feat: add metrics poller with ring buffers and GPU aggregates

This commit is contained in:
2026-08-14 10:41:04 -06:00
parent 28cc34dc59
commit 7dba134863
2 changed files with 179 additions and 0 deletions
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import { fetchMetrics, type LlamaSwapConfig } from "./llamaswap";
import { gpuInfos, parseGpuMetrics, type GpuMetricKind, type GpuSample } from "./metrics-parser";
const RING_SIZE = 60;
function avg(values: number[]): number {
return values.reduce((a, b) => a + b, 0) / (values.length || 1);
}
function max(values: number[]): number {
return values.reduce((a, b) => Math.max(a, b), -Infinity);
}
function sum(values: number[]): number {
return values.reduce((a, b) => a + b, 0);
}
const AGGREGATE: Record<GpuMetricKind, (values: number[]) => number> = {
util_percent: avg,
memory_util_percent: avg,
temperature: max,
power: sum,
fan: avg,
};
function key(gpuId: string, kind: GpuMetricKind): string {
return `${gpuId}|${kind}`;
}
type FetchFn = (cfg: LlamaSwapConfig) => Promise<string>;
export class MetricsPoller {
private buffers = new Map<string, number[]>();
private gpuName = new Map<string, string>();
private gpuIds: string[] = [];
private listeners = new Set<() => void>();
private timer?: ReturnType<typeof setInterval>;
private lastError?: string;
constructor(
private cfg: LlamaSwapConfig,
private intervalMs = 5000,
private fetchFn: FetchFn = fetchMetrics,
) {}
start(): void {
void this.tick();
this.timer = setInterval(() => void this.tick(), this.intervalMs);
}
stop(): void {
if (this.timer) clearInterval(this.timer);
this.timer = undefined;
}
on(listener: () => void): () => void {
this.listeners.add(listener);
return () => {
this.listeners.delete(listener);
};
}
async tick(): Promise<void> {
try {
const text = await this.fetchFn(this.cfg);
this.apply(parseGpuMetrics(text));
this.lastError = undefined;
} catch (err) {
this.lastError = err instanceof Error ? err.message : String(err);
} finally {
for (const listener of this.listeners) listener();
}
}
private apply(samples: GpuSample[]): void {
const byKind = new Map<GpuMetricKind, Map<string, number>>();
for (const s of samples) {
if (!byKind.has(s.kind)) byKind.set(s.kind, new Map());
byKind.get(s.kind)!.set(s.id, s.value);
if (!this.gpuName.has(s.id)) this.gpuName.set(s.id, s.name);
}
this.gpuIds = [...this.gpuName.keys()].sort((a, b) => parseInt(a, 10) - parseInt(b, 10));
for (const [kind, values] of byKind) {
for (const [id, value] of values) this.push(key(id, kind), value);
const all = [...values.values()];
if (all.length > 0) this.push(key("all", kind), AGGREGATE[kind](all));
}
}
private push(k: string, value: number): void {
let ring = this.buffers.get(k);
if (!ring) {
ring = [];
this.buffers.set(k, ring);
}
ring.push(value);
if (ring.length > RING_SIZE) ring.shift();
}
getValue(gpuId: string, kind: GpuMetricKind): number | undefined {
const ring = this.buffers.get(key(gpuId, kind));
return ring ? ring[ring.length - 1] : undefined;
}
getHistory(gpuId: string, kind: GpuMetricKind): number[] {
const ring = this.buffers.get(key(gpuId, kind));
return ring ? [...ring] : [];
}
gpus(): { id: string; name: string }[] {
return this.gpuIds.map((id) => ({ id, name: this.gpuName.get(id) ?? "" }));
}
isOffline(): boolean {
return this.lastError !== undefined;
}
}
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import assert from "node:assert/strict";
import { readFileSync } from "node:fs";
import { test } from "node:test";
import { type LlamaSwapConfig } from "../src/lib/util";
import { MetricsPoller } from "../src/lib/metrics-poller";
import { parseGpuMetrics } from "../src/lib/metrics-parser";
const FIXTURE = readFileSync(new URL("./fixtures/metrics.txt", import.meta.url), "utf8");
const FIXTURE2 = FIXTURE
.replace(/llamaswap_gpu_util_percent\{id="0"[^}]*\} 100/, 'llamaswap_gpu_util_percent{id="0",name="RTX PRO 6000"} 30')
.replace(/llamaswap_gpu_util_percent\{id="1"[^}]*\} 100/, 'llamaswap_gpu_util_percent{id="1",name="RTX PRO 6000"} 50')
.replace(/llamaswap_gpu_util_percent\{id="2"[^}]*\} 100/, 'llamaswap_gpu_util_percent{id="2",name="RTX 5090"} 80');
function stubFetch(bodies: string[]) {
let i = 0;
return async () => bodies[Math.min(i++, bodies.length - 1)];
}
const CFG: LlamaSwapConfig = { baseUrl: "http://test" };
test("poller stores per-GPU history and computes aggregates", async () => {
const poller = new MetricsPoller(CFG, 5000, stubFetch([FIXTURE, FIXTURE2]));
await poller.tick();
await poller.tick();
assert.equal(poller.getValue("0", "util_percent"), 30);
assert.deepEqual(poller.getHistory("0", "util_percent"), [100, 30]);
const allUtil = poller.getValue("all", "util_percent");
assert.ok(allUtil !== undefined);
assert.ok(Math.abs(allUtil - (30 + 50 + 80) / 3) < 1e-9);
const allTemp = poller.getValue("all", "temperature");
assert.equal(allTemp, 64);
const allPower = poller.getValue("all", "power");
assert.ok(allPower !== undefined);
assert.ok(Math.abs(allPower - (316.56 + 336.17 + 377.28)) < 1e-9);
assert.deepEqual(poller.gpus().map((g) => g.id), ["0", "1", "2"]);
assert.equal(poller.gpus()[2].name, "NVIDIA GeForce RTX 5090");
});
test("poller ring buffer caps at 60 samples", async () => {
const poller = new MetricsPoller(CFG, 5000, stubFetch([FIXTURE]));
for (let i = 0; i < 70; i++) await poller.tick();
assert.equal(poller.getHistory("0", "fan").length, 60);
});
test("poller reports offline after a fetch failure and recovers", async () => {
let fail = true;
const fetchFn = async () => {
if (fail) throw new Error("boom");
return FIXTURE;
};
const poller = new MetricsPoller(CFG, 5000, fetchFn);
await poller.tick();
assert.equal(poller.isOffline(), true);
fail = false;
await poller.tick();
assert.equal(poller.isOffline(), false);
assert.ok(poller.getValue("0", "util_percent") !== undefined);
});