Module `Lwt_unix.IO_vectors`

Sequences of buffer slices for writev.

type t: Mutable sequences of I/O vectors. An I/O vector describes a slice of a bytes or Bigarray buffer. Each I/O vector is a triple containing a reference to the buffer, an offset into the buffer where the slice begins, and the length of the slice.

type _bigarray = (char, Stdlib.Bigarray.int8_unsigned_elt, Stdlib.Bigarray.c_layout) Stdlib.Bigarray.Array1.t: Type abbreviation equivalent to Lwt_bytes.t. Do not use this type name directly; use Lwt_bytes.t instead.

val create : unit -> t: Creates an empty I/O vector sequence.

val append_bytes : t -> bytes -> int -> int -> unit: append_bytes vs buffer offset length appends a slice of the bytes buffer buffer beginning at offset and with length length to the I/O vector sequence vs.

val append_bigarray : t -> _bigarray -> int -> int -> unit: append_bigarray vs buffer offset length appends a slice of the Bigarray buffer buffer beginning at offset and with length length to the I/O vector sequence vs.

val drop : t -> int -> unit: drop vs n adjusts the I/O vector sequence vs so that it no longer includes its first n bytes.

val is_empty : t -> bool: is_empty vs is true if and only if vs has no I/O vectors, or all I/O vectors in vs have zero bytes.

val byte_count : t -> int

byte_count vs is the total number of bytes in vs.

since: 4.2.0

val system_limit : int option

Some systems limit the number of I/O vectors that can be passed in a single call to their writev or readv system calls. On those systems, if the limit is n, this value is equal to Some n. On systems without such a limit, the value is equal to None.

Unless you need atomic I/O operations, you can ignore this limit. The Lwt binding automatically respects it internally. See Lwt_unix.writev.

A typical limit is 1024 vectors.