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.scheduler.offers;
  
  import java.util.concurrent.ScheduledExecutorService;
  
  import javax.inject.Inject;
  
  import com.google.common.base.Supplier;
  
  import org.apache.aurora.common.quantity.Amount;
  import org.apache.aurora.common.quantity.Time;
  import org.apache.aurora.scheduler.async.AsyncModule.AsyncExecutor;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   * Determines if and when a deferred action should be performed.
   */
  public interface Deferment {
  
    /**
     * Defers an action to possibly be performed at some point in the future.
     *
     * @param action Callback to perform the deferred action.
     */
    void defer(Runnable action);
  
    /**
     * Never performs deferred actions.
     */
    class Noop implements Deferment {
      @Override
      public void defer(Runnable action) {
        // no-op
      }
    }
  
    /**
     * Performs a deferred action after a dynamic delay.
     */
    class DelayedDeferment implements Deferment {
      private final Supplier<Amount<Long, Time>> delay;
      private final ScheduledExecutorService executor;
  
      @Inject
      public DelayedDeferment(
          Supplier<Amount<Long, Time>> delay,
          @AsyncExecutor ScheduledExecutorService executor) {
  
        this.delay = requireNonNull(delay);
        this.executor = requireNonNull(executor);
      }
  
      @Override
      public void defer(Runnable action) {
        Amount<Long, Time> actionDelay = delay.get();
        executor.schedule(action, actionDelay.getValue(), actionDelay.getUnit().getTimeUnit());
      }
    }
  }
  