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Sysinfo Module ​

The sysinfo module exposes psutil-style system and process monitoring to Lua/Fennel.

Usage ​

fennel
(local sysinfo (require :sysinfo))

Top-Level API ​

  • (sysinfo/platform) -> map:
    • :os, :arch, :lua, :features
  • (sysinfo/system) -> System object
  • (sysinfo/sleep seconds) -> convenience sleep helper

System API ​

  • (sys:refresh) -> boolean
  • (sys:cpu-usage) -> {:percent :warmup :interval :per-core}
  • (sys:cpu-times) -> cumulative counters map
  • (sys:mem-virtual) -> {:total :used :available :free :percent}
  • (sys:process-current) -> Process
  • (sys:process pid) -> Process or nil
  • (sys:process-list opts) -> sequence of Process

Process API ​

Process objects expose:

  • p.pid -> pid number
  • (p:exists) -> boolean
  • (p:name) -> string or nil
  • (p:refresh) -> boolean
  • (p:cpu) -> {:percent :warmup :interval}
  • (p:cpu-times) -> {:user :system}
  • (p:mem) -> {:rss :vms :percent}

CPU Sampling Semantics ​

CPU usage is delta-based and stateful:

  • First (sys:cpu-usage) and first (p:cpu) return warmup:
    • {:percent nil :warmup true ...}
  • refresh also records a sample baseline; two refreshes across time are sufficient to warm subsequent CPU reads.
  • Subsequent calls after elapsed time compute percent from the delta between samples.
  • No internal blocking/sleep is required; callers sample naturally in their own update loop.

Platform Behavior ​

The API surface is stable across Linux, Windows, and macOS. Fields unsupported on a given platform resolve to nil, and feature availability is advertised via (sysinfo/platform).features.

See also ​