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.cron.quartz;
  
  import java.util.Optional;
  
  import javax.inject.Inject;
  
  import com.google.common.collect.FluentIterable;
  import com.google.common.collect.Iterables;
  
  import org.apache.aurora.scheduler.base.JobKeys;
  import org.apache.aurora.scheduler.cron.CronScheduler;
  import org.apache.aurora.scheduler.cron.CrontabEntry;
  import org.apache.aurora.scheduler.storage.entities.IJobKey;
  import org.quartz.CronTrigger;
  import org.quartz.Scheduler;
  import org.quartz.SchedulerException;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import static java.util.Objects.requireNonNull;
  
  import static org.apache.aurora.scheduler.cron.quartz.Quartz.jobKey;
  
  class CronSchedulerImpl implements CronScheduler {
    private static final Logger LOG = LoggerFactory.getLogger(CronSchedulerImpl.class);
  
    private final Scheduler scheduler;
  
    @Inject
    CronSchedulerImpl(Scheduler scheduler) {
      this.scheduler = requireNonNull(scheduler);
    }
  
    @Override
    public Optional<CrontabEntry> getSchedule(IJobKey jobKey) throws IllegalStateException {
      requireNonNull(jobKey);
  
      try {
        return Optional.of(Iterables.getOnlyElement(
            FluentIterable.from(scheduler.getTriggersOfJob(jobKey(jobKey)))
                .filter(CronTrigger.class)
                .transform(Quartz::crontabEntry)));
      } catch (SchedulerException e) {
        LOG.error(
            "Error reading job " + JobKeys.canonicalString(jobKey) + " cronExpression Quartz: " + e,
            e);
        return Optional.empty();
      }
    }
  }
  