Package org.tukaani.xz

Class BasicArrayCache

java.lang.Object
org.tukaani.xz.ArrayCache
org.tukaani.xz.BasicArrayCache
public class BasicArrayCache
extends ArrayCache
A basic ArrayCache implementation.

This caches exact array sizes, that is, getByteArray will return an array whose size is exactly the requested size. A limited number of different array sizes are cached at the same time; least recently used sizes will be dropped from the cache if needed (can happen if several different (de)compression options are used with the same cache).

The current implementation uses LinkedHashMap to map different array sizes to separate array-based data structures which hold SoftReferences to the cached arrays. In the common case this should give good performance and fairly low memory usage overhead.

A statically allocated global BasicArrayCache instance is available via getInstance() which is a good choice in most situations where caching is wanted.

Since:
1.7

  • Constructor Details

    • BasicArrayCache

      public BasicArrayCache()

  • Method Details

    • getInstance

      public static BasicArrayCache getInstance()
      Returns a statically-allocated BasicArrayCache instance. This is often a good choice when a cache is needed.

    • getByteArray

      public byte[] getByteArray​(int size, boolean fillWithZeros)
      Allocates a new byte array, hopefully reusing an existing array from the cache.
      Overrides:
      getByteArray in class ArrayCache
      Parameters:
      size - size of the array to allocate
      fillWithZeros - if true, all the elements of the returned array will be zero; if false, the contents of the returned array is undefined

    • putArray

      public void putArray​(byte[] array)
      Puts the given byte array to the cache. The caller must no longer use the array.

      Small arrays aren't cached and will be ignored by this method.

      Overrides:
      putArray in class ArrayCache

    • getIntArray

      public int[] getIntArray​(int size, boolean fillWithZeros)
      This is like getByteArray but for int arrays.
      Overrides:
      getIntArray in class ArrayCache
      Parameters:
      size - the minimum size of the array to allocate; an implementation may return an array that is larger than the given size
      fillWithZeros - if true, the caller expects that the first size elements in the array are zero; if false, the array contents can be anything, which speeds things up when reusing a cached array

    • putArray

      public void putArray​(int[] array)
      Puts the given int array to the cache. The caller must no longer use the array.

      Small arrays aren't cached and will be ignored by this method.

      Overrides:
      putArray in class ArrayCache