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/*
* Copyright 2019-2021 Diligent Graphics LLC
* Copyright 2015-2019 Egor Yusov
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* In no event and under no legal theory, whether in tort (including negligence),
* contract, or otherwise, unless required by applicable law (such as deliberate
* and grossly negligent acts) or agreed to in writing, shall any Contributor be
* liable for any damages, including any direct, indirect, special, incidental,
* or consequential damages of any character arising as a result of this License or
* out of the use or inability to use the software (including but not limited to damages
* for loss of goodwill, work stoppage, computer failure or malfunction, or any and
* all other commercial damages or losses), even if such Contributor has been advised
* of the possibility of such damages.
*/
#pragma once
/// \file
/// Defines Diligent::IReferenceCounters interface
#include "InterfaceID.h"
DILIGENT_BEGIN_NAMESPACE(Diligent)
typedef long ReferenceCounterValueType;
#if DILIGENT_CPP_INTERFACE
/// Base interface for a reference counter object that stores the number of strong and
/// weak references and the pointer to the object. It is necessary to separate reference
/// counters from the object to support weak pointers.
class IReferenceCounters
{
public:
/// Increments the number of strong references by 1.
/// \return The number of strong references after incrementing the counter.
/// \remark The method is thread-safe and does not require explicit synchronization.
/// \note In a multithreaded environment, the returned number may not be reliable
/// as other threads may simultaneously change the actual value of the counter.
virtual ReferenceCounterValueType AddStrongRef() = 0;
/// Decrements the number of strong references by 1 and destroys the referenced object
/// when the counter reaches zero. If there are no more weak references, destroys the
/// reference counters object itself.
/// \return The number of strong references after decrementing the counter.
/// \remark The referenced object is destroyed when the last strong reference is released.\n
/// If there are no more weak references, the reference counters object itself is
/// also destroyed.\n
/// The method is thread-safe and does not require explicit synchronization.
/// \note In a multithreaded environment, the returned number may not be reliable
/// as other threads may simultaneously change the actual value of the counter.
/// The only reliable value is 0 as the object is destroyed when the last
/// strong reference is released.
virtual ReferenceCounterValueType ReleaseStrongRef() = 0;
/// Increments the number of weak references by 1.
/// \return The number of weak references after incrementing the counter.
/// \remark The method is thread-safe and does not require explicit synchronization.
/// \note In a multithreaded environment, the returned number may not be reliable
/// as other threads may simultaneously change the actual value of the counter.
virtual ReferenceCounterValueType AddWeakRef() = 0;
/// Decrements the number of weak references by 1. If there are no more strong and weak
/// references, destroys the reference counters object itself.
/// \return The number of weak references after decrementing the counter.
/// \remark The method is thread-safe and does not require explicit synchronization.
/// \note In a multithreaded environment, the returned number may not be reliable
/// as other threads may simultaneously change the actual value of the counter.
virtual ReferenceCounterValueType ReleaseWeakRef() = 0;
/// Gets the pointer to the IUnknown interface of the referenced object.
/// \param [out] ppObject - Memory address where the pointer to the object
/// will be stored.
/// \remark If the object was destroyed, nullptr will be written to *ppObject.
/// If the object was not released, the pointer to the object's IUnknown interface
/// will be stored. In this case, the number of strong references to the object
/// will be incremented by 1.\n
/// The method is thread-safe and does not require explicit synchronization.
virtual void GetObject(struct IObject** ppObject) = 0;
/// Returns the number of outstanding strong references.
/// \return The number of strong references.
/// \note In a multithreaded environment, the returned number may not be reliable
/// as other threads may simultaneously change the actual value of the counter.
/// The only reliable value is 0 as the object is destroyed when the last
/// strong reference is released.
virtual ReferenceCounterValueType GetNumStrongRefs() const = 0;
/// Returns the number of outstanding weak references.
/// \return The number of weak references.
/// \note In a multithreaded environment, the returned number may not be reliable
/// as other threads may simultaneously change the actual value of the counter.
virtual ReferenceCounterValueType GetNumWeakRefs() const = 0;
};
#else
struct IObject;
struct IReferenceCounters;
// clang-format off
typedef struct IReferenceCountersMethods
{
ReferenceCounterValueType (*AddStrongRef) (struct IReferenceCounters*);
ReferenceCounterValueType (*ReleaseStrongRef) (struct IReferenceCounters*);
ReferenceCounterValueType (*AddWeakRef) (struct IReferenceCounters*);
ReferenceCounterValueType (*ReleaseWeakRef) (struct IReferenceCounters*);
void (*GetObject) (struct IReferenceCounters*, struct IObject** ppObject);
ReferenceCounterValueType (*GetNumStrongRefs) (struct IReferenceCounters*);
ReferenceCounterValueType (*GetNumWeakRefs) (struct IReferenceCounters*);
} IReferenceCountersMethods;
typedef struct IReferenceCountersVtbl
{
IReferenceCountersMethods ReferenceCounters;
} IReferenceCountersVtbl;
// clang-format on
typedef struct IReferenceCounters
{
struct IReferenceCountersVtbl* pVtbl;
} IReferenceCounters;
// clang-format off
# define IReferenceCounters_AddStrongRef(This) CALL_IFACE_METHOD(ReferenceCounters, AddStrongRef, This)
# define IReferenceCounters_ReleaseStrongRef(This) CALL_IFACE_METHOD(ReferenceCounters, ReleaseStrongRef, This)
# define IReferenceCounters_AddWeakRef(This) CALL_IFACE_METHOD(ReferenceCounters, AddWeakRef, This)
# define IReferenceCounters_ReleaseWeakRef(This) CALL_IFACE_METHOD(ReferenceCounters, ReleaseWeakRef, This)
# define IReferenceCounters_GetObject(This, ...) CALL_IFACE_METHOD(ReferenceCounters, GetObject, This, __VA_ARGS__)
# define IReferenceCounters_GetNumStrongRefs(This) CALL_IFACE_METHOD(ReferenceCounters, GetNumStrongRefs, This)
# define IReferenceCounters_GetNumWeakRefs(This) CALL_IFACE_METHOD(ReferenceCounters, GetNumWeakRefs, This)
// clang-format on
#endif
DILIGENT_END_NAMESPACE // namespace Diligent
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