UbergRPCAdaptor.java

/**
 * Adaptor for Grpc which does all the translation from generic uber types to grpc entities and
 * places the call to a grpc ManagedChannel. This class manages multiple channels and routes new
 * calls based on host fetched from UberInternalCallOptions.
 */
public class UbergRPCAdaptor implements UberChannel {

  private static final Logger LOGGER = Logger.getLogger(UbergRPCAdaptor.class.getName());

  // static variable singleInstance of type Singleton
  @Nullable private static UbergRPCAdaptor singleInstance;

  private final Map<HostPortPair, ManagedChannel> channelMap = new HashMap<>();
  private HostPortPair curHostPortPair;

  private UbergRPCAdaptor(HostPortPair hostPortPair) {
    createAndAddChannel(hostPortPair);
  }

  private void createAndAddChannel(HostPortPair hostPortPair) {
    ManagedChannel channel =
        ManagedChannelBuilder.forAddress(hostPortPair.getHost(), hostPortPair.getPort())
            .usePlaintext()
            .build();
    channelMap.put(hostPortPair, channel);
    curHostPortPair = hostPortPair;
  }

  /**
   * Instantiates {@link UbergRPCAdaptor}.
   *
   * @param hostPortPair initial hostport pair to initialize {@link UbergRPCAdaptor} with.
   * @return the singleton instance of {@link UbergRPCAdaptor}.
   */
  public static UbergRPCAdaptor getInstance(HostPortPair hostPortPair) {
    if (singleInstance == null) {
      singleInstance = new UbergRPCAdaptor(hostPortPair);
    }
    return singleInstance;
  }

  @Override
  public synchronized <RequestT, ResponseT, T> UberClientCall<RequestT, ResponseT> newCall(
      MethodInfo<T> methodInfo, UberInternalCallOptions uberInternalCallOptions) {
      // fetch channel corresponding to host and port in uberInternalCallOptions from internal channel map
      return new UberClientCall<>(
          channel.newCall(
              (MethodDescriptor<RequestT, ResponseT>) methodInfo.getTransportMethodInfo(),
              uberInternalCallOptions.getCallOptions()));
     }

  @Override
  public String authority() {
     // to be filled
  }

  @Override
  @Nullable
  public ManagedChannel shutdown() {
     // to be filled
  }

  @Override
  public boolean isShutdown() {
     // to be filled
  }

  @Override
  public boolean isTerminated() {
     // to be filled
  }

  @Override
  @Nullable
  public ManagedChannel shutdownNow() {
      // to be filled
  }

  @Override
  public boolean awaitTermination(long timeout, TimeUnit unit) {
    // to be filled
  }