This document defines a message system for sending messages between different components. It defines classes for addresses, messages, and message queues. Addresses are assigned unique IDs and associated with components. Messages have a from and to address and an exec method to handle the message for a given component. The message system stores outgoing messages in queues mapped by the destination address. It executes pending messages for a component by polling the queue and calling exec.

1. Лекция 3. «Message System»

20. public class Address {
static private AtomicInteger abonentIdCreator = new AtomicInteger();
final private int abonentId;
public Address(){
this.abonentId = abonentIdCreator.incrementAndGet();
}
public int getAbonentId() {
return abonentId;
}
}
public interface Abonent {
Address getAddress();
}

21. public abstract class Msg {
final private Address from;
final private Address to;
public Msg(Address from, Address to){
this.from = from;
this.to = to;
}
protected Address getFrom(){
return from;
}
protected Address getTo(){
return to;
}
public abstract void exec(Abonent abonent);
}

22. public abstract class MsgToFrontend extends Msg {
public MsgToFrontend(Address from, Address to) {
super(from, to);
}
public void exec(Abonent abonent) {
if(abonent instanceof Frontend){
exec((Frontend)abonent);
}
}
public abstract void exec(Frontend frontend);
}

23. public class MsgUpdateUserId extends MsgToFrontend {
final private int sessionId;
final private int userId;
public GameInfoMsg(Address from, Address to, int sessionId, int userId) {
super(from, to);
this. sessionId = sessionId;
this. userId = userId;
}
public void exec(Frontend frontend) {
frontend.updateUserId(sessionId, userId);
}
}

24. private Map<Address, ArrayBlockingQueue<Msg>> messages
= new HashMap<Address, ArrayBlockingQueue<Msg>>();
public void sendMessage(Msg message){
Queue<Msg> messageQueue = messages.get(message.getTo());
messageQueue.add(message);
}
public void execForAbonent(Abonent abonent) {
Queue<Msg> messageQueue = messages.get(abonent.getAddress());
while(!messageQueue.isEmpty()){
Msg message = messageQueue.poll();
message.exec(abonent);
}
}

27. public void run() {
while (true) {
messageSystem.execForAbonent(this);
Thread.sleep(TICK_TIME);
}
}