SocketUtil.java

package com.faforever.client.net;

import org.apache.commons.compress.utils.IOUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.lang.invoke.MethodHandles;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;
import java.util.concurrent.Executor;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.function.Consumer;

public final class SocketUtil {

  private static final Logger logger = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass());

  private SocketUtil() {
    throw new AssertionError("Not instantiatable");
  }

  /**
   * Reads the specified socket and processes them using the specified consumer.
   *
   * @param executor the {@link Executor} to run the background thread in
   */
  public static void readSocket(ThreadPoolExecutor executor, final DatagramSocket socket, Consumer<DatagramPacket> consumer) {
    String localSocketAddress = socket.getLocalSocketAddress().toString();
    logger.debug("Reading socket {}", localSocketAddress);

    executor.execute(() -> {
      byte[] buffer = new byte[1500];
      DatagramPacket datagramPacket = new DatagramPacket(buffer, buffer.length);

      try {
        while (!socket.isClosed()) {
          socket.receive(datagramPacket);

          // Passing the original datagramPacket can cause locks
          byte[] payload = new byte[datagramPacket.getLength()];
          System.arraycopy(datagramPacket.getData(), 0, payload, 0, datagramPacket.getLength());

          DatagramPacket packetCopy = new DatagramPacket(payload, payload.length);
          packetCopy.setSocketAddress(datagramPacket.getSocketAddress());
          consumer.accept(packetCopy);
        }
      } catch (SocketException e) {
        if (!e.getMessage().equals("socket closed")) {
          logger.warn("Socket has been closed: ({})", e.getMessage());
        }
      } catch (IOException e) {
        logger.warn("Exception while forwarding socket: " + localSocketAddress, e);
        throw new RuntimeException(e);
      } finally {
        IOUtils.closeQuietly(socket);
      }

      logger.debug("Socket {} closed gracefully", localSocketAddress);
    });
  }
}