Module Uring.Region

Region handles carving up a block of external memory into smaller chunks. This is currently just a slab allocator of a fixed size, on the basis that most IO operations operate on predictable chunks of memory. Since the block of memory in a region is contiguous, it can be used in Uring's fixed buffer model to map it into kernel space for more efficient IO.

type t

t is a contiguous region of memory

type chunk

chunk is an offset into a region of memory allocated from some region t. It is of a length set when the region t associated with it was initialised.

exception No_space

No_space is raised when an allocation request cannot be satisfied.

val init : block_size:int -> Cstruct.buffer -> int -> t

init ~block_size buf slots initialises a region from the buffer buf with total size of block_size * slots.

val alloc : t -> chunk

alloc t will allocate a single chuck of length block_size from the region t.

val free : chunk -> unit

free chunk will return the memory chunk back to the region t where it can be reallocated.

val length : chunk -> int

length chunk is the block size.

val to_offset : chunk -> int

to_offset chunk will convert the chunk into an integer offset in its associated region. This can be used in IO calls involving that memory.

val to_cstruct : ?len:int -> chunk -> Cstruct.t

to_cstruct chunk is a cstruct of chunk's slice of the region. Note that this is a zero-copy view into the underlying region t and so chunk should not be freed until this cstruct is no longer used.

  • parameter len

    Use only the first len bytes of chunk.

val to_bigstring : ?len:int -> chunk -> Cstruct.buffer

to_bigstring is like to_cstruct, but creates a Bigarray. Note that this is a zero-copy view into the underlying region t and so chunk should not be freed until this Bigarray reference is no longer used.

  • parameter len

    Use only the first len bytes of chunk.

val to_string : ?len:int -> chunk -> string

to_string ?len chunk will return a copy of chunk as an OCaml string.

  • parameter len

    Use only the first len bytes of chunk.

val avail : t -> int

avail t is the number of free chunks of memory remaining in the region.