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.beam.runners.dataflow.worker;
  
  import static org.junit.Assert.assertFalse;
  
  import java.lang.reflect.Field;
  import java.lang.reflect.Modifier;
  import java.util.ArrayList;
  import java.util.HashSet;
  
  /** Static helpers for testing Windmill state. */
  public class WindmillStateTestUtils {
    /**
     * Assert that no field (including compiler-generated fields) within {@code obj} point back to a
     * non-null instance of (a subclass of) {@code clazz}.
     */
    public static void assertNoReference(Object obj, Class<?> clazz) throws Exception {
      assertNoReference(obj, clazz, new ArrayList<String>(), new HashSet<Object>());
    }
  
    public static void assertNoReference(
        Object obj, Class<?> clazz, ArrayList<String> path, HashSet<Object> visited)
        throws Exception {
      if (obj == null || visited.contains(obj)) {
        return;
      }
      Class<?> thisClazz = obj.getClass();
      assertFalse(
          "Found invalid path " + path + " back to " + clazz.getName(),
          clazz.isAssignableFrom(thisClazz));
  
      visited.add(obj);
      if (obj instanceof Object[]) {
        Object[] arr = (Object[]) obj;
        for (int i = 0; i < arr.length; i++) {
          try {
            path.add(thisClazz.getName() + "[" + i + "]");
            assertNoReference(arr[i], clazz, path, visited);
          } finally {
            path.remove(path.size() - 1);
          }
        }
      } else {
        Class<?> currClazz = thisClazz;
        while (currClazz != null) {
          for (Field f : currClazz.getDeclaredFields()) {
            if (Modifier.isStatic(f.getModifiers())) {
              continue;
            }
  
            boolean accessible = f.isAccessible();
            try {
              path.add(thisClazz.getName() + "#" + f.getName());
              f.setAccessible(true);
              assertNoReference(f.get(obj), clazz, path, visited);
            } finally {
              path.remove(path.size() - 1);
              f.setAccessible(accessible);
            }
          }
          currClazz = currClazz.getSuperclass();
        }
      }
    }
  }
  