Allow Reader to implement AsyncSeek and provide a way for loaders to "ask" for a compatible reader.
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… communicate what features they need from the read.
atlv24
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Dec 13, 2025
| @@ -1,3 +1,5 @@ | |||
| #[cfg(feature = "trace")] | |||
| use crate::io::ReaderRequiredFeatures; | |||
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nit: this could be in the #[cfg(feature = "trace")] use { block below
atlv24
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Dec 13, 2025
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nice job, looks good to me
kristoff3r
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Dec 13, 2025
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| fn reader_required_features( | ||
| &self, | ||
| settings: &dyn Settings, | ||
| ) -> Result<ReaderRequiredFeatures, ProcessError>; |
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Can't this have a default implementation? That would remove a bunch of boilerplate.
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Objective
AsyncSeektrait byAsyncSeekForwardforReaderto address #12880 #14194, we replacedAsyncSeekwithAsyncSeekForward. This allowed us to support more kinds of sources, but the cost was that loaders were more limited in what they could do with the reader.AsyncSeekForwardmade it difficult to deal with this (or impossible in some cases).AsyncSeektrait bound onReadermay limit options to stream bytes #12880.Solution
AssetLoaderto say which "features" of a reader it needs.AssetReaderso it can decide how to handle it.AssetReaderError::UnsupportedFeature.This design is kind of "weak" - there's no guarantee that a loader that requests
AnySeekwill get a reader that actually implementsAsyncSeek. Or on the other side, there's no guarantee that a loader actually requests the features that it uses. However, in practice it's likely enough: errors are likely to guide users to the correct situation. In the future, we could perhaps have a "sieve reader", which blocks any features the loader didn't explicitly request. Perhaps this is a debug only feature, or something that can be toggled.Testing