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package derms.net.runicast;
import derms.io.Serial;
import derms.net.MessagePayload;
import derms.util.ThreadPool;
import java.io.IOException;
import java.net.SocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.DatagramChannel;
import java.util.Queue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.atomic.AtomicLong;
import java.util.logging.Logger;
/** The sending end of a reliable unicast connection. */
public class ReliableUnicastSender<T extends MessagePayload> {
private final AtomicLong next; // Next sequence number.
private final AtomicLong unacked; // Sequence number of first unacknowledged message.
private final Queue<Message<T>> sent;
private final DatagramChannel sock;
private final Logger log;
private final ExecutorService pool;
/**
* Connect to the specified address and port.
*
* @param raddr The remote IP address to connect to.
*/
public ReliableUnicastSender(SocketAddress raddr) throws IOException {
this.next = new AtomicLong(0);
this.unacked = new AtomicLong(0);
this.sent = new LinkedBlockingQueue<Message<T>>();
this.sock = DatagramChannel.open();
sock.connect(raddr);
this.log = Logger.getLogger(getClass().getName());
this.pool = Executors.newCachedThreadPool();
pool.execute(new ReceiveAcks<T>(unacked, sent, sock));
pool.execute(new Retransmit<T>(unacked, sent, sock));
}
public void send(T payload) throws IOException {
Message<T> msg = new Message<T>(next.get(), payload);
ByteBuffer buf = Serial.encode(msg);
sock.send(buf, sock.getRemoteAddress());
sent.add(msg);
next.incrementAndGet();
log.info("Sent " + msg);
}
/** Wait for all messages to be acknowledged and close the connection. */
public void close() throws InterruptedException, IOException {
// Wait for receiver to acknowledge all sent messages.
log.info("Waiting for acknowledgements...");
while (unacked.get() < next.get()) {
Thread.yield();
if (Thread.interrupted())
throw new InterruptedException();
}
log.info("Shutting down.");
sock.close();
ThreadPool.shutdown(pool, log);
}
/** Close the connection immediately, without waiting for acknowledgements. */
public void closeNow() throws IOException {
log.info("Shutting down.");
sock.close();
ThreadPool.shutdownNow(pool, log);
}
}
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