[GitHub] [druid] cryptoe commented on a change in pull request #11888: add 'TypeStrategy' to types

[GitBox <gi...@apache.org>]

cryptoe commented on a change in pull request #11888:
URL: https://github.com/apache/druid/pull/11888#discussion_r760137051



##########
File path: core/src/main/java/org/apache/druid/segment/column/TypeStrategies.java
##########
@@ -0,0 +1,463 @@
+/*
+ * 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.druid.segment.column;
+
+import com.google.common.base.Preconditions;
+import com.google.common.collect.Ordering;
+import com.google.common.primitives.Floats;
+import com.google.common.primitives.Longs;
+import org.apache.druid.common.config.NullHandling;
+import org.apache.druid.java.util.common.ISE;
+import org.apache.druid.java.util.common.StringUtils;
+
+import javax.annotation.Nullable;
+import java.nio.ByteBuffer;
+import java.util.Arrays;
+import java.util.Comparator;
+import java.util.concurrent.ConcurrentHashMap;
+
+public class TypeStrategies
+{
+  public static final int VALUE_OFFSET = Byte.BYTES;
+  public static final int NULLABLE_LONG_SIZE = Byte.BYTES + Long.BYTES;
+  public static final int NULLABLE_DOUBLE_SIZE = Byte.BYTES + Double.BYTES;
+  public static final int NULLABLE_FLOAT_SIZE = Byte.BYTES + Float.BYTES;
+
+  public static final LongTypeStrategy LONG = new LongTypeStrategy();
+  public static final FloatTypeStrategy FLOAT = new FloatTypeStrategy();
+  public static final DoubleTypeStrategy DOUBLE = new DoubleTypeStrategy();
+  public static final StringTypeStrategy STRING = new StringTypeStrategy();
+  public static final ConcurrentHashMap<String, TypeStrategy<?>> COMPLEX_STRATEGIES = new ConcurrentHashMap<>();
+
+  /**
+   * Get an {@link TypeStrategy} registered to some {@link TypeSignature#getComplexTypeName()}.
+   */
+  @Nullable
+  public static TypeStrategy<?> getComplex(String typeName)
+  {
+    return COMPLEX_STRATEGIES.get(typeName);
+  }
+
+  /**
+   * hmm... this might look familiar... (see ComplexMetrics)
+   *
+   * Register a complex type name -> {@link TypeStrategy} mapping.
+   *
+   * If the specified type name is already used and the supplied {@link TypeStrategy} is not of the
+   * same type as the existing value in the map for said key, an {@link ISE} is thrown.
+   *
+   * @param strategy The {@link TypeStrategy} object to be associated with the 'type' in the map.
+   */
+  public static void registerComplex(String typeName, TypeStrategy<?> strategy)
+  {
+    Preconditions.checkNotNull(typeName);
+    COMPLEX_STRATEGIES.compute(typeName, (key, value) -> {
+      if (value == null) {
+        return strategy;
+      } else {
+        if (!value.getClass().getName().equals(strategy.getClass().getName())) {
+          throw new ISE(
+              "Incompatible strategy for type[%s] already exists. Expected [%s], found [%s].",
+              key,
+              strategy.getClass().getName(),
+              value.getClass().getName()
+          );
+        } else {
+          return value;
+        }
+      }
+    });
+  }
+
+  /**
+   * Clear and set the 'null' byte of a nullable value to {@link NullHandling#IS_NULL_BYTE} to a {@link ByteBuffer} at
+   * the supplied position. This method does not change the buffer position, limit, or mark, because it does not expect
+   * to own the buffer given to it (i.e. buffer aggs)
+   *
+   * Nullable types are stored with a leading byte to indicate if the value is null, followed by the value bytes
+   * (if not null)
+   *
+   * layout: | null (byte) | value |
+   *
+   * @return number of bytes written (always 1)
+   */
+  public static int writeNull(ByteBuffer buffer, int offset)
+  {
+    buffer.put(offset, NullHandling.IS_NULL_BYTE);
+    return 1;
+  }
+
+  /**
+   * Checks if a 'nullable' value's null byte is set to {@link NullHandling#IS_NULL_BYTE}. This method will mask the
+   * value of the null byte to only check if the null bit is set, meaning that the higher bits can be utilized for
+   * flags as necessary (e.g. using high bits to indicate if the value has been set or not for aggregators).
