66 lines
1.7 KiB
Markdown
66 lines
1.7 KiB
Markdown
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# Arena Allocator
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Arena allocators are region based allocators that tie many allocations to a
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single region of memory. Benefits are massivly simplified allocation and
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deallocation for complex structures, increased performance due to improved
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cache locality, and reduced memory fragmentation as long as individual items
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don't need to be deallocated. For programs that need to micro-manage individual
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allocations this is not an ideal solution.
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Deallocating a region of memory with arenas is extremely fast, because the
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arena length is just set to 0. Allocating memory is also extremely fast. This
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implementation also grows the arena on demand using mmap and mprotect.
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Extending the library with a new type of allocation strategy should be easy.
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# Reference
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## `arena_t arena_new()`
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Allocate a new arena.
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If `arena_new()` fails, the struct member `data` is set to NULL. This can be
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checked with `arena_new_failed()`
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## `bool arena_new_failed(arena_t *a)`
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Returns true if creating a new arena failed
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## `int arena_delete(arena_t *a)`
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Delete underlying buffer of arena. Should only be used with arenas from
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`arena_new()`.
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Returns 0 on success, -1 on failure
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## `arena_t arena_attach(void *ptr, size_t size)`
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Attach an arena to an existing memory region. The arena will not expand if
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capacity is exceeded.
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## `void *arena_detatch(arena_t arena)`
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Detach an arena from an existing memory region. Returns the underlying data.
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## `void arena_reset(arena_t *a)`
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Resets an arena.
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## `void *arena_alloc(arena_t *a, size_t len)`
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Allocate memory with an arena. Returns NULL and sets errno on failure.
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## `void *arena_calloc(arena_t *a, size_t nmemb, size_t size)`
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Allocate and zero memory with an arena. Returns NULL and sets errno on
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failure.
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