Circuit Breaker

Protect your application and downstream systems from cascading failures by automatically “tripping” when a procedure fails repeatedly.

Once open, subsequent calls fail fast with a CIRCUIT_OPEN error, preventing resource exhaustion.


const fetchService = procedure
  .name("inventoryService")
  .circuitBreaker({
    failureThreshold: 3,        // Trip after 3 consecutive failures
    resetTimeout: 60000,        // Stay open for 1 minute before checking again
    onStateChange: (state, name) => {
      console.log(`Circuit Breaker ${name} transitioned to ${state}`);
    },
  })
  .query(async () => {
    return await fetchInventoryFromSupplier();
  });

Circuit Breaker Options

Option	Type	Default	Description
`failureThreshold`	`number`	`5`	Number of consecutive failures required to open the circuit.
`resetTimeout`	`number`	`30000`	Cooldown period in ms before transitioning to half-open state.
`onStateChange`	`(state, name) => void`	—	Callback run when transitioning between `CLOSED`, `OPEN`, and `HALF_OPEN`.

Circuit States

CLOSED: Normal operation. All calls pass through to the handler.
OPEN: Tripped due to failures. All calls fail immediately with a CIRCUIT_OPEN error.
HALF_OPEN: After the resetTimeout cooldown, the circuit allows a single test request through. If it succeeds, the circuit returns to CLOSED. If it fails, it returns to OPEN for another cooldown.