@Test
public void shouldReturnFailureWithCircuitBreakerOpenException() {
// Given
// Create a custom configuration for a CircuitBreaker
CircuitBreakerConfig circuitBreakerConfig =
CircuitBreakerConfig.custom()
.ringBufferSizeInClosedState(2)
.ringBufferSizeInHalfOpenState(2)
.failureRateThreshold(50)
.waitDurationInOpenState(Duration.ofMillis(1000))
.build();
// Create a CircuitBreakerRegistry with a custom global configuration
CircuitBreakerRegistry circuitBreakerRegistry = CircuitBreakerRegistry.of(circuitBreakerConfig);
CircuitBreaker circuitBreaker = circuitBreakerRegistry.circuitBreaker("testName");
circuitBreaker.recordFailure(new RuntimeException());
circuitBreaker.recordFailure(new RuntimeException());
assertThat(circuitBreaker.getState()).isEqualTo(CircuitBreaker.State.OPEN);
// When
Try.CheckedRunnable checkedRunnable =
CircuitBreaker.decorateCheckedRunnable(
() -> {
throw new RuntimeException("BAM!");
},
circuitBreaker);
Try result = Try.run(checkedRunnable);
// Then
assertThat(result.isFailure()).isTrue();
assertThat(result.failed().get()).isInstanceOf(CircuitBreakerOpenException.class);
}
@Test
public void shouldThrowCircuitBreakerOpenException() {
// tag::shouldThrowCircuitBreakerOpenException[]
// Given
CircuitBreakerConfig circuitBreakerConfig =
CircuitBreakerConfig.custom()
.ringBufferSizeInClosedState(2)
.waitDurationInOpenState(Duration.ofMillis(1000))
.build();
CircuitBreakerRegistry circuitBreakerRegistry = CircuitBreakerRegistry.of(circuitBreakerConfig);
CircuitBreaker circuitBreaker = circuitBreakerRegistry.circuitBreaker("uniqueName");
// Simulate a failure attempt
circuitBreaker.recordFailure(new RuntimeException());
// CircuitBreaker is still CLOSED, because 1 failure is allowed
assertThat(circuitBreaker.getState()).isEqualTo(CircuitBreaker.State.CLOSED);
// Simulate a failure attempt
circuitBreaker.recordFailure(new RuntimeException());
// CircuitBreaker is OPEN, because the failure rate is above 50%
assertThat(circuitBreaker.getState()).isEqualTo(CircuitBreaker.State.OPEN);
// When I decorate my function and invoke the decorated function
Try<String> result =
Try.of(CircuitBreaker.decorateCheckedSupplier(() -> "Hello", circuitBreaker))
.map(value -> value + " world");
// Then the call fails, because CircuitBreaker is OPEN
assertThat(result.isFailure()).isTrue();
// Exception is CircuitBreakerOpenException
assertThat(result.failed().get()).isInstanceOf(CircuitBreakerOpenException.class);
// end::shouldThrowCircuitBreakerOpenException[]
}
@Test
public void shouldNotRecordIOExceptionAsAFailure() {
// tag::shouldNotRecordIOExceptionAsAFailure[]
// Given
CircuitBreakerConfig circuitBreakerConfig =
CircuitBreakerConfig.custom()
.ringBufferSizeInClosedState(2)
.ringBufferSizeInHalfOpenState(2)
.waitDurationInOpenState(Duration.ofMillis(1000))
.recordFailure(
throwable ->
API.Match(throwable)
.of(Case(instanceOf(WebServiceException.class), true), Case($(), false)))
.build();
CircuitBreakerRegistry circuitBreakerRegistry = CircuitBreakerRegistry.of(circuitBreakerConfig);
CircuitBreaker circuitBreaker = circuitBreakerRegistry.circuitBreaker("testName");
// Simulate a failure attempt
circuitBreaker.recordFailure(new RuntimeException());
// CircuitBreaker is still CLOSED, because 1 failure is allowed
assertThat(circuitBreaker.getState()).isEqualTo(CircuitBreaker.State.CLOSED);
// When
Try.CheckedRunnable checkedRunnable =
CircuitBreaker.decorateCheckedRunnable(
() -> {
throw new SocketTimeoutException("BAM!");
},
circuitBreaker);
Try result = Try.run(checkedRunnable);
// Then
assertThat(result.isFailure()).isTrue();
// CircuitBreaker is still CLOSED, because SocketTimeoutException has not been recorded as a
// failure
assertThat(circuitBreaker.getState()).isEqualTo(CircuitBreaker.State.CLOSED);
assertThat(result.failed().get()).isInstanceOf(IOException.class);
// end::shouldNotRecordIOExceptionAsAFailure[]
}
@Test(expected = IllegalArgumentException.class)
public void zeroWaitIntervalShouldFail() {
CircuitBreakerConfig.custom().waitInterval(0).build();
}
@Test(expected = IllegalArgumentException.class)
public void zeroMaxFailuresShouldFail() {
CircuitBreakerConfig.custom().maxFailures(0).build();
}