//////////////////////////////////////////////////////////////////////////////// // The Loki Library // Copyright (c) 2001 by Andrei Alexandrescu // This code accompanies the book: // Alexandrescu, Andrei. "Modern C++ Design: Generic Programming and Design // Patterns Applied". Copyright (c) 2001. Addison-Wesley. // Permission to use, copy, modify, distribute and sell this software for any // purpose is hereby granted without fee, provided that the above copyright // notice appear in all copies and that both that copyright notice and this // permission notice appear in supporting documentation. // The author or Addison-Wesley Longman make no representations about the // suitability of this software for any purpose. It is provided "as is" // without express or implied warranty. //////////////////////////////////////////////////////////////////////////////// #ifndef LOKI_SMALLOBJ_INC_ #define LOKI_SMALLOBJ_INC_ // $Id$ #include "LokiExport.h" #include "Threads.h" #include "Singleton.h" #include #include // needed for std::nothrow_t parameter. #ifndef LOKI_DEFAULT_CHUNK_SIZE #define LOKI_DEFAULT_CHUNK_SIZE 4096 #endif #ifndef LOKI_MAX_SMALL_OBJECT_SIZE #define LOKI_MAX_SMALL_OBJECT_SIZE 256 #endif #ifndef LOKI_DEFAULT_OBJECT_ALIGNMENT #define LOKI_DEFAULT_OBJECT_ALIGNMENT 4 #endif #ifndef LOKI_DEFAULT_SMALLOBJ_LIFETIME #define LOKI_DEFAULT_SMALLOBJ_LIFETIME ::Loki::LongevityLifetime::DieAsSmallObjectParent #endif #if defined(LOKI_SMALL_OBJECT_USE_NEW_ARRAY) && defined(_MSC_VER) #pragma message("Don't define LOKI_SMALL_OBJECT_USE_NEW_ARRAY when using a Microsoft compiler to prevent memory leaks.") #pragma message("now calling '#undef LOKI_SMALL_OBJECT_USE_NEW_ARRAY'") #undef LOKI_SMALL_OBJECT_USE_NEW_ARRAY #endif /// \defgroup SmallObjectGroup Small objects /// /// \defgroup SmallObjectGroupInternal Internals /// \ingroup SmallObjectGroup namespace Loki { namespace LongevityLifetime { /** @struct DieAsSmallObjectParent @ingroup SmallObjectGroup Lifetime policy to manage lifetime dependencies of SmallObject base and child classes. The Base class should have this lifetime */ template struct DieAsSmallObjectParent : DieLast {}; /** @struct DieAsSmallObjectChild @ingroup SmallObjectGroup Lifetime policy to manage lifetime dependencies of SmallObject base and child classes. The Child class should have this lifetime */ template struct DieAsSmallObjectChild : DieDirectlyBeforeLast {}; } class FixedAllocator; /** @class SmallObjAllocator @ingroup SmallObjectGroupInternal Manages pool of fixed-size allocators. Designed to be a non-templated base class of AllocatorSingleton so that implementation details can be safely hidden in the source code file. */ class LOKI_EXPORT SmallObjAllocator { protected: /** The only available constructor needs certain parameters in order to initialize all the FixedAllocator's. This throws only if @param pageSize # of bytes in a page of memory. @param maxObjectSize Max # of bytes which this may allocate. @param objectAlignSize # of bytes between alignment boundaries. */ SmallObjAllocator( std::size_t pageSize, std::size_t maxObjectSize, std::size_t objectAlignSize ); /** Destructor releases all blocks, all Chunks, and FixedAllocator's. Any outstanding blocks are unavailable, and should not be used after this destructor is called. The destructor is deliberately non-virtual because it is protected, not public. */ ~SmallObjAllocator( void ); public: /** Allocates a block of memory of requested size. Complexity is often constant-time, but might be O(C) where C is the number of Chunks in a FixedAllocator. @par Exception Safety Level Provides either strong-exception safety, or no-throw exception-safety level depending upon doThrow parameter. The reason it provides two levels of exception safety is because it is used by both the nothrow and throwing new operators. The underlying implementation will never throw of its own accord, but this can decide to throw if it does not allocate. The only exception it should emit is std::bad_alloc. @par Allocation Failure If it does not allocate, it will call TrimExcessMemory and attempt to allocate again, before it decides to throw or return NULL. Many allocators loop through several new_handler functions, and terminate if they can not allocate, but not this one. It only makes one attempt using its own implementation of the new_handler, and then returns NULL or throws so that the program can decide what to do at a higher level. (Side note: Even though the C++ Standard allows allocators and new_handlers to terminate if they fail, the Loki allocator does not do that since that policy is not polite to a host program.) @param size # of bytes needed for allocation. @param doThrow True if this should throw if unable to allocate, false if it should provide no-throw exception safety level. @return NULL if nothing allocated and doThrow is false. Else the pointer to an available block of memory. */ void * Allocate( std::size_t size, bool doThrow ); /** Deallocates a block of memory at a given place and of a specific size. Complexity is almost always constant-time, and is O(C) only if it has to search for which Chunk deallocates. This never throws. */ void Deallocate( void * p, std::size_t size ); /** Deallocates a block of memory at a given place but of unknown size size. Complexity is O(F + C) where F is the count of FixedAllocator's in the pool, and C is the number of Chunks in all FixedAllocator's. This does not throw exceptions. This overloaded version of Deallocate is called by the nothow delete operator - which is called when the nothrow new operator is used, but a constructor throws an exception. */ void Deallocate( void * p ); /// Returns max # of bytes which this can allocate. inline std::size_t GetMaxObjectSize() const { return maxSmallObjectSize_; } /// Returns # of bytes between allocation boundaries. inline std::size_t GetAlignment() const { return objectAlignSize_; } /** Releases empty Chunks from memory. Complexity is O(F + C) where F is the count of FixedAllocator's in the pool, and C is the number of Chunks in all FixedAllocator's. This will never throw. This is called by