//           NO ACCESS TO *this PERMITTED AFTER REFERENCE COUNT == 0 for cached objects.

//           THE OBJECT MAY ALREADY BE GONE.

void

SharedObject::removeRef() const {

    const UnifiedCacheBase *cache = this->cachePtr;

    int32_t updatedRefCount = umtx_atomic_dec(&hardRefCount);

    U_ASSERT(updatedRefCount >= 0);

    if (updatedRefCount == 0) {

        if (cache) {

            cache->handleUnreferencedObject();

        } else {

            delete this;

        }

    }

}

int32_t

SharedObject::getRefCount() const {

    return umtx_loadAcquire(hardRefCount);

}

void

SharedObject::deleteIfZeroRefCount() const {

    if (this->cachePtr == nullptr && getRefCount() == 0) {

        delete this;

    }

}

U_NAMESPACE_END