Class DirectWriter

java.lang.Object
org.apache.lucene.util.packed.DirectWriter

public final class DirectWriter extends Object
Class for writing packed integers to be directly read from Directory. Integers can be read on-the-fly via DirectReader.

Unlike PackedInts, it optimizes for read i/o operations and supports > 2B values. Example usage:

   int bitsPerValue = DirectWriter.bitsRequired(100); // values up to and including 100
   IndexOutput output = dir.createOutput("packed", IOContext.DEFAULT);
   DirectWriter writer = DirectWriter.getInstance(output, numberOfValues, bitsPerValue);
   for (int i = 0; i < numberOfValues; i++) {
     writer.add(value);
   }
   writer.finish();
   output.close();
 
See Also:
  • Method Summary

    Modifier and Type
    Method
    Description
    void
    add(long l)
    Adds a value to this writer
    static int
    bitsRequired(long maxValue)
    Returns how many bits are required to hold values up to and including maxValue
    void
    finishes writing
    getInstance(DataOutput output, long numValues, int bitsPerValue)
    Returns an instance suitable for encoding numValues using bitsPerValue
    static int
    unsignedBitsRequired(long maxValue)
    Returns how many bits are required to hold values up to and including maxValue, interpreted as an unsigned value.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
  • Method Details

    • add

      public void add(long l) throws IOException
      Adds a value to this writer
      Throws:
      IOException
    • finish

      public void finish() throws IOException
      finishes writing
      Throws:
      IOException
    • getInstance

      public static DirectWriter getInstance(DataOutput output, long numValues, int bitsPerValue)
      Returns an instance suitable for encoding numValues using bitsPerValue
    • bitsRequired

      public static int bitsRequired(long maxValue)
      Returns how many bits are required to hold values up to and including maxValue
      Parameters:
      maxValue - the maximum value that should be representable.
      Returns:
      the amount of bits needed to represent values from 0 to maxValue.
      See Also:
    • unsignedBitsRequired

      public static int unsignedBitsRequired(long maxValue)
      Returns how many bits are required to hold values up to and including maxValue, interpreted as an unsigned value.
      Parameters:
      maxValue - the maximum value that should be representable.
      Returns:
      the amount of bits needed to represent values from 0 to maxValue.
      See Also: