Issues with request.dynamic's set_queue() method

[AEManov20]

Hello, I'm currently trying to implement functionality for going backwards in a request.dynamic's history. Here is what it roughly looks like:

previous_requests = request.queue(interactive = false)
dynamic_requests = request.dynamic(prefetch = 9, request_handler)

radio = fallback([previous_requests, dynamic_requests])

radio = crossfade(radio,
    fade_in = crossfade_dur_seconds,
    fade_out = crossfade_dur_seconds)

radio = fallback(track_sensitive = false, [radio, blank()])

previous_songs_meta = ref([])

def on_track_handler(m)
    if not list.is_empty(current_song_meta()) then
        previous_songs_meta := list.add(current_song_meta(), previous_songs_meta())
    end
    current_song_meta := m
end

dynamic_requests.on_track(on_track_handler)
previous_requests.on_track(on_track_handler)

# ...

def play_prev_handler(req, resp)
    log("Trying to revert to previous song...")

    if list.is_empty(previous_songs_meta()) then
        log("No history of previous songs left")
        log("Nothing to do")

        resp.status_code(304)
        resp.http_version("1.1")
    else
        prev_song_uri =
            try
                list.assoc("initial_uri", list.hd(previous_songs_meta()))
            catch e do
                null()
            end
        
        previous_songs_meta := list_pop(previous_songs_meta())

        if (not null.defined(prev_song_uri)) or (not null.defined(dynamic_requests.current())) then
            log("Prevoius song's metadata doesn't have an URI")
            log("Nothing to do")

            resp.status_code(304)
            resp.http_version("1.1")
        else
            log("Previous song has been discovered")
            queue = dynamic_requests.queue()

            curr_req = null.get(dynamic_requests.current())
            prev_req = request.create(null.get(prev_song_uri))

            queue = list.add(curr_req, queue)
            dynamic_requests.set_queue(queue)

            previous_requests.push(prev_req)

            radio.skip()

            resp.status_code(204)
            resp.http_version("1.1")
        end
    end
end

In the method play_prev_handler the set_queue call works in theory, that is it upon calling the queue method, the changes are reflected, however whenever the program skips to the next song it (the request.dynamic) completely ignores the changes the program has made.

[vitoyucepi]

Hi @AEManov20,

however whenever the program skips to the next song it (the request.dynamic) completely ignores the changes the program has made.

Can you add logging for the state of dynamic_requests after the changes have been made?
For example log("#{dynamic_requests.queue()} #{dynamic_requests.current()}").

[AEManov20]

Yes, it's a good start (thanks for telling me about list.tl() 😆 I was looking for a pop method for a while in the docs), I also need to get the currently playing request on dynamic_requests, requeue it on dynamic_requests and radio.skip() so the code might be something like:

# ...
if list.assoc.mem("initial_uri", last_song_meta) then
  log("Previous song has been discovered")
  
  prev_req = request.create(last_song_meta["initial_uri"])
  previous_requests.push(prev_req)

  # get the currently playing request
  curr_req = null.get(dynamic_requests.current())
  # push it back onto the dynamic_requests so it's played again
  # right after the previous_requests queue is empty
  dynamic_requests.set_queue(list.add(curr_req, dynamic_requests.queue()))

  # skip whatever is playing on the radio (which is crossfaded fallback([previous_requests, dynamic_requests]))
  radio.skip()

  resp.status_code(204)
else
# ...

[vitoyucepi]

Could you write and test the function that will only requeue the dynamic_requests on http request?

[AEManov20]

Well, I completely rewrote the script in a more basic environment and the logs say something about failing to prepare the request after requesting the following sequence of endpoints - '/next', '/prev', '/next'. And what seems to happen is that the queued song with set_queue get skipped altogether because of the failure and it just jumps straight to the one after it.

Here is the script and the logs respectively:

playlist_path = environment.get("LS_PLAYLIST_PATH")
samplerate = int_of_string(environment.get("LS_SAMPLERATE"))
icecast_port = int_of_string(environment.get("LS_ICECAST_PORT"))
icecast_host = environment.get("LS_ICECAST_HOST")
icecast_password = environment.get("LS_ICECAST_PASSWORD")

encoder = %vorbis(
    samplerate = samplerate
)

playlist_filenames = playlist.files(playlist_path)
current_index = ref(0)

def get_current_index()
    out = current_index()

    current_index := current_index() + 1

    if current_index() >= list.length(playlist_filenames) then
        current_index := 0
    end

    out
end

def request_handler()
    request.create(list.nth(playlist_filenames, get_current_index()))
end

previous_requests = request.queue(interactive = false)
dynamic_requests = request.dynamic(prefetch = 9, request_handler)

radio = fallback([previous_requests, dynamic_requests])
radio = fallback(track_sensitive = false, [radio, blank()])

previous_songs_meta = ref([])
current_song_meta = ref([])

