exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/impl/Hash64AsDouble.java

/*
 * 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.drill.exec.expr.fn.impl;

import org.apache.drill.exec.expr.DrillSimpleFunc;
import org.apache.drill.exec.expr.annotations.FunctionTemplate;
import org.apache.drill.exec.expr.annotations.Output;
import org.apache.drill.exec.expr.annotations.Param;
import org.apache.drill.exec.expr.annotations.FunctionTemplate.FunctionScope;
import org.apache.drill.exec.expr.holders.BigIntHolder;
import org.apache.drill.exec.expr.holders.VarDecimalHolder;
import org.apache.drill.exec.expr.holders.NullableVarDecimalHolder;
import org.apache.drill.exec.expr.holders.Float4Holder;
import org.apache.drill.exec.expr.holders.Float8Holder;
import org.apache.drill.exec.expr.holders.IntHolder;
import org.apache.drill.exec.expr.holders.NullableBigIntHolder;
import org.apache.drill.exec.expr.holders.NullableFloat4Holder;
import org.apache.drill.exec.expr.holders.NullableFloat8Holder;
import org.apache.drill.exec.expr.holders.NullableIntHolder;

/*
 * Class contains hash64 function definitions for different data types.
 *
 * NOTE: These functions are used internally by Drill to perform hash distribution and in hash join. For
 * numeric data types we would like to apply implicit casts in the join method however for this to work
 * as expected we would need to hash the same value represented in different data types (int, bigint, float etc)
 * to hash to the same node, this is why we cast all numeric values to double before performing the actual hash.
 */
@SuppressWarnings("unused")
public class Hash64AsDouble {
  @FunctionTemplate(name = "hash64AsDouble", scope = FunctionScope.SIMPLE, nulls = FunctionTemplate.NullHandling.INTERNAL)
  public static class NullableFloatHash implements DrillSimpleFunc {

    @Param
    NullableFloat4Holder in;
    @Output
    BigIntHolder out;

    public void setup() {
    }

    public void eval() {
      if (in.isSet == 0) {
        out.value = 0;
      } else {
        out.value = org.apache.drill.exec.expr.fn.impl.HashHelper.hash64((double) in.value, 0);
      }
    }
  }

  @FunctionTemplate(name = "hash64AsDouble", scope = FunctionScope.SIMPLE, nulls = FunctionTemplate.NullHandling.INTERNAL)
  public static class FloatHash implements DrillSimpleFunc {

    @Param
    Float4Holder in;
    @Output
    BigIntHolder out;

    public void setup() {
    }

    public void eval() {
      out.value = org.apache.drill.exec.expr.fn.impl.HashHelper.hash64((double) in.value, 0);
    }
  }

  @FunctionTemplate(name = "hash64AsDouble", scope = FunctionScope.SIMPLE, nulls = FunctionTemplate.NullHandling.INTERNAL)
  public static class NullableDoubleHash implements DrillSimpleFunc {

    @Param
    NullableFloat8Holder in;
    @Output
    BigIntHolder out;

    public void setup() {
    }

    public void eval() {
      if (in.isSet == 0) {
        out.value = 0;
      } else {
        out.value = org.apache.drill.exec.expr.fn.impl.HashHelper.hash64(in.value, 0);
      }
    }
  }

  @FunctionTemplate(name = "hash64AsDouble", scope = FunctionScope.SIMPLE, nulls = FunctionTemplate.NullHandling.INTERNAL)
  public static class DoubleHash implements DrillSimpleFunc {

    @Param
    Float8Holder in;
    @Output
    BigIntHolder out;

    public void setup() {
    }

    public void eval() {
      out.value = org.apache.drill.exec.expr.fn.impl.HashHelper.hash64(in.value, 0);
    }
  }

  @FunctionTemplate(name = "hash64AsDouble", scope = FunctionScope.SIMPLE, nulls = FunctionTemplate.NullHandling.INTERNAL)
  public static class NullableBigIntHash implements DrillSimpleFunc {

    @Param
    NullableBigIntHolder in;
    @Output
    BigIntHolder out;

    public void setup() {
    }

    public void eval() {
      if (in.isSet == 0) {
        out.value = 0;
      } else {
        out.value = org.apache.drill.exec.expr.fn.impl.HashHelper.hash64((double) in.value, 0);
      }
    }
  }

  @FunctionTemplate(name = "hash64AsDouble", scope = FunctionScope.SIMPLE, nulls = FunctionTemplate.NullHandling.INTERNAL)
  public static class NullableIntHash implements DrillSimpleFunc {
    @Param
    NullableIntHolder in;
    @Output
    BigIntHolder out;

    public void setup() {
    }

    public void eval() {
      if (in.isSet == 0) {
        out.value = 0;
      } else {
        out.value = org.apache.drill.exec.expr.fn.impl.HashHelper.hash64((double) in.value, 0);
      }
    }
  }

  @FunctionTemplate(name = "hash64AsDouble", scope = FunctionScope.SIMPLE, nulls = FunctionTemplate.NullHandling.INTERNAL)
  public static class BigIntHash implements DrillSimpleFunc {

    @Param
    BigIntHolder in;
    @Output
    BigIntHolder out;

    public void setup() {
    }

    public void eval() {
      out.value = org.apache.drill.exec.expr.fn.impl.HashHelper.hash64((double) in.value, 0);
    }
  }

  @FunctionTemplate(name = "hash64AsDouble", scope = FunctionScope.SIMPLE, nulls = FunctionTemplate.NullHandling.INTERNAL)
  public static class IntHash implements DrillSimpleFunc {
    @Param
    IntHolder in;
    @Output
    BigIntHolder out;

    public void setup() {
    }

    public void eval() {
      // TODO: implement hash function for other types
      out.value = org.apache.drill.exec.expr.fn.impl.HashHelper.hash64((double) in.value, 0);
    }
  }

  @FunctionTemplate(name = "hash64AsDouble", scope = FunctionScope.SIMPLE, nulls = FunctionTemplate.NullHandling.INTERNAL)
  public static class VarDecimalHash implements DrillSimpleFunc {
    @Param VarDecimalHolder in;
    @Output BigIntHolder out;

    public void setup() {
    }

    public void eval() {
      java.math.BigDecimal bd = org.apache.drill.exec.util.DecimalUtility.getBigDecimalFromDrillBuf(in.buffer,
              in.start, in.end - in.start, in.scale);
      out.value = org.apache.drill.exec.expr.fn.impl.HashHelper.hash64(bd.doubleValue(), 0);
    }
  }

  @FunctionTemplate(name = "hash64AsDouble", scope = FunctionScope.SIMPLE, nulls = FunctionTemplate.NullHandling.INTERNAL)
  public static class NullableVarDecimalHash implements DrillSimpleFunc {
    @Param NullableVarDecimalHolder in;
    @Output BigIntHolder out;

    public void setup() {
    }

    public void eval() {
      if (in.isSet == 0) {
        out.value = 0;
      } else {
        java.math.BigDecimal bd = org.apache.drill.exec.util.DecimalUtility.getBigDecimalFromDrillBuf(in.buffer,
                in.start, in.end - in.start, in.scale);
        out.value = org.apache.drill.exec.expr.fn.impl.HashHelper.hash64(bd.doubleValue(), 0);
      }
    }
  }
}