Async_sendfile (p.async_sendfile.v0.12.0.doc.async_sendfile.Async

module Limiter : sig ... end

val sendfile : 
  ?limiter:Limiter.t ->
  ?delivery_unit:Core.Byte_units.t ->
  socket_fd:Async_unix.Fd.t ->
  file:string ->
  unit ->
  unit Async_kernel.Deferred.Or_error.t

Use sendfile(2) to deliver all bytes from file to socket_fd. Return success iff the whole file was successfully delivered.