SmallObjectAllocator.h File Reference

Declaration of SmallObjectAllocator. More...

#include "UtilPrereqs.h"
#include <vector>
#include <cstdio>

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Classes
class	orxonox::SmallObjectAllocator
	This class is used to allocate and free small objects (usually not polymorphic). More...
struct	orxonox::SmallObjectAllocator::Chunk
	The memory chunk is at the same time an element of a single linked list. More...

Namespaces
	orxonox
	Die Wagnis Klasse hat die folgenden Aufgaben:

Detailed Description

Declaration of SmallObjectAllocator.

The default implementations of new and delete are designed to work with objects of arbitrary size. They are thus not optimal for small objects. SmallObjectAllocator allocates a large memory block and divides it into small chunks. These chunks are returned by the function alloc() and can be used to create a new object using the placement new operator. Instead of delete, the function free() is used to give the memory back to SmallObjectAllocator.

Example:

SmallObjectAllocator allocator(sizeof(MySmallObject));  // Create an allocator. The size of the memory chunks must equal the size of the desired class

void* chunk = allocator.alloc();                        // Allocate a memory chunk
MySmallObject* object = new (chunk) MySmallObject();    // Call the placement new operator

object->someFunction();                                 // Do something with the object

object->~MySmallObject();                               // Call the destructor
allocator.free(object);                                 // Free the allocated memory

Important: You have to call the destructor of the object manually, because this is not automatically done by the allocator nor free().

Note

The destructor can be ignored if it is empty or not implemented. This saves another amount of time.

Remarks

For a distributed usage of SmallObjectAllocator it may be a good idea to create a static function that returns an instance to it. The allocator then works like a singleton and can be accesses from everywhere.