org.aksw.limes.core.io.cache

Class HybridCache

java.lang.Object

org.aksw.limes.core.io.cache.ACache

org.aksw.limes.core.io.cache.MemoryCache

org.aksw.limes.core.io.cache.HybridCache

All Implemented Interfaces:

Serializable, ICache

public class HybridCache
extends MemoryCache
implements Serializable

This cache implements a hybrid between memory and file cache. It generates a hash for each data source associated with it and serializes the content of the corresponding data source into a file. If another mapping task is associated with the same data source, it retrieves the corresponding data from the file, which is obviously more efficient for online data sources (no HTTP latency, offline processing, etc.). Else, it retrieves the data, generates a hash and caches it on the hard drive. Enhancing it with folders: specify the folder, where the application has permissions to read and write files.

Version:

Jul 8, 2016

Author:

Axel-C. Ngonga Ngomo (ngonga@informatik.uni-leipzig.de), Lyko, Mohamed Sherif (sherif@informatik.uni-leipzig.de)

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected Iterator<Instance>	instanceIterator
protected TreeMap<String,Instance>	instanceMap

Constructor Summary

Constructors

Constructor and Description
HybridCache()
HybridCache(File folder) Create cache specifying the parent folder.

Method Summary

Modifier and Type	Method and Description
void	addInstance(Instance i)
void	addTriple(String s, String p, String o) Adds a new spo statement to the cache
boolean	containsInstance(Instance i)
boolean	containsUri(String uri)
ArrayList<Instance>	getAllInstances() Returns all the instance contained in the cache
ArrayList<String>	getAllUris()
static HybridCache	getData(File folder, KBInfo kb) Method to get Data of the specified endpoint, and cache it to the "cache" folder in the folder specified.
static HybridCache	getData(KBInfo kb)
File	getFolder() Returns the file pointing to the parent folder of cache.
Instance	getInstance(String uri)
Instance	getNextInstance() Returns the next instance in the list of instances
static HybridCache	getNoPrefixData(File folder, KBInfo kb) This method is used by learners which do not have prefix information and with a specified folder containing the cache folder.
static HybridCache	getNoPrefixData(KBInfo kb) This method is used by learners which do not have prefix information.
static HybridCache	loadFromFile(File file) Tries to load the content of the cache from a file
void	resetIterator()
void	saveToFile(File file) Tries to serialize the content of the cache to a file.
void	setFolder(File folder) Set the parent folder of the cache sub folder.
int	size()
String	toString()

Methods inherited from class org.aksw.limes.core.io.cache.MemoryCache

addProperty, clone, equals, getAllProperties, getSample, hashCode, parseCSVtoRDFModel, replaceInstance

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

instanceMap

protected TreeMap<String,Instance> instanceMap

instanceIterator

protected Iterator<Instance> instanceIterator

Constructor Detail

HybridCache

public HybridCache()

HybridCache

public HybridCache(File folder)

Create cache specifying the parent folder. Make shure the Application has write permissions there.

Parameters:

folder - File pointing to the the parent folder of the (to-be-created) "cache" folder.

Method Detail

loadFromFile

public static HybridCache loadFromFile(File file)
                                throws IOException

Tries to load the content of the cache from a file

Parameters:

file - File from which the content is to be loaded

Returns:

A Hybrid cache

Throws:

IOException - if file not found

getData

public static HybridCache getData(KBInfo kb)

getData

public static HybridCache getData(File folder,
                                  KBInfo kb)

Method to get Data of the specified endpoint, and cache it to the "cache" folder in the folder specified.

Parameters:

folder - Path to the parent folder of the "cache" folder.

kb - Endpoint specification.

Returns:

HybridCache of the data

getNoPrefixData

public static HybridCache getNoPrefixData(KBInfo kb)

This method is used by learners which do not have prefix information.

Parameters:

kb - Info to the knowledge base to query

Returns:

A cache filled with the entities to link

getNoPrefixData

public static HybridCache getNoPrefixData(File folder,
                                          KBInfo kb)

This method is used by learners which do not have prefix information and with a specified folder containing the cache folder.

Parameters:

folder - Path to parent folder of the supposed cache folder.

kb - Info to the knowledge base to query

Returns:

A cache filled with the entities to link

getNextInstance

public Instance getNextInstance()

Returns the next instance in the list of instances

Overrides:

getNextInstance in class MemoryCache

Returns:

null if no next instance, else the next instance

getAllInstances

public ArrayList<Instance> getAllInstances()

Returns all the instance contained in the cache

Overrides:

getAllInstances in class MemoryCache

Returns:

ArrayList containing all instances

addInstance

public void addInstance(Instance i)

Overrides:

addInstance in class MemoryCache

getInstance

public Instance getInstance(String uri)

Overrides:

getInstance in class MemoryCache

Parameters:

uri - URI to look for

Returns:

The instance with the URI uri if it is in the cache, else null

size

public int size()

Overrides:

size in class MemoryCache

Returns:

The size of the cache

addTriple

public void addTriple(String s,
                      String p,
                      String o)

Adds a new spo statement to the cache

Overrides:

addTriple in class MemoryCache

Parameters:

s - The URI of the instance linked to o via p

p - The property which links s and o

o - The value of the property of p for the entity s

containsUri

public boolean containsUri(String uri)

Overrides:

containsUri in class MemoryCache

Parameters:

uri - The URI to looks for

Returns:

True if an instance with the URI uri is found in the cache, else false

resetIterator

public void resetIterator()

Overrides:

resetIterator in class MemoryCache

toString

public String toString()

Overrides:

toString in class MemoryCache

getAllUris

public ArrayList<String> getAllUris()

Overrides:

getAllUris in class MemoryCache

containsInstance

public boolean containsInstance(Instance i)

Overrides:

containsInstance in class MemoryCache

Parameters:

i - The instance to look for

Returns:

true if the URI of the instance is found in the cache

saveToFile

public void saveToFile(File file)

Tries to serialize the content of the cache to a file. If it fails, no file is written to avoid the corruption of future data sources.

Parameters:

file - File wherein the content of the cache is to be serialized

getFolder

public File getFolder()

Returns the file pointing to the parent folder of cache.

Returns:

File folder

setFolder

public void setFolder(File folder)

Set the parent folder of the cache sub folder.

Parameters:

folder - Pointing to the parent folder holding the cache.