The proxy auto-detect path (when proxiesVideos is off) HEADed a
googlevideo URL with a 5 s timeout on every video. The verdict is a
property of the network, not the video, so the cost was paid for no
reason on videos 2..N. On a network where the CDN is blocked the full
5 s timeout was added to playback startup every single time.
Two changes:
1) ProxyDetectionCache (actor, per-instance, 10 min TTL). First miss
pays the HEAD once and caches the verdict; subsequent videos hit
the cache synchronously. Concurrent callers share one in-flight
probe. The last-seen sample CDN URL is retained so future probes
don't need a fresh URL from the current video.
2) PlayerService kicks off InvidiousAPI.prewarmProxyDetection() in
parallel with the videoWith... API call. By the time streams come
back, the verdict is usually already cached and proxyStreamsIfNeeded
is a sync lookup. Cheap when there's nothing to prewarm.
Cache invalidation:
- on InstancesManager.update (URL change, proxy toggle flip)
- on InstancesManager.remove
- TTL covers the network-change case for now (no NWPathMonitor yet)
