resilience4j-circuitB-study.java

    @Test
    public void testCB() {
        final CircuitBreaker breaker = CircuitBreaker.of("", CircuitBreakerConfig.custom()
            .slidingWindowSize(60)
            .slidingWindowType(SlidingWindowType.TIME_BASED)
            .failureRateThreshold(80.0f)
            .minimumNumberOfCalls(200)
            .permittedNumberOfCallsInHalfOpenState(50)
            .waitDurationInOpenState(Duration.ofSeconds(30))
            .build());

        final AtomicInteger calls = new AtomicInteger();
        final AtomicInteger errors = new AtomicInteger();
        final AtomicInteger notPermitted = new AtomicInteger();
        final AtomicBoolean ahopen = new AtomicBoolean();

        final Supplier<String> supplier = breaker.decorateSupplier(() -> {
            boolean hopen = State.HALF_OPEN.equals(breaker.getState());
            boolean odd = calls.incrementAndGet() % (hopen ? 5 : 5) == 0;

            if (hopen) {
                ahopen.set(true);
                System.out.println("CALL IN HALF-OPEN");
            }

            if (!odd) {
                throw new IllegalArgumentException();
            } else {
                return "";
            }
        });

        for (int i = 0; i < 1000; i++) {
            try {
                Thread.sleep(130);
                supplier.get();
            } catch (Throwable t) {
                System.out.println("Calls count: " + calls.get());
                System.out.println("Errors count: " + errors.get());
                System.out.println("Failure rate: " + breaker.getMetrics().getFailureRate());
                System.out.println();
                System.out.println();

                if (t instanceof IllegalArgumentException) {
                    errors.incrementAndGet();
                } else if (t instanceof CallNotPermittedException) {
                    notPermitted.incrementAndGet();
                }
            }
        }

        System.out.println();
        System.out.println();
        System.out.println("Calls count: " + calls.get());
        System.out.println("Errors count: " + errors.get());
        System.out.println("Not permitted count: " + notPermitted.get());
    }