boundary/folsom

This system is a metrics collection and analysis library, specifically the Folsom library for Erlang. It provides tools for gathering and querying system and application metrics, supporting various data types like counters, gauges, and histograms. The library enables metric grouping by tags, tracks Erlang VM statistics, and implements sampling strategies such as sliding windows and exponential decay.

Users can now group and query metrics by tags using folsom\_metrics:tag\_metric/2 and untag\_metric/2, and retrieve all metrics for a given tag or a specific metric type. Additionally, the library now collects Erlang VM statistics including memory, system info, process info, port info, and ETS/Dets info via the folsom\_vm\_metrics module.

(repo-wide) · high confidence

Introduces the Folsom metrics library, providing a comprehensive set of tools for collecting and analyzing system metrics. This release adds support for counters, gauges, histograms, history, meters, meter readers, and spirals, along with exponentially decaying and sliding window sampling strategies. It also includes an EWMA (Exponentially Weighted Moving Average) implementation for calculating rates and acceleration, and a timer server for automated meter ticking.

src · high confidence

The project now includes the Folsom metrics library, replacing the previous 'emetrics' implementation. This adds support for new metric types including spirals, sliding windows, and exponential decay sampling, alongside enhanced system information reporting such as port counts and scheduler bindings.

include · high confidence

The legacy dispatch configuration file (priv/dispatch.conf) has been removed, eliminating the previous routing rules for the emetrics VM resource.

priv · high confidence

Added new test files to the test suite: \folsom\_erlang\_checks.erl\ for general metric operations, \folsom\_sample\_slide\_test.erl\ and \slide\_statem\_eqc.erl\/\slide\_uniform\_eqc.erl\ for sliding window samples, and \folsom\_tests.erl\ for core functionality. Also added \cpu\_topo\_data\ containing CPU topology test fixtures. These changes increase test coverage for metric creation, deletion, tagging, and sliding window resizing/trimming.

test · high confidence

Written by watchdog.canine.dev from the codebase's own history, inside the signed delivery this page is composed from.

• CAI 53 → 53 (+0.6)
• Rubric changed (rubric-2026.08.19 → rubric-2026.09.15) — scores are not directly comparable.

• Code Health 90 → 97 (+7.3)
• Architecture 100 → 100 (+0.0)
• Maturity 34 → 46 (+12.3)
• Readiness 41 → 39 (-1.1)
• Security 100 → 67 (-33.3)
• Event Sourcing 100 → 100 (+0.0)

• Coverage not included — suite not readable by the collector
• Dependency hygiene not measured — dependency manifest found but not parsed for hygiene
• No exposed public API
• Test reliability not included
• complexity unreadable for .erl, .hrl — churn × complexity hotspots could not be measured
• dormant codebase — no living knowledge left to concentrate

• Coverage not measured — no coverage collector is wired up
• Dependency hygiene PARTLY measured — rebar3 pinning read, dependency currency not (no rebar.lock-pinned Hex declaration to grade)
• Documentation: no architecture or design documentation (README.md)
• Documentation: no usage examples (README.md)
• Duplicated block (8 lines × 2) (src/folsom_metrics_meter.erl)
• No SBOM
• No artifact signing
• No build provenance
• No dependency lockfile committed (rebar.config)

Written by watchdog.canine.dev from the codebase's own history, inside the signed delivery this page is composed from.

boundary/folsom was measured the same way every project in this corpus was: the same rubric, at a pinned commit, with the result published in full. Point a surveyor at a repository you know and see whether you agree with it.