lean_ctx/proxy/
metrics.rs

1use std::sync::atomic::{AtomicU64, Ordering};
2
3use serde::{Deserialize, Serialize};
4
5static REQUESTS_TOTAL: AtomicU64 = AtomicU64::new(0);
6static TOKENS_SAVED_TOTAL: AtomicU64 = AtomicU64::new(0);
7static BYTES_COMPRESSED: AtomicU64 = AtomicU64::new(0);
8
9/// File holding the cross-process proxy totals. The proxy runs as its own
10/// (long-lived) process, so the only way the `gain` CLI / dashboard can learn
11/// how many provider turns actually carried the injected prefix is to read a
12/// persisted counter. This is what makes the net-of-injection figure honest.
13const PROXY_METRICS_FILE: &str = "proxy_metrics.json";
14
15/// Persist every Nth request. The body is tiny but we still avoid a write on
16/// every single request under high benchmark throughput; losing a few requests
17/// of accuracy between flushes is immaterial for a meter.
18const PERSIST_EVERY: u64 = 4;
19
20pub fn record_request(tokens_saved: u64, bytes_compressed: u64) {
21    let n = REQUESTS_TOTAL.fetch_add(1, Ordering::Relaxed) + 1;
22    TOKENS_SAVED_TOTAL.fetch_add(tokens_saved, Ordering::Relaxed);
23    BYTES_COMPRESSED.fetch_add(bytes_compressed, Ordering::Relaxed);
24    if n == 1 || n.is_multiple_of(PERSIST_EVERY) {
25        persist();
26    }
27}
28
29#[derive(Debug, Clone, Default, Serialize, Deserialize)]
30pub struct ProxyMetrics {
31    pub requests_total: u64,
32    pub tokens_saved_total: u64,
33    pub bytes_compressed: u64,
34}
35
36pub fn snapshot() -> ProxyMetrics {
37    ProxyMetrics {
38        requests_total: REQUESTS_TOTAL.load(Ordering::Relaxed),
39        tokens_saved_total: TOKENS_SAVED_TOTAL.load(Ordering::Relaxed),
40        bytes_compressed: BYTES_COMPRESSED.load(Ordering::Relaxed),
41    }
42}
43
44fn metrics_path() -> Option<std::path::PathBuf> {
45    crate::core::data_dir::lean_ctx_data_dir()
46        .ok()
47        .map(|d| d.join(PROXY_METRICS_FILE))
48}
49
50/// Atomically write the current in-process totals to disk. The proxy owns these
51/// totals for its lifetime, so a plain overwrite (not an additive merge) keeps
52/// the file in lock-step with the live atomics.
53pub fn persist() {
54    let Some(path) = metrics_path() else {
55        return;
56    };
57    let Ok(json) = serde_json::to_string(&snapshot()) else {
58        return;
59    };
60    let tmp = path.with_extension("json.tmp");
61    if std::fs::write(&tmp, json).is_ok() {
62        let _ = std::fs::rename(&tmp, &path);
63    }
64}
65
66/// Cross-process read of the persisted proxy totals, used by the `gain`
67/// CLI/dashboard to reconcile savings against the real number of provider turns.
68pub fn load_persisted() -> Option<ProxyMetrics> {
69    let path = metrics_path()?;
70    let data = std::fs::read_to_string(path).ok()?;
71    serde_json::from_str(&data).ok()
72}
lean_ctx/proxy/metrics.rs

lean_ctx/proxy/
metrics.rs
