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.common.util;
  
  import com.google.common.base.Preconditions;
  
  /**
   * A sampler that implements logic for fractional random selection.
   *
   * @author William Farner
   */
  public class Sampler {
  
    private final Random rand;
    private final double threshold;
  
    /**
     * Creates a new sampler using the default system {@link Random}.
     *
     * @param selectPercent Percentage to randomly select, must be between 0 and 100 (inclusive).
     */
    public Sampler(float selectPercent) {
      this(selectPercent, Random.Util.newDefaultRandom());
    }
  
    /**
     * Creates a new sampler using the provided {@link Random}.
     *
     * @param selectPercent Percentage to randoml select, must be between 0 and 100 (inclusive).
     * @param rand The random utility to use for generating random numbers.
     */
    public Sampler(float selectPercent, Random rand) {
      Preconditions.checkArgument((selectPercent >= 0) && (selectPercent <= 100),
          "Invalid selectPercent value: " + selectPercent);
  
      this.threshold = selectPercent / 100;
      this.rand = Preconditions.checkNotNull(rand);
    }
  
    public boolean select() {
      return rand.nextDouble() < threshold;
    }
  }
  