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.isolation;
  
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.Map.Entry;
  
  /**
   * Base class for plugins so we can sample information about their initialization
   */
  public interface SamplingTestPlugin {
  
      /**
       * @return the ClassLoader used to statically initialize this plugin class
       */
      ClassLoader staticClassloader();
  
      /**
       * @return the ClassLoader used to initialize this plugin instance
       */
      ClassLoader classloader();
  
      /**
       * @return All known instances of this class, including this instance.
       */
      default List<SamplingTestPlugin> allInstances() {
          return Collections.singletonList(this);
      }
  
      /**
       * @return a group of other SamplingTestPlugin instances known by this plugin
       * This should only return direct children, and not reference this instance directly
       */
      default Map<String, SamplingTestPlugin> otherSamples() {
          return Collections.emptyMap();
      }
  
      /**
       * @return a flattened list of child samples including this entry keyed as "this"
       */
      default Map<String, SamplingTestPlugin> flatten() {
          Map<String, SamplingTestPlugin> out = new HashMap<>();
          Map<String, SamplingTestPlugin> otherSamples = otherSamples();
          if (otherSamples != null) {
              for (Entry<String, SamplingTestPlugin> child : otherSamples.entrySet()) {
                  for (Entry<String, SamplingTestPlugin> flattened : child.getValue().flatten().entrySet()) {
                      String key = child.getKey();
                      if (!flattened.getKey().isEmpty()) {
                          key += "." + flattened.getKey();
                      }
                      out.put(key, flattened.getValue());
                  }
              }
          }
          out.put("", this);
          return out;
      }
  
      /**
       * Log the parent method call as a child sample.
       * Stores only the last invocation of each method if there are multiple invocations.
       * @param samples The collection of samples to which this method call should be added
       */
      default void logMethodCall(Map<String, SamplingTestPlugin> samples) {
          StackTraceElement[] stackTraces = Thread.currentThread().getStackTrace();
          if (stackTraces.length < 2) {
              return;
          }
          // 0 is inside getStackTrace
          // 1 is this method
          // 2 is our caller method
          StackTraceElement caller = stackTraces[2];
  
          samples.put(caller.getMethodName(), new MethodCallSample(
              caller,
              Thread.currentThread().getContextClassLoader(),
              getClass().getClassLoader()
          ));
      }
  
      class MethodCallSample implements SamplingTestPlugin {
  
          private final StackTraceElement caller;
          private final ClassLoader staticClassLoader;
          private final ClassLoader dynamicClassLoader;
  
          public MethodCallSample(
              StackTraceElement caller,
              ClassLoader staticClassLoader,
              ClassLoader dynamicClassLoader
          ) {
              this.caller = caller;
              this.staticClassLoader = staticClassLoader;
              this.dynamicClassLoader = dynamicClassLoader;
          }
  
          @Override
          public ClassLoader staticClassloader() {
              return staticClassLoader;
          }
  
          @Override
          public ClassLoader classloader() {
              return dynamicClassLoader;
          }
  
          @Override
          public String toString() {
              return caller.toString();
          }
      }
  }
  