Java Code Examples for java.util.concurrent.CompletionStage#handle()

private DeferredResult<Object> adaptCompletionStage(CompletionStage<?> future) {
	DeferredResult<Object> result = new DeferredResult<>();
	future.handle((BiFunction<Object, Throwable, Object>) (value, ex) -> {
		if (ex != null) {
			if (ex instanceof CompletionException && ex.getCause() != null) {
				ex = ex.getCause();
			}
			result.setErrorResult(ex);
		}
		else {
			result.setResult(value);
		}
		return null;
	});
	return result;
}
 

/**
 * Returns a wrapper of {@code stage} that if {@code stage} failed with exception of
 * {@code exceptionType}, that exception is caught and wrapped inside a {@link Maybe} to complete
 * the wrapper stage normally.
 *
 * <p>This is useful if the asynchronous code is interested in recovering from its own exception
 * without having to deal with other exception types.
 */
public static <T, E extends Throwable> CompletionStage<Maybe<T, E>> catchException(
    Class<E> exceptionType, CompletionStage<? extends T> stage) {
  requireNonNull(exceptionType);
  CompletableFuture<Maybe<T, E>> future = new CompletableFuture<>();
  stage.handle((v, e) -> {
    try {
      if (e == null) {
        future.complete(Maybe.of(v));
      } else {
        unwrapFutureException(exceptionType, e)
            .map(cause -> future.complete(Maybe.except(cause)))
            .orElseGet(() -> future.completeExceptionally(e));
      }
    } catch (Throwable x) {  // Just in case there was a bug. Don't hang the thread.
      if (x != e) x.addSuppressed(e);
      future.completeExceptionally(x);
    }
    return null;
  });
  return future;
}
 

@Override
public DeferredResult<?> adaptToDeferredResult(Object returnValue) {
	Assert.isInstanceOf(CompletionStage.class, returnValue, "CompletionStage expected");
	final DeferredResult<Object> result = new DeferredResult<Object>();
	@SuppressWarnings("unchecked")
	CompletionStage<?> future = (CompletionStage<?>) returnValue;
	future.handle(new BiFunction<Object, Throwable, Object>() {
		@Override
		public Object apply(Object value, Throwable ex) {
			if (ex != null) {
				result.setErrorResult(ex);
			}
			else {
				result.setResult(value);
			}
			return null;
		}
	});
	return result;
}
 

private CompletionStage<AsyncResultSet> executeAsyncOnSession(Statement statement) {
    try {
        this.semaphore.acquire();
        CompletionStage<AsyncResultSet> async = this.session.executeAsync(statement);
        async.handle((result, exception) -> {
            this.semaphore.release();
            if (exception != null) {
                return exception;
            } else {
                return result;
            }
        });
        return async;
    } catch (InterruptedException e) {
        this.semaphore.release();
        Thread.currentThread().interrupt();
        throw new JanusGraphException("Interrupted while acquiring resource to execute query on Session.");
    }
}
 

@Override
protected CompletionStage<HttpServletResponse> doExecute(final Routes.Route route,
                                                         final HttpServletRequest req, final HttpServletResponse resp,
                                                         final String prefix) throws IOException {
    final CompletionStage<HttpServletResponse> stage;
    if (spy.isHasBeforeEvent()) {
        final BeforeRequest event = new BeforeRequest(req, resp);
        event.setRoute(route);
        event.setPrefix(prefix);
        beforeRequestEvent.fire(event);
        stage = super.doExecute(event.getRoute(), req, resp, event.getPrefix());
    } else {
        stage = super.doExecute(route, req, resp, prefix);
    }
    if (!spy.isHasAfterEvent()) {
        return stage;
    }
    return stage.handle((r, t) -> {
        afterResponseEvent.fire(new AfterResponse(req, resp));
        return r;
    });
}
 

/**
 * Adds a callback that transfers the outcome of the specified {@link CompletionStage} to the specified
 * {@link AsyncMethodCallback}.
 *
 * <pre>{@code
 * > public class MyThriftService implements ThriftService.AsyncIface {
 * >     @Override
 * >     public void myServiceMethod(AsyncMethodCallback<MyResult> callback) {
 * >         final CompletableFuture<MyResult> future = ...;
 * >         AsyncMethodCallbacks.transfer(future, callback);
 * >     }
 * > }
 * }</pre>
 */
public static <T> void transfer(CompletionStage<T> src, AsyncMethodCallback<? super T> dest) {
    requireNonNull(src, "src");
    requireNonNull(dest, "dest");
    src.handle((res, cause) -> {
        try {
            if (cause != null) {
                invokeOnError(dest, cause);
            } else {
                dest.onComplete(res);
            }
        } catch (Exception e) {
            CompletionActions.log(e);
        }
        return null;
    });
}
 

/**
 * Creates a new {@link RpcResponse} that is completed successfully or exceptionally based on the
 * completion of the specified {@link CompletionStage}.
 */
static RpcResponse from(CompletionStage<?> stage) {
    requireNonNull(stage, "stage");
    final CompletableRpcResponse res = new CompletableRpcResponse();
    stage.handle((value, cause) -> {
        if (cause != null) {
            res.completeExceptionally(cause);
        } else if (value instanceof RpcResponse) {
            ((RpcResponse) value).handle((rpcResponseResult, rpcResponseCause) -> {
                if (rpcResponseCause != null) {
                    res.completeExceptionally(Exceptions.peel(rpcResponseCause));
                } else {
                    res.complete(rpcResponseResult);
                }
                return null;
            });
        } else {
            res.complete(value);
        }
        return null;
    });
    return res;
}
 

