Files
scrabble-game/backend/internal/game/metrics.go
T
Ilia Denisov dcd8de8b00
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Stage 12: observability & performance (OTel/OTLP, domain metrics, guest GC)
- pkg/telemetry: shared OTel provider bootstrap (none/stdout/otlp + W3C
  propagators + Go runtime metrics); backend/internal/telemetry becomes a thin
  facade keeping its gin middleware.
- Telemetry parity: gateway and the Telegram connector gain telemetry runtimes
  and config (GATEWAY_/TELEGRAM_ SERVICE_NAME + OTEL_*); otelgrpc instruments the
  backend push server, the gateway's backend+connector clients and the connector
  server. Default exporter stays none (collector/dashboards are Stage 14).
- Operational metrics (variant attribute on game-scoped ones): game_replay_duration,
  game_move_validate_duration, games_started_total, games_abandoned_total,
  game_cache_active, chat_messages_total{kind}, gateway edge_request_duration.
  Wired via the SetMetrics setter pattern (default no-op meter).
- TODO-3: account.GuestReaper deletes guests with no game seat past
  BACKEND_GUEST_RETENTION (default 30d, swept every BACKEND_GUEST_REAP_INTERVAL).
- Tests: pkg/telemetry exporter selection; game/social/edge metric recording via
  a manual reader; config (otlp accepted, guest knobs); inttest guest reaper.
- Docs: PLAN.md re-scopes Stage 12 and adds Stage 13 (alphabet-on-wire) + Stage 14
  (CI/deploy) with the agreed dictionary-versioning resolution; ARCHITECTURE 11/13,
  TESTING, the three READMEs and FUNCTIONAL(+ru) updated.
2026-06-04 14:22:15 +02:00

110 lines
4.1 KiB
Go

package game
import (
"context"
"time"
"go.opentelemetry.io/otel/attribute"
"go.opentelemetry.io/otel/metric"
"go.opentelemetry.io/otel/metric/noop"
"go.uber.org/zap"
"scrabble/backend/internal/engine"
)
// meterName scopes the game domain's OpenTelemetry instruments.
const meterName = "scrabble/backend/game"
// gameMetrics holds the game domain's operational instruments. Every game-scoped
// measurement carries a "variant" attribute (english/russian/erudit). The
// instruments default to no-ops (see defaultGameMetrics), so recording is always
// safe; SetMetrics installs the real meter during startup wiring.
type gameMetrics struct {
replay metric.Float64Histogram
validate metric.Float64Histogram
started metric.Int64Counter
abandoned metric.Int64Counter
}
// defaultGameMetrics returns instruments backed by a no-op meter, recording
// nothing until SetMetrics installs a real one.
func defaultGameMetrics() *gameMetrics {
return newGameMetrics(noop.NewMeterProvider().Meter(meterName))
}
// newGameMetrics builds the instruments on meter, falling back to no-op
// instruments on the (rare) construction error so the game domain never fails to
// start over telemetry.
func newGameMetrics(meter metric.Meter) *gameMetrics {
return &gameMetrics{
replay: histogram(meter, "game_replay_duration", "Seconds to rebuild a live game from its journal on a cache miss."),
validate: histogram(meter, "game_move_validate_duration", "Seconds to validate and score a tentative play (EvaluatePlay)."),
started: counter(meter, "games_started_total", "Games created and started."),
abandoned: counter(meter, "games_abandoned_total", "Player seats dropped by the turn-timeout sweeper."),
}
}
// SetMetrics installs the meter the game domain records to and registers the
// observable gauge reporting the live games resident in the cache by variant. It
// must be called during startup wiring; the default is a no-op meter.
func (svc *Service) SetMetrics(meter metric.Meter) {
if meter == nil {
return
}
svc.metrics = newGameMetrics(meter)
if _, err := meter.Int64ObservableGauge("game_cache_active",
metric.WithDescription("Live games currently resident in the in-memory cache, by variant."),
metric.WithInt64Callback(func(_ context.Context, o metric.Int64Observer) error {
for variant, n := range svc.cache.countByVariant() {
o.Observe(int64(n), metric.WithAttributes(attribute.String("variant", variant)))
}
return nil
}),
); err != nil {
svc.log.Warn("game: register cache gauge", zap.Error(err))
}
}
// recordReplay records the duration of a cache-miss journal replay for variant.
func (m *gameMetrics) recordReplay(ctx context.Context, v engine.Variant, start time.Time) {
m.replay.Record(ctx, time.Since(start).Seconds(), variantAttr(v))
}
// recordValidate records the duration of one play validation for variant.
func (m *gameMetrics) recordValidate(ctx context.Context, v engine.Variant, start time.Time) {
m.validate.Record(ctx, time.Since(start).Seconds(), variantAttr(v))
}
// recordStarted counts one started game of variant.
func (m *gameMetrics) recordStarted(ctx context.Context, v engine.Variant) {
m.started.Add(ctx, 1, variantAttr(v))
}
// recordAbandoned counts one seat dropped by the turn-timeout sweeper in a game of
// variant.
func (m *gameMetrics) recordAbandoned(ctx context.Context, v engine.Variant) {
m.abandoned.Add(ctx, 1, variantAttr(v))
}
// variantAttr is the shared "variant" attribute option, usable for both Record and
// Add measurements.
func variantAttr(v engine.Variant) metric.MeasurementOption {
return metric.WithAttributes(attribute.String("variant", v.String()))
}
func histogram(m metric.Meter, name, desc string) metric.Float64Histogram {
h, err := m.Float64Histogram(name, metric.WithUnit("s"), metric.WithDescription(desc))
if err != nil {
h, _ = noop.NewMeterProvider().Meter(meterName).Float64Histogram(name)
}
return h
}
func counter(m metric.Meter, name, desc string) metric.Int64Counter {
c, err := m.Int64Counter(name, metric.WithDescription(desc))
if err != nil {
c, _ = noop.NewMeterProvider().Meter(meterName).Int64Counter(name)
}
return c
}