performance-monitoring

name	Performance & Monitoring
description	Logging, caching, health checks, and query optimization for SE104_VLEAGUE

Performance & Monitoring Skill

Implementation Status

Feature	Status
Structured logging (nestjs-pino)	✅ Implemented
Request timing (LoggingInterceptor)	✅ Implemented
In-memory caching	✅ Implemented (standings)
Health checks	✅ Implemented
Rate limiting	✅ Implemented (ThrottlerGuard)
Sentry error tracking (frontend)	✅ Implemented
Audit logging	✅ Available (not globally applied)

---

Structured Logging (nestjs-pino)

Configured in src/common/logger/logger.module.ts:

• Production: JSON structured logs, redaction of sensitive fields
• Development: Pretty-printed with pino-pretty
• Request ID: Auto-generated per request, included in all logs
• Redaction: Automatically redacts authorization, cookie, password fields

// Usage in services
import { Logger } from '@nestjs/common';

@Injectable()
export class MyService {
  private readonly logger = new Logger(MyService.name);

  async doWork() {
    this.logger.log('Processing started');
    this.logger.warn('Slow operation detected');
    this.logger.error('Operation failed', error.stack);
  }
}

---

Request Timing (LoggingInterceptor)

Global interceptor in src/common/interceptors/logging.interceptor.ts:

• Logs every request entry and exit with timing
• Visual indicators: 🟢 <100ms, 🟡 <500ms, 🔴 >500ms
• Adds Server-Timing header to responses
• Logs response body size

---

Caching

Configuration

// app.module.ts
CacheModule.register({
  ttl: 60000, // 60s default TTL
  max: 100, // Max 100 items in cache
  isGlobal: true,
});

Usage — Standings Controller

@Controller('standings')
@UseInterceptors(CacheInterceptor)
export class StandingsController {
  @Get()
  @CacheTTL(30000) // 30 seconds
  async getStandings(@Query('seasonId') seasonId: string) {}
}

---

Rate Limiting (ThrottlerGuard)

Global guard with 4 named configurations:

Name	Limit	TTL
default	100 requests	60s
short	20 requests	1s
medium	50 requests	10s
long	30 requests	60s

Override per-endpoint:

@Throttle({ short: { limit: 5, ttl: 60000 } })  // 5/min
@Post('login')
async login() {}

@SkipThrottle()  // Bypass entirely
@Get('me')
async getMe() {}

---

Health Checks

GET /api/health — Public, skip throttle.

Checks:

1. Database connectivity: Prisma $queryRaw ping
2. Memory heap: Warning if heap exceeds 150MB

Response:

{
  "status": "ok",
  "info": {
    "database": { "status": "up" },
    "memory_heap": { "status": "up" }
  }
}

---

Sentry (Frontend)

Configured in main.tsx:

Sentry.init({
  dsn: import.meta.env.VITE_SENTRY_DSN,
  integrations: [Sentry.browserTracingIntegration(), Sentry.replayIntegration()],
  tracesSampleRate: 1.0, // 100% in dev
  replaysSessionSampleRate: 0.1, // 10%
  replaysOnErrorSampleRate: 1.0, // 100% on errors
});

ErrorBoundary component reports errors to Sentry.

---

Audit Logging

AuditLogInterceptor (src/common/interceptors/audit-log.interceptor.ts):

• Logs POST/PATCH/PUT/DELETE mutations
• Captures: entity, action, user ID, IP address
• Available but NOT globally applied — use @UseInterceptors(AuditLogInterceptor) selectively

---

Query Optimization Best Practices

1. Select fields: this.prisma.team.findMany({ select: { id: true, name: true } })
2. Pagination: Always skip/take with count() for large tables
3. Indexes: Key columns (seasonId, teamId, status) already indexed
4. Avoid N+1: Use include for nested relations
5. Parallel queries: Promise.all([findMany(), count()]) for paginated results
6. Computed standings: Calculated from match events (not stored), cached 30s via interceptor