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;
  
  import java.util.Objects;
  import java.util.UUID;
  
  import javax.inject.Inject;
  
  import org.apache.aurora.common.util.Clock;
  import org.apache.aurora.scheduler.storage.entities.ITaskConfig;
  
  /**
   * A function that generates universally-unique (not guaranteed, but highly confident) task IDs.
   */
  public interface TaskIdGenerator {
  
    /**
     * Generates a universally-unique ID for the task.  This is not necessarily a repeatable
     * operation, two subsequent invocations with the same object need not return the same value.
     *
     * @param task Configuration of the task to create an ID for.
     * @param instanceId Instance ID for the task.
     * @return A universally-unique ID for the task.
     */
    String generate(ITaskConfig task, int instanceId);
  
    class TaskIdGeneratorImpl implements TaskIdGenerator {
      private final Clock clock;
  
      @Inject
      TaskIdGeneratorImpl(Clock clock) {
        this.clock = Objects.requireNonNull(clock);
      }
  
      @Override
      public String generate(ITaskConfig task, int instanceId) {
        String sep = "-";
        return new StringBuilder()
            .append(task.getJob().getRole())
            .append(sep)
            .append(task.getJob().getEnvironment())
            .append(sep)
            .append(task.getJob().getName())
            .append(sep)
            .append(instanceId)
            .append(sep)
            .append(UUID.randomUUID())
            .toString().replaceAll("[^\\w-]", sep);  // Constrain character set.
      }
    }
  }
  