def on_track_handler(m)
    if not list.is_empty(current_song_meta()) then
        previous_songs_meta := list.add(current_song_meta(), previous_songs_meta())
    end
    current_song_meta := m
end

dynamic_requests.on_track(on_track_handler)

def get_currently_playing_handler(req, resp)
    if null.defined(radio.last_metadata()) then
        resp.content_type("application/json")
        resp.data(metadata.json.stringify(null.get(radio.last_metadata())))
        resp.status_code(200)
    else
        resp.status_code(418)
    end
end

def get_queue_handler(req, resp)
    resp.content_type("application/json")
    resp.data(
        json.stringify(
            list.map(
                fun(e) -> metadata.json.stringify(request.metadata(e)), 
                dynamic_requests.queue())))
    resp.status_code(200)
end

def play_next_handler(req, resp)
    radio.skip()
    resp.status_code(200)
end

def play_prev_handler(req, resp)
    log("Trying to revert to previous song...")
  
    if list.is_empty(previous_songs_meta()) then
        log("No history of previous songs left")
        log("Nothing to do")
    
        resp.status_code(304)
    else
        last_song_meta = list.hd(previous_songs_meta())
        previous_songs_meta := list.tl(previous_songs_meta())
    
        if list.assoc.mem("initial_uri", last_song_meta) then
            log("Previous song has been discovered")
            
            prev_req = request.create(last_song_meta["initial_uri"])
            previous_requests.push(prev_req)

            # get the currently playing request
            curr_req = null.get(dynamic_requests.current())
            # push it back onto the dynamic_requests so it's played again
            # right after the previous_requests queue is empty
            dynamic_requests.set_queue(list.add(curr_req, dynamic_requests.queue()))

            # skip whatever is playing on the radio (which is crossfaded fallback([previous_requests, dynamic_requests]))
            radio.skip()

            resp.status_code(204)
        else
            log("Prevoius song's metadata doesn't have an URI")
            log("Nothing to do")
    
            resp.status_code(304)
        end
    end
end

harbor.http.register(port=8080, method="GET", "/current", get_currently_playing_handler)
harbor.http.register(port=8080, method="GET", "/queue", get_queue_handler)
harbor.http.register(port=8080, method="POST", "/next", play_next_handler)
harbor.http.register(port=8080, method="POST", "/prev", play_prev_handler)

output.icecast(encoder,
    host = icecast_host, port = icecast_port,
    password = icecast_password, mount = "main.flac",
    radio)

