mirage-flow-combinators

Flow implementations and combinators for MirageOS specialized to lwt
Library mirage-flow-combinators
include Mirage_flow.S
type error

The type for flow errors.

val pp_error : error Fmt.t

pp_error is the pretty-printer for errors.

type nonrec write_error#row

The type for write errors.

and write_error = private [>
| Mirage_flow.write_error
]

The type for write errors.

val pp_write_error : write_error Fmt.t

pp_write_error is the pretty-printer for write errors.

type flow

The type for flows. A flow represents the state of a single reliable stream that is connected to an endpoint.

read flow blocks until some data is available and returns a fresh buffer containing it.

The returned buffer will be of a size convenient to the flow implementation, but will always have at least 1 byte.

If the remote endpoint calls close then calls to read will keep returning data until all the in-flight data has been read. read flow will return `Eof when the remote endpoint has called close and when there is no more in-flight data.

val write : flow -> Cstruct.t -> ( unit, write_error ) result Lwt.t

write flow buffer writes a buffer to the flow. There is no indication when the buffer has actually been read and, therefore, it must not be reused. The contents may be transmitted in separate packets, depending on the underlying transport. The result Ok () indicates success, Error `Closed indicates that the connection is now closed and therefore the data could not be written. Other errors are possible.

val writev : flow -> Cstruct.t list -> ( unit, write_error ) result Lwt.t

writev flow buffers writes a sequence of buffers to the flow. There is no indication when the buffers have actually been read and, therefore, they must not be reused. The result Ok () indicates success, Error `Closed indicates that the connection is now closed and therefore the data could not be written. Other errors are possible.

val close : flow -> unit Lwt.t

close flow flushes all pending writes and signals the remote endpoint that there will be no future writes. Once the remote endpoint has read all pending data, it is expected that calls to read on the remote return `Eof.

Note it is still possible for the remote endpoint to write to the flow and for the local endpoint to call read. This state where the local endpoint has called close but the remote endpoint has not called close is similar to that of a half-closed TCP connection or a Unix socket after shutdown(SHUTDOWN_WRITE).

close flow waits until the remote endpoint has also called close before returning. At this point no data can flow in either direction and resources associated with the flow can be freed.

type refill = Cstruct.t -> int -> int -> int Lwt.t

The type for refill functions.

val make : ?close:( unit -> unit Lwt.t ) -> ?input:refill -> ?output:refill -> unit -> flow

make ~close ~input ~output () is a flow using input to refill its internal input buffer when needed and output to refill its external output buffer. It is using close to eventually clean-up other resources on close.

String flows

val input_string : string -> refill

input_string buf is the refill function reading its inputs from the string buf.

val output_bytes : bytes -> refill

output_bytes buf is the refill function writing its outputs in the buffer buf.

val string : ?input:string -> ?output:bytes -> unit -> flow

The flow built using input_string and output_bytes.

val input_strings : string list -> refill

input_strings bufs is the refill function reading its inputs from the list of buffers bufs. Empty strings are ignored.

val output_bytess : bytes list -> refill

output_bytess buf is the refill function writing its outputs in the list of buffers buf. Empty strings are ignored.

val strings : ?input:string list -> ?output:bytes list -> unit -> flow

The flow built using input_strings and output_bytess.

Cstruct buffers flows

val input_cstruct : Cstruct.t -> refill

Same as input_string but for Cstruct.t buffers.

val output_cstruct : Cstruct.t -> refill

Same as output_string buf for Cstruct.t buffers.

val cstruct : ?input:Cstruct.t -> ?output:Cstruct.t -> unit -> flow

Same as string but for Cstruct.t buffers.

val input_cstructs : Cstruct.t list -> refill

Same as input_strings but for Cstruct.t buffers.

val output_cstructs : Cstruct.t list -> refill

Same as output_strings but for Cstruct.t buffers.

val cstructs : ?input:Cstruct.t list -> ?output:Cstruct.t list -> unit -> flow

Same as strings but for Cstruct.t buffers.