hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/tracing/GrpcServerInterceptor.java

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF 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
 * <p>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * 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.apache.hadoop.hdds.tracing;

import io.opentracing.Scope;
import org.apache.ratis.thirdparty.io.grpc.ForwardingServerCallListener.SimpleForwardingServerCallListener;
import org.apache.ratis.thirdparty.io.grpc.Metadata;
import org.apache.ratis.thirdparty.io.grpc.ServerCall;
import org.apache.ratis.thirdparty.io.grpc.ServerCall.Listener;
import org.apache.ratis.thirdparty.io.grpc.ServerCallHandler;
import org.apache.ratis.thirdparty.io.grpc.ServerInterceptor;

/**
 * Interceptor to add the tracing id to the outgoing call header.
 */
public class GrpcServerInterceptor implements ServerInterceptor {

  @Override
  public <ReqT, RespT> Listener<ReqT> interceptCall(
      ServerCall<ReqT, RespT> call, Metadata headers,
      ServerCallHandler<ReqT, RespT> next) {

    return new SimpleForwardingServerCallListener<ReqT>(
        next.startCall(call, headers)) {
      @Override
      public void onMessage(ReqT message) {
        try (Scope scope = TracingUtil
            .importAndCreateScope(
                call.getMethodDescriptor().getFullMethodName(),
                headers.get(GrpcClientInterceptor.TRACING_HEADER))) {
          super.onMessage(message);
        }
      }
    };
  }
}