Fix audio filter plugin initialization delay

.changeset/bound-audio-filter-init-timeout.md

@@ -0,0 +1,6 @@
+---
+livekit-ffi: patch
+---
+
+Add timeout for audio filter plugin initialization
+

livekit-ffi/src/server/audio_plugin.rs

@@ -15,10 +15,13 @@
 use std::{
     pin::Pin,
     task::{Context, Poll},
+    time::Duration,
 };
 
+use super::FfiServer;
 use futures_util::Stream;
 use livekit::{
+    registered_audio_filter_plugins,
     webrtc::{audio_stream::native::NativeAudioStream, prelude::AudioFrame},
     AudioFilterAudioStream,
 };
@@ -42,3 +45,33 @@ impl Stream for AudioStreamKind {
         }
     }
 }
+
+const AUDIO_FILTER_INIT_TIMEOUT: Duration = Duration::from_secs(5);
+
+/// Initializes all registered audio-filter plugins for a freshly connected room.
+///
+/// Best-effort: on timeout or failure the room stays connected with the filter
+/// disabled. The [`tokio::task::spawn_blocking`] task cannot be cancelled, so on
+/// timeout it is detached and finishes in the background.
+///
+pub async fn initialize_audio_filters(server: &'static FfiServer, url: String, token: String) {
+    let started = std::time::Instant::now();
+    let init = server.async_runtime.spawn_blocking(move || {
+        for filter in registered_audio_filter_plugins().into_iter() {
+            filter.on_load(&url, &token).map_err(|e| e.to_string())?;
+        }
+        Ok::<(), String>(())
+    });
+
+    let outcome = match tokio::time::timeout(AUDIO_FILTER_INIT_TIMEOUT, init).await {
+        Ok(join_result) => join_result.map_err(|e| e.to_string()).and_then(|r| r),
+        Err(_) => Err(format!("timed out after {:?}", AUDIO_FILTER_INIT_TIMEOUT)),
+    };
+
+    if let Err(e) = outcome {
+        log::debug!("error while initializing audio filter after {:?}: {}", started.elapsed(), e);
+        log::error!(
+            "audio filter cannot be enabled: ensure you are connecting to LiveKit Cloud and that the filter is properly configured"
+        );
+    }
+}

livekit-ffi/src/server/room.rs

@@ -16,7 +16,7 @@ use std::collections::HashMap;
 use std::time::Duration;
 use std::{collections::HashSet, slice, sync::Arc};
 
-use livekit::{prelude::*, registered_audio_filter_plugins};
+use livekit::prelude::*;
 use livekit::{ChatMessage, StreamReader};
 use livekit_protocol as lk_proto;
 use parking_lot::Mutex;
@@ -148,28 +148,10 @@ impl FfiRoom {
         let connect = async move {
             match Room::connect(&connect.url, &connect.token, options.clone()).await {
                 Ok((room, mut events)) => {
-                    // initialize audio filters
-                    let result = server
-                        .async_runtime
-                        .spawn_blocking(move || {
-                            for filter in registered_audio_filter_plugins().into_iter() {
-                                filter.on_load(&req.url, &req.token).map_err(|e| e.to_string())?;
-                            }
-                            Ok::<(), String>(())
-                        })
-                        .await
-                        .map_err(|e| e.to_string());
-                    match result {
-                        Err(e) | Ok(Err(e)) => {
-                            log::warn!("error while initializing audio filter: {}", e);
-                            log::error!(
-                                "audio filter cannot be enabled: ensure you are connecting to LiveKit Cloud and that the filter is properly configured"
-                            );
-                            // Skip returning an error here to keep the rtc session alive
-                            // But in this case, the filter isn't enabled in the session.
-                        }
-                        Ok(Ok(_)) => (),
-                    };
+                    crate::server::audio_plugin::initialize_audio_filters(
+                        server, req.url, req.token,
+                    )
+                    .await;
 
                     // Successfully connected to the room
                     // Forward the initial state for the FfiClient