Metrics Middleware

Invoker middleware that collects RPC-level metrics without changing request behaviour. Every outgoing RPC call is wrapped to record the Telegram method name, request status, and latency.

Install

go get github.com/mtgo-labs/middlewares/metrics

Quick Start

import (
    "database/sql"

    tg "github.com/mtgo-labs/mtgo/telegram"
    "github.com/mtgo-labs/middlewares/metrics"
    _ "modernc.org/sqlite"
)

db, _ := sql.Open("sqlite", "bot.db")
mc, _ := metrics.NewSQLiteCollector(db)
defer mc.Close()

mw := metrics.New(mc, metrics.Config{EnableMethodLabels: true})
client.UseInvokerMiddleware(mw.Middleware())

Metrics collected

Metric	Type	Labels	Description
rpc_requests_total	counter	method, status	Total RPC requests
rpc_latency_seconds	histogram	method	RPC round-trip latency
rpc_in_flight	gauge	method	Currently in-flight requests
rpc_flood_wait_total	counter	method	FLOOD_WAIT errors
rpc_timeout_total	counter	method	Timed-out or cancelled requests

Status values

Status	Condition
success	RPC returned no error
error	RPC returned an error (non-flood, non-timeout)
flood_wait	FLOOD_WAIT / FLOOD_PREMIUM_WAIT
timeout	context.DeadlineExceeded
cancelled	context.Canceled

Collectors

SQLite

Persists cumulative counters to SQL with automatic schema migration. Counters stay in memory for zero-latency writes; a background goroutine snapshots to the database at a configurable interval. Survives process restarts.

mc, _ := metrics.NewSQLiteCollector(db, metrics.WithFlushInterval(30*time.Second))

In-memory

For tests and ephemeral bots:

mc := metrics.NewMemoryCollector()

Prometheus

Standard Prometheus counters, histograms, and gauges:

pc := metrics.NewPrometheusCollector("mtgo")
prometheus.MustRegister(pc.Collectors()...)

Custom

Implement the Collector interface for OpenTelemetry, StatsD, or any backend.

Composition

Register metrics first (outermost) so it observes the final result including retries:

client.UseInvokerMiddleware(mw.Middleware())              // metrics
client.UseInvokerMiddleware(floodwait.New().Middleware())  // retries
client.UseInvokerMiddleware(ratelimit.New(30, 10).Middleware())