arena_allocator - A custom allocator written in C

A working implementation of arena allocator in C

WARNING: For the latest updates, check out this repo.

This is an example project trying to implement arena allocator to improve memory allocation in C.

Features

Growing arenas An arena is a linked list of buffer, where new memory gets allocated. If a single buffer is fulled, a new buffer will created and linked with the previous one. This way an arena can grow in size if needed.
Reset mechanism Without freeing the whole memory, we can reset the counters of the buffers in an arena. This arena allocator uses a monotonic allocator to allocate memory in buffers.

How to use this library

Just copy and past the file arena_allocator.h in your project. Then add these lines to your source files:

#define ARENA_ALLOCATOR_IMPLEMENTATION
#include "arena_allocator.h"

Usage example

#define ARENA_ALLOCATOR_IMPLEMENTATION
#include "arena_allocator.h"

struct Phonebook {
    const char *name;
    int phoneNumber;
};

int main() {
    Arena default_arena = {nullptr, nullptr};
    
    char *msg = (char *)arena_alloc(&default_arena, strlen("Hello World"));
    strcpy(msg, "Hello World");
    printf("%s\n", msg);

    int *arr = arena_alloc_arr(&default_arena, int, 100);
    for (int i = 0; i < 100; ++i) {
        arr[i] = i + 1;
    }

    struct Phonebook *phoneBook = arena_alloc_struct(&default_arena, Phonebook);
    phonebook->name = "John Doe";
    phonebook->number = 1234567890;

    msg = (char *)arena_realloc(&default_arena, msg, strlen("Hello World!!!!!!"), 
                                strlen("Hello World"));
    strcpy(msg, "Hello World!!!!!!");
    printf("%s\n", msg);

    arena_free(&default_arena);
}

Known issues

I don't know of any, file a issue to inform me about such.

Feel free to open a new GitHub issue or pull request to suggest any changes!!