@fortify-ts/bulkhead

Bulkhead (concurrency limiter) pattern for the Fortify-TS resilience library.

Installation

``bash
npm install @fortify-ts/bulkhead


or


pnpm add @fortify-ts/bulkhead
`

Features

- Concurrency Limiting: Control maximum parallel executions
- Request Queueing: Queue excess requests with optional timeout
- Rejection Handling: Reject when at capacity
- Metrics: Track active and queued requests

Usage

$3

`typescript
import { Bulkhead } from '@fortify-ts/bulkhead';

const bulkhead = new Bulkhead({
maxConcurrent: 10,
});

try {
const result = await bulkhead.execute(async (signal) => {
return fetch('/api/data', { signal });
});
} catch (error) {
if (error instanceof BulkheadFullError) {
console.log('Too many concurrent requests');
}
}
`

$3

`typescript
const bulkhead = new Bulkhead({
maxConcurrent: 10,
maxQueue: 100, // Queue up to 100 requests
queueTimeout: 5000, // 5 second queue timeout
});
`

$3

`typescript
const bulkhead = new Bulkhead({
// Maximum concurrent executions
maxConcurrent: 10,

// Maximum queued requests (0 = no queue)
maxQueue: 100,

// Queue timeout in milliseconds
queueTimeout: 5000,

// Rejection callback
onRejected: (activeCount, queuedCount) => {
console.log(Rejected: ${activeCount} active, ${queuedCount} queued);
},

// Optional logger
logger: myLogger,
});
`

$3

`typescript
// Get current counts
const activeCount = bulkhead.getActiveCount();
const queuedCount = bulkhead.getQueuedCount();

// Check if at capacity
const isFull = activeCount >= config.maxConcurrent;
`

$3

`typescript
// Close bulkhead (rejects queued requests)
await bulkhead.close();
`

Configuration Reference

| Option | Type | Default | Description |
|--------|------|---------|-------------|
| maxConcurrent | number | 10 | Max parallel executions |
| maxQueue | number | 0 | Max queued requests |
| queueTimeout | number | - | Queue timeout (ms) |
| onRejected | function | - | Rejection callback |
| logger | FortifyLogger | - | Optional logger |

Error Types

| Error | Description |
|-------|-------------|
| BulkheadFullError | Bulkhead and queue at capacity |
| BulkheadClosedError` | Bulkhead has been closed |

License

MIT