smallobj.h

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        template <class, class> class T,
        std::size_t C,
        std::size_t M,
        std::size_t O,
        template <class> class L,
        class X
    >
    inline unsigned int GetLongevity(
        AllocatorSingleton< T, C, M, O, L, X > * )
    {
        // Returns highest possible value.
        return 0xFFFFFFFF;
    }


    /** @class SmallObjectBase
        @ingroup SmallObjectGroup
     Base class for small object allocation classes.
     The shared implementation of the new and delete operators are here instead
     of being duplicated in both SmallObject or SmallValueObject, later just 
     called Small-Objects.  This class is not meant to be used directly by clients, 
     or derived from by clients. Class has no data members so compilers can 
     use Empty-Base-Optimization.

     @par ThreadingModel
     This class doesn't support ObjectLevelLockable policy for ThreadingModel.
     The allocator is a singleton, so a per-instance mutex is not necessary.
     Nor is using ObjectLevelLockable recommended with SingletonHolder since
     the SingletonHolder::MakeInstance function requires a mutex that exists
     prior to when the object is created - which is not possible if the mutex
     is inside the object, such as required for ObjectLevelLockable.  If you
     attempt to use ObjectLevelLockable, the compiler will emit errors because
     it can't use the default constructor in ObjectLevelLockable.  If you need
     a thread-safe allocator, use the ClassLevelLockable policy.

     @par Lifetime Policy
     
     The SmallObjectBase template needs a lifetime policy because it owns
     a singleton of SmallObjAllocator which does all the low level functions. 
     When using a Small-Object in combination with the SingletonHolder template
     you have to choose two lifetimes, that of the Small-Object and that of
     the singleton. The rule is: The Small-Object lifetime must be greater than
     the lifetime of the singleton hosting the Small-Object. Violating this rule
     results in a crash on exit, because the hosting singleton tries to delete
     the Small-Object which is then already destroyed. 
     
     The lifetime policies recommended for use with Small-Objects hosted 
     by a SingletonHolder template are 
         - LongevityLifetime::DieAsSmallObjectParent / LongevityLifetime::DieAsSmallObjectChild
         - SingletonWithLongevity
         - FollowIntoDeath (not supported by MSVC 7.1)
         - NoDestroy
     
     The default lifetime of Small-Objects is 
     LongevityLifetime::DieAsSmallObjectParent to
     insure that memory is not released before a object with the lifetime
     LongevityLifetime::DieAsSmallObjectChild using that
     memory is destroyed. The LongevityLifetime::DieAsSmallObjectParent
     lifetime has the highest possible value of a SetLongevity lifetime, so
     you can use it in combination with your own lifetime not having also
     the highest possible value.
     
     The DefaultLifetime and PhoenixSingleton policies are *not* recommended 
     since they can cause the allocator to be destroyed and release memory 
     for singletons hosting a object which inherit from either SmallObject
     or SmallValueObject.  
     
     @par Lifetime usage
    
        - LongevityLifetime: The Small-Object has 
          LongevityLifetime::DieAsSmallObjectParent policy and the Singleton
          hosting the Small-Object has LongevityLifetime::DieAsSmallObjectChild. 
          The child lifetime has a hard coded SetLongevity lifetime which is 
          shorter than the lifetime of the parent, thus the child dies 
          before the parent.
         
        - Both Small-Object and Singleton use SingletonWithLongevity policy.
          The longevity level for the singleton must be lower than that for the
          Small-Object. This is why the AllocatorSingleton's GetLongevity function 
          returns the highest value.
         
        - FollowIntoDeath lifetime: The Small-Object has 
          FollowIntoDeath::With<LIFETIME>::AsMasterLiftime
          policy and the Singleton has 
          FollowIntoDeath::AfterMaster<MASTERSINGLETON>::IsDestroyed policy,
          where you could choose the LIFETIME. 
        
        - Both Small-Object and Singleton use NoDestroy policy. 
          Since neither is ever destroyed, the destruction order does not matter.
          Note: you will get memory leaks!
         
        - The Small-Object has NoDestroy policy but the Singleton has
          SingletonWithLongevity policy. Note: you will get memory leaks!
         
     
     You should *not* use NoDestroy for the singleton, and then use
     SingletonWithLongevity for the Small-Object. 
     
