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Class type Uq_engines.multiplex_controller


class type multiplex_controller = object .. end
A multiplex_controller is a quite low-level device to abstract bidirectional socket connections. It is independent of any real device.

There can be a reader, a writer (or both), or alternatively, the shutdown process may be in progress. One cannot have more than one reader and more than more writer.


method alive : bool
If the controller is alive, the socket is not yet completely down.
method mem_supported : bool
Whether start_mem_reading and start_mem_writing are possible
method event_system : Unixqueue.event_system
Returns the event system
method reading : bool
True iff there is a reader
method start_reading : ?peek:(unit -> unit) ->
when_done:(exn option -> int -> unit) -> string -> int -> int -> unit
Start reading from the connection. When data is available, the when_done callback is invoked. The int is the number of read bytes. It is 0 if an error occurred which is indicated by the exception. The exception End_of_file is used when the end of the data stream is reached. The exception Cancelled indicates that reading has been cancelled in the meantime.

This starts one-time read job only, i.e. it is not restarted after when_done has been invoked.

It is an error to start reading several times.

The function peek is called immediately before data is read in from the underlying communication channel.

For getting an engine-based version of start_reading, use a signal_engine:

 
    let (e, signal) = signal_engine esys in
    mplex # start_reading ~when_done:(fun xo n -> signal (xo,n)) ...
 
Now e will transition to `Done(x0,n) when the read is done.
method start_mem_reading : ?peek:(unit -> unit) ->
when_done:(exn option -> int -> unit) ->
Netsys_mem.memory -> int -> int -> unit
Same as start_reading, but puts the data into a memory buffer. There is an optimization for the case that the descriptor is a connected socket, or supports Unix.read. If this is not possible the method raises Mem_not_supported.
method cancel_reading : unit -> unit
Cancels the read job. The when_done callback is invoked with the number of bytes read so far (which may be 0) and the exception Cancelled.

It is no error if there is no reader.

method writing : bool
True iff there is a writer
method start_writing : when_done:(exn option -> int -> unit) -> string -> int -> int -> unit
Start writing to the connection. When data is written, the when_done callback is invoked. The int is the number of written bytes. It is 0 if an error occurred which is indicated by the exception. The exception Cancelled indicates that writing has been cancelled in the meantime.

This starts one-time write job only, i.e. it is not restarted after when_done has been invoked.

It is an error to start writing several times.

See the comment for start_reading for how to get an engine-based version of this method.

method start_mem_writing : when_done:(exn option -> int -> unit) ->
Netsys_mem.memory -> int -> int -> unit
Same as start_writing, but takes the data from a memory buffer. There is an optimization for the case that the descriptor is a connected socket, or supports Unix.write. If this is not possible the method raises Mem_not_supported.
method supports_half_open_connection : bool
Whether the underlying transport mechanism can close the write side of the connection only (half-open connection).
method start_writing_eof : when_done:(exn option -> unit) -> unit -> unit
Start writing the EOF marker to the connection. When it is written, the when_done callback is invoked. The exception Cancelled indicates that writing has been cancelled in the meantime.

This starts one-time write job only, i.e. it is not restarted after when_done has been invoked.

It is an error to start writing several times. It is an error to write EOF when the socket does not support half-open connections.

See the comment for start_reading for how to get an engine-based version of this method.

method cancel_writing : unit -> unit
Cancels the write job. The when_done callback is invoked with the number of bytes read so far (which may be 0) and the exception Canelled.

It is no error if there is no writer.

method read_eof : bool
Whether the EOF marker has been read
method wrote_eof : bool
Whether the EOF marker has been written
method shutting_down : bool
True iff the shutdown is in progress
method start_shutting_down : ?linger:float -> when_done:(exn option -> unit) -> unit -> unit
Start shutting down the connection. After going through the shutdown procedure, the when_done callback is invoked. The exception indicates whether an error happened. Cancelled means that the shutdown operation has been cancelled in the meantime.

The underlying file descriptor (if any) is not closed. A shutdown is only a protocol handshake. After a shutdown, both read_eof and wrote_eof are true. Call inactivate to close the descriptor.

Optionally, one can linger for a certain period of time. It is only lingered when the EOF was written before the EOF is seen on input. Defaults to linger 60.0. Set to 0 to turn off.

See the comment for start_reading for how to get an engine-based version of this method.

method cancel_shutting_down : unit -> unit
Cancels the shutdown procedure. After that, the state of the connection is undefined. The when_done callback is invoked with the exception Cancelled.

It is no error if no shutdown is in progress.

method inactivate : unit -> unit
Inactivates the connection immediately, and releases any resources the controller is responsible for (e.g. closes file descriptors). Note that this is more than cancelling all pending operations and shutting the connection down. However, the details of this method are implementation-defined. Callbacks are not invoked.
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