This PR implements a custom scheduler for audio threads, which reduces thread use and (often) memory consumption.
To save threads and memory (e.g., packet buffer allocations), Songbird parks Mixer tasks which do not have any live Tracks.
These are now all co-located on a single async 'Idle' task.
This task is responsible for managing UDP keepalive messages for each task, maintaining event state, and executing any Mixer task messages.
Whenever any message arrives which adds a `Track`, the mixer task is moved to a live thread.
The Idle task inspects task counts and execution time on each thread, choosing the first live thread with room, and creating a new one if needed.
Each live thread is responsible for running as many live mixers as it can in a single tick every 20ms: this currently defaults to 16 mixers per thread, but is user-configurable.
A live thread also stores RTP packet blocks to be written into by each sub-task.
Each live thread has a conservative limit of 18ms that it will aim to stay under: if all work takes longer than this, it will offload the task with the highest mixing cost once per tick onto another (possibly new) live worker thread.
Adds the "receive" feature, which is disabled by default. When this is disabled, the UDP receive task is not compiled and not run, and as an optimisation the UDP receive buffer size is set to 0. All related events are also removed.
This also removes the UDP Tx task, and moves packet and keepalive sends back into the mixer thread. This allows us to entirely remove channels and various allocations between the mixer and an async task created only for sending data (i.e., fewer memcopies).
If "receive" is enabled, UDP sends are now non-blocking due to technical constraints -- failure to send is non-fatal, but *will* drop affected packets. Given that blocking on a UDP send indicates that the OS cannot clear send buffers fast enough, this should alleviate OS load.
Closes#131.
This extensive PR rewrites the internal mixing logic of the driver to use symphonia for parsing and decoding audio data, and rubato to resample audio. Existing logic to decode DCA and Opus formats/data have been reworked as plugins for symphonia. The main benefit is that we no longer need to keep yt-dlp and ffmpeg processes alive, saving a lot of memory and CPU: all decoding can be done in Rust! In exchange, we now need to do a lot of the HTTP handling and resumption ourselves, but this is still a huge net positive.
`Input`s have been completely reworked such that all default (non-cached) sources are lazy by default, and are no longer covered by a special-case `Restartable`. These now span a gamut from a `Compose` (lazy), to a live source, to a fully `Parsed` source. As mixing is still sync, this includes adapters for `AsyncRead`/`AsyncSeek`, and HTTP streams.
`Track`s have been reworked so that they only contain initialisation state for each track. `TrackHandles` are only created once a `Track`/`Input` has been handed over to the driver, replacing `create_player` and related functions. `TrackHandle::action` now acts on a `View` of (im)mutable state, and can request seeks/readying via `Action`.
Per-track event handling has also been improved -- we can now determine and propagate the reason behind individual track errors due to the new backend. Some `TrackHandle` commands (seek etc.) benefit from this, and now use internal callbacks to signal completion.
Due to associated PRs on felixmcfelix/songbird from avid testers, this includes general clippy tweaks, API additions, and other repo-wide cleanup. Thanks go out to the below co-authors.
Co-authored-by: Gnome! <45660393+GnomedDev@users.noreply.github.com>
Co-authored-by: Alakh <36898190+alakhpc@users.noreply.github.com>
This change fixes tasks hanging due to rare cases of messages being lost between full Discord reconnections by placing a configurable timeout on the `ConnectionInfo` responses. This is a companion fix to [serenity#1255](https://github.com/serenity-rs/serenity/pull/1255). To make this doable, `Config`s are now used by all versions of `Songbird`/`Call`, and relevant functions are added to simplify setup with configuration. These are now non-exhaustive, correcting an earlier oversight. For future extensibility, this PR moves the return type of `join`/`join_gateway` into a custom future (no longer leaking flume's `RecvFut` type).
Additionally, this fixes the Makefile's feature sets for driver/gateway-only compilation.
This is a breaking change in:
* the return types of `join`/`join_gateway`
* moving `crate::driver::Config` -> `crate::Config`,
* `Config` and `JoinError` becoming `#[non_breaking]`.
This was tested via `cargo make ready`, and by testing `examples/serenity/voice_receive` with various timeout settings.
* Add Makefile for common contributor tasks
Narrows down a few commands to automatically format when building, and neatly expose testing/benching.
Empty files added to describe contributor guidelines, overall architecture.
* First draft of contributor guidelines
* Simple architecture diagrams
* Add PNG variants of architecture diagrams
Swapping to these because not having Fira Sans installed on a viewing machine leads to terrible kerning.
* Architecture description.
* MD cross-refs.
