Package net.i2p.data

Class SDSCache<V extends SimpleDataStructure>

java.lang.Object

net.i2p.data.SDSCache<V>

public class SDSCache<V extends SimpleDataStructure>
extends Object

A least recently used cache with a max size, for SimpleDataStructures. The index to the cache is the first 4 bytes of the data, so the data must be sufficiently random. This caches the SDS objects, and also uses SimpleByteCache to cache the unused byte arrays themselves Following is sample usage:

    private static final SDSCache<Foo> _cache = new SDSCache(Foo.class, LENGTH, 1024);

    public static Foo create(byte[] data) {
        return _cache.get(data);
    }

    public static Foo create(byte[] data, int off) {
        return _cache.get(data, off);
    }

    public static Foo create(InputStream in) throws IOException {
        return _cache.get(in);
    }

  

Since:

0.8.3

Author:

zzz

Constructor Summary

Constructors

Constructor	Description
SDSCache(Class<V> rvClass, int len, int max)

Method Summary

Modifier and Type	Method	Description
void	clear()
V	get(byte[] data)	WARNING - If the SDS is found in the cache, the passed-in byte array will be returned to the SimpleByteCache for reuse.
V	get(byte[] b, int off)
V	get(InputStream in)

Methods inherited from class java.lang.Object

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

Constructor Details

SDSCache

public SDSCache(Class<V> rvClass,
 int len,
 int max)

Parameters:

rvClass - the class that we are storing, i.e. an extension of SimpleDataStructure

len - the length of the byte array in the SimpleDataStructure

max - maximum size of the cache assuming 128MB of mem. The actual max size will be scaled based on available memory.

Method Details

clear

public void clear()

Since:

0.9.17

get

public V get(byte[] data)

WARNING - If the SDS is found in the cache, the passed-in byte array will be returned to the SimpleByteCache for reuse. Do NOT save a reference to the passed-in data, or use or modify it, after this call.

Parameters:

data - non-null, the byte array for the SimpleDataStructure

Returns:

the cached value if available, otherwise makes a new object and returns it

Throws:

IllegalArgumentException - if data is not the correct number of bytes

NullPointerException

get

public V get(byte[] b,
 int off)

get

public V get(InputStream in)
      throws IOException

Throws:

IOException