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.kafka.connect.runtime;
  
  import org.apache.kafka.clients.CommonClientConfigs;
  import org.apache.kafka.common.MetricName;
  import org.apache.kafka.common.metrics.KafkaMetric;
  import org.apache.kafka.common.metrics.MetricsContext;
  import org.apache.kafka.common.metrics.MetricsReporter;
  import org.apache.kafka.common.utils.MockTime;
  
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  
  /**
   * A specialization of {@link ConnectMetrics} that uses a custom {@link MetricsReporter} to capture the metrics
   * that were created, and makes those metrics available even after the metrics were removed from the
   * {@link org.apache.kafka.common.metrics.Metrics} registry.
   *
   * This is needed because many of the Connect metric groups are specific to connectors and/or tasks, and therefore
   * their metrics are removed from the {@link org.apache.kafka.common.metrics.Metrics} registry when the connector
   * and tasks are closed. This instance keeps track of the metrics that were created so that it is possible for
   * tests to {@link #currentMetricValue(MetricGroup, String) read the metrics' value} even after the connector
   * and/or tasks have been closed.
   *
   * If the same metric is created a second time (e.g., a worker task is re-created), the new metric will replace
   * the previous metric in the custom reporter.
   */
  public class MockConnectMetrics extends ConnectMetrics {
  
      private static final Map<String, String> DEFAULT_WORKER_CONFIG = new HashMap<>();
  
      static {
          DEFAULT_WORKER_CONFIG.put(WorkerConfig.KEY_CONVERTER_CLASS_CONFIG, "org.apache.kafka.connect.json.JsonConverter");
          DEFAULT_WORKER_CONFIG.put(WorkerConfig.VALUE_CONVERTER_CLASS_CONFIG, "org.apache.kafka.connect.json.JsonConverter");
          DEFAULT_WORKER_CONFIG.put(CommonClientConfigs.METRIC_REPORTER_CLASSES_CONFIG, MockMetricsReporter.class.getName());
      }
  
      public MockConnectMetrics() {
          this(new MockTime());
      }
  
      public MockConnectMetrics(MockTime time) {
          super("mock", new WorkerConfig(WorkerConfig.baseConfigDef(), DEFAULT_WORKER_CONFIG), time, "cluster-1");
      }
  
      @Override
      public MockTime time() {
          return (MockTime) super.time();
      }
  
      /**
       * Get the current value of the named metric, which may have already been removed from the
       * {@link org.apache.kafka.common.metrics.Metrics} but will have been captured before it was removed.
       *
       * @param metricGroup the metric metricGroup that contained the metric
       * @param name        the name of the metric
       * @return the current value of the metric
       */
      public Object currentMetricValue(MetricGroup metricGroup, String name) {
          return currentMetricValue(this, metricGroup, name);
      }
  
      /**
       * Get the current value of the named metric, which may have already been removed from the
       * {@link org.apache.kafka.common.metrics.Metrics} but will have been captured before it was removed.
       *
       * @param metricGroup the metric metricGroup that contained the metric
       * @param name        the name of the metric
       * @return the current value of the metric
       */
      public double currentMetricValueAsDouble(MetricGroup metricGroup, String name) {
          Object value = currentMetricValue(metricGroup, name);
          return value instanceof Double ? (Double) value : Double.NaN;
      }
  
      /**
       * Get the current value of the named metric, which may have already been removed from the
       * {@link org.apache.kafka.common.metrics.Metrics} but will have been captured before it was removed.
       *
       * @param metricGroup the metric metricGroup that contained the metric
       * @param name        the name of the metric
       * @return the current value of the metric
       */
      public String currentMetricValueAsString(MetricGroup metricGroup, String name) {
          Object value = currentMetricValue(metricGroup, name);
          return value instanceof String ? (String) value : null;
      }
  
      /**
       * Get the current value of the named metric, which may have already been removed from the
       * {@link org.apache.kafka.common.metrics.Metrics} but will have been captured before it was removed.
       *
       * @param metrics the {@link ConnectMetrics} instance
       * @param metricGroup the metric metricGroup that contained the metric
       * @param name        the name of the metric
       * @return the current value of the metric
       */
      public static Object currentMetricValue(ConnectMetrics metrics, MetricGroup metricGroup, String name) {
          MetricName metricName = metricGroup.metricName(name);
          for (MetricsReporter reporter : metrics.metrics().reporters()) {
              if (reporter instanceof MockMetricsReporter) {
                  return ((MockMetricsReporter) reporter).currentMetricValue(metricName);
              }
          }
          return null;
      }
  
      /**
       * Get the current value of the named metric, which may have already been removed from the
       * {@link org.apache.kafka.common.metrics.Metrics} but will have been captured before it was removed.
       *
       * @param metrics the {@link ConnectMetrics} instance
       * @param metricGroup the metric metricGroup that contained the metric
       * @param name        the name of the metric
       * @return the current value of the metric
       */
      public static double currentMetricValueAsDouble(ConnectMetrics metrics, MetricGroup metricGroup, String name) {
          Object value = currentMetricValue(metrics, metricGroup, name);
          return value instanceof Double ? (Double) value : Double.NaN;
      }
  
      /**
       * Get the current value of the named metric, which may have already been removed from the
       * {@link org.apache.kafka.common.metrics.Metrics} but will have been captured before it was removed.
       *
       * @param metrics the {@link ConnectMetrics} instance
       * @param metricGroup the metric metricGroup that contained the metric
       * @param name        the name of the metric
       * @return the current value of the metric
       */
      public static String currentMetricValueAsString(ConnectMetrics metrics, MetricGroup metricGroup, String name) {
          Object value = currentMetricValue(metrics, metricGroup, name);
          return value instanceof String ? (String) value : null;
      }
  
      public static class MockMetricsReporter implements MetricsReporter {
          private final Map<MetricName, KafkaMetric> metricsByName = new HashMap<>();
  
          private MetricsContext metricsContext;
  
          public MockMetricsReporter() {
          }
  
          @Override
          public void configure(Map<String, ?> configs) {
              // do nothing
          }
  
          @Override
          public void init(List<KafkaMetric> metrics) {
              for (KafkaMetric metric : metrics) {
                  metricsByName.put(metric.metricName(), metric);
              }
          }
  
          @Override
          public void metricChange(KafkaMetric metric) {
              metricsByName.put(metric.metricName(), metric);
          }
  
          @Override
          public void metricRemoval(KafkaMetric metric) {
              // don't remove metrics, or else we won't be able to access them after the metric metricGroup is closed
          }
  
          @Override
          public void close() {
              // do nothing
          }
  
          /**
           * Get the current value of the metric.
           *
           * @param metricName the name of the metric that was registered most recently
           * @return the current value of the metric
           */
          public Object currentMetricValue(MetricName metricName) {
              KafkaMetric metric = metricsByName.get(metricName);
              return metric != null ? metric.metricValue() : null;
          }
  
          @Override
          public void contextChange(MetricsContext metricsContext) {
              this.metricsContext = metricsContext;
          }
  
          public MetricsContext getMetricsContext() {
              return this.metricsContext;
          }
      }
  }
  