content: /**
   * 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 org.apache.aurora;
  
  import java.util.concurrent.TimeUnit;
  import java.util.concurrent.TimeoutException;
  import java.util.function.Function;
  import java.util.stream.Collector;
  
  import com.google.common.collect.ImmutableList;
  import com.google.common.collect.ImmutableMap;
  import com.google.common.collect.ImmutableMultimap;
  import com.google.common.collect.ImmutableSet;
  import com.google.common.util.concurrent.Service;
  import com.google.common.util.concurrent.Service.State;
  import com.google.common.util.concurrent.ServiceManager;
  import com.google.inject.Inject;
  
  import org.apache.aurora.common.application.Lifecycle;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import static java.util.stream.Collector.Characteristics.UNORDERED;
  
  /**
   * Utilities for working with Guava.
   */
  public final class GuavaUtils {
    private GuavaUtils() {
      // Utility class.
    }
  
    public static class LifecycleShutdownListener extends ServiceManager.Listener {
      private final Lifecycle lifecycle;
      private static final Logger LOG = LoggerFactory.getLogger(LifecycleShutdownListener.class);
  
      @Inject
      LifecycleShutdownListener(Lifecycle lifecycle) {
        this.lifecycle = lifecycle;
      }
  
      @Override
      public void failure(Service service) {
        LOG.error("Service: " + service + " failed unexpectedly. Triggering shutdown.");
        lifecycle.shutdown();
      }
    }
  
    /**
     * Collector to create a Guava ImmutableSet.
     */
    public static <T> Collector<T, ?, ImmutableSet<T>> toImmutableSet() {
      return Collector.of(
          ImmutableSet.Builder<T>::new,
          ImmutableSet.Builder::add,
          (l, r) -> l.addAll(r.build()),
          ImmutableSet.Builder::build,
          UNORDERED);
    }
  
    /**
     * Collector to create a Guava ImmutableList.
     */
    public static <T> Collector<T, ?, ImmutableList<T>> toImmutableList() {
      return Collector.of(
          ImmutableList.Builder<T>::new,
          ImmutableList.Builder::add,
          (l, r) -> l.addAll(r.build()),
          ImmutableList.Builder::build);
    }
  
    /**
     * Collector to create a Guava ImmutableMap.
     */
    public static <T, K, V> Collector<T, ?, ImmutableMap<K, V>> toImmutableMap(
        Function<? super T, ? extends K> keyMapper,
        Function<? super T, ? extends V> valueMapper) {
      return Collector.of(
          ImmutableMap.Builder<K, V>::new,
          (r, t) -> r.put(keyMapper.apply(t), valueMapper.apply(t)),
          (l, r) -> l.putAll(r.build()),
          ImmutableMap.Builder::build,
          UNORDERED);
    }
  
    /**
     * Interface for mocking. The Guava ServiceManager class is final.
     */
    public interface ServiceManagerIface {
      ServiceManagerIface startAsync();
  
      void awaitHealthy();
  
      ServiceManagerIface stopAsync();
  
      void awaitStopped(long timeout, TimeUnit unit) throws TimeoutException;
  
      ImmutableMultimap<State, Service> servicesByState();
    }
  
    /**
     * Create a new {@link ServiceManagerIface} that wraps a {@link ServiceManager}.
     *
     * @param delegate Service manager to delegate to.
     * @return A wrapper.
     */
    public static ServiceManagerIface serviceManager(final ServiceManager delegate) {
      return new ServiceManagerIface() {
        @Override
        public ServiceManagerIface startAsync() {
          delegate.startAsync();
          return this;
        }
  
        @Override
        public void awaitHealthy() {
          delegate.awaitHealthy();
        }
  
        @Override
        public ServiceManagerIface stopAsync() {
          delegate.stopAsync();
          return this;
        }
  
        @Override
        public void awaitStopped(long timeout, TimeUnit unit) throws TimeoutException {
          delegate.awaitStopped(timeout, unit);
        }
  
        @Override
        public ImmutableMultimap<State, Service> servicesByState() {
          return delegate.servicesByState();
        }
      };
    }
  }
  