AllocatorSingleto::ClearExtraMemory, the new_handler function for Loki's allocator, and is called internally when an allocation fails. @return True if any memory released, or false if none released. */ bool TrimExcessMemory( void ); /** Returns true if anything in implementation is corrupt. Complexity is O(F + C + B) where F is the count of FixedAllocator's in the pool, C is the number of Chunks in all FixedAllocator's, and B is the number of blocks in all Chunks. If it determines any data is corrupted, this will return true in release version, but assert in debug version at the line where it detects the corrupted data. If it does not detect any corrupted data, it returns false. */ bool IsCorrupt( void ) const; private: /// Default-constructor is not implemented. SmallObjAllocator( void ); /// Copy-constructor is not implemented. SmallObjAllocator( const SmallObjAllocator & ); /// Copy-assignment operator is not implemented. SmallObjAllocator & operator = ( const SmallObjAllocator & ); /// Pointer to array of fixed-size allocators. Loki::FixedAllocator * pool_; /// Largest object size supported by allocators. const std::size_t maxSmallObjectSize_; /// Size of alignment boundaries. const std::size_t objectAlignSize_; }; /** @class AllocatorSingleton @ingroup SmallObjectGroupInternal This template class is derived from SmallObjAllocator in order to pass template arguments into it, and still have a default constructor for the singleton. Each instance is a unique combination of all the template parameters, and hence is singleton only with respect to those parameters. The template parameters have default values and the class has typedefs identical to both SmallObject and SmallValueObject so that this class can be used directly instead of going through SmallObject or SmallValueObject. That design feature allows clients to use the new_handler without having the name of the new_handler function show up in classes derived from SmallObject or SmallValueObject. Thus, the only functions in the allocator which show up in SmallObject or SmallValueObject inheritance hierarchies are the new and delete operators. */ template < template 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 LifetimePolicy = LOKI_DEFAULT_SMALLOBJ_LIFETIME, class MutexPolicy = LOKI_DEFAULT_MUTEX > class AllocatorSingleton : public SmallObjAllocator { public: /// Defines type of allocator. typedef AllocatorSingleton< ThreadingModel, chunkSize, maxSmallObjectSize, objectAlignSize, LifetimePolicy > MyAllocator; /// Defines type for thread-safety locking mechanism. typedef ThreadingModel< MyAllocator, MutexPolicy > MyThreadingModel; /// Defines singleton made from allocator. typedef Loki::SingletonHolder< MyAllocator, Loki::CreateStatic, LifetimePolicy, ThreadingModel > MyAllocatorSingleton; /// Returns reference to the singleton. inline static AllocatorSingleton & Instance( void ) { return MyAllocatorSingleton::Instance(); } /// The default constructor is not meant to be called directly. inline AllocatorSingleton() : SmallObjAllocator( chunkSize, maxSmallObjectSize, objectAlignSize ) {} /// The destructor is not meant to be called directly. inline ~AllocatorSingleton( void ) {} /** Clears any excess memory used by the allocator. Complexity is O(F + C) where F is the count of FixedAllocator's in the pool, and C is the number of Chunks in all FixedAllocator's. This never throws. @note This function can be used as a new_handler when Loki and other memory allocators can no longer allocate. Although the C++ Standard allows new_handler functions to terminate the program when they can not release any memory, this will not do so. */ static void ClearExtraMemory( void ); /** Returns true if anything in implementation is corrupt. Complexity is O(F + C + B) where F is the count of FixedAllocator's in the pool, C is the number of Chunks in all FixedAllocator's, and B is the number of blocks in all Chunks. If it determines any data is corrupted, this will return true in release version, but assert in debug version at the line where it detects the corrupted data. If it does not detect any corrupted data, it returns false. */ static bool IsCorrupted( void ); private: /// Copy-constructor is not implemented. AllocatorSingleton( const AllocatorSingleton & ); /// Copy-assignment operator is not implemented. AllocatorSingleton & operator = ( const AllocatorSingleton & ); }; template < template class T, std::size_t C, std::size_t M, std::size_t O, template class L, class X > void AllocatorSingleton< T, C, M, O, L, X >::ClearExtraMemory( void ) { typename MyThreadingModel::Lock lock; (void)lock; // get rid of warning Instance().TrimExcessMemory(); } template < template class T, std::size_t C, std::size_t M, std::size_t O, template class L, class X > bool AllocatorSingleton< T, C, M, O, L, X >::IsCorrupted( void ) { typename MyThreadingModel::Lock lock; (void)lock; // get rid of warning return Instance().IsCorrupt(); } /** This standalone function provides the longevity level for Small-Object Allocators which use the Loki::SingletonWithLongevity policy. The SingletonWithLongevity class can find this function through argument- dependent lookup. @par Longevity Levels No Small-Object Allocator depends on any other Small-Object allocator, so this does not need to calculate dependency levels among allocators, and it returns just a constant. All allocators must live longer than the objects which use the allocators, it must return a longevity level higher than any such object. */ template < template class T, std::size_t C, std::size_t M, std::size_t O, template 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::AsMasterLiftime policy and the Singleton has FollowIntoDeath::AfterMaster::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 ThreadingModel, std::size_t chunkSize, std::size_t maxSmallObjectSize, std::size_t objectAlignSize, template 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 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 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 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 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