/**
 * Returns a {@link CompletionStage} that makes sure the current {@link RequestContext} is set and
 * then invokes the input {@code stage}.
 */
default <T> CompletionStage<T> makeContextAware(CompletionStage<T> stage) {
    final CompletableFuture<T> future = JavaVersionSpecific.get().newRequestContextAwareFuture(this);
    stage.handle((result, cause) -> {
        try (SafeCloseable ignored = push()) {
            if (cause != null) {
                future.completeExceptionally(cause);
            } else {
                future.complete(result);
            }
        } catch (Throwable t) {
            future.completeExceptionally(t);
        }
        return null;
    });
    return future;
}
 

@Override
public CompletionStage<Boolean> initialize(boolean reset) throws Exception {
    CompletionStage<RestResponse> caches = client.caches();
    RestResponse result = caches.toCompletableFuture().get();
    String body = result.getBody();
    if (result.getStatus() != 200) {
        log.log(Level.SEVERE, body);
        return CompletableFuture.completedFuture(Boolean.FALSE);
    }
    boolean hasProto = cacheExists(body, PROTO_CACHE);
    boolean hasSearch = cacheExists(body, cacheName);
    if (reset) {
        reset(hasProto, PROTO_CACHE, SEARCH_PROTO_KEY);
        reset(hasProto, PROTO_CACHE, COMMON_PROTO_KEY);
        reset(hasSearch, cacheName, null);
    }

    CompletionStage<RestResponse> cs = null;

    if (reset || !hasProto) {
        cs = registerProto(COMMON_PROTO_KEY).thenCompose(r -> registerProto(SEARCH_PROTO_KEY));
    }

    if (reset || !hasSearch) {
        RestEntity configEntity = new StringRestEntityOkHttp(MediaType.APPLICATION_JSON, JSON_CACHE_CONFIG);
        CompletionStage<RestResponse> searchCs = getCache().createWithConfiguration(configEntity);
        cs = (cs != null) ? cs.thenCombine(searchCs, RFN) : searchCs;
    }
    return (cs != null) ? cs.handle((r, t) -> (t == null)) : CompletableFuture.completedFuture(Boolean.TRUE);
}
 

private DeferredResult<Object> adaptCompletionStage(CompletionStage<?> future) {
	DeferredResult<Object> result = new DeferredResult<>();
	future.handle((BiFunction<Object, Throwable, Object>) (value, ex) -> {
		if (ex != null) {
			result.setErrorResult(ex);
		}
		else {
			result.setResult(value);
		}
		return null;
	});
	return result;
}
 

private static <T> CompletionStage<T> naiveExceptionHandlingCode(
    CompletionStage<T> stage) {
  return stage.handle((v, e) -> {
    assertThat(e).isInstanceOf(MyException.class);
    return null;
  });
}
 

/** Demo utility method for external reliable toCompletableFuture */
static <T> CompletableFuture<T> toCompletableFuture(CompletionStage<T> stage) {
    CompletableFuture<T> f = new CompletableFuture<>();
    stage.handle((T t, Throwable ex) -> {
                     if (ex != null) f.completeExceptionally(ex);
                     else f.complete(t);
                     return null;
                 });
    return f;
}
 

void delegateWhenComplete(CompletionStage<? extends HttpResponse> stage) {
    requireNonNull(stage, "stage");
    stage.handle((delegate, thrown) -> {
        if (thrown != null) {
            close(Exceptions.peel(thrown));
        } else if (delegate == null) {
            close(new NullPointerException("delegate stage produced a null response: " + stage));
        } else {
            delegate(delegate);
        }
        return null;
    });
}
 

@Test
public void handleShouldAcceptUnwrappedException() {
    CompletionStage<String> completionStage = createCompletionStage(EXCEPTION);

    BiFunction<String, Throwable, ?> handler = mock(BiFunction.class);
    completionStage.handle(handler);

    finish(completionStage);
    verify(handler, times(1)).apply(null, EXCEPTION);
}
 

@Test
public void handleShouldBeCalled() {
    CompletionStage<String> completionStage = createCompletionStage(VALUE);

    BiFunction<String, Throwable, Integer> consumer = mock(BiFunction.class);
    completionStage.handle(consumer);

    finish(completionStage);

    verify(consumer).apply(VALUE, null);
}
 

/**
 * Creates a CompletionStage that, when it completes, will capture into a Try whether the given completionStage
 * was successful or not
 *
 * @param completionStage the completion stage that will complete
 * @param <V>             the value type
 *
 * @return a Try which is the result of the call
 */
public static <V> CompletionStage<Try<V>> tryStage(CompletionStage<V> completionStage) {
    return completionStage.handle((value, throwable) -> {
        if (throwable != null) {
            return failed(throwable);
        }
        return succeeded(value);
    });
}