+   *
+   * Note that writing nullable values with the methods of {@link Types} will always clear and set the null byte to
+   * either {@link NullHandling#IS_NULL_BYTE} or {@link NullHandling#IS_NOT_NULL_BYTE}, losing any flag bits.
+   *
+   * layout: | null (byte) | value |
+   */
+  public static boolean isNullableNull(ByteBuffer buffer, int offset)
+  {
+    // use & so that callers can use the high bits of the null byte to pack additional information if necessary
+    return (buffer.get(offset) & NullHandling.IS_NULL_BYTE) == NullHandling.IS_NULL_BYTE;
+  }
+
+  /**
+   * Write a non-null long value to a {@link ByteBuffer} at the supplied offset. The first byte is always cleared and
+   * set to {@link NullHandling#IS_NOT_NULL_BYTE}, the long value is written in the next 8 bytes.
+   *
+   * layout: | null (byte) | long |
+   *
+   * This method does not change the buffer position, limit, or mark, because it does not expect to own the buffer
+   * given to it (i.e. buffer aggs)
+   *
+   * @return number of bytes written (always 9)
+   */
+  public static int writeNullableLong(ByteBuffer buffer, int offset, long value)
+  {
+    buffer.put(offset++, NullHandling.IS_NOT_NULL_BYTE);
+    buffer.putLong(offset, value);
+    return NULLABLE_LONG_SIZE;
+  }
+
+  /**
+   * Reads a non-null long value from a {@link ByteBuffer} at the supplied offset. This method should only be called
+   * if and only if {@link #isNullableNull} for the same offset returns false.
+   *
+   * layout: | null (byte) | long |
+   *
+   * This method does not change the buffer position, limit, or mark, because it does not expect  to own the buffer
+   * given to it (i.e. buffer aggs)
+   */
+  public static long readNullableLong(ByteBuffer buffer, int offset)
+  {
+    assert !isNullableNull(buffer, offset);
+    return buffer.getLong(offset + VALUE_OFFSET);
+  }
+
+  /**
+   * Write a non-null double value to a {@link ByteBuffer} at the supplied offset. The first byte is always cleared and
+   * set to {@link NullHandling#IS_NOT_NULL_BYTE}, the double value is written in the next 8 bytes.
+   *
+   * layout: | null (byte) | double |
+   *
+   * This method does not change the buffer position, limit, or mark, because it does not expect to own the buffer
+   * given to it (i.e. buffer aggs)
+   *
+   * @return number of bytes written (always 9)
+   */
+  public static int writeNullableDouble(ByteBuffer buffer, int offset, double value)
+  {
+    buffer.put(offset++, NullHandling.IS_NOT_NULL_BYTE);
+    buffer.putDouble(offset, value);
+    return NULLABLE_DOUBLE_SIZE;
+  }
+
+  /**
+   * Reads a non-null double value from a {@link ByteBuffer} at the supplied offset. This method should only be called
+   * if and only if {@link #isNullableNull} for the same offset returns false.
+   *
+   * layout: | null (byte) | double |
+   *
+   * This method does not change the buffer position, limit, or mark, because it does not expect to own the buffer
+   * given to it (i.e. buffer aggs)
+   */
+  public static double readNullableDouble(ByteBuffer buffer, int offset)
+  {
+    assert !isNullableNull(buffer, offset);
+    return buffer.getDouble(offset + VALUE_OFFSET);
+  }
+
+  /**
+   * Write a non-null float value to a {@link ByteBuffer} at the supplied offset. The first byte is always cleared and
+   * set to {@link NullHandling#IS_NOT_NULL_BYTE}, the float value is written in the next 4 bytes.
