anthorob
4cf7c47645
Replaced the bot's audio handling system by removing Lavaplayer dependencies and migrating to a Lavalink v4 node. Updated `MusicManager`, `TrackScheduler`, and related classes to utilize the `LavalinkClient`. Refactored playlist and track loading logic, task integrations, and event dispatch to integrate with the remote node. Deprecated the custom Udio source, preserving references for a future plugin port. Documented configuration and deployment details for the new audio architecture.
171 lines
8.7 KiB
Markdown
171 lines
8.7 KiB
Markdown
# Music
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**Package:** `me.bobert.netneutrality.music`
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**Engine:** a remote [Lavalink](https://lavalink.dev) v4 node driven by
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[`dev.arbjerg:lavalink-client`](https://github.com/lavalink-devs/Lavalink-Client) 3.4.0.
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The music subsystem provides per-guild audio playback: searching/loading tracks from multiple
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sources, queueing, scheduling, and streaming audio into a Discord voice channel. Since the
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migration to Lavalink, **decoding, source resolution and voice sending happen on the node**, not in
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the bot process. The bot only sends REST/WebSocket commands and reacts to the node's events, which
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means new sources (YouTube, LavaSrc, …) are added by configuring server-side plugins rather than by
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changing Java code.
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## Key classes
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| Class | Responsibility |
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|---|---|
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| `MusicServiceImpl` | Owns the shared `LavalinkClient`, registers the node, and dispatches its event flux. |
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| `MusicManager` | Central per-guild coordinator; resolves the guild's `Link` and exposes a synchronous facade. |
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| `QueueManager` | Holds the guild's track queue (`LinkedBlockingDeque<TrackInfo>`); enqueue/skip/shuffle. |
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| `TrackScheduler` | Event sink for `onTrackStart` / `onTrackEnd` / `onTrackException` / `onTrackStuck`; caches the current track. |
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| `TrackLoadingHandler` | `AbstractAudioLoadResultHandler`; handles track/playlist/search/no-match/failure results. |
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| `TrackInfo` | Value object pairing a Lavalink `Track` with its requester (`Member`). |
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| `SourceFinder` | Identifies the source/type of a query (YouTube, SoundCloud, HTTP, …). |
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| `StuckTrackRecoveryHandler` | Retry-then-skip logic for tracks the node reports as stuck. |
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`MusicServiceImpl` keeps a `Map<String, MusicManager>` of managers keyed by guild id, so each guild
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has its own link, scheduler, and queue.
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## Startup
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`MusicServiceImpl` is a priority-40 [`Lifecycle`](architecture.md#startup-lifecycle) component. Its
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constructor creates the `LavalinkClient` (the bot user id is derived from the token) and `start()`
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registers the configured node. **A node that is unreachable never prevents the bot from booting**:
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the client retries in the background and music commands reply with an error in the meantime.
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Because the client must exist before JDA is built, `App.initJDA()` (priority 60) installs
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`new JDAVoiceUpdateListener(music.getClient())` as the gateway's voice dispatch interceptor. JDA's
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`AudioManager` is therefore **not** used for playback; voice connections are opened and closed
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through `JDA#getDirectAudioController()`.
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### Settings
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| Setting | Default | Meaning |
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|---|---|---|
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| `NETNEUTRALITY_LAVALINK_URI` | `ws://lavalink:2333` | WebSocket URI of the node |
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| `NETNEUTRALITY_LAVALINK_PASSWORD` | — | Node password; music is disabled when missing |
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| `NETNEUTRALITY_LAVALINK_NAME` | `main` | Node name used in logs |
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## Audio pipeline (end-to-end)
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```
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/play query
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│
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▼
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MusicManager.play(query, ctx)
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│ SourceFinder identifies the source and builds the identifier
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▼
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link.loadItem(identifier).subscribe(new TrackLoadingHandler(...))
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│
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├─ ontrackLoaded ──▶ connect to voice (MusicUtils) ──▶ QueueManager.queue(track, member)
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├─ onPlaylistLoaded / onSearchResultLoaded ──▶ install a LoadPlaylistTask (choice buttons)
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├─ noMatches ──▶ reply "nothing found"
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└─ loadFailed ──▶ reply / log error
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│
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▼
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QueueManager: if nothing is playing, send createOrUpdatePlayer().setTrack(...); else append
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│
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▼
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Lavalink node decodes and streams the audio to the Discord voice gateway
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│
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▼ (track ends)
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node event ──▶ MusicServiceImpl dispatcher ──▶ TrackScheduler.onTrackEnd ──▶ QueueManager.startNextTrack()
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```
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- **Event dispatch** — `MusicServiceImpl` holds a single subscription per event type
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(`TrackStartEvent`, `TrackEndEvent`, `TrackExceptionEvent`, `TrackStuckEvent`,
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`WebSocketClosedEvent`) and routes each event to the owning guild's `TrackScheduler`. All
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subscriptions are disposed in `stop()`.
