protected ListenableFuture getRouteData()

in java/client/src/main/java/org/apache/rocketmq/client/java/impl/ClientImpl.java [633:711]
72 lines of code
9 McCabe index (conditional complexity)

    protected ListenableFuture<TopicRouteData> getRouteData(final String topic) {
        SettableFuture<TopicRouteData> future0 = SettableFuture.create();
        TopicRouteData topicRouteData = topicRouteCache.get(topic);
        // If route result was cached before, get it directly.
        if (null != topicRouteData) {
            future0.set(topicRouteData);
            return future0;
        }
        inflightRouteFutureLock.lock();
        try {
            // If route was fetched by last in-flight request, get it directly.
            topicRouteData = topicRouteCache.get(topic);
            if (null != topicRouteData) {
                future0.set(topicRouteData);
                return future0;
            }
            Set<SettableFuture<TopicRouteData>> inflightFutures = inflightRouteFutureTable.get(topic);
            // Request is in-flight, return future directly.
            if (null != inflightFutures) {
                inflightFutures.add(future0);
                return future0;
            }
            inflightFutures = new HashSet<>();
            inflightFutures.add(future0);
            inflightRouteFutureTable.put(topic, inflightFutures);
        } finally {
            inflightRouteFutureLock.unlock();
        }
        final ListenableFuture<TopicRouteData> future = fetchTopicRoute(topic);
        Futures.addCallback(future, new FutureCallback<TopicRouteData>() {
            @Override
            public void onSuccess(TopicRouteData topicRouteData) {
                inflightRouteFutureLock.lock();
                try {
                    final Set<SettableFuture<TopicRouteData>> newFutureSet =
                        inflightRouteFutureTable.remove(topic);
                    if (null == newFutureSet) {
                        // Should never reach here.
                        log.error("[Bug] in-flight route futures was empty, topic={}, clientId={}", topic,
                            clientId);
                        return;
                    }
                    log.debug("Fetch topic route successfully, topic={}, in-flight route future "
                        + "size={}, clientId={}", topic, newFutureSet.size(), clientId);
                    for (SettableFuture<TopicRouteData> newFuture : newFutureSet) {
                        newFuture.set(topicRouteData);
                    }
                } catch (Throwable t) {
                    // Should never reach here.
                    log.error("[Bug] Exception raised while update route data, topic={}, clientId={}", topic,
                        clientId, t);
                } finally {
                    inflightRouteFutureLock.unlock();
                }
            }

            @Override
            public void onFailure(Throwable t) {
                inflightRouteFutureLock.lock();
                try {
                    final Set<SettableFuture<TopicRouteData>> newFutureSet =
                        inflightRouteFutureTable.remove(topic);
                    if (null == newFutureSet) {
                        // Should never reach here.
                        log.error("[Bug] in-flight route futures was empty, topic={}, clientId={}", topic, clientId);
                        return;
                    }
                    log.debug("Failed to fetch topic route, topic={}, in-flight route future " +
                        "size={}, clientId={}", topic, newFutureSet.size(), clientId, t);
                    for (SettableFuture<TopicRouteData> future : newFutureSet) {
                        future.setException(t);
                    }
                } finally {
                    inflightRouteFutureLock.unlock();
                }
            }
        }, MoreExecutors.directExecutor());
        return future0;
    }