Arena allocator

My personal approach to arena allocation. Read more about the design and motivation of this allocator here: https://ziap.github.io/blog/arena

How to use

The code is implemented in C as an STB-style single-header library. The header is portable and can be used on its own. But platform-specific source files are also available to "configure" the library to use the system page allocator. This separation breaks the rule of header-only libraries, but it allows for easier addition of target platforms.

Using the library as a single-header header library is the same as any other library of the same type: select exactly one C source file that instantiates the code by defining ARENA_IMPLEMENTATION.

#define ARENA_IMPLEMENTATION
#include "arena.h"

The platform-specific source files act as the instantiation source files. So if you use one of those, don't define ARENA_IMPLEMENTATION anywhere else.

Adding a new platform

To add a new platform, redefine these two macros to call your platform's allocator.

#define ARENA_BACKEND_ALLOC(size) ...
#define ARENA_BACKEND_DEALLOC(ptr, size) ...

#define ARENA_IMPLEMENTATION
#include "arena.h"

You can also define ARENA_BACKEND_RESIZE if your platform supports efficient reallocation, but it is not required, as the library can automatically implement that with ARENA_BACKEND_ALLOC and ARENA_BACKEND_DEALLOC.

Configuration

Some macros that you can redefine to configure the library:

Macro	Usage
ARENA_MEMCPY	Redefine if your platform can't use libc's memcpy
ARENA_ALIGNMENT	Customize the memory alignment. Default is sizeof(void*)
ARENA_MAX_SIZE	The maximum size of each chunk, should be page-aligned

License

This project is licensed under the MIT License.