+   *
+   * layout: | null (byte) | float |
+   *
+   * This method does not change the buffer position, limit, or mark, because it does not expect to own the buffer
+   * given to it (i.e. buffer aggs)
+   *
+   * @return number of bytes written (always 5)
+   */
+  public static int writeNullableFloat(ByteBuffer buffer, int offset, float value)
+  {
+    buffer.put(offset++, NullHandling.IS_NOT_NULL_BYTE);
+    buffer.putFloat(offset, value);
+    return NULLABLE_FLOAT_SIZE;
+  }
+
+  /**
+   * Reads a non-null float value from a {@link ByteBuffer} at the supplied offset. This method should only be called
+   * if and only if {@link #isNullableNull} for the same offset returns false.
+   *
+   * layout: | null (byte) | float |
+   *
+   * This method does not change the buffer position, limit, or mark, because it does not expect to own the buffer
+   * given to it (i.e. buffer aggs)
+   */
+  public static float readNullableFloat(ByteBuffer buffer, int offset)
+  {
+    assert !isNullableNull(buffer, offset);
+    return buffer.getFloat(offset + VALUE_OFFSET);
+  }
+
+
+  public static final class LongTypeStrategy implements TypeStrategy<Long>
+  {
+    private static final Comparator<Long> COMPARATOR = Comparator.nullsFirst(Longs::compare);
+
+    @Override
+    public int estimateSizeBytes(Long value)
+    {
+      return Long.BYTES;
+    }
+
+    @Override
+    public Long read(ByteBuffer buffer)
+    {
+      return buffer.getLong();
+    }
+
+    @Override
+    public int write(ByteBuffer buffer, Long value, int maxSizeBytes)
+    {
+      final int max = Math.min(buffer.limit() - buffer.position(), maxSizeBytes);
+      final int sizeBytes = Long.BYTES;
+      final int remaining = max - sizeBytes;
+      if (remaining >= 0) {
+        buffer.putLong(value);
+        return sizeBytes;
+      }
+      return remaining;
+    }
+
+    @Override
+    public int compare(Long o1, Long o2)
+    {
+      return COMPARATOR.compare(o1, o2);
+    }
+  }
+
+  public static final class FloatTypeStrategy implements TypeStrategy<Float>
+  {
+    private static final Comparator<Float> COMPARATOR = Comparator.nullsFirst(Floats::compare);
+
+    @Override
+    public int estimateSizeBytes(Float value)
+    {
+      return Float.BYTES;
+    }
+
+    @Override
+    public Float read(ByteBuffer buffer)
+    {
+      return buffer.getFloat();
+    }
+
+    @Override
+    public int write(ByteBuffer buffer, Float value, int maxSizeBytes)
+    {
+      final int max = Math.min(buffer.limit() - buffer.position(), maxSizeBytes);
+      final int sizeBytes = Float.BYTES;
+      final int remaining = max - sizeBytes;
+      if (remaining >= 0) {
+        buffer.putFloat(value);
+        return sizeBytes;
+      }
+      return remaining;
+    }
+
+    @Override
+    public int compare(Float o1, Float o2)
+    {
+      return COMPARATOR.compare(o1, o2);
+    }
+  }
+
+  public static final class DoubleTypeStrategy implements TypeStrategy<Double>
+  {
+    private static final Comparator<Double> COMPARATOR = Comparator.nullsFirst(Double::compare);
+
+    @Override
+    public int estimateSizeBytes(Double value)
+    {
+      return Double.BYTES;
+    }
+
+    @Override
+    public Double read(ByteBuffer buffer)
+    {
+      return buffer.getDouble();
+    }
+
+    @Override
+    public int write(ByteBuffer buffer, Double value, int maxSizeBytes)
+    {
+      final int max = Math.min(buffer.limit() - buffer.position(), maxSizeBytes);
+      final int sizeBytes = Double.BYTES;
+      final int remaining = max - sizeBytes;
+      if (remaining >= 0) {
+        buffer.putDouble(value);
+        return sizeBytes;
+      }
+      return remaining;
+    }
+
+    @Override
+    public int compare(Double o1, Double o2)
