Java Futures.transformAsync方法代碼示例

import com.google.common.util.concurrent.Futures; //導入方法依賴的package包/類
@Produces
static ListenableFuture<Recipe> recipe(
    List<String> ingredients,
    SearchResponse searchResponse,
    Supplier<Random> randomSupplier,
    YummlyApi yummly) {
  int totalCount = searchResponse.totalMatchCount();

  ListenableFuture<SearchResponse> future = Futures.immediateFuture(null);
  // Get a random recipe to return. Search request fails randomly so try a few times.
  Executor executor = RequestContext.current().contextAwareEventLoop();
  Random random = randomSupplier.get();
  for (int i = 0; i < 5; i++) {
    int resultIndex = random.nextInt(totalCount);
    future =
        Futures.transformAsync(
            future,
            result -> {
              if (result != null && !result.matches().isEmpty()) {
                return Futures.immediateFuture(result);
              }
              return yummly.search(
                  EggworldConstants.EGG_QUERY,
                  ingredients,
                  resultIndex,
                  1,
                  true,
                  ImmutableList.of());
            },
            executor);
  }

  return Futures.transform(future, r -> r.matches().get(0), MoreExecutors.directExecutor());
}
 

import com.google.common.util.concurrent.Futures; //導入方法依賴的package包/類
@Override
public ListenableFuture<Void> submit() {
    LOG.debug("Submitting transaction for shard {}", shardRoot);

    checkTransactionReadied();

    final AsyncFunction<Boolean, Void> validateFunction = input -> prepare();
    final AsyncFunction<Void, Void> prepareFunction = input -> commit();

    // transform validate into prepare
    final ListenableFuture<Void> prepareFuture = Futures.transformAsync(validate(), validateFunction,
        MoreExecutors.directExecutor());
    // transform prepare into commit and return as submit result
    return Futures.transformAsync(prepareFuture, prepareFunction, MoreExecutors.directExecutor());
}
 

import com.google.common.util.concurrent.Futures; //導入方法依賴的package包/類
private static ListenableFuture<Void> doSubmit(final DOMStoreThreePhaseCommitCohort cohort) {
    final AsyncFunction<Boolean, Void> validateFunction = input -> cohort.preCommit();
    final AsyncFunction<Void, Void> prepareFunction = input -> cohort.commit();

    final ListenableFuture<Void> prepareFuture = Futures.transformAsync(cohort.canCommit(), validateFunction,
        MoreExecutors.directExecutor());
    return Futures.transformAsync(prepareFuture, prepareFunction, MoreExecutors.directExecutor());
}
 

import com.google.common.util.concurrent.Futures; //導入方法依賴的package包/類
@Override
public Future<RpcResult<Void>> makeBreakfast(EggsType eggsType, Class<? extends ToastType> toastType,
        int toastDoneness) {
    // Call makeToast and use JdkFutureAdapters to convert the Future to a ListenableFuture, The
    // OpendaylightToaster impl already returns a ListenableFuture so the conversion is actually a no-op.

    ListenableFuture<RpcResult<Void>> makeToastFuture = JdkFutureAdapters
            .listenInPoolThread(makeToast(toastType, toastDoneness), executor);

    ListenableFuture<RpcResult<Void>> makeEggsFuture = makeEggs(eggsType);

    // Combine the 2 ListenableFutures into 1 containing a list RpcResults.

    ListenableFuture<List<RpcResult<Void>>> combinedFutures = Futures
            .allAsList(ImmutableList.of(makeToastFuture, makeEggsFuture));

    // Then transform the RpcResults into 1.

    return Futures.transformAsync(combinedFutures, results -> {
        boolean atLeastOneSucceeded = false;
        Builder<RpcError> errorList = ImmutableList.builder();
        for (RpcResult<Void> result : results) {
            if (result.isSuccessful()) {
                atLeastOneSucceeded = true;
            }

            if (result.getErrors() != null) {
                errorList.addAll(result.getErrors());
            }
        }

        return Futures.immediateFuture(RpcResultBuilder.<Void>status(atLeastOneSucceeded)
                .withRpcErrors(errorList.build()).build());
    });
}
 

import com.google.common.util.concurrent.Futures; //導入方法依賴的package包/類
/**
 * Checks the referenced URL and returns a future to an updated referenced
 * URL. The future referenced URL is not persisted, but the caller should do
 * that to ensure the checking records are correct.
 */
ListenableFuture<ReferencedURL> checkUrl(final ReferencedURL rurl)
{
	final ListenableFuture<Pair<ReferencedURL, Boolean>> checkUrlFuture = checkUrl(rurl, true);

	// Map the Pair to just the ReferencedUrl
	final ListenableFuture<ReferencedURL> mapToRurl = Futures.transformAsync(checkUrlFuture,
		new AsyncFunction<Pair<ReferencedURL, Boolean>, ReferencedURL>()
		{
			@Override
			public ListenableFuture<ReferencedURL> apply(Pair<ReferencedURL, Boolean> input)
			{
				return Futures.immediateFuture(input.getFirst());
			}
		});

