content: /*
   * Copyright (C) 2014 The Android Open Source Project
   *
   * Licensed 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 androidx.test.espresso;
  
  import static androidx.test.internal.util.Checks.checkNotNull;
  
  import java.util.concurrent.atomic.AtomicReference;
  
  /** Holds Espresso's object graph. */
  public final class GraphHolder {
    private static final String TAG = GraphHolder.class.getSimpleName();
  
    private static final AtomicReference<GraphHolder> instance =
        new AtomicReference<GraphHolder>(null);
  
    private final BaseLayerComponent component;
  
    private GraphHolder(BaseLayerComponent component) {
      this.component = checkNotNull(component);
    }
  
    static BaseLayerComponent baseLayer() {
      GraphHolder instanceRef = instance.get();
      if (null == instanceRef) {
        instanceRef = new GraphHolder(DaggerBaseLayerComponent.create());
        if (instance.compareAndSet(null, instanceRef)) {
          return instanceRef.component;
        } else {
          return instance.get().component;
        }
      } else {
        return instanceRef.component;
      }
    }
  }
  