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, and proto3 and repr-c, which enable 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, EncodedSizes, 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 open API questions are tracked at https://github.com/driftsys/ridl/issues/350.

ridl-rt supports Rust 1.83 or newer (rust-version = "1.83"). Raising that minimum is a breaking change, shipped in a 0.x minor release like any other.

The crate builds as edition 2021 and edition 2024: edition 2021 is tested with Rust 1.83 and with the pinned toolchain, and edition 2024 is tested with the pinned toolchain (edition 2024 did not exist before Rust 1.85, so the minimum cannot build it).

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.