67 lines
1.9 KiB
Rust
67 lines
1.9 KiB
Rust
|
#![forbid(unsafe_code)]
|
||
|
|
|
||
|
|
use std::time::Instant;
|
||
|
|
|
||
|
|
/// Sample per-process CPU pressure from Linux procfs.
|
||
|
|
///
|
||
|
|
/// Inputs: none when constructed; call `sample_percent()` over time.
|
||
|
|
/// Outputs: percentage of one CPU core used by the current process over the
|
||
|
|
/// elapsed sampling window.
|
||
|
|
/// Why: this gives the launcher and server lightweight pressure telemetry
|
||
|
|
/// without adding a heavyweight system-information dependency.
|
||
|
|
#[derive(Debug, Clone, Default)]
|
||
|
|
pub struct ProcessCpuSampler {
|
||
|
|
last: Option<(Instant, u64)>,
|
||
|
|
}
|
||
|
|
|
||
|
|
impl ProcessCpuSampler {
|
||
|
|
#[must_use]
|
||
|
|
pub fn new() -> Self {
|
||
|
|
Self::default()
|
||
|
|
}
|
||
|
|
|
||
|
|
pub fn sample_percent(&mut self) -> Option<f32> {
|
||
|
|
let now = Instant::now();
|
||
|
|
let runtime_ns = read_process_runtime_ns()?;
|
||
|
|
let previous = self.last.replace((now, runtime_ns))?;
|
||
|
|
let elapsed_ns = now
|
||
|
|
.saturating_duration_since(previous.0)
|
||
|
|
.as_nanos()
|
||
|
|
.min(u128::from(u64::MAX)) as u64;
|
||
|
|
if elapsed_ns == 0 || runtime_ns < previous.1 {
|
||
|
|
return None;
|
||
|
|
}
|
||
|
|
Some(runtime_ns.saturating_sub(previous.1) as f32 * 100.0 / elapsed_ns as f32)
|
||
|
|
}
|
||
|
|
|
||
|
|
pub fn sample_tenths_percent(&mut self) -> Option<u32> {
|
||
|
|
self.sample_percent()
|
||
|
|
.map(|pct| (pct * 10.0).clamp(0.0, u32::MAX as f32) as u32)
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
fn read_process_runtime_ns() -> Option<u64> {
|
||
|
|
let text = std::fs::read_to_string("/proc/self/schedstat").ok()?;
|
||
|
|
text.split_whitespace().next()?.parse::<u64>().ok()
|
||
|
|
}
|
||
|
|
|
||
|
|
#[cfg(test)]
|
||
|
|
mod tests {
|
||
|
|
use super::*;
|
||
|
|
use std::thread;
|
||
|
|
use std::time::Duration;
|
||
|
|
|
||
|
|
#[test]
|
||
|
|
fn schedstat_runtime_reads() {
|
||
|
|
assert!(read_process_runtime_ns().is_some());
|
||
|
|
}
|
||
|
|
|
||
|
|
#[test]
|
||
|
|
fn sampler_returns_percentage_after_two_samples() {
|
||
|
|
let mut sampler = ProcessCpuSampler::new();
|
||
|
|
assert!(sampler.sample_percent().is_none());
|
||
|
|
thread::sleep(Duration::from_millis(10));
|
||
|
|
let _ = sampler.sample_percent();
|
||
|
|
}
|
||
|
|
}
|