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Implementation Architecture

The API implements a distributed token bucket algorithm for precise throughput control. Each IP address receives an isolated bucket with the following constraints:
  • Bucket Capacity: 500 tokens
  • Refill Rate: 500 tokens/second
  • Time Resolution: Millisecond precision

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Rate Control Headers

The system implements RFC 6585 compliant rate control headers:
HeaderTypeDescription
X-RateLimit-LimitIntegerBucket capacity
X-RateLimit-RemainingIntegerCurrent token count
X-RateLimit-ResetUnix TimestampNext refill timestamp
Implementation example: 
X-RateLimit-Limit: 500
X-RateLimit-Remaining: 499
X-RateLimit-Reset: 1702544876

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Throughput Control Response

When bucket capacity is exceeded: 
{
  "status": 429,
  "message": "Rate limit exceeded: throughput constraint violation",
  "error_code": "RATE_LIMIT_EXCEEDED"
}
The response includes a Retry-After header indicating millisecond-precision backoff duration.

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Implementation Patterns

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Token Monitoring

Implement continuous token monitoring: 
function monitorRateLimit(response: Response): void {
  const remaining = parseInt(response.headers.get('X-RateLimit-Remaining'));
  const resetTime = parseInt(response.headers.get('X-RateLimit-Reset'));
  const currentTime = Math.floor(Date.now() / 1000);
  
  console.log(`Tokens remaining: ${remaining}`);
  console.log(`Reset in: ${resetTime - currentTime}s`);
}

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Backoff Implementation

Implement exponential backoff with jitter: 
async function backoffStrategy(retryCount: number): Promise<void> {
  const base = 100; // Base delay in ms
  const maxDelay = 10000; // Maximum delay in ms
  const jitter = Math.random() * 100;
  
  const delay = Math.min(
    maxDelay,
    Math.pow(2, retryCount) * base + jitter
  );
  
  await new Promise(resolve => setTimeout(resolve, delay));
}