BlockBufferAllocator< PARENT_ALLOCATOR > Class Template Reference

#include <blockbufferallocator.h>

Detailed Description

template<typename PARENT_ALLOCATOR>
class maxon::BlockBufferAllocator< PARENT_ALLOCATOR >

Block buffer allocator. A fixed allocator which contains the size of the initialized memoryblock/size. The first memory request (and any Resize calls) that are smaller than this size will return this static memory. All other requests will be routed to the PARENT_ALLOCATOR. The BlockBufferAllocator is not thread-safe!

Here an example for the use of a BlockBufferAllocator:

StringEncodingRef utf8encoder = StringEncodings::Get(Id("utf8"));
BaseArray<Char, 16, BASEARRAYFLAGS::NONE, BlockBufferAllocator<NullAllocator>> dstArray(BlockBufferAllocator<NullAllocator>(block.GetFirst(), block.GetCount()));
dstArray.EnsureCapacity(block.GetCount(), true);
iferr (utf8encoder.EncodeString(_txt, dstArray))
{
}

In the example a BaseArray will use the guaranteed 1024 bytes from the stack / fixed allocator first. Only when the BaseArray grows bigger than 1024 characters more memory from the DefaultAllocator will be fetched. This is a convenient way to allow routines be flexible without (length) limits, but avoiding constant unnecessary memory allocations.

Template Parameters

PARENT_ALLOCATOR

The allocator that shall be used when a request cannot be satisfied using the static memory.

Public Member Functions
	BlockBufferAllocator (void *memoryBuffer, Int memBlockSize)
	BlockBufferAllocator (const BlockBufferAllocator &parent)
Int	ComputeArraySize (Int currentSize, Int increment, Int minChunkSize)
void *	Alloc (Int32 s, MAXON_SOURCE_LOCATION_DECLARATION)
void *	Alloc (Int64 s, MAXON_SOURCE_LOCATION_DECLARATION)
void *	Realloc (void *p, Int32 n, MAXON_SOURCE_LOCATION_DECLARATION)
void *	Realloc (void *p, Int64 n, MAXON_SOURCE_LOCATION_DECLARATION)
template<typename T >
void	Free (T *&p)
Bool	IsCompatibleWithDefaultAllocator (void *p) const

Private Member Functions
	BlockBufferAllocator ()

Private Attributes
void *	_memoryBuffer
Int	_memBlockSize
Bool	_memoryUsed
PARENT_ALLOCATOR	_allocator

Constructor & Destructor Documentation

BlockBufferAllocator() [1/3]

BlockBufferAllocator ( )

private

Default constructor, disabled because the pointer and size is needed.

BlockBufferAllocator() [2/3]

BlockBufferAllocator	(	void *	memoryBuffer,
		Int	memBlockSize
	)

Constructor, with the given memory block.

Parameters

[in]	memoryBuffer	Pointer to memory that is mapped to the allocator.
[in]	memBlockSize	Size of the memory block.

BlockBufferAllocator() [3/3]

BlockBufferAllocator ( const BlockBufferAllocator< PARENT_ALLOCATOR > &  parent )

explicit

Copy constructor.

Member Function Documentation

ComputeArraySize()

Int ComputeArraySize	(	Int	currentSize,
		Int	increment,
		Int	minChunkSize
	)

Computes the new size for a growing array THREADSAFE.

Parameters

[in]	currentSize	Current number of elements.
[in]	increment	Number of elements to be added (>= 1)
[in]	minChunkSize	The minimum number of elements upon array creation.

Returns

New number of elements.

Alloc() [1/2]

void* Alloc	(	Int32	s,
		MAXON_SOURCE_LOCATION_DECLARATION
	)

Allocates a memory block. The memory is not cleared, it may contain a certain byte pattern in debug mode.

Parameters

[in]	s	Block size in bytes (values < 0 will return nullptr)
[in]	allocLocation	Pass MAXON_SOURCE_LOCATION(_NAME) to add the current source line and file.

Returns

Memory block address or nullptr.

Alloc() [2/2]

void* Alloc	(	Int64	s,
		MAXON_SOURCE_LOCATION_DECLARATION
	)

Allocates a memory block. The memory is not cleared, it may contain a certain byte pattern in debug mode.

Parameters

[in]	s	Block size in bytes (values < 0 will return nullptr)
[in]	allocLocation	Pass MAXON_SOURCE_LOCATION(_NAME) to add the current source line and file.

Returns

Memory block address or nullptr.

Realloc() [1/2]

void* Realloc	(	void *	p,
		Int32	n,
		MAXON_SOURCE_LOCATION_DECLARATION
	)

Resizes a memory block. The content of the memory block is preserved up to the lesser of the new and old sizes, even if the block is moved to a new location. The additional memory is not cleared, it may contain a certain byte pattern in debug mode. In case that p is a nullptr the function behaves like Alloc. If the function fails to allocate the requested block of memory a nullptr is returned and the memory block pointed to by argument p is not deallocated (it is still valid with its contents unchanged). THREADSAFE.

Parameters

[in]	p	Current memory block (can be nullptr)
[in]	n	New block size in bytes (values < 0 will return nullptr)
[in]	allocLocation	Pass MAXON_SOURCE_LOCATION(_NAME) to add the current source line and file.

Returns

Memory block address or nullptr if resize is not possible (p is still valid in this case)

Realloc() [2/2]

void* Realloc	(	void *	p,
		Int64	n,
		MAXON_SOURCE_LOCATION_DECLARATION
	)

Resizes a memory block. The content of the memory block is preserved up to the lesser of the new and old sizes, even if the block is moved to a new location. The additional memory is not cleared, it may contain a certain byte pattern in debug mode. In case that p is a nullptr the function behaves like Alloc. If the function fails to allocate the requested block of memory a nullptr is returned and the memory block pointed to by argument p is not deallocated (it is still valid with its contents unchanged). THREADSAFE.

Parameters

[in]	p	Current memory block (can be nullptr)
[in]	n	New block size in bytes (values < 0 will return nullptr)
[in]	allocLocation	Pass MAXON_SOURCE_LOCATION(_NAME) to add the current source line and file.

Returns

Memory block address or nullptr if resize is not possible (p is still valid in this case)

Free()

void Free

(

T *&

p

)

Frees a memory block.

Parameters

[in,out]

p

Memory block address (can be nullptr, will be nullptr after return)

IsCompatibleWithDefaultAllocator()

Bool IsCompatibleWithDefaultAllocator

(

void *

p

)

const

Returns if a memory block allocated via this allocator can be reallocated or freed by the DefaultAllocator.

Parameters

[in]

p

Memory block address.

Returns

True if the memory block can be reallocated or freed by the DefaultAllocator.

Member Data Documentation

_memoryBuffer

void* _memoryBuffer

private

_memBlockSize

Int _memBlockSize

private

_memoryUsed

Bool _memoryUsed

private

_allocator

PARENT_ALLOCATOR _allocator

private