Exception Policy¶

Controls what happens when recovery finds no valid stored entry — re-throw the original exception, return null, or run your own logic.

Three Strategies¶

Strategy	Behaviour	Config value
`RETHROW`	Re-throws the original upstream exception	`rethrow` (default)
`NEVER_THROW`	Returns `null` (or `RecoveredPayloadHandler` result)	`never_throw`
`CUSTOM`	Your own `MethodExceptionPolicy` bean	`custom`

RETHROW (Default)¶

The upstream exception propagates to the caller when no stored entry is found or all entries are expired.

application.yml

failover:
  exception-policy: rethrow

Use RETHROW when callers must know that the upstream is unavailable and cannot gracefully handle a null response.

NEVER_THROW¶

Returns null (or the value from RecoveredPayloadHandler) instead of propagating the exception. The caller receives null on no recovery.

application.yml

failover:
  exception-policy: never_throw

Combine with RecoveredPayloadHandler

Pair never_throw with a RecoveredPayloadHandler to return an empty list, a default object, or any safe fallback instead of null. See Recovered Payload Handler.

CUSTOM — Implement MethodExceptionPolicy¶

LogAndNeverThrowPolicy.java

@Component
public class LogAndNeverThrowPolicy implements MethodExceptionPolicy {

    @Override
    public void handle(MethodExceptionContext context) {
        log.warn("Failover: no recovery for '{}', suppressing exception",
                 context.getFailover().name(), context.getCause());
        // returning without throwing means the caller gets null
    }
}

application.yml

failover:
  exception-policy: custom

MethodExceptionContext carries: - getFailover() — the @Failover annotation metadata - getArgs() — the original method arguments - getCause() — the upstream exception - getClazz() — the return type class

Next Steps¶

Recovered Payload Handler — return a safe default on null recovery
Properties Reference — failover.exception-policy