/**
* Handles a publish request.
*
* @param request The publish request to handle.
* @return A completable future to be completed with the publish response.
*/
@SuppressWarnings("unchecked")
private CompletableFuture<PublishResponse> handlePublish(PublishRequest request) {
if (request.session() != id)
return Futures.exceptionalFuture(new UnknownSessionException("incorrect session ID"));
if (request.previousVersion() != eventVersion) {
return CompletableFuture.completedFuture(
PublishResponse.builder()
.withStatus(Response.Status.ERROR)
.withError(RaftError.Type.INTERNAL_ERROR)
.withVersion(eventVersion)
.build());
}
eventVersion = request.eventVersion();
List<CompletableFuture<Void>> futures = new ArrayList<>(request.events().size());
for (Event<?> event : request.events()) {
Listeners<Object> listeners = eventListeners.get(event.name());
if (listeners != null) {
futures.add(listeners.accept(event.message()));
}
}
return CompletableFuture.allOf(futures.toArray(new CompletableFuture<?>[futures.size()]))
.handleAsync(
(result, error) -> {
completeVersion = Math.max(completeVersion, request.eventVersion());
return PublishResponse.builder()
.withStatus(Response.Status.OK)
.withVersion(eventVersion)
.build();
},
context.executor());
}
/** Recursively submits a query. */
@SuppressWarnings("unchecked")
private <T> CompletableFuture<T> submit(QueryRequest request, CompletableFuture<T> future) {
if (!isOpen()) {
future.completeExceptionally(new IllegalStateException("session not open"));
return future;
}
long sequence = ++requestSequence;
this.<QueryRequest, QueryResponse>request(request)
.whenComplete(
(response, error) -> {
if (error == null) {
// If the query consistency level is CAUSAL, we can simply complete queries in
// sequential order.
if (request.query().consistency() == Query.ConsistencyLevel.CAUSAL) {
sequenceResponse(
sequence,
() -> {
responseVersion = Math.max(responseVersion, response.version());
completeResponse(response, future);
});
}
// If the query consistency level is strong, the query must be executed
// sequentially. In order to ensure responses
// are received in a sequential manner, we compare the response version number with
// the highest version for which
// we've received a response and resubmit queries with output resulting from stale
// (prior) versions.
else {
sequenceResponse(
sequence,
() -> {
if (response.version() > 0 && response.version() < responseVersion) {
submit(request, future);
} else {
responseVersion = Math.max(responseVersion, response.version());
completeResponse(response, future);
}
});
}
} else {
future.completeExceptionally(error);
}
});
return future;
}