ridl-rt

The library that code generated from ridl links, and a runtime implements.

ridl-rt defines, once, the vocabulary that generated code and a runtime agree on: identity and the interaction descriptors (contract), the payload encodings (encoding), the contract and transport errors and the two errors a generated client call and a generated serve return (error), encoding and decoding a payload (payload), the ports a runtime implements and generated code calls (port), and time, the envelope, and the values a read returns (sample). It contains no runtime: a runtime is a separate crate that implements the port module's traits. It also carries the caller-side call table and the waker registry every runtime would otherwise write alone (correlate), and the traits a generated face implements for its fixed methods — Bind::new, Events::next_event, Publish::commit, and under std Timeout — which a consumer brings into scope with the generated prelude of each interface whose face it uses (face). One more module holds the optional trace context that a call or an event carries across a port (trace); with the std feature it also holds the application's hook for that context (Propagation, AlreadySet, set_propagation and propagation).

With its default features the crate is no_std and allocates nothing; it contains no unsafe code and has no dependency in any feature combination. It declares one cargo feature per payload encoding — flatbuffers, which enables the FlatBuffers reading and writing helpers, proto3, which enables the proto3 varint, tag, reader and writer helpers, and repr-c, which enables nothing in this version — and a std feature, off by default, that links the standard library and enables task::block_on, task::noop_waker and task::flag_waker, and the propagation hook of the trace module.

Versioning

ridl-rt is a 0.x crate. A breaking change bumps the minor version (0.1 → 0.2), not the major version. A public struct whose fields are all public and that carries no #[non_exhaustive] cannot gain a field without a breaking change, because code outside the crate can build it as a struct literal: CatalogRef, Member, Timing, PayloadInfo, Encoded, Violation, RawSample, RawOccurrence, Claim, Watermark, Changed, Envelope, Sample, Occurrence, TraceContext. The public tuple structs — Ordinal, InterfaceNo, CatalogHash, Correlation, ClaimId, Timestamp, Duration — follow the same rule. So do the unit structs FlatBuffers, Proto3 and ReprC (src/encoding.rs), TrackerFull (src/sample.rs) and AlreadySet (src/trace.rs): each is a unit struct with no field that code outside the crate uses as a value or a pattern, so a field added to any of them breaks that code.

The API questions that the reviews of 0.1 raised are settled; the issue that tracked them is https://github.com/driftsys/ridl/issues/350.

ridl-rt supports Rust 1.88 or newer (rust-version = "1.88"). Raising that minimum is a breaking change, shipped in a 0.x minor release like any other. Releases before the one that raised it to 1.88 supported Rust 1.83.

The crate builds as edition 2021 and edition 2024: edition 2021 is tested with Rust 1.88 and with the pinned toolchain, and edition 2024 is tested with the pinned toolchain.

What 0.1 leaves out

• streams
• Inline
• the three payload codecs (proto3, FlatBuffers, repr(C))
• Encoding::FORMAT
• Family
• Access
• Constrained
• the runtimes (ridl-loopback, ridl-transport-ws)
• the engine

License

MIT. See LICENSE.