org.apache.jetspeed.cache
Class FileCache

java.lang.Object
  org.apache.jetspeed.cache.FileCache

All Implemented Interfaces:

java.util.Comparator

public class FileCache

extends java.lang.Object

implements java.util.Comparator

FileCache keeps a cache of files up-to-date with a most simple eviction policy. The eviction policy will keep n items in the cache, and then start evicting the items ordered-by least used first. The cache runs a thread to check for both evictions and refreshes.

Version:

$Id: FileCache.java,v 1.5 2004/03/25 16:27:41 jford Exp $

Author:

David S. Taylor David Sean Taylor

Nested Class Summary

protected class

FileCache.FileCacheScanner inner class that runs as a thread to scan the cache for updates or evictions

Field Summary

protected java.util.List	listeners
protected int	maxSize
protected long	scanRate

Constructor Summary

FileCache()
Default constructor.

FileCache(int initialCapacity, int loadFactor, long scanRate, int maxSize)
Set all parameters on the cache

FileCache(long scanRate, int maxSize)
Set scanRate and maxSize

Method Summary

void	addListener(FileCacheEventListener listener) Add a File Cache Event Listener
int	compare(java.lang.Object o1, java.lang.Object o2) Comparator function for sorting by last accessed during eviction
protected void	evict() Evicts entries based on last accessed time stamp
FileCacheEntry	get(java.lang.String key) Gets an entry from the cache given a key
java.lang.Object	getDocument(java.lang.String key) Gets an entry from the cache given a key
java.util.Iterator	getIterator() get an iterator over the cache values
int	getMaxSize() Get the maximum size of the cache
long	getScanRate() Get the refresh scan rate
int	getSize() get the size of the cache
void	put(java.io.File file, java.lang.Object document) Puts a file entry in the file cache
void	put(java.lang.String key, java.lang.Object document) Puts a file entry in the file cache
java.lang.Object	remove(java.lang.String key) Removes a file entry from the file cache
void	setMaxSize(int maxSize) Set the new maximum size of the cache
void	setScanRate(long scanRate) Set the new refresh scan rate on managed files.
void	startFileScanner() Start the file Scanner running at the current scan rate.
void	stopFileScanner() Stop the file Scanner

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Comparator

equals

Field Detail

scanRate

protected long scanRate

maxSize

protected int maxSize

listeners

protected java.util.List listeners

Constructor Detail

FileCache

public FileCache()

Default constructor. Use default values for scanReate and maxSize

FileCache

public FileCache(long scanRate,
                 int maxSize)

Set scanRate and maxSize

Parameters:

scanRate - how often in seconds to refresh and evict from the cache

maxSize - the maximum allowed size of the cache before eviction starts

FileCache

public FileCache(int initialCapacity,
                 int loadFactor,
                 long scanRate,
                 int maxSize)

Set all parameters on the cache

Parameters:

initialCapacity - the initial size of the cache as passed to HashMap

loadFactor - how full the hash table is allowed to get before increasing

scanRate - how often in seconds to refresh and evict from the cache

maxSize - the maximum allowed size of the cache before eviction starts

Method Detail

setScanRate

public void setScanRate(long scanRate)

Set the new refresh scan rate on managed files.

Parameters:

scanRate - the new scan rate in seconds

getScanRate

public long getScanRate()

Get the refresh scan rate

Returns:

the current refresh scan rate in seconds

setMaxSize

public void setMaxSize(int maxSize)

Set the new maximum size of the cache

Parameters:

maxSize - the maximum size of the cache

getMaxSize

public int getMaxSize()

Get the maximum size of the cache

Returns:

the current maximum size of the cache

get

public FileCacheEntry get(java.lang.String key)

Gets an entry from the cache given a key

Parameters:

key - the key to look up the entry by

Returns:

the entry

getDocument

public java.lang.Object getDocument(java.lang.String key)

Gets an entry from the cache given a key

Parameters:

key - the key to look up the entry by

Returns:

the entry

put

public void put(java.io.File file,
                java.lang.Object document)
         throws java.io.IOException

Puts a file entry in the file cache

Parameters:

file - The file to be put in the cache

document - the cached document

Throws:

java.io.IOException

put

public void put(java.lang.String key,
                java.lang.Object document)
         throws java.io.IOException

Puts a file entry in the file cache

Parameters:

document - the cached document

Throws:

java.io.IOException

remove

public java.lang.Object remove(java.lang.String key)

Removes a file entry from the file cache

Parameters:

key - the full path name of the file

Returns:

the entry removed

addListener

public void addListener(FileCacheEventListener listener)

Add a File Cache Event Listener

Parameters:

listener - the event listener

startFileScanner

public void startFileScanner()

Start the file Scanner running at the current scan rate.

stopFileScanner

public void stopFileScanner()

Stop the file Scanner

evict

protected void evict()

Evicts entries based on last accessed time stamp

compare

public int compare(java.lang.Object o1,
                   java.lang.Object o2)

Comparator function for sorting by last accessed during eviction

Specified by:

compare in interface java.util.Comparator

getIterator

public java.util.Iterator getIterator()

get an iterator over the cache values

Returns:

iterator over the cache values

getSize

public int getSize()

get the size of the cache

Returns:

the size of the cache