Resilience4j

https://resilience4j.github.io/resilience4j/
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Resilience4j is a lightweight fault tolerance library for Java that provides higher-order functions...
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### Decorating functional interfaces with Resilience4j

Source: https://resilience4j.github.io/resilience4j

Demonstrates how to configure and stack decorators like CircuitBreaker, Retry, and Bulkhead on a supplier. It also shows how to execute a supplier with a CircuitBreaker and how to handle asynchronous calls with a ThreadPoolBulkhead and TimeLimiter.

```java
// Create a CircuitBreaker with default configuration
CircuitBreaker circuitBreaker = CircuitBreaker
  .ofDefaults("backendService");

// Create a Retry with default configuration
// 3 retry attempts and a fixed time interval between retries of 500ms
Retry retry = Retry
  .ofDefaults("backendService");

// Create a Bulkhead with default configuration
Bulkhead bulkhead = Bulkhead
  .ofDefaults("backendService");

Supplier<String> supplier = () -> backendService
  .doSomething(param1, param2)

// Decorate your call to backendService.doSomething() 
// with a Bulkhead, CircuitBreaker and Retry
// **note: you will need the resilience4j-all dependency for this
Supplier<String> decoratedSupplier = Decorators.ofSupplier(supplier)
  .withCircuitBreaker(circuitBreaker)
  .withBulkhead(bulkhead)
  .withRetry(retry)  
  .decorate();

// When you don't want to decorate your lambda expression,
// but just execute it and protect the call by a CircuitBreaker.
String result = circuitBreaker
  .executeSupplier(backendService::doSomething);

// You can also run the supplier asynchronously in a ThreadPoolBulkhead
 ThreadPoolBulkhead threadPoolBulkhead = ThreadPoolBulkhead
  .ofDefaults("backendService");

// The Scheduler is needed to schedule a timeout 
// on a non-blocking CompletableFuture
ScheduledExecutorService scheduledExecutorService = Executors.newScheduledThreadPool(3);
TimeLimiter timeLimiter = TimeLimiter.of(Duration.ofSeconds(1));

CompletableFuture<String> future = Decorators.ofSupplier(supplier)
    .withThreadPoolBulkhead(threadPoolBulkhead)
    .withTimeLimiter(timeLimiter, scheduledExecutorService)
    .withCircuitBreaker(circuitBreaker)
    .withFallback(asList(TimeoutException.class, 
                         CallNotPermittedException.class, 
                         BulkheadFullException.class),  
                  throwable -> "Hello from Recovery")
    .get().toCompletableFuture();
```
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