logring

A power-cut-safe log store for embedded devices in Rust (no_std, no alloc, embassy-friendly): many tracks of any shrink_wrap type written at once into a ring, with sessions, recordings and markers, read back over wire_weaver, as a USB disk, or with the logring PC tool.

Its main medium is an SD card: a small normal exFAT region (128 MB by default, configurable) for files that can be read and written as usual, and the rest is a preallocated ring file (logring.wlr). Over USB the device shows up as a normal disk: the rw files work as usual, and the log appears as read-only files split by recording and by time; exports to MF4, MCAP and CSV. The card is formatted on the device: put in a new card, say yes, done.

crate	what
crates/logring	the engine: format, writer, recovery, reader, TrackStore, the view model, media
crates/logring_export	PC-side reader and exporter (CSV, MCAP, MF4)
crates/logring_cli	the logring command line tool
crates/logring_py	the logring Python module (PyO3 + maturin)

cargo install --path crates/logring_cli
logring info card.img         # sessions, recordings, tracks, counters
logring export card.img --format csv --out ./out

import logring

card = logring.open("card.img")
df = card.track("can1_rx").to_pandas()

The medium is a trait (LogMedium, from wire_weaver's ww_stream), so storage other than SD (SPI/QSPI flash, eMMC) can follow. Not tied to one product: rePort (hardware project P2424) is the first user, and this is meant to be the base for every logging device built after it.

See AGENTS.md for how the repo is laid out, FEATURES.md for what is implemented, planned and still an idea, and CHANGELOG.md for the history.

Licensed under MIT OR Apache-2.0.