     @par Examples:
     
     - test/SmallObj/SmallSingleton.cpp
     - test/Singleton/Dependencies.cpp
     */
    template
    <
        template <class, class> class ThreadingModel,
        std::size_t chunkSize,
        std::size_t maxSmallObjectSize,
        std::size_t objectAlignSize,
        template <class> class LifetimePolicy,
        class MutexPolicy
    >
    class SmallObjectBase
    {

#if (LOKI_MAX_SMALL_OBJECT_SIZE != 0) && (LOKI_DEFAULT_CHUNK_SIZE != 0) && (LOKI_DEFAULT_OBJECT_ALIGNMENT != 0)

    public:        
        /// Defines type of allocator singleton, must be public 
        /// to handle singleton lifetime dependencies.
        typedef AllocatorSingleton< ThreadingModel, chunkSize,
            maxSmallObjectSize, objectAlignSize, LifetimePolicy > ObjAllocatorSingleton;
    
    private:

        /// Defines type for thread-safety locking mechanism.
        typedef ThreadingModel< ObjAllocatorSingleton, MutexPolicy > MyThreadingModel;

        /// Use singleton defined in AllocatorSingleton.
        typedef typename ObjAllocatorSingleton::MyAllocatorSingleton MyAllocatorSingleton;
        
    public:

        /// Throwing single-object new throws bad_alloc when allocation fails.
#ifdef _MSC_VER
        /// @note MSVC complains about non-empty exception specification lists.
        static void * operator new ( std::size_t size )
#else
        static void * operator new ( std::size_t size ) throw ( std::bad_alloc )
#endif
        {
            typename MyThreadingModel::Lock lock;
            (void)lock; // get rid of warning
            return MyAllocatorSingleton::Instance().Allocate( size, true );
        }

        /// Non-throwing single-object new returns NULL if allocation fails.
        static void * operator new ( std::size_t size, const std::nothrow_t & ) throw ()
        {
            typename MyThreadingModel::Lock lock;
            (void)lock; // get rid of warning
            return MyAllocatorSingleton::Instance().Allocate( size, false );
        }

        /// Placement single-object new merely calls global placement new.
        inline static void * operator new ( std::size_t size, void * place )
        {
            return ::operator new( size, place );
        }

        /// Single-object delete.
        static void operator delete ( void * p, std::size_t size ) throw ()
        {
            typename MyThreadingModel::Lock lock;
            (void)lock; // get rid of warning
            MyAllocatorSingleton::Instance().Deallocate( p, size );
        }

        /** Non-throwing single-object delete is only called when nothrow
         new operator is used, and the constructor throws an exception.
         */
        static void operator delete ( void * p, const std::nothrow_t & ) throw()
        {
            typename MyThreadingModel::Lock lock;
            (void)lock; // get rid of warning
            MyAllocatorSingleton::Instance().Deallocate( p );
        }

        /// Placement single-object delete merely calls global placement delete.
        inline static void operator delete ( void * p, void * place )
        {
            ::operator delete ( p, place );
        }

#ifdef LOKI_SMALL_OBJECT_USE_NEW_ARRAY

        /// Throwing array-object new throws bad_alloc when allocation fails.
#ifdef _MSC_VER
        /// @note MSVC complains about non-empty exception specification lists.
        static void * operator new [] ( std::size_t size )
#else
        static void * operator new [] ( std::size_t size )
            throw ( std::bad_alloc )
#endif
        {
            typename MyThreadingModel::Lock lock;
            (void)lock; // get rid of warning
            return MyAllocatorSingleton::Instance().Allocate( size, true );
        }

        /// Non-throwing array-object new returns NULL if allocation fails.
        static void * operator new [] ( std::size_t size,
            const std::nothrow_t & ) throw ()
        {
            typename MyThreadingModel::Lock lock;
            (void)lock; // get rid of warning
            return MyAllocatorSingleton::Instance().Allocate( size, false );
        }

        /// Placement array-object new merely calls global placement new.
        inline static void * operator new [] ( std::size_t size, void * place )
        {
            return ::operator new( size, place );
        }

