Master MCP Server

/** * Lightweight metrics, health checks, and profiling utilities. */ export type Labels = Record<string, string> export class Counter { private value = 0 inc(delta = 1): void { this.value += delta } get(): number { return this.value } } export class Gauge { private value = 0 set(v: number): void { this.value = v } add(delta: number): void { this.value += delta } get(): number { return this.value } } export class Histogram { private readonly buckets: number[] private counts: number[] private sum = 0 constructor(buckets = [0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1, 2.5, 5, 10]) { this.buckets = [...buckets].sort((a, b) => a - b) this.counts = Array(this.buckets.length + 1).fill(0) } observe(value: number): void { this.sum += value for (let i = 0; i < this.buckets.length; i++) { if (value <= this.buckets[i]) { this.counts[i]++ return } } this.counts[this.counts.length - 1]++ } snapshot(): { buckets: number[]; counts: number[]; sum: number } { return { buckets: [...this.buckets], counts: [...this.counts], sum: this.sum } } } export class MetricRegistry { private counters = new Map<string, Counter>() private gauges = new Map<string, Gauge>() private histograms = new Map<string, Histogram>() counter(name: string): Counter { let c = this.counters.get(name) if (!c) { c = new Counter() this.counters.set(name, c) } return c } gauge(name: string): Gauge { let g = this.gauges.get(name) if (!g) { g = new Gauge() this.gauges.set(name, g) } return g } histogram(name: string, buckets?: number[]): Histogram { let h = this.histograms.get(name) if (!h) { h = new Histogram(buckets) this.histograms.set(name, h) } return h } list(): { counters: Record<string, number>; gauges: Record<string, number>; histograms: Record<string, ReturnType<Histogram['snapshot']>> } { const counters: Record<string, number> = {} const gauges: Record<string, number> = {} const histograms: Record<string, ReturnType<Histogram['snapshot']>> = {} for (const [k, v] of this.counters.entries()) counters[k] = v.get() for (const [k, v] of this.gauges.entries()) gauges[k] = v.get() for (const [k, v] of this.histograms.entries()) histograms[k] = v.snapshot() return { counters, gauges, histograms } } } export class HealthCheckRegistry { private checks = new Map<string, () => Promise<{ ok: boolean; info?: unknown }>>() register(name: string, fn: () => Promise<{ ok: boolean; info?: unknown }>): void { this.checks.set(name, fn) } unregister(name: string): void { this.checks.delete(name) } async run(): Promise<{ status: 'ok' | 'degraded' | 'fail'; results: Record<string, { ok: boolean; info?: unknown }> }> { const entries: [string, { ok: boolean; info?: unknown }][] = [] for (const [name, fn] of this.checks) { try { const res = await fn() entries.push([name, res]) } catch (e) { entries.push([name, { ok: false, info: e instanceof Error ? e.message : String(e) }]) } } const results = Object.fromEntries(entries) const oks = entries.filter(([, r]) => r.ok).length const status: 'ok' | 'degraded' | 'fail' = oks === entries.length ? 'ok' : oks > 0 ? 'degraded' : 'fail' return { status, results } } } /** Monitors event loop delay by scheduling microtasks. Returns a stop function. */ export function monitorEventLoopLag(callback: (lagMs: number) => void, intervalMs = 500): () => void { let timer: any let stopped = false const tick = () => { if (stopped) return const start = now() timer = setTimeout(() => { const lag = now() - start - intervalMs callback(Math.max(0, lag)) tick() }, intervalMs) } tick() return () => { stopped = true if (typeof clearTimeout === 'function' && timer) clearTimeout(timer) } } export function now(): number { if (typeof performance !== 'undefined' && typeof performance.now === 'function') return performance.now() return Date.now() } export function collectSystemMetrics(): Record<string, unknown> { const g: any = globalThis as any const out: Record<string, unknown> = { timestamp: new Date().toISOString() } try { if (g.process?.memoryUsage) { const m = g.process.memoryUsage() out.memory = { rss: m.rss, heapTotal: m.heapTotal, heapUsed: m.heapUsed, external: m.external, } } if (g.os?.loadavg) { const l = g.os.loadavg() out.loadavg = { '1m': l[0], '5m': l[1], '15m': l[2] } } } catch { // ignore } // Workers: best-effort if (!out.memory && (performance as any)?.memory) { out.memory = (performance as any).memory } return out }