package netchannel

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Pool and reuse shared memory blocks. This saves having to reallocate and reshare pages of memory, which is slow. A block is half the size of a page, since network packets usually don't require more than this.

type t
val make : (Xen_os.Xen.Gntref.t -> Io_page.t -> unit) -> t

make grant_access is a shared pool of blocks. When a new page is first allocated, grant_access is called to share it.

val use : t -> (id:Cstruct.uint16 -> Xen_os.Xen.Gntref.t -> Cstruct.t -> ('a * unit Lwt.t) Lwt.t) -> ('a * unit Lwt.t) Lwt.t

use t fn calls fn ~id gref block with a free shared block of memory and that block's unique ID (note: the gref is NOT unique). The function should return a thread that indicates when the request has been added to the queue, by returning a result value and a second thread indicating when the block can be returned to the pool.

val blocks_needed : int -> int

Rounds a size in bytes up to the number of blocks needed for it.

val shutdown : t -> unit

Unshare and free all the pages of the pool once all outstanding requests have completed. Calling use after shutdown will return an error.