liquidsoap-1  | 2024/07/19 16:20:57 [main_flac:3] Content type is {audio=pcm(stereo)}.
liquidsoap-1  | 2024/07/19 16:20:57 [request_queue:3] Content type is {audio=pcm(stereo)}.
liquidsoap-1  | 2024/07/19 16:20:57 [request.dynamic.2:3] Content type is {audio=pcm(stereo)}.
liquidsoap-1  | 2024/07/19 16:20:57 [blank.2:3] Content type is {audio=pcm(stereo)}.
liquidsoap-1  | 2024/07/19 16:20:57 [video.converter:3] Couldn't find preferred video converter: ffmpeg.
liquidsoap-1  | 2024/07/19 16:20:57 [audio.converter:3] Using samplerate converter: libsamplerate.
liquidsoap-1  | 2024/07/19 16:20:57 [clock.main:3] Streaming loop starts in auto-sync mode
liquidsoap-1  | 2024/07/19 16:20:57 [clock.main:3] Delegating synchronization to CPU clock
liquidsoap-1  | 2024/07/19 16:20:57 [video.text:3] Using native implementation
liquidsoap-1  | 2024/07/19 16:20:57 [decoder.flac:3] Libflac recognizes "/media/songs/A1 Look Your Back!.flac" as FLAC (44100Hz,2 channels).
liquidsoap-1  | 2024/07/19 16:20:57 [switch.2:3] Switch to blank.2.
liquidsoap-1  | 2024/07/19 16:20:57 [request.dynamic.2:3] Prepared "/media/songs/A1 Look Your Back!.flac" (RID 1).
liquidsoap-1  | 2024/07/19 16:20:57 [switch.2:3] Switch to switch with transition.
liquidsoap-1  | 2024/07/19 16:20:57 [main_flac:3] Connecting mount main.flac for source@icecast...
liquidsoap-1  | 2024/07/19 16:20:57 [main_flac:3] Connection setup was successful.
liquidsoap-1  | 2024/07/19 16:20:57 [switch:3] Switch to request.dynamic.2.
liquidsoap-1  | 2024/07/19 16:20:57 [decoder.flac:3] Libflac recognizes "/media/songs/A2 A Seagull & Clouds.flac" as FLAC (44100Hz,2 channels).
liquidsoap-1  | 2024/07/19 16:20:57 [decoder.flac:3] Libflac recognizes "/media/songs/A3 Flying Beagle.flac" as FLAC (44100Hz,2 channels).
liquidsoap-1  | 2024/07/19 16:20:57 [decoder.flac:3] Libflac recognizes "/media/songs/A4 Fluffy.flac" as FLAC (44100Hz,2 channels).
liquidsoap-1  | 2024/07/19 16:20:57 [decoder.flac:3] Libflac recognizes "/media/songs/B1 Sand Storm.flac" as FLAC (44100Hz,2 channels).
liquidsoap-1  | 2024/07/19 16:20:57 [decoder.flac:3] Libflac recognizes "/media/songs/B2 Baby Talk.flac" as FLAC (44100Hz,2 channels).
liquidsoap-1  | 2024/07/19 16:20:57 [decoder.flac:3] Libflac recognizes "/media/songs/B3 The Second Summer.flac" as FLAC (44100Hz,2 channels).
liquidsoap-1  | 2024/07/19 16:20:57 [decoder.flac:3] Libflac recognizes "/media/songs/B4 Ducky Ducky.flac" as FLAC (44100Hz,2 channels).
liquidsoap-1  | 2024/07/19 16:20:57 [decoder.flac:3] Libflac recognizes "/media/songs/A1 Look Your Back!.flac" as FLAC (44100Hz,2 channels).
liquidsoap-1  | 2024/07/19 16:20:57 [decoder.flac:3] Libflac recognizes "/media/songs/A2 A Seagull & Clouds.flac" as FLAC (44100Hz,2 channels).
==== Initialization ====
liquidsoap-1  | 2024/07/19 16:21:20 [request.dynamic.2:3] Prepared "/media/songs/A2 A Seagull & Clouds.flac" (RID 2).
liquidsoap-1  | 2024/07/19 16:21:20 [decoder.flac:3] Libflac recognizes "/media/songs/A3 Flying Beagle.flac" as FLAC (44100Hz,2 channels).
==== After triggering /next ====
liquidsoap-1  | 2024/07/19 16:21:57 [lang:3] Trying to revert to previous song...
liquidsoap-1  | 2024/07/19 16:21:57 [lang:3] Previous song has been discovered
liquidsoap-1  | 2024/07/19 16:21:57 [decoder.flac:3] Libflac recognizes "/media/songs/A1 Look Your Back!.flac" as FLAC (44100Hz,2 channels).
liquidsoap-1  | 2024/07/19 16:21:57 [request_queue:3] Prepared "/media/songs/A1 Look Your Back!.flac" (RID 12).
liquidsoap-1  | 2024/07/19 16:21:57 [switch:3] Switch to request_queue with forgetful transition.
==== After triggering /prev ====
liquidsoap-1  | 2024/07/19 16:22:22 [request.dynamic.2:1] Failed to prepare track: request not ready.
liquidsoap-1  | 2024/07/19 16:22:22 [request.dynamic.2:3] Prepared "/media/songs/A3 Flying Beagle.flac" (RID 3).
liquidsoap-1  | 2024/07/19 16:22:22 [switch:3] Switch to request.dynamic.2.
liquidsoap-1  | 2024/07/19 16:22:22 [replay_metadata:3] Content type is {audio=pcm(stereo)}.
liquidsoap-1  | 2024/07/19 16:22:22 [decoder.flac:3] Libflac recognizes "/media/songs/A4 Fluffy.flac" as FLAC (44100Hz,2 channels).
==== After triggering /next again ====

[AEManov20]

Alright, right after I posted that last reply I realized my mistake, I was using a request, which was already used before (i.e. by dynamic_requests), so i needed to recreate it.

Here is the fixed code of the handler (now it works and it doesn't show that error):

def play_prev_handler(req, resp)
    log("Trying to revert to previous song...")
  
    if list.is_empty(previous_songs_meta()) then
        log("No history of previous songs left")
        log("Nothing to do")
    
        resp.status_code(304)
    else
        last_song_meta = list.hd(previous_songs_meta())
        previous_songs_meta := list.tl(previous_songs_meta())
    
        if list.assoc.mem("initial_uri", last_song_meta) then
            log("Previous song has been discovered")
            
            prev_req = request.create(last_song_meta["initial_uri"])
            previous_requests.push(prev_req)

            # get the currently playing request
            curr_req_meta = request.metadata(null.get(dynamic_requests.current()))
            curr_req = request.create(curr_req_meta["initial_uri"])
            # push it back onto the dynamic_requests so it's played again
            # right after the previous_requests queue is empty
            dynamic_requests.set_queue(list.add(curr_req, dynamic_requests.queue()))

            # skip whatever is playing on the radio (which is crossfaded fallback([previous_requests, dynamic_requests]))
            radio.skip()

            resp.status_code(204)
        else
            log("Prevoius song's metadata doesn't have an URI")
            log("Nothing to do")
    
            resp.status_code(304)
        end
    end
end

[AEManov20]

Thank you very much for the help, by the way!