content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you 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.asterix.runtime.evaluators.functions.utils;
  
  import java.io.DataOutput;
  import java.security.NoSuchAlgorithmException;
  import java.security.SecureRandom;
  
  import org.apache.asterix.common.exceptions.ErrorCode;
  import org.apache.asterix.common.exceptions.RuntimeDataException;
  import org.apache.asterix.formats.nontagged.SerializerDeserializerProvider;
  import org.apache.asterix.om.base.AMutableDouble;
  import org.apache.asterix.om.types.BuiltinType;
  import org.apache.hyracks.api.dataflow.value.ISerializerDeserializer;
  import org.apache.hyracks.api.exceptions.HyracksDataException;
  import org.apache.hyracks.data.std.api.IPointable;
  import org.apache.hyracks.data.std.util.ArrayBackedValueStorage;
  
  public final class RandomHelper {
  
      private final SecureRandom random;
  
      private double seed;
  
      private boolean isFirst;
  
      private final AMutableDouble aDouble = new AMutableDouble(0);
  
      @SuppressWarnings("rawtypes")
      private final ISerializerDeserializer doubleSerde =
              SerializerDeserializerProvider.INSTANCE.getSerializerDeserializer(BuiltinType.ADOUBLE);
  
      private final ArrayBackedValueStorage resultStorage = new ArrayBackedValueStorage();
      private final DataOutput dataOutput = resultStorage.getDataOutput();
  
      public RandomHelper(boolean withSeed) throws HyracksDataException {
          if (withSeed) {
              try {
                  random = SecureRandom.getInstance("SHA1PRNG");
              } catch (NoSuchAlgorithmException e) {
                  throw new RuntimeDataException(ErrorCode.ILLEGAL_STATE, "random()");
              }
          } else {
              random = new SecureRandom();
          }
          isFirst = true;
      }
  
      public void setSeed(double seedVal) throws HyracksDataException {
          if (isFirst || seedVal != seed) {
              seed = seedVal;
              isFirst = false;
              random.setSeed(Double.doubleToLongBits(seedVal));
          }
      }
  
      public void nextDouble(IPointable resultPointable) throws HyracksDataException {
          aDouble.setValue(random.nextDouble());
          resultStorage.reset();
          doubleSerde.serialize(aDouble, dataOutput);
          resultPointable.set(resultStorage);
      }
  }
  