code: /*
   * 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.skywalking.oap.server.receiver.envoy;
  
  import io.envoyproxy.envoy.service.metrics.v2.MetricsServiceGrpc;
  import io.envoyproxy.envoy.service.metrics.v3.StreamMetricsMessage;
  import io.envoyproxy.envoy.service.metrics.v3.StreamMetricsResponse;
  import io.grpc.Status;
  import io.grpc.stub.StreamObserver;
  import io.prometheus.client.Metrics;
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.stream.Collectors;
  import lombok.SneakyThrows;
  import lombok.extern.slf4j.Slf4j;
  import org.apache.skywalking.oap.server.library.util.StringUtil;
  import org.apache.skywalking.oap.meter.analyzer.prometheus.PrometheusMetricConverter;
  import org.apache.skywalking.oap.server.core.CoreModule;
  import org.apache.skywalking.oap.server.core.analysis.meter.MeterSystem;
  import org.apache.skywalking.oap.server.library.module.ModuleManager;
  import org.apache.skywalking.oap.server.library.module.ModuleStartException;
  import org.apache.skywalking.oap.server.library.util.prometheus.metrics.Metric;
  import org.apache.skywalking.oap.server.receiver.envoy.als.ServiceMetaInfo;
  import org.apache.skywalking.oap.server.receiver.envoy.metrics.adapters.ProtoMetricFamily2MetricsAdapter;
  import org.apache.skywalking.oap.server.telemetry.TelemetryModule;
  import org.apache.skywalking.oap.server.telemetry.api.CounterMetrics;
  import org.apache.skywalking.oap.server.telemetry.api.HistogramMetrics;
  import org.apache.skywalking.oap.server.telemetry.api.MetricsCreator;
  import org.apache.skywalking.oap.server.telemetry.api.MetricsTag;
  
  @Slf4j
  public class MetricServiceGRPCHandler extends MetricsServiceGrpc.MetricsServiceImplBase {
      private final CounterMetrics counter;
      private final HistogramMetrics histogram;
      private final List<PrometheusMetricConverter> converters;
  
      private final EnvoyMetricReceiverConfig config;
  
      public MetricServiceGRPCHandler(final ModuleManager moduleManager,
                                      final EnvoyMetricReceiverConfig config) throws ModuleStartException {
          this.config = config;
  
          MetricsCreator metricsCreator = moduleManager.find(TelemetryModule.NAME)
                                                       .provider()
                                                       .getService(MetricsCreator.class);
          counter = metricsCreator.createCounter(
              "envoy_metric_in_count", "The count of envoy service metrics received", MetricsTag.EMPTY_KEY,
              MetricsTag.EMPTY_VALUE
          );
          histogram = metricsCreator.createHistogramMetric(
              "envoy_metric_in_latency", "The process latency of service metrics receiver", MetricsTag.EMPTY_KEY,
              MetricsTag.EMPTY_VALUE
          );
  
          final MeterSystem meterSystem = moduleManager.find(CoreModule.NAME).provider().getService(MeterSystem.class);
  
          converters = config.rules()
                             .stream()
                             .map(rule -> new PrometheusMetricConverter(rule, meterSystem))
                             .collect(Collectors.toList());
      }
  
      @Override
      public StreamObserver<StreamMetricsMessage> streamMetrics(StreamObserver<StreamMetricsResponse> responseObserver) {
          return new StreamObserver<StreamMetricsMessage>() {
              private volatile boolean isFirst = true;
              private ServiceMetaInfo service;
  
              @Override
              @SneakyThrows
              public void onNext(StreamMetricsMessage message) {
                  if (log.isDebugEnabled()) {
                      log.debug("Received msg {}", message);
                  }
  
                  if (isFirst) {
                      isFirst = false;
                      service = config.serviceMetaInfoFactory()
                                      .fromStruct(message.getIdentifier().getNode().getMetadata());
                  }
  
                  if (log.isDebugEnabled()) {
                      log.debug("Envoy metrics reported from service[{}]", service);
                  }
  
                  if (service != null && StringUtil.isNotEmpty(service.getServiceName()) && StringUtil.isNotEmpty(
                      service.getServiceInstanceName())) {
                      List<Metrics.MetricFamily> list = message.getEnvoyMetricsList();
                      Map<String, List<Metric>> groupingMetrics = new HashMap<>();
                      for (final Metrics.MetricFamily metricFamily : list) {
                          counter.inc();
                          try (final HistogramMetrics.Timer ignored = histogram.createTimer()) {
                              final ProtoMetricFamily2MetricsAdapter adapter = new ProtoMetricFamily2MetricsAdapter(
                                  metricFamily, config.getClusterManagerMetricsAdapter());
                              adapter.adapt().forEach(it -> {
                                  it.getLabels().putIfAbsent("app", service.getServiceName());
                                  it.getLabels().putIfAbsent("instance", service.getServiceInstanceName());
  
                                  List<Metric> metricList = groupingMetrics.computeIfAbsent(
                                      it.getName(),
                                      name -> new ArrayList<>()
                                  );
                                  metricList.add(it);
                              });
                          }
                      }
                      groupingMetrics.forEach(
                          (name, metrics) ->
                              converters.forEach(converter -> converter.toMeter(metrics.stream())));
                  }
              }
  
              @Override
              public void onError(Throwable throwable) {
                  Status status = Status.fromThrowable(throwable);
                  if (Status.CANCELLED.getCode() == status.getCode()) {
                      if (log.isDebugEnabled()) {
                          log.error("Envoy client cancelled sending metrics", throwable);
                      }
                      return;
                  }
                  log.error("Error in receiving metrics from envoy", throwable);
              }
  
              @Override
              public void onCompleted() {
                  responseObserver.onNext(StreamMetricsResponse.newBuilder().build());
                  responseObserver.onCompleted();
              }
          };
      }
  }
  