org.nuxeo.common.file
Class LRUFileCache

java.lang.Object
  org.nuxeo.common.file.LRUFileCache

All Implemented Interfaces:

FileCache

public class LRUFileCache
extends Object
implements FileCache

A LRU cache of Files with capped filesystem size.

When a new file is put in the cache, if the total size becomes more that the maximum size then least recently access entries are removed until the new file fits.

A file will never be actually removed from the filesystem while the File object returned by getFile(java.lang.String) is still referenced.

The cache keys are restricted to a subset of ASCII: letters, digits and dashes. Usually a MD5 or SHA1 hash is used.

Field Summary

static Pattern

SIMPLE_ASCII Allowed key pattern, used as file path.

Constructor Summary

LRUFileCache(File dir, long maxSize)
Constructs a cache in the given directory with the given maximum size (in bytes).

Method Summary

void	clear() Clears the cache.
File	getFile(String key) Gets a file from the cache.
int	getNumberOfItems() Gets the number of items in the cache.
long	getSize() Gets the size of the cache, in bytes.
File	getTempFile() Creates a temporary file.
File	putFile(String key, File file) Puts a file in the cache.
File	putFile(String key, InputStream in) Puts a file in the cache.

Methods inherited from class java.lang.Object

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

Field Detail

SIMPLE_ASCII

public static final Pattern SIMPLE_ASCII

Allowed key pattern, used as file path.

Constructor Detail

LRUFileCache

public LRUFileCache(File dir,
                    long maxSize)

Constructs a cache in the given directory with the given maximum size (in bytes).

Parameters:

dir - the directory to use to store cached files

maxSize - the maximum size of the cache (in bytes)

Method Detail

getSize

public long getSize()

Description copied from interface: FileCache

Gets the size of the cache, in bytes.

Specified by:

getSize in interface FileCache

getNumberOfItems

public int getNumberOfItems()

Description copied from interface: FileCache

Gets the number of items in the cache.

Specified by:

getNumberOfItems in interface FileCache

getTempFile

public File getTempFile()
                 throws IOException

Description copied from interface: FileCache

Creates a temporary file.

Specified by:

getTempFile in interface FileCache

Throws:

IOException

putFile

public File putFile(String key,
                    InputStream in)
             throws IOException

Puts a file in the cache.

The key is used as a file name in the directory cache.

Specified by:

putFile in interface FileCache

Parameters:

key - the cache key

in - the input stream to cache (closed afterwards)

Returns:

the cached file

Throws:

IOException

putFile

public File putFile(String key,
                    File file)
             throws IllegalArgumentException,
                    IOException

Puts a file in the cache.

The file must have been created through FileCache.getTempFile(). The file is "given" to this method, who will delete it or rename it.

The key is used as a file name in the directory cache.

Specified by:

putFile in interface FileCache

Parameters:

key - the cache key

file - the file to cache

Returns:

the cached file

Throws:

IllegalArgumentException - if the key is illegal

IOException

getFile

public File getFile(String key)

Description copied from interface: FileCache

Gets a file from the cache.

A returned file will never be deleted from the filesystem while the returned file object is still referenced, although it may be purged from the cache.

Specified by:

getFile in interface FileCache

Parameters:

key - the cache key

Returns:

the cached file, or null if absent

clear

public void clear()

Description copied from interface: FileCache

Clears the cache.

Files will not be deleted from the filesystm while the returned file objects are still referenced.

Specified by:

clear in interface FileCache