git.gumartinm.name Git - JavaForFun/blob

   1 package de.spring.webservices.rest.controller.adapters;
   2
   3 import java.util.concurrent.CompletableFuture;
   4
   5 import org.slf4j.Logger;
   6 import org.slf4j.LoggerFactory;
   7 import org.springframework.web.context.request.async.DeferredResult;
   8
   9 public class CompletableFutureAdapter {
  10         private static final Logger LOGGER = LoggerFactory.getLogger(CompletableFutureAdapter.class);
  11
  12         // With no value, we depend on the Tomcat/Jboss/Jetty/etc timeout value for asynchronous requests.
  13         // Spring will answer after 60 secs with an empty response (by default) and HTTP 503 status (by default) when timeout.
  14         private static final long ASYNC_TIMEOUT = 60000;  /* milliseconds */
  15
  16
  17         @FunctionalInterface
  18         public interface DeferredCall<T> {
  19
  20                 public T doCall();
  21         }
  22
  23         public static final <T> DeferredResult<T> deferredAdapter(CompletableFuture<T> completableFuture) {
  24
  25         DeferredResult<T> deferredResult = new DeferredResult<>(ASYNC_TIMEOUT);
  26
  27         completableFuture
  28                 .thenAcceptAsync(deferredResult::setResult)
  29                 .exceptionally(exception -> {
  30                         Throwable realException = launderException(exception);
  31
  32                                 LOGGER.error("error: ", realException);
  33
  34                                 deferredResult.setErrorResult(exception);
  35                                 return null;
  36                         });
  37
  38         return deferredResult;
  39         }
  40
  41         private static final Throwable launderException(Throwable exception) {
  42                 return exception.getCause() != null
  43                            ? exception.getCause()
  44                            : exception;
  45         }
  46 }