@Override
public Set<Subscription> loadByTopic(final String topicQuery) {
final Set<String> topicSubQueries = decomposeTopicQuery(topicQuery);
final Map<String, Optional<Subscription>> cachedResults =
subscriptionCache.loadTopicSubscriptions(topicSubQueries);
final Set<Subscription> result = new HashSet<Subscription>();
// Iterate through the results from the cache, and remove any topics
// that were found from the list of topics left to query, and add
// the non-null subscriptions to the list of results
for (String topic : cachedResults.keySet()) {
if (cachedResults.get(topic).isPresent()) {
result.add(cachedResults.get(topic).get());
topicSubQueries.remove(topic);
}
}
// all topics that are found in the cache will be removed, so if no
// topic subqueries are left, we are done
if (!topicSubQueries.isEmpty()) {
Collection<Subscription> dbResults =
dbi.withHandle(
new HandleCallback<Collection<Subscription>>() {
@Override
public Collection<Subscription> withHandle(Handle handle) throws Exception {
final Set<Subscription> dbResult = new HashSet<Subscription>();
InClauseExpander in = new InClauseExpander(topicSubQueries);
Iterator<Subscription> subscriptionsIter =
handle
.createQuery(
"select id, metadata, channel, topic from subscriptions where topic in ("
+ in.getExpansion()
+ ")")
.bindNamedArgumentFinder(in)
.map(new SubscriptionMapper())
.iterator();
if (subscriptionsIter != null) {
while (subscriptionsIter.hasNext()) {
Subscription dbSubscription = subscriptionsIter.next();
dbResult.add(dbSubscription);
subscriptionCache.addTopicSubscriptions(
dbSubscription.getTopic(), Optional.of(dbSubscription));
topicSubQueries.remove(dbSubscription.getTopic());
}
}
return dbResult;
}
});
// Add the database results to the results from the cache
result.addAll(dbResults);
// Add empty subscriptions to the cache
if (!topicSubQueries.isEmpty()) {
subscriptionCache.addEmptyTopicSubscriptions(topicSubQueries);
}
}
return ImmutableSet.copyOf(result);
}
