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.bookkeeper.common.component;
  
  import static com.google.common.base.Preconditions.checkArgument;
  import static com.google.common.base.Preconditions.checkNotNull;
  
  import com.google.common.annotations.VisibleForTesting;
  import com.google.common.collect.ImmutableList;
  import com.google.common.collect.Lists;
  import java.lang.Thread.UncaughtExceptionHandler;
  import java.util.List;
  import lombok.extern.slf4j.Slf4j;
  
  /**
   * A stack of {@link LifecycleComponent}s.
   */
  @Slf4j
  public class LifecycleComponentStack implements LifecycleComponent {
  
      public static Builder newBuilder() {
          return new Builder();
      }
  
      /**
       * Builder to build a stack of {@link LifecycleComponent}s.
       */
      public static class Builder {
  
          private String name;
          private ComponentInfoPublisher componentInfoPublisher;
          private final List<LifecycleComponent> components;
  
          private Builder() {
              components = Lists.newArrayList();
          }
  
          public Builder withComponentInfoPublisher(ComponentInfoPublisher componentInfoPublisher) {
              checkNotNull(componentInfoPublisher, "ComponentInfoPublisher is null");
              this.componentInfoPublisher = componentInfoPublisher;
              return this;
          }
  
          public Builder addComponent(LifecycleComponent component) {
              checkNotNull(component, "Lifecycle component is null");
              components.add(component);
              return this;
          }
  
          public Builder withName(String name) {
              this.name = name;
              return this;
          }
  
          public LifecycleComponentStack build() {
              checkNotNull(name, "Lifecycle component stack name is not provided");
              checkArgument(!components.isEmpty(), "Lifecycle component stack is empty : " + components);
              return new LifecycleComponentStack(
                  name,
                  componentInfoPublisher != null ? componentInfoPublisher : new ComponentInfoPublisher(),
                  ImmutableList.copyOf(components));
          }
  
      }
  
      private final String name;
      private final ImmutableList<LifecycleComponent> components;
      private final ComponentInfoPublisher componentInfoPublisher;
  
      private LifecycleComponentStack(String name,
                                      ComponentInfoPublisher componentInfoPublisher,
                                      ImmutableList<LifecycleComponent> components) {
          this.name = name;
          this.componentInfoPublisher = componentInfoPublisher;
          this.components = components;
      }
  
      @VisibleForTesting
      public int getNumComponents() {
          return components.size();
      }
  
      @VisibleForTesting
      public LifecycleComponent getComponent(int index) {
          return components.get(index);
      }
  
      @Override
      public String getName() {
          return name;
      }
  
      @Override
      public Lifecycle.State lifecycleState() {
          return components.get(0).lifecycleState();
      }
  
      @Override
      public void addLifecycleListener(LifecycleListener listener) {
          components.forEach(component -> component.addLifecycleListener(listener));
      }
  
      @Override
      public void removeLifecycleListener(LifecycleListener listener) {
          components.forEach(component -> component.removeLifecycleListener(listener));
      }
  
      @Override
      public void publishInfo(ComponentInfoPublisher componentInfoPublisher) {
          components.forEach(component -> {
              if (log.isDebugEnabled()) {
                  log.debug("calling publishInfo on {} ", component);
              }
              component.publishInfo(componentInfoPublisher);
          });
      }
  
      @Override
      public void start() {
          components.forEach(component -> {
              if (log.isDebugEnabled()) {
                  log.debug("calling publishInfo on {} ", component);
              }
              component.publishInfo(componentInfoPublisher);
          });
          componentInfoPublisher.startupFinished();
  
          components.forEach(component -> component.start());
      }
  
      @Override
      public void stop() {
          components.reverse().forEach(component -> component.stop());
      }
  
      @Override
      public void close() {
          components.reverse().forEach(component -> component.close());
      }
  
      @Override
      public void setExceptionHandler(UncaughtExceptionHandler handler) {
          components.forEach(component -> component.setExceptionHandler(handler));
      }
  }
  