org.hypergraphdb.storage

Interface HGStoreImplementation

All Known Implementing Classes:

StorageWithAnnotatedIncidence

public interface HGStoreImplementation

A HGStoreImplementation provides the crucial storage layer for a HyperGraphDB instance. This interface allows one to plug different storage layers based on different lower-level stores and thus obtain various performance characteristics or transaction guarantees. Implementing this interface is not trivial and some core assumption must be carefully observed.

Note that this interface is an SPI (Service Provider Interface) and it is not intended to be used by an application. Instead, applications should use the HGStore class which offers the same functionality, but in the context of a HyperGraphDB instance. All methods here are intended for use by HyperGraphDB itself.

Method Summary

Methods

Modifier and Type	Method and Description
void	addIncidenceLink(HGPersistentHandle handle, HGPersistentHandle newLink) And an element to the incidence set of a given atom (as identified by the handle parameter).
boolean	containsData(HGPersistentHandle handle) Return true if the data space contains data with the given handle and false otherwise.
boolean	containsLink(HGPersistentHandle handle) Return true if there is a primitive link for the given handle.
Object	getConfiguration() Each different storage mechanism provides its own configuration object with parameters that can be set before storage is initialized.
byte[]	getData(HGPersistentHandle handle) Return the data corresponding to a given handle or null if it is not found.
HGRandomAccessResult<HGPersistentHandle>	getIncidenceResultSet(HGPersistentHandle handle) Return the incidence set associate with the given handle.
long	getIncidenceSetCardinality(HGPersistentHandle handle) Return the number of elements of the incidence set for the given handle or 0 if no such set exists.
<KeyType,ValueType> HGIndex<KeyType,ValueType>	getIndex(String name) Get the HyperGraphDB index with the given name.
<KeyType,ValueType> HGIndex<KeyType,ValueType>	getIndex(String name, ByteArrayConverter<KeyType> keyConverter, ByteArrayConverter<ValueType> valueConverter, Comparator<?> comparator, boolean isBidirectional, boolean createIfNecessary) Retrieve the index with the given name, or create a new index if no index with that name exists.
HGPersistentHandle[]	getLink(HGPersistentHandle handle) Return the link corresponding to a given handle or null if it is not found.
HGTransactionFactory	getTransactionFactory() Return the transaction factory associated with this storage instance.
void	removeData(HGPersistentHandle handle) Remove the data corresponding to a given handle.
void	removeIncidenceLink(HGPersistentHandle handle, HGPersistentHandle oldLink) Remove a specifiec element from the incidence set of a given atom (as identified by the handle parameter).
void	removeIncidenceSet(HGPersistentHandle handle) Remove the incidence set associated with the given handle.
void	removeIndex(String name) Remove the index with the given name.
void	removeLink(HGPersistentHