package mirage-flow-combinators

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String flows
Cstruct buffers flows

mirage-flow-combinators
- Mirage_flow_combinators
  - CONCRETE
  - Concrete
    
    S
  - Copy
    
    A
    
    B
    
    Clock
  - F
  - Proxy
    
    A
    
    B
    
    Clock

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In-memory, function-based flows.

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 = 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.

val read : flow -> (Cstruct.t Mirage_flow.or_eof, error) result Lwt.t

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.

When read returns `Eof or an error, close (or shutdown) should be called on the flow by the client. Once read returned `Eof or an error, no subsequent read call will be successful.

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 sent 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.

The promise is resolved when the buffer has been accepted by the implementation (if a partial write occured, write will wait until the remainder of the buffer has been accepted by the implementation).

If write returns an error, close (or shutdown) should be called on the flow by the client. Once write returned an error, no subsequent write or writev call will be successful.

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 sent 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.

The promise is resolved when the buffers have been accepted by the implementation (if a partial write occured, writev will wait until all buffers have been accepted by the implementation).

If writev returns an error, close (or shutdown) should be called on the flow by the client. Once writev returned an error, no subsequent writev or write call will be successful.

val shutdown : flow -> [ `read | `write | `read_write ] -> unit Lwt.t

shutdown flow mode shuts down the flow for the specific mode: A flow which is shutdown `read (or `read_write) will never be read again (subsequent calls will return `Eof); a flow which is shutdown `write (or `read_write) flushes all pending writes and signals the remote endpoint there won't be any future write or writev calls (subsequent calls will return `Closed). E.g. in TCP, the signalling is done by sending a segment with the FIN flag.

If this flow is layered upon another flow' (e.g. TLS over TCP), and the internal state after shutdown is `Closed, close on the underlying flow' is executed.

val close : flow -> unit Lwt.t

close flow terminates the flow and frees all associated data. Any subsequent read or write will return an error. A subsequent close will not do anything (esp. not raising an exception), but it may log an error.

If this flow is layered upon another flow' (e.g. TLS over TCP), close on the underlying flow' is executed.

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.