What is a polymorphic allocator?

A polymorphic allocator is a single allocator type with a member that can define the allocator behaviour via dynamic dispatch rather than through the template mechanism. This allows you to have containers which use specific, customised allocation, but which are still of a common type.

What is an allocator in programming?

In C++ computer programming, allocators are a component of the C++ Standard Library. The standard library provides several data structures, such as list and set, commonly referred to as containers. Allocators handle all the requests for allocation and deallocation of memory for a given container.

What is a pool allocator?

A Pool allocator (or simply, a Memory pool) is a variation of the fast Bump-allocator, which in general allows O(1) allocation, when a free block is found right away, without searching a free-list. To achieve this fast allocation, usually a pool allocator uses blocks of a predefined size.

What is use of allocator in C++?

Allocators are used by the C++ Standard Library to handle the allocation and deallocation of elements stored in containers. All C++ Standard Library containers except std::array have a template parameter of type allocator , where Type represents the type of the container element.

What makes a good allocator?

Effective allocators are disciplined people. They methodise their work to enable more rational decision making, by adopting a framework that is consulted each time an allocation decision comes to hand.

What is a bump allocator?

The idea behind a bump allocator seems to be that you just “bump” the end of memory forward to handle each request, but you cannot free things up one item at a time – you free everything at once.

What is fixed size allocator?

Memory pools, also called fixed-size blocks allocation, is the use of pools for memory management that allows dynamic memory allocation comparable to malloc or C++’s operator new. A more efficient solution is preallocating a number of memory blocks with the same size called the memory pool.

What is an allocator allowed to do?

The basic functionality the allocator is expected to have is the following: T* allocate(size_t n); allocates enough storage to store n instances of T and returns a pointer to it. void deallocate(T* p, size_t n); releases the storage.

What are allocators good for?

This is useful e.g. for allocating objects of the same size in a pool, to improve performance, or might be necessary if there’s a special area of memory where your objects need to live.

What is efficient capital allocation?

Under allocational efficiency, all goods, services, and capital is allotted and distributed to its very best use. By definition, efficiency means that capital is put to its optimal use and that there is no other distribution of capital that exists which would produce better outcomes.

What is memory arena?

Memory Arena (also known as break space)–the area where dynamic runtime memory is stored. The memory arena consists of the heap and unused memory. The heap is where all user-allocated memory is located.

What is a memory pool C++?

A “Memory Pool” allocates a big amount of memory on startup, and will separate this block into smaller chunks. Every time you request memory from the pool, it is taken from the previously allocated chunks, and not from the OS. The biggest advantages are: Very little (to none) heap-fragmentation.