private void connect()

in core/src/main/java/com/datastax/oss/driver/internal/core/channel/ChannelFactory.java [180:268]
80 lines of code
13 McCabe index (conditional complexity)

  private void connect(
      EndPoint endPoint,
      DriverChannelOptions options,
      NodeMetricUpdater nodeMetricUpdater,
      ProtocolVersion currentVersion,
      boolean isNegotiating,
      List<ProtocolVersion> attemptedVersions,
      CompletableFuture<DriverChannel> resultFuture) {

    NettyOptions nettyOptions = context.getNettyOptions();

    Bootstrap bootstrap =
        new Bootstrap()
            .group(nettyOptions.ioEventLoopGroup())
            .channel(nettyOptions.channelClass())
            .option(ChannelOption.ALLOCATOR, nettyOptions.allocator())
            .handler(
                initializer(endPoint, currentVersion, options, nodeMetricUpdater, resultFuture));

    nettyOptions.afterBootstrapInitialized(bootstrap);

    ChannelFuture connectFuture = bootstrap.connect(endPoint.resolve());

    connectFuture.addListener(
        cf -> {
          if (connectFuture.isSuccess()) {
            Channel channel = connectFuture.channel();
            DriverChannel driverChannel =
                new DriverChannel(endPoint, channel, context.getWriteCoalescer(), currentVersion);
            // If this is the first successful connection, remember the protocol version and
            // cluster name for future connections.
            if (isNegotiating) {
              ChannelFactory.this.protocolVersion = currentVersion;
            }
            if (ChannelFactory.this.clusterName == null) {
              ChannelFactory.this.clusterName = driverChannel.getClusterName();
            }
            Map<String, List<String>> supportedOptions = driverChannel.getOptions();
            if (ChannelFactory.this.productType == null && supportedOptions != null) {
              List<String> productTypes = supportedOptions.get("PRODUCT_TYPE");
              String productType =
                  productTypes != null && !productTypes.isEmpty()
                      ? productTypes.get(0)
                      : UNKNOWN_PRODUCT_TYPE;
              ChannelFactory.this.productType = productType;
              DriverConfig driverConfig = context.getConfig();
              if (driverConfig instanceof TypesafeDriverConfig
                  && productType.equals(DATASTAX_CLOUD_PRODUCT_TYPE)) {
                ((TypesafeDriverConfig) driverConfig)
                    .overrideDefaults(
                        ImmutableMap.of(
                            DefaultDriverOption.REQUEST_CONSISTENCY,
                            ConsistencyLevel.LOCAL_QUORUM.name()));
              }
            }
            resultFuture.complete(driverChannel);
          } else {
            Throwable error = connectFuture.cause();
            if (error instanceof UnsupportedProtocolVersionException && isNegotiating) {
              attemptedVersions.add(currentVersion);
              Optional<ProtocolVersion> downgraded =
                  context.getProtocolVersionRegistry().downgrade(currentVersion);
              if (downgraded.isPresent()) {
                LOG.debug(
                    "[{}] Failed to connect with protocol {}, retrying with {}",
                    logPrefix,
                    currentVersion,
                    downgraded.get());
                connect(
                    endPoint,
                    options,
                    nodeMetricUpdater,
                    downgraded.get(),
                    true,
                    attemptedVersions,
                    resultFuture);
              } else {
                resultFuture.completeExceptionally(
                    UnsupportedProtocolVersionException.forNegotiation(
                        endPoint, attemptedVersions));
              }
            } else {
              // Note: might be completed already if the failure happened in initializer(), this is
              // fine
              resultFuture.completeExceptionally(error);
            }
          }
        });
  }