@creadev.org/qos

Quality of Service utilities - retry, timeout, circuit breaker, throttler, bulkhead.

Install

npm install @creadev.org/qos

Usage

Retry with Backoff

import { withRetry } from '@creadev.org/qos';

// Retry with automatic backoff
const result = await withRetry(fetchData(), { 
  retries: 3,
  backoff: 'exponential'
});

Circuit Breaker

import { CircuitBreaker } from '@creadev.org/qos';

const breaker = new CircuitBreaker({
  failureThreshold: 5,
  resetTimeoutMs: 30000
});

try {
  const result = await breaker.execute(() => apiCall());
} catch (err) {
  // Circuit open - failures threshold reached
}

Throttler (from vant)

import { Throttler } from '@creadev.org/qos';

// Throttle to max 10 calls per second
const t = new Throttler({ limit: 10, window: 1000 });
const throttledFn = t.throttle(() => doWork());
// Excess calls are silently dropped

Bulkhead (from vant)

import { Bulkhead } from '@creadev.org/qos';

// Max 5 concurrent
const b = new Bulkhead({ concurrency: 5 });
await b.run(() => apiCall()); // Queued if at limit

Timeout

import { withTimeout } from '@creadev.org/qos';

// Auto-timeout with rejection
const result = await withTimeout(fetchData(), { ms: 5000 });

API

withRetry

| Option | Type | Default | Description | |--------|------|---------|--------------| | retries | number | 3 | Number of retry attempts | | backoff | 'fixed' | 'exponential' | 'exponential' | Backoff strategy | | baseDelayMs | number | 1000 | Base delay |

CircuitBreaker

| Method | Description | |--------|-------------| | breaker.execute(fn) | Execute function, respects circuit state | | breaker.status | 'closed' | 'open' | 'half-open' |

Throttler

| Method | Description | |--------|-------------| | new Throttler(opts) | Create with limit, window ms | | t.throttle(fn) | Wrap function, drops excess calls | | t.clear() | Clear all tracked calls | | t.stats() | Get { tracked, uptime } |

Bulkhead

| Method | Description | |--------|-------------| | new Bulkhead(opts) | Create with concurrency | | b.run(fn) | Execute, queue if at limit | | b.isFull() | Check if at capacity | | b.getStatus() | Get { running, queued, uptime } |

withTimeout

| Option | Type | Description | |--------|------|--------------| | ms | number | Timeout in milliseconds |

License

MIT