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.runningaggregates.std;
  
  import org.apache.asterix.formats.nontagged.SerializerDeserializerProvider;
  import org.apache.asterix.om.base.AInt64;
  import org.apache.asterix.om.base.AMutableInt64;
  import org.apache.asterix.om.types.ATypeTag;
  import org.apache.asterix.om.types.BuiltinType;
  import org.apache.asterix.om.types.hierachy.ATypeHierarchy;
  import org.apache.asterix.runtime.evaluators.functions.PointableHelper;
  import org.apache.hyracks.algebricks.core.algebra.functions.FunctionIdentifier;
  import org.apache.hyracks.algebricks.runtime.base.IScalarEvaluator;
  import org.apache.hyracks.algebricks.runtime.base.IWindowAggregateEvaluator;
  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.primitive.VoidPointable;
  import org.apache.hyracks.data.std.util.ArrayBackedValueStorage;
  import org.apache.hyracks.dataflow.common.data.accessors.IFrameTupleReference;
  
  /**
   * Evaluator for {@code ntile()} window function
   */
  public class NtileRunningAggregateEvaluator implements IWindowAggregateEvaluator {
  
      private final IScalarEvaluator evalNumGroups;
  
      private final VoidPointable argNumGroups = VoidPointable.FACTORY.createPointable();
  
      private final FunctionIdentifier funId;
  
      @SuppressWarnings("unchecked")
      private final ISerializerDeserializer<AInt64> serde =
              SerializerDeserializerProvider.INSTANCE.getSerializerDeserializer(BuiltinType.AINT64);
  
      private final ArrayBackedValueStorage resultStorage = new ArrayBackedValueStorage();
  
      private final AMutableInt64 aInt64 = new AMutableInt64(0);
  
      private long partitionLength;
  
      private long groupSize;
  
      private long groupRemainder;
  
      private long resultValue;
  
      private long count;
  
      private boolean isNull;
  
      NtileRunningAggregateEvaluator(IScalarEvaluator evalNumGroups, FunctionIdentifier funId) {
          this.evalNumGroups = evalNumGroups;
          this.funId = funId;
      }
  
      @Override
      public void init() throws HyracksDataException {
      }
  
      @Override
      public void initPartition(long partitionLength) {
          this.partitionLength = partitionLength;
          resultValue = 0;
          isNull = false;
          groupSize = 1;
          groupRemainder = 0;
      }
  
      @Override
      public void step(IFrameTupleReference tuple, IPointable result) throws HyracksDataException {
          if (resultValue == 0) {
              evaluateGroupSize(tuple);
              resultValue = count = 1;
          } else if (count < groupSize) {
              count++;
          } else if (count == groupSize && groupRemainder > 0) {
              groupRemainder--;
              count++;
          } else {
              resultValue++;
              count = 1;
          }
  
          if (isNull) {
              PointableHelper.setNull(result);
          } else {
              resultStorage.reset();
              aInt64.setValue(resultValue);
              serde.serialize(aInt64, resultStorage.getDataOutput());
              result.set(resultStorage);
          }
      }
  
      private void evaluateGroupSize(IFrameTupleReference tuple) throws HyracksDataException {
          evalNumGroups.evaluate(tuple, argNumGroups);
          byte[] bytes = argNumGroups.getByteArray();
          int offset = argNumGroups.getStartOffset();
          if (bytes[offset] == ATypeTag.SERIALIZED_NULL_TYPE_TAG) {
              isNull = true;
          } else {
              long numGroups = ATypeHierarchy.getLongValue(funId.getName(), 0, bytes, offset);
              if (numGroups > 0 && numGroups <= partitionLength) {
                  groupSize = partitionLength / numGroups;
                  groupRemainder = partitionLength % numGroups;
              }
          }
      }
  }
  