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Overview

This library aims to provide functionality for handling common tasks efficiently through a set of simple APIs.

The public APIs placed in the pub package, are currently implemented classes with functionality:

AsyncHandler - an interface for handling asynchronous operations

To get a value "Success" value or fallback to "Default" value after 2 seconds asynchronously, here is what we typically do:

ExecutorService executorService = Executors.newFixedThreadPool(2);
CompletableFuture<String> completableFuture = CompletableFuture.supplyAsync(() -> {
	return "Success";
}, executorService);
String result = "Default";
try {
    result = completableFuture.get(2000L, TimeUnit.MILLISECONDS);
} catch (InterruptedException e) {
...
} catch (ExecutionException e) {
...
} catch (TimeoutException e) {
...
}
System.out.println(result);

What we want to achieve is simple, but there is too much information we need to take care of in this case. What is an ExecutorService, what is CompletetableFuture, why are there so many different exceptions, and what should we do in case they occurred?

AsyncHandler gives you a set of simple APIs to handle asynchronous operations, taking care of timeout, retries, and unnecessary try-catch blocks. Now, here is how we achieve the equivalent result with AsyncHandler:

AsyncHandler.withDefault().awaitWithTimeout(() -> "Success", 2_000L, "Default");

1 line of code, it computes the result asynchronously and gives you back the "Default" if it fails.

  • Truly async, a task executed by a worker and then consumed asynchronously:
ThrowableConsumer<String> resultHandler = result -> {
    System.out.println("Task completed successfully with result: " + result);
};
AsyncHandler.withDefault().awaitAsync(() -> "Hello World", resultHandler);
  • Timeout with retries:
AsyncHandler.withDefault().awaitWithTimeoutRetries(() -> "Success", 5_000L, 5, "Default");
  • Retries with backoff strategy:
AsyncHandler.withDefault().awaitBackoff(() -> someExpensiveOperation(), 5, "Default");
  • Retries with backoff and timeout:
AsyncHandler.withDefault().awaitBackoffWithTimeout(() -> someExpensiveOperation(), 60_000L, 5, "Default");
  • AsychHandler can also be customized, with custom backoff configs and thread-pool size:
// a backoff config with an initial delay of 100 milliseconds, a multiple of 2 and the max delay for 30 seconds
BackoffConfig backoffConfig = new BackoffConfig(100L, 2, 30_000);
AsyncHandler.withDefault().awaitBackoffWithBackoffConfig(() -> someExpensiveOperation(), 5, "Default", backoffConfig);

// custom pool size:
String val = AsyncHandler.withPoolSize(5).await(() -> "Result", "Default"); 
// with cached pool size:
String anotherVal = AsyncHandler.withCachedPoolSize(5).await(() -> "Result", "Default");

More detail documentation can be found in the AsyncHandler interface.