code: // Licensed to the Software Freedom Conservancy (SFC) under one
  // or more contributor license agreements.  See the NOTICE file
  // distributed with this work for additional information
  // regarding copyright ownership.  The SFC licenses this file
  // to you under the Apache License, Version 2.0 (the
  // "License"); you may not use this file except in compliance
  // with the License.  You may obtain a copy of the License at
  //
  //   http://www.apache.org/licenses/LICENSE-2.0
  //
  // Unless required by applicable law or agreed to in writing,
  // software distributed under the License is distributed on an
  // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  // KIND, either express or implied.  See the License for the
  // specific language governing permissions and limitations
  // under the License.
  
  package org.openqa.selenium.remote.tracing;
  
  import static org.openqa.selenium.remote.tracing.HttpTracing.newSpanAsChildOf;
  import static org.openqa.selenium.remote.tracing.Tags.HTTP_REQUEST;
  import static org.openqa.selenium.remote.tracing.Tags.HTTP_RESPONSE;
  import static org.openqa.selenium.remote.tracing.Tags.KIND;
  
  import java.net.URL;
  import org.openqa.selenium.internal.Require;
  import org.openqa.selenium.remote.http.ClientConfig;
  import org.openqa.selenium.remote.http.HttpClient;
  import org.openqa.selenium.remote.http.HttpRequest;
  import org.openqa.selenium.remote.http.HttpResponse;
  import org.openqa.selenium.remote.http.WebSocket;
  
  public class TracedHttpClient implements HttpClient {
  
    private final Tracer tracer;
    private final HttpClient delegate;
  
    private TracedHttpClient(Tracer tracer, HttpClient delegate) {
      this.tracer = Require.nonNull("Tracer", tracer);
      this.delegate = Require.nonNull("Actual handler", delegate);
    }
  
    @Override
    public WebSocket openSocket(HttpRequest request, WebSocket.Listener listener) {
      return delegate.openSocket(request, listener);
    }
  
    @Override
    public HttpResponse execute(HttpRequest req) {
      try (Span span = newSpanAsChildOf(tracer, req, "httpclient.execute")) {
        KIND.accept(span, Span.Kind.CLIENT);
        HTTP_REQUEST.accept(span, req);
        tracer.getPropagator().inject(span, req, (r, key, value) -> r.setHeader(key, value));
        HttpResponse response = delegate.execute(req);
        HTTP_RESPONSE.accept(span, response);
        return response;
      }
    }
  
    @Override
    public void close() {
      delegate.close();
    }
  
    public static class Factory implements HttpClient.Factory {
  
      private final Tracer tracer;
      private final HttpClient.Factory delegate;
  
      public Factory(Tracer tracer, HttpClient.Factory delegate) {
        this.tracer = Require.nonNull("Tracer", tracer);
        this.delegate = Require.nonNull("Actual handler", delegate);
      }
  
      public HttpClient createClient(ClientConfig config) {
        HttpClient client = delegate.createClient(config);
        return new TracedHttpClient(tracer, client);
      }
  
      @Override
      public HttpClient createClient(URL url) {
        HttpClient client = delegate.createClient(url);
        return new TracedHttpClient(tracer, client);
      }
    }
  }
  