	// If the above futures throw an exception, it's probably because we
	// haven't been able to check the URL (eg,
	// java.nio.UnresolvedAddressException) so return an updated
	// ReferencedURL based on the old one.
	return Futures.catchingAsync(mapToRurl, Throwable.class, new AsyncFunction<Throwable, ReferencedURL>()
	{
		@Override
		public ListenableFuture<ReferencedURL> apply(Throwable t)
		{
			final String url = rurl.getUrl();
			if( LOGGER.isDebugEnabled() )
			{
				LOGGER.debug("Exception checking " + url, t);
			}
			ReferencedURL newRurl = new ReferencedURL();
			newRurl.setId(rurl.getId());
			newRurl.setUrl(rurl.getUrl());
			newRurl.setSuccess(false);
			newRurl.setStatus(0);
			newRurl.setTries(rurl.getTries() + 1);
			newRurl.setLastChecked(new Date(System.currentTimeMillis()));
			newRurl.setLastIndexed(new Date());
			newRurl.setMessage(t.getClass().getName() + ": " + t.getMessage());

			return Futures.immediateFuture(newRurl);
		}
	});
}
 

import com.google.common.util.concurrent.Futures; //導入方法依賴的package包/類
@Override
public ListenableFuture<RpcResult<TransactionStatus>> commit() {
    return Futures.transformAsync(submit(), input -> SUCCESS_FUTURE);
}
 

import com.google.common.util.concurrent.Futures; //導入方法依賴的package包/類
@Override
public ListenableFuture<RpcResult<TransactionStatus>> commit() {
    return Futures.transformAsync(submit(), input -> SUCCESS_FUTURE, MoreExecutors.directExecutor());
}
 

import com.google.common.util.concurrent.Futures; //導入方法依賴的package包/類
public static ListenableFuture<RpcResult<TransactionStatus>> convertToLegacyCommitFuture(final CheckedFuture<Void,TransactionCommitFailedException> from) {
    return Futures.transformAsync(from, input -> SUCCESS_FUTURE);
}
 

import com.google.common.util.concurrent.Futures; //導入方法依賴的package包/類
private void checkStatusAndMakeToast(final MakeToastInput input, final SettableFuture<RpcResult<Void>> futureResult,
        final int tries) {
    // Read the ToasterStatus and, if currently Up, try to write the status to Down.
    // If that succeeds, then we essentially have an exclusive lock and can proceed
    // to make toast.
    final ReadWriteTransaction tx = dataBroker.newReadWriteTransaction();
    ListenableFuture<Optional<Toaster>> readFuture = tx.read(OPERATIONAL, TOASTER_IID);

    final ListenableFuture<Void> commitFuture =
        Futures.transformAsync(readFuture, toasterData -> {
            ToasterStatus toasterStatus = ToasterStatus.Up;
            if (toasterData.isPresent()) {
                toasterStatus = toasterData.get().getToasterStatus();
            }

            LOG.debug("Read toaster status: {}", toasterStatus);

            if (toasterStatus == ToasterStatus.Up) {

                if (outOfBread()) {
                    LOG.debug("Toaster is out of bread");
                    return Futures.immediateFailedCheckedFuture(
                            new TransactionCommitFailedException("", makeToasterOutOfBreadError()));
                }

                LOG.debug("Setting Toaster status to Down");

                // We're not currently making toast - try to update the status to Down
                // to indicate we're going to make toast. This acts as a lock to prevent
                // concurrent toasting.
                tx.put(OPERATIONAL, TOASTER_IID, buildToaster(ToasterStatus.Down));
                return tx.submit();
            }

            LOG.debug("Oops - already making toast!");

            // Return an error since we are already making toast. This will get
            // propagated to the commitFuture below which will interpret the null
            // TransactionStatus in the RpcResult as an error condition.
            return Futures.immediateFailedCheckedFuture(
                    new TransactionCommitFailedException("", makeToasterInUseError()));
        });

    Futures.addCallback(commitFuture, new FutureCallback<Void>() {
        @Override
        public void onSuccess(final Void result) {
            // OK to make toast
            currentMakeToastTask.set(executor.submit(new MakeToastTask(input, futureResult)));
        }

        @Override
        public void onFailure(final Throwable ex) {
            if (ex instanceof OptimisticLockFailedException) {

                // Another thread is likely trying to make toast simultaneously and updated the
                // status before us. Try reading the status again - if another make toast is
                // now in progress, we should get ToasterStatus.Down and fail.

                if (tries - 1 > 0) {
                    LOG.debug("Got OptimisticLockFailedException - trying again");
                    checkStatusAndMakeToast(input, futureResult, tries - 1);
                } else {
                    futureResult.set(RpcResultBuilder.<Void>failed()
                            .withError(ErrorType.APPLICATION, ex.getMessage()).build());
                }
            } else if (ex instanceof TransactionCommitFailedException) {
                LOG.debug("Failed to commit Toaster status", ex);

                // Probably already making toast.
                futureResult.set(RpcResultBuilder.<Void>failed()
                        .withRpcErrors(((TransactionCommitFailedException)ex).getErrorList()).build());
            } else {
                LOG.debug("Unexpected error committing Toaster status", ex);
                futureResult.set(RpcResultBuilder.<Void>failed().withError(ErrorType.APPLICATION,
                        "Unexpected error committing Toaster status", ex).build());
            }
        }
    });
}