net.fabricmc.fabric.api.networking.v1

Interface ServerLoginNetworking.LoginSynchronizer

Enclosing class:

ServerLoginNetworking

Functional Interface:

This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.

@FunctionalInterface
public static interface ServerLoginNetworking.LoginSynchronizer

Allows blocking client log-in until all all futures passed into waitFor(Future) are completed.

Method Summary

Modifier and Type	Method and Description
void	waitFor(Future<?> future) Allows blocking client log-in until the future is done.

Method Detail

waitFor

void waitFor(Future<?> future)

Allows blocking client log-in until the future is done.

Since packet reception happens on netty's event loops, this allows handlers to perform logic on the Server Thread, etc. For instance, a handler can prepare an upcoming query request or check necessary login data on the server thread.

Here is an example where the player log-in is blocked so that a credential check and building of a followup query request can be performed properly on the logical server thread before the player successfully logs in:

 ServerLoginNetworking.registerGlobalReceiver(CHECK_CHANNEL, (server, handler, understood, buf, synchronizer, responseSender) -> {
 	if (!understood) {
 		handler.disconnect(new LiteralText("Only accept clients that can check!"));
 		return;
 	}

 	String checkMessage = buf.readString(32767);

 	// Just send the CompletableFuture returned by the server's submit method
 	synchronizer.waitFor(server.submit(() -> {
 		LoginInfoChecker checker = LoginInfoChecker.get(server);

 		if (!checker.check(handler.getConnectionInfo(), checkMessage)) {
 			handler.disconnect(new LiteralText("Invalid credentials!"));
 			return;
 		}

 		responseSender.send(UPCOMING_CHECK, checker.buildSecondQueryPacket(handler, checkMessage));
 	}));
 });
 

Usually it is enough to pass the return value for ThreadExecutor.submit(Runnable) for future.

Parameters:

future - the future that must be done before the player can log in