p2ps.imp.discovery.cache
Class CacheFile

java.lang.Object
  p2ps.imp.discovery.cache.CacheFile

public class CacheFile

extends java.lang.Object

A wrapper for a cache file containing sequentially stored byte arrays. When a byte array is deleted, the index of that byte array is added to a deleted list corresponding to its size. When a byte array is added, the index of a slot large enough for that byte array is retrieved from the relevant deleted list. If no suitable slot exists then the cache file is expanded.

Version:

$Revision: 295 $

Author:

Ian Wang

Field Summary

static int	DEFAULT_FILE_BLOCK_SIZE
static int	DEFAULT_FILE_BLOCK_TOLERANCE
static int	DEFAULT_MAXIMUM_ITEM_SIZE

Constructor Summary

CacheFile(java.io.File file)

CacheFile(java.io.File file, int maxsize, int blocksize)

CacheFile(java.io.File file, int maxsize, int blocksize, int tolerance)

Method Summary

int	add(byte[] bytes) Adds a byte array to the cache file.
void	close() Close the cach file
byte[]	get(int id)
int	getBlockSize()
static void	main(java.lang.String[] args)
byte[]	remove(int id) Removes the byte[] with the specified id

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_FILE_BLOCK_SIZE

public static final int DEFAULT_FILE_BLOCK_SIZE

See Also:

Constant Field Values

DEFAULT_FILE_BLOCK_TOLERANCE

public static final int DEFAULT_FILE_BLOCK_TOLERANCE

See Also:

Constant Field Values

DEFAULT_MAXIMUM_ITEM_SIZE

public static final int DEFAULT_MAXIMUM_ITEM_SIZE

See Also:

Constant Field Values

Constructor Detail

CacheFile

public CacheFile(java.io.File file)
          throws java.io.FileNotFoundException,
                 java.io.IOException

CacheFile

public CacheFile(java.io.File file,
                 int maxsize,
                 int blocksize)
          throws java.io.FileNotFoundException,
                 java.io.IOException

CacheFile

public CacheFile(java.io.File file,
                 int maxsize,
                 int blocksize,
                 int tolerance)
          throws java.io.FileNotFoundException,
                 java.io.IOException

Method Detail

getBlockSize

public int getBlockSize()

Returns:

the file block size

add

public int add(byte[] bytes)
        throws java.io.IOException

Adds a byte array to the cache file.

Returns:

the id for the byte[]

Throws:

java.io.IOException

remove

public byte[] remove(int id)

Removes the byte[] with the specified id

get

public byte[] get(int id)

Returns:

the byte[] with the specified id or null if invalid id

close

public void close()

Close the cach file

main

public static void main(java.lang.String[] args)
                 throws java.io.IOException

Throws:

java.io.IOException