+    {
+      return COMPARATOR.compare(o1, o2);
+    }
+  }
+
+  public static final class StringTypeStrategy implements TypeStrategy<String>
+  {
+    // copy of lexicographical comparator
+    private static final Ordering<String> ORDERING = Ordering.from(String::compareTo).nullsFirst();
+
+    @Override
+    public int estimateSizeBytes(String value)
+    {
+      if (value == null) {
+        return 0;
+      }
+      return Integer.BYTES + StringUtils.toUtf8(value).length;
+    }
+
+    @Override
+    public String read(ByteBuffer buffer)
+    {
+      // | length (int) | bytes |
+      final int length = buffer.getInt();
+      final byte[] blob = new byte[length];
+      buffer.get(blob, 0, length);
+      return StringUtils.fromUtf8(blob);
+    }
+
+    @Override
+    public int write(ByteBuffer buffer, String value, int maxSizeBytes)
+    {
+      final byte[] bytes = StringUtils.toUtf8(value);
+      final int max = Math.min(buffer.limit() - buffer.position(), maxSizeBytes);
+      final int sizeBytes = Integer.BYTES + bytes.length;
+      final int remaining = max - sizeBytes;
+      if (remaining >= 0) {
+        buffer.putInt(bytes.length);
+        buffer.put(bytes, 0, bytes.length);
+        return sizeBytes;
+      }
+      return remaining;
+    }
+
+    @Override
+    public int compare(String s, String s2)
+    {
+      // copy of lexicographical string comparator in druid processing
+      // Avoid comparisons for equal references
+      // Assuming we mostly compare different strings, checking s.equals(s2) will only make the comparison slower.
+      //noinspection StringEquality
+      if (s == s2) {
+        return 0;
+      }
+
+      return ORDERING.compare(s, s2);
+    }
+  }
+
+  public static final class ArrayTypeStrategy implements TypeStrategy<Object[]>
+  {
+    private final Comparator<Object> elementComparator;
+    private final TypeStrategy elementStrategy;
+
+    public ArrayTypeStrategy(TypeSignature<?> type)
+    {
+      this.elementStrategy = type.getElementType().getNullableStrategy();
+      this.elementComparator = Comparator.nullsFirst(elementStrategy);
+    }
+
+    @Override
+    public int estimateSizeBytes(Object[] value)
+    {
+      if (value == null) {
+        return 0;
+      }
+      return Integer.BYTES + Arrays.stream(value).mapToInt(elementStrategy::estimateSizeBytes).sum();
+    }
+
+    @Override
+    public Object[] read(ByteBuffer buffer)
+    {
+      final int arrayLength = buffer.getInt();
+      final Object[] array = new Object[arrayLength];
+      for (int i = 0; i < arrayLength; i++) {
+        array[i] = elementStrategy.read(buffer);
+      }
+      return array;
+    }
+
+    @Override
+    public int write(ByteBuffer buffer, Object[] value, int maxSizeBytes)
+    {
+      final int max = Math.min(buffer.limit() - buffer.position(), maxSizeBytes);
+      int sizeBytes = Integer.BYTES;
+      int remaining = max - sizeBytes;
+      if (remaining < 0) {
+        return remaining;
+      }
+      int extraNeeded = 0;
+
+      buffer.putInt(value.length);
+      for (Object o : value) {
+        int written = elementStrategy.write(buffer, o, remaining);
+        if (written < 0) {
+          extraNeeded += written;
+          remaining = 0;
+        } else {
+          sizeBytes += written;
+          remaining -= sizeBytes;
+        }
+      }
+      return extraNeeded < 0 ? extraNeeded : sizeBytes;
+    }
+
+    @Override
+    public int compare(Object[] o1, Object[] o2)
+    {
+      final int iter = Math.max(o1.length, o2.length);

Review comment:
       umm should this be math.min as might have a scenario we can get indexOutofBoundException ?




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