Package org.eclipse.mat.collect

Class ArrayLongCompressed

java.lang.Object
org.eclipse.mat.collect.ArrayLongCompressed
public class ArrayLongCompressed extends Object
This class compresses fixed-size long[] in a very fast and memory efficient manner if many leading and/or trailing bits of the stored longs are not used commonly. The internal data is never copied during the process of retrieving or reconstructing objects of this class and allows for fast I/O writing and reading of the underlying byte[]. Furthermore alomst no additinal data is used beside the underlying byte[]. Thereby the memory consumption of this data structure is kept at a minmum to build efficient long[] caches.

  • Constructor Summary

    Constructors
    Constructor
    Description
    ArrayLongCompressed(byte[] bytes)
    Create LongArrayCompressed from bytes formerly got from toByteArray().
    ArrayLongCompressed(int size, int leadingClearBits, int trailingClearBits)
    Create LongArrayCompressed from number of longs to be stored, the number of leading and trailing clear bits.
    ArrayLongCompressed(long[] longs)
    Create LongArrayCompressed from longs representing the data to be stored in compressed form.
    ArrayLongCompressed(long[] longs, int offset, int length)
    Create LongArrayCompressed from longs representing the data to be stored in compressed form (from offset to offset+length).

  • Method Summary

    Modifier and Type
    Method
    Description
    long
    get(int index)
    Get value from the given index.
    void
    set(int index, long value)
    Set value at the given index.
    byte[]
    toByteArray()
    Get bytes representing the internal data structure with which an LongArrayCompressed can be reconstructed.

    Methods inherited from class java.lang.Object

    equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

    • ArrayLongCompressed

      public ArrayLongCompressed(byte[] bytes)
      Create LongArrayCompressed from bytes formerly got from toByteArray().
      Parameters:
      bytes - bytes formerly got from toByteArray()

    • ArrayLongCompressed

      public ArrayLongCompressed(int size, int leadingClearBits, int trailingClearBits)
      Create LongArrayCompressed from number of longs to be stored, the number of leading and trailing clear bits. Everything else is stored in the internal data structure.
      Parameters:
      size - number of longs to be stored
      leadingClearBits - number of leading clear bits
      trailingClearBits - number of trailing clear bits

    • ArrayLongCompressed

      public ArrayLongCompressed(long[] longs)
      Create LongArrayCompressed from longs representing the data to be stored in compressed form.
      Parameters:
      longs - longs representing the data to be stored in compressed form

    • ArrayLongCompressed

      public ArrayLongCompressed(long[] longs, int offset, int length)
      Create LongArrayCompressed from longs representing the data to be stored in compressed form (from offset to offset+length).
      Parameters:
      longs - longs representing the data to be stored in compressed form
      offset - offset from which on to compress the longs
      length - number of longs to compress from the given array

  • Method Details

    • set

      public void set(int index, long value)
      Set value at the given index.
      Parameters:
      index - index at which the value should be set
      value - value to be set at the given index

    • get

      public long get(int index)
      Get value from the given index.
      Parameters:
      index - index at which the value should be set
      Returns:
      value found at the given index

    • toByteArray

      public byte[] toByteArray()
      Get bytes representing the internal data structure with which an LongArrayCompressed can be reconstructed.
      Returns:
      bytes representing the internal data structure with which an LongArrayCompressed can be reconstructed