feat(s2n-quic-xdp): add ring module #1706
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| /// | ||
| /// See [xsk.h](https://github.com/xdp-project/xdp-tools/blob/a76e7a2b156b8cfe38992206abe9df1df0a29e38/headers/xdp/xsk.h#L34-L42). | ||
| #[derive(Debug)] | ||
| pub struct Cursor<T: Copy + fmt::Debug> { |
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nit: can you match the ordering in the xsk. Also desc -> ring. Finally a brief comment on cached_len and why you added it for optimization.
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I want to preserve the desc rather than ring. Ring is just used all over the place and I wanted to say that this points to the descriptors.
I can add the docs and reorder, though.
| /// Returns the cached producer cursor which is also maxed by the cursor mask | ||
| /// | ||
| /// See [xsk.h](https://github.com/xdp-project/xdp-tools/blob/a76e7a2b156b8cfe38992206abe9df1df0a29e38/headers/xdp/xsk.h#L60). | ||
| #[inline] | ||
| pub fn cached_producer(&self) -> u32 { | ||
| self.cached_producer.0 & self.mask | ||
| } |
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can you update this documentation to mention the wrapping and modulo operation and power of 2.
| ConsumerAcquire(u16), | ||
| ConsumerRelease(u16), | ||
| ProducerAcquire(u16), | ||
| ProducerRelease(u16), |
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would testing with u32 be useful since some of the values on Cursor are u32
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Not in this case since we're limiting the queue size for the sake of memory usage. Having the smaller lengths also consumes less of the fuzzer input so the corpus is smaller as well.
But functionally, as long as we're testing a few queue sizes the behavior should all be the same.
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Description of changes:
This change adds the XDP ring data structure for coordinating with the kernel. Most of this code is based on the xsk.h file from the xdp-project.
Each ring type (TX, RX, Fill, Comp) wraps the generic Ring structure and exports a well-typed API.
Call-outs:
I considered generating bindings from the libxdp project for this. However, the implementation is all contained in the header, which bindgen has a hard time with - none of the meaningful functions are actually exposed. This means this logic has to be either wrapped in a C module or it needs to be ported to Rust. In this case I opted for porting it, since we'd potentially incurring runtime costs without cross-language LTO enabled. It also keeps the build simpler.
Testing:
I added a bolero test for the ring cursor implementation. It defines a FIFO queue as an oracle and ensures the behavior of the ring matches.
By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.