Kaz Wesley a3914f33c1 API for storing metadata (#3291) ... API for storing metadata. See: https://www.pivotaltracker.com/story/show/181149277 # Important Notes **New APIs**: - Storing metadata is implemented with `profiler::MetadataLogger`. - A full metadata storage/retrieval example is in [the top-level doctests](https://github.com/enso-org/enso/blob/wip/kw/profiling-metadata-api/lib/rust/profiler/data/src/lib.rs) for profiler::data, a crate which implements an API for profiling data consumers (it abstracts away the low-level details of the event log, and checks its invariants in the process) [after review of this new API here I'll open a PR to add it to the design doc]. **Implementation**: - `profiler::Event` is parameterized by a metadata type, so that different types of metadata can be dependency-injected into it. - A data consumer defines its metadata type as an enum of all the kinds of metadata it is interested in. - Producing the metadata enum is accomplished without defining its type (which would require dependencies from around the app): A `MetadataLogger` internally use a serialization helper `Variant` to serialize its variant of the metadata enum without knowledge of the other possible variants. **Performance impact**: still in the low ns/measurement range, comparable to pushing to a vec. *Note*: `LocalVecBuilder` is currently present under the name `Log`, which is accurate but probably too overloaded. I'd like to find the right name for it, document it with examples, and move it to its own crate under data-structures, but I don't want doing that to hold up this PR.		2022-02-28 09:55:56 +00:00
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src	API for storing metadata (#3291)	2022-02-28 09:55:56 +00:00
Cargo.toml	Profiling framework: core performance-logging implementation (#3238)	2022-02-10 09:24:29 -08:00