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- **Synchronous facade** — every Lavalink operation returns a reactive `Mono`. `MusicManager`
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subscribes internally so the 13 music commands keep their existing synchronous signatures;
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failures are reported through `LogHandler` and the attached `MusicChannelContext`.
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- **Current track** — the node's player state is only readable via REST, so the last
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`TrackStartEvent` is cached on the scheduler and used by `getCurrentlyPlaying()` and by the queue
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to decide whether playback must be started.
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- **Requester tracking** — each queued item is a `TrackInfo` (track + requesting `Member`), used for
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now-playing/queue displays and vote-skip. Duplicate rejection compares the encoded track payload.
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- **Playlists / search** — playlist and search loads produce a
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[`LoadPlaylistTask`](tasks.md#concrete-task-catalog) with per-result buttons
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(`LoadTrackFromPlaylistTask`), tying the music and [task](tasks.md) subsystems together. Playlist
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size is bounded by the [`MUSIC_MAXPLAYLISTSIZE`](persistence.md#gsettings) guild setting.
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- **Stuck tracks** — the first `TrackStuckEvent` re-queues the track and seeks back to the last
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known position; a second consecutive event skips to the next track.
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- **Output** — playback messages are posted through a
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[`MusicChannelContext`](contexts.md#musicchannelcontext) so they land in the guild's configured
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music channel.
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## Running the node
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`docker-compose.yml` defines a `lavalink` service (image `ghcr.io/lavalink-devs/lavalink:4.2`, the
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minimum version that handles DAVE end-to-end encrypted voice) on the `netneutrality` network, with
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`lavalink/application.yml` mounted read-only at `/opt/Lavalink/application.yml`. The bot depends on
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it and the node depends on the existing `ejs-api` (yt-cipher) container.
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```bash
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docker compose up -d lavalink
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docker compose logs -f lavalink # wait for "Lavalink is ready to accept connections"
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```
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### Adding a server-side plugin
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Plugins are declared in `lavalink/application.yml` and downloaded by the node on boot into the
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`netneutrality-lavalink-plugins` volume — no bot rebuild is required:
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```yaml
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lavalink:
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plugins:
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- dependency: "dev.lavalink.youtube:youtube-plugin:1.18.2"
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snapshot: false
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```
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A plugin that is not on the default Lavalink repository can be pulled from any Maven repository by
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adding `repository:` to the entry. The node currently runs a JitPack build of the SABR-enabled
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YouTube fork ([`ashton045/youtube-source`](https://jitpack.io/#ashton045/youtube-source), branch
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`feat/sabr-support`) — no local build of the fork is required, JitPack publishes a ready Lavalink
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plugin jar:
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```yaml
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lavalink:
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plugins:
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- dependency: "com.github.ashton045.youtube-source:youtube-plugin:17619654b1"
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repository: "https://jitpack.io"
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snapshot: false
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```
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The node logs `Failed to check for updates for youtube-plugin: Not Found` on boot; this is harmless,
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JitPack publishes no `maven-metadata.xml` for commit-pinned versions.
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Plugin-specific configuration goes under the top-level `plugins:` key. The YouTube plugin is
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configured there with the remote cipher URL, poToken and visitorData, which used to live in
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`MusicServiceImpl.start()`.
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## Udio support (deferred)
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Udio playback is **temporarily unavailable**. The previous implementation was a client-side
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Lavaplayer `AudioSourceManager`, and Lavalink can only resolve sources that live on the server.
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`SourceFinder` still recognises Udio URLs but returns no identifier, and `MusicManager.play` replies
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that Udio is temporarily unsupported.
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The original `UdioAudioSourceManager`, `UdioAudioTrack` and their test have been preserved verbatim
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under [`docs/reference/udio-lavalink-plugin/`](reference/udio-lavalink-plugin) — they are **not
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compiled** — as the reference for a future Lavalink **server plugin** port. That plugin is out of
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scope of this migration and is tracked as a follow-up.
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## Guild lifecycle & cleanup
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- `MusicPlayerAutoDisconnect` (scheduled task) leaves voice when the channel is empty or the queue
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has run out; the connected channel is read from the bot's gateway voice state.
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- `MusicManagerCleanup` (scheduled task) evicts unused per-guild `MusicManager` instances.
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- On shutdown, `MusicServiceImpl.stop()` disposes the event subscriptions, clears the queues,
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destroys every player and closes the client
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(called from [`App.shutdown()`](architecture.md#shutdown-lifecycle)).
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## Related commands
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All music commands extend [`MusicCommand`](commands.md#base-implementations-corecommandimpl) (guild
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only + music role/channel enforced): `PlayCommand`, `SkipCommand`/`VoteSkipCommand`,
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`QueueCommand`/`ViewQueueCommand`, `ClearQueueCommand`, `ShuffleCommand`, `JoinCommand`/`LeaveCommand`,
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`CurrentlyPlayingCommand`, `ResumeCommand`/`StopCommand`, `VolumeCommand`, `BitconnectCommand`. See
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[commands.md](commands.md#command-catalog).
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