cedlemo / ocaml-libmpdclient Goto Github PK

finish the playback_options commands in bin/Ompdc

Use Connexion instead of Connection

when the lib is used in a synchrone way, a classical connection works like this:

• write "mycommand args\n"
• read "mpd responeOK\n" or "ACK {} ..."

in an asynchrone way:

• there is a thread with the "idle" command
• when the noidle command is send (that returns nothing) and then a new command is send, it occurs that the response is like this "OK\nOK\n".

if at this line,

It would be better to add a Buffer in the connection record and use bigger maxlen.

• Check all Unix and Lwt_unix functions for uncaugth exception
• 8733902 -> catch possible exception from Unix.connect

next :

./_build/default/bin/ompdc.exe status -p 20
Connection refused connect 
ompdc: internal error, uncaught exception:
       Unix.Unix_error(Unix.ENOTCONN, "recv", "")

Use:

• Capitalized_snake_case for modules
• use t for the main type of the module. (ie. Client.t and not Client.c)

#20

https://www.musicpd.org/doc/html/protocol.html#binary-responses

The MPD server can send binary data.

How to implement it ?

The Mpd specifications have been updated:
https://www.musicpd.org/doc/html/protocol.html#general-protocol-syntax

what is the form of the request that is recognized at the Connection level ?
what is the form of the request returned to the Client level ?
what is the form of the request recognized at the Client level ?

Do it both for the non-Lwt and Lwt connexion and client.

Use Notty in order to display information and clean terminal (could be used for futur consol mpd client like ncmpcpp)

create 2 threads and run them with Lwt.join

• one that redraw frequently the Notty.term
• one that listen to the mpd events

for the first one thread, implementation idea :

• Lwt_timeout ?
• Lwt_unix (https://github.com/pqwy/notty/blob/master/examples/life.ml#L81) seems to be the good choice

for the second thread how to present data to the first thread ?

• use a global reference (declare a reference in the global scope ?)
• does Lwt offerts a way to exchange data between thread ?

Display error message when a command returns an Mpd error response.

In travis, use docker and install mpd server in order to test all the commands.

• Connection
• Client
• Playback
• Playback_options

Write test cases for Connection_lwt regexes

The interface does not seem to redrawn as expected when resize events occur.

https://github.com/inhabitedtype/angstrom

Create a new branch where all the unix or others exceptions are transformed to classical Error.

2 pbs:

In docker the tests for playback fail because the mpd server can not play any songs.
And it can not play because after

• running an interactive session:

docker run --interactive --tty ocaml-libmpdclient/ubuntu-17.04

• launching mpd

mpd
Jan 06 17:11 : server_socket: bind to '[::1]:6600' failed: Cannot assign requested address (continuing anyway, because binding to '127.0.0.1:6600' succeeded)
Jan 06 17:11 : errno: Failed to open /home/ocaml-libmpdclient/mpd/tag_cache: No such file or directory

• loading the bach playlist and check to see if everything is ok:

ocaml-libmpdclient@422228ad13e0:~/ocaml-libmpdclient$ ./_build/default/samples/try_mpd_queries.exe "load bach"
received: OK MPD 0.19.0

received: OK

ocaml-libmpdclient@422228ad13e0:~/ocaml-libmpdclient$ ./_build/default/samples/try_mpd_queries.exe "playlist"
received: OK MPD 0.19.0

received: 0:file: kunst01.mp3
1:file: kunst02.mp3
2:file: kunst03.mp3
3:file: kunst04.mp3
4:file: kunst05.mp3
5:file: kunst06.mp3
6:file: kunst07.mp3
7:file: kunst08.mp3
8:file: kunst09.mp3
9:file: kunst10.mp3
10:file: kunst11.mp3
OK

When I try to play something and check the status:

ocaml-libmpdclient@422228ad13e0:~/ocaml-libmpdclient$ ./_build/default/samples/try_mpd_queries.exe "play"
received: OK MPD 0.19.0

received: OK

ocaml-libmpdclient@422228ad13e0:~/ocaml-libmpdclient$ ./_build/default/samples/try_mpd_queries.exe "status"
received: OK MPD 0.19.0

received: volume: -1
repeat: 0
random: 0
single: 0
consume: 0
playlist: 2
playlistlength: 11
mixrampdb: 0.000000
state: pause
song: 0
songid: 1
time: 0:230
elapsed: 0.000
bitrate: 0
audio: 22050:24:2
error: Failed to open audio output
nextsong: 1
nextsongid: 2
OK

• Pb n 1 : It seems that the server was not able to open the audio output.
• Pb n 2 : why the play command returns an OK while in the status there is obviously a pb ?

How to configure mpd ? is the current mpd.conf is enough ? is there any audio ouput in the default docker image ? should I create a dummy audio output (/dev/null)?
How to create a fake audio ouput?

cedlemo/rameau#5 (comment)

A request to mpd returns something like "one or multiple lines" + "\nOK\n".

they are identified in https://github.com/cedlemo/OCaml-libmpdclient/blob/master/lib/Connection_lwt.ml#L152

with

let request_response mpd_data =
  let pattern = "\\(\\(\n\\|.\\)*OK\n\\)" in
  check_full_response mpd_data pattern 1 0

more globaly a request is done via https://github.com/cedlemo/OCaml-libmpdclient/blob/master/lib/Client_lwt.ml#L66

let request client cmd =
  let {connection = c; _} = client in
  Connection_lwt.write c (cmd ^ "\n")
  >>= fun _ ->
    Connection_lwt.read_request_response c
    >>= fun response ->
      let parsed_response = Protocol.parse_response response in
      Lwt.return parsed_response

And the request is parsed in order to see if Mpd returned an Error or an Ok response with:
https://github.com/cedlemo/OCaml-libmpdclient/blob/master/lib/Protocol.ml#L81

let parse_response mpd_response =
  let ok_response_reg = Str.regexp "\\(\\(\n\\|.\\)*\\)OK$" in
  if (Str.string_match ok_response_reg mpd_response 0 == true) then
    let str = Str.matched_group 1 mpd_response in
    if str = "" then Ok (None) else Ok (Some str)
  else
    Error (parse_error_response mpd_response)

which means that the response returned by parse_response can possibly have a "\n" at the end which when parsed by Music_database_lwt.list can generate for example an album name like "an_album\n".
This new line char break further request to mpd.

from

type response = Ok of string | Error of (ack_error * int * string * string)

to

type response = Ok of string option | Error of (ack_error * int * string * string)

The way Client.status return when there is an error is really bad. use something like the result type and remove the empty Status type.

1. None / Some

The functions of the API should :

• when, an exception occurs,

  • print an explicit error message
  • return None with Lwt.return_none

• on success.

  • return Some

It is then up to the user of the Api to exit with an error code in the thread launched in Lwt_main.run

2. Create exceptions proper to the library.

The functions of the API should :

• when, an exception occurs,

  • print an explicit error message
  • throws a libmpd exception with Lwt.fail
  • catch libmpd exceptin in the main thread and exit with an error code

• on success.

  • return value normaly

3. Let the user catch all the low level exception in the main thread.