content: /*
   * Copyright The OpenTelemetry Authors
   * SPDX-License-Identifier: Apache-2.0
   */
  
  package io.opentelemetry.javaagent.instrumentation.netty.v3_8.client;
  
  import static io.opentelemetry.javaagent.instrumentation.netty.v3_8.client.NettyClientSingletons.instrumenter;
  
  import io.opentelemetry.context.Context;
  import io.opentelemetry.context.Scope;
  import io.opentelemetry.instrumentation.api.util.VirtualField;
  import io.opentelemetry.javaagent.instrumentation.netty.v3_8.HttpRequestAndChannel;
  import io.opentelemetry.javaagent.instrumentation.netty.v3_8.NettyConnectionContext;
  import org.jboss.netty.channel.Channel;
  import org.jboss.netty.channel.ChannelHandlerContext;
  import org.jboss.netty.channel.MessageEvent;
  import org.jboss.netty.channel.SimpleChannelDownstreamHandler;
  import org.jboss.netty.handler.codec.http.HttpRequest;
  
  public class HttpClientRequestTracingHandler extends SimpleChannelDownstreamHandler {
  
    private static final VirtualField<Channel, NettyConnectionContext> connectionContextField =
        VirtualField.find(Channel.class, NettyConnectionContext.class);
    private static final VirtualField<Channel, NettyClientRequestAndContexts> requestContextsField =
        VirtualField.find(Channel.class, NettyClientRequestAndContexts.class);
  
    @Override
    public void writeRequested(ChannelHandlerContext ctx, MessageEvent event) throws Exception {
      Object message = event.getMessage();
      if (!(message instanceof HttpRequest)) {
        super.writeRequested(ctx, event);
        return;
      }
  
      Context parentContext = null;
      NettyConnectionContext connectionContext = connectionContextField.get(ctx.getChannel());
      if (connectionContext != null) {
        parentContext = connectionContext.remove();
      }
      if (parentContext == null) {
        parentContext = Context.current();
      }
  
      HttpRequestAndChannel request =
          HttpRequestAndChannel.create((HttpRequest) message, ctx.getChannel());
      if (!instrumenter().shouldStart(parentContext, request)) {
        super.writeRequested(ctx, event);
        return;
      }
  
      Context context = instrumenter().start(parentContext, request);
      requestContextsField.set(
          ctx.getChannel(), NettyClientRequestAndContexts.create(parentContext, context, request));
  
      try (Scope ignored = context.makeCurrent()) {
        super.writeRequested(ctx, event);
      } catch (Throwable throwable) {
        instrumenter().end(context, request, null, throwable);
        throw throwable;
      }
      // span is ended normally in HttpClientResponseTracingHandler
    }
  }
  