gov.noaa.pmel.tmap.las.product.server

Class Cache

java.lang.Object

java.util.AbstractMap<K,V>

java.util.HashMap<K,V>

java.util.LinkedHashMap<java.lang.String,java.io.File>

gov.noaa.pmel.tmap.las.product.server.Cache

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable, java.util.Map<java.lang.String,java.io.File>

public class Cache
extends java.util.LinkedHashMap<java.lang.String,java.io.File>
implements java.io.Serializable

This class manages cached file in a queue. The last accessed file is moved to the head of the queue. If the queue size reached its limit, the least recently accessed file will be removed from the queue and deleted. This class synchronizes access. The class has supporting function for serializing and deserializing cache information to a local file.

Author:

Yonghua Wei

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class java.util.AbstractMap

java.util.AbstractMap.SimpleEntry<K,V>, java.util.AbstractMap.SimpleImmutableEntry<K,V>

Field Summary

Fields

Modifier and Type	Field and Description
static long	DELETE_CACHE
static long	GET_CACHE

Constructor Summary

Constructors

Constructor and Description
Cache(int cacheSize, long maxBytes)

Method Summary

Methods

Modifier and Type	Method and Description
void	addDocToCache(gov.noaa.pmel.tmap.jdom.LASDocument doc, java.lang.String cacheFileName)
void	addFile(java.lang.String query, java.io.File file) Add a file to the cache if the cache object is enabled.
void	addToCache(LASBackendResponse lasResponse, java.lang.String cacheFileName)
boolean	cacheHit(LASBackendResponse lasResponse)
void	clean() Delete all the files in this cache object
int	getCacheSize()
long	getCurrentBytes()
java.io.File	getFile(java.lang.String query, long time) Get the file identified by a string if the cache object is enabled.
java.util.ArrayList<java.lang.String>	getFiles(java.lang.String key) Get all the files form the cache that are associated with a particular (compound response) key.
long	getMaxBytes()
boolean	isEnabled() Test if this cache object is enabled
void	loadCacheFromStore(java.io.File cacheFile) Load a local file and populate this cache object
void	removeFile(java.lang.String filename)
void	saveCacheToStore(java.io.File cacheFile) Serialize this cache object to a local file
void	setCacheSize(int cacheSize)
void	setCurrentBytes(long currentBytes)
void	setEnabled(boolean enabled) Enable or disable this cache object according to the input parameter
void	setMaxBytes(long maxBytes)

Methods inherited from class java.util.LinkedHashMap

clear, containsValue, get

Methods inherited from class java.util.HashMap

clone, containsKey, entrySet, isEmpty, keySet, put, putAll, remove, size, values

Methods inherited from class java.util.AbstractMap

equals, hashCode, toString

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.Map

containsKey, entrySet, equals, hashCode, isEmpty, keySet, put, putAll, remove, size, values

Field Detail

DELETE_CACHE

public static long DELETE_CACHE

GET_CACHE

public static long GET_CACHE

Constructor Detail

Cache

public Cache(int cacheSize,
     long maxBytes)

Method Detail

isEnabled

public boolean isEnabled()

Test if this cache object is enabled

setEnabled

public void setEnabled(boolean enabled)

Enable or disable this cache object according to the input parameter

Parameters:

enabled - specified if this cache object should be enabled or disabled.

addFile

public void addFile(java.lang.String query,
           java.io.File file)

Add a file to the cache if the cache object is enabled.

Parameters:

query - a string that is the key to the file. The file can be retrieved using this string.

file - the File object that need to be stored in cache.

getFile

public java.io.File getFile(java.lang.String query,
                   long time)

Get the file identified by a string if the cache object is enabled.

Parameters:

query - a string that is the key to the file. The file can be retrieved using this string.

time - only a file newer than this time should be returned. If this parameter is equal to Cache.DELETE_CACHE, cache file will be deleted and return null. If this parameter is equal to Cache.GET_CACHE, cache file will always be returned if it exists.

Returns:

a File object that points to the cache file in local file system if cache file exists, otherwise return null.

removeFile

public void removeFile(java.lang.String filename)

clean

public void clean()

Delete all the files in this cache object

saveCacheToStore

public void saveCacheToStore(java.io.File cacheFile)
                      throws gov.noaa.pmel.tmap.exception.LASException

Serialize this cache object to a local file

Parameters:

cacheFile - the local file to store this cache object

Throws:

gov.noaa.pmel.tmap.exception.LASException

loadCacheFromStore

public void loadCacheFromStore(java.io.File cacheFile)
                        throws gov.noaa.pmel.tmap.exception.LASException

Load a local file and populate this cache object

Parameters:

cacheFile - the local file to load

Throws:

gov.noaa.pmel.tmap.exception.LASException

cacheHit

public boolean cacheHit(LASBackendResponse lasResponse)

addToCache

public void addToCache(LASBackendResponse lasResponse,
              java.lang.String cacheFileName)

addDocToCache

public void addDocToCache(gov.noaa.pmel.tmap.jdom.LASDocument doc,
                 java.lang.String cacheFileName)

getMaxBytes

public long getMaxBytes()

Returns:

the maxBytes

getCacheSize

public int getCacheSize()

Returns:

the cacheSize

setMaxBytes

public void setMaxBytes(long maxBytes)

Parameters:

maxBytes - the maxBytes to set

setCacheSize

public void setCacheSize(int cacheSize)

Parameters:

cacheSize - the cacheSize to set

getFiles

public java.util.ArrayList<java.lang.String> getFiles(java.lang.String key)

Get all the files form the cache that are associated with a particular (compound response) key. It's a bit more complicated than matching the key string in the name because the response from a compound product might have other files with other keys. This is handled by parsing through all the response and find the results.

Parameters:

key -

Returns:

getCurrentBytes

public long getCurrentBytes()

Returns:

the currentBytes

setCurrentBytes

public void setCurrentBytes(long currentBytes)

Parameters:

currentBytes - the currentBytes to set