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Circuit Breaker

The Circuit Breaker in Solvix protects your application from cascading failures when a service becomes unstable.

It temporarily stops requests to failing services and allows them to recover before retrying.

Why Circuit Breaker?​

In production systems:

  • APIs can fail repeatedly
  • Retrying continuously can overload services
  • Downstream systems can collapse

Circuit breaker prevents this by "breaking the circuit".

Basic usage​

const client = createClient({
  circuitBreaker: {
    failureThreshold: 5,
    cooldownTime: 10000,
  },
});

Configuration​

circuitBreaker: {
  failureThreshold: number,
  cooldownTime: number
}

Options explained​

failureThreshold​

Number of consecutive failures before circuit opens.

failureThreshold: 5;

cooldownTime​

Time (ms) before retrying requests after circuit opens.

cooldownTime: 10000;

How it works​

  1. Requests succeed → circuit stays closed
  2. Failures increase → threshold reached
  3. Circuit opens → requests are blocked
  4. Cooldown period starts
  5. After cooldown → circuit allows limited requests
  6. If successful → circuit closes again

States​

Closed​

  • Normal operation
  • Requests flow normally

Open​

  • Requests blocked
  • Immediate failure returned

Half-Open​

  • Limited requests allowed
  • Used to test recovery

Example​

const client = createClient({
  circuitBreaker: {
    failureThreshold: 3,
    cooldownTime: 5000,
  },
});

Integration with retry​

Circuit breaker works with retry engine:

  • Retry handles temporary failures
  • Circuit breaker handles persistent failures

Error behavior​

When circuit is open:

try {
  await client.get("/api");
} catch (error) {
  console.log(error.message); // Circuit open
}

Best practices​

  • Set reasonable thresholds
  • Combine with retry and rate limiting
  • Monitor failure patterns
  • Avoid too aggressive blocking

Summary​

Circuit breaker prevents system overload by stopping requests to failing services.