        /// Array-object delete.
        static void operator delete [] ( void * p, std::size_t size ) throw ()
        {
            typename MyThreadingModel::Lock lock;
            (void)lock; // get rid of warning
            MyAllocatorSingleton::Instance().Deallocate( p, size );
        }

        /** Non-throwing array-object delete is only called when nothrow
         new operator is used, and the constructor throws an exception.
         */
        static void operator delete [] ( void * p,
            const std::nothrow_t & ) throw()
        {
            typename MyThreadingModel::Lock lock;
            (void)lock; // get rid of warning
            MyAllocatorSingleton::Instance().Deallocate( p );
        }

        /// Placement array-object delete merely calls global placement delete.
        inline static void operator delete [] ( void * p, void * place )
        {
            ::operator delete ( p, place );
        }
#endif  // #if use new array functions.

#endif  // #if default template parameters are not zero

    protected:
        inline SmallObjectBase( void ) {}
        inline SmallObjectBase( const SmallObjectBase & ) {}
        inline SmallObjectBase & operator = ( const SmallObjectBase & )
        { return *this; }
        inline ~SmallObjectBase() {}
    }; // end class SmallObjectBase


    /** @class SmallObject
        @ingroup SmallObjectGroup
     SmallObject Base class for polymorphic small objects, offers fast
     allocations & deallocations.  Destructor is virtual and public.  Default
     constructor is trivial.   Copy-constructor and copy-assignment operator are
     not implemented since polymorphic classes almost always disable those
     operations.  Class has no data members so compilers can use
     Empty-Base-Optimization.
     */
    template
    <
        template <class, class> class ThreadingModel = LOKI_DEFAULT_THREADING_NO_OBJ_LEVEL,
        std::size_t chunkSize = LOKI_DEFAULT_CHUNK_SIZE,
        std::size_t maxSmallObjectSize = LOKI_MAX_SMALL_OBJECT_SIZE,
        std::size_t objectAlignSize = LOKI_DEFAULT_OBJECT_ALIGNMENT,
        template <class> class LifetimePolicy = LOKI_DEFAULT_SMALLOBJ_LIFETIME,
        class MutexPolicy = LOKI_DEFAULT_MUTEX
    >
    class SmallObject : public SmallObjectBase< ThreadingModel, chunkSize,
            maxSmallObjectSize, objectAlignSize, LifetimePolicy, MutexPolicy >
    {

    public:
        virtual ~SmallObject() {}
    protected:
        inline SmallObject( void ) {}

    private:
        /// Copy-constructor is not implemented.
        SmallObject( const SmallObject & );
        /// Copy-assignment operator is not implemented.
        SmallObject & operator = ( const SmallObject & );
    }; // end class SmallObject


    /** @class SmallValueObject
        @ingroup SmallObjectGroup
     SmallValueObject Base class for small objects with value-type
     semantics - offers fast allocations & deallocations.  Destructor is
     non-virtual, inline, and protected to prevent unintentional destruction
     through base class.  Default constructor is trivial.   Copy-constructor
     and copy-assignment operator are trivial since value-types almost always
     need those operations.  Class has no data members so compilers can use
     Empty-Base-Optimization.
     */
    template
    <
        template <class, class> class ThreadingModel = LOKI_DEFAULT_THREADING_NO_OBJ_LEVEL,
        std::size_t chunkSize = LOKI_DEFAULT_CHUNK_SIZE,
        std::size_t maxSmallObjectSize = LOKI_MAX_SMALL_OBJECT_SIZE,
        std::size_t objectAlignSize = LOKI_DEFAULT_OBJECT_ALIGNMENT,
        template <class> class LifetimePolicy = LOKI_DEFAULT_SMALLOBJ_LIFETIME,
        class MutexPolicy = LOKI_DEFAULT_MUTEX
    >
    class SmallValueObject : public SmallObjectBase< ThreadingModel, chunkSize,
            maxSmallObjectSize, objectAlignSize, LifetimePolicy, MutexPolicy >
    {
    protected:
        inline SmallValueObject( void ) {}
        inline SmallValueObject( const SmallValueObject & ) {}
        inline SmallValueObject & operator = ( const SmallValueObject & )
        { return *this; }
        inline ~SmallValueObject() {}
    }; // end class SmallValueObject

} // namespace Loki

#endif // end file guardian