content: /*
   * 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
   *
   *   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.apache.bifromq.baserpc.server;
  
  import org.apache.bifromq.baserpc.RPCContext;
  import org.apache.bifromq.baserpc.metrics.IRPCMeter;
  import org.apache.bifromq.baserpc.metrics.RPCMetric;
  import io.grpc.stub.StreamObserver;
  import io.micrometer.core.instrument.Timer;
  import java.util.Map;
  import java.util.concurrent.CompletionStage;
  import java.util.function.BiFunction;
  import java.util.function.Function;
  
  /**
   * Utility for handling unary request.
   */
  public final class UnaryResponse {
      public static <RespT> void response(Function<String, CompletionStage<RespT>> reqHandler,
                                          StreamObserver<RespT> observer) {
          response((tenantId, metadata) -> reqHandler.apply(tenantId), observer);
      }
  
      public static <RespT> void response(BiFunction<String, Map<String, String>, CompletionStage<RespT>> reqHandler,
                                          StreamObserver<RespT> observer) {
          IRPCMeter.IRPCMethodMeter meter = RPCContext.METER_KEY_CTX_KEY.get();
          String tenantId = RPCContext.TENANT_ID_CTX_KEY.get();
          Map<String, String> metadata = RPCContext.CUSTOM_METADATA_CTX_KEY.get();
          Timer.Sample sample = Timer.start();
          meter.recordCount(RPCMetric.UnaryReqReceivedCount);
          reqHandler.apply(tenantId, metadata)
              .whenComplete((v, e) -> {
                  sample.stop(meter.timer(RPCMetric.UnaryReqProcessLatency));
                  if (e != null) {
                      observer.onError(e);
                      meter.recordCount(RPCMetric.UnaryReqFailCount);
                  } else {
                      observer.onNext(v);
                      observer.onCompleted();
                      meter.recordCount(RPCMetric.UnaryReqFulfillCount);
                  }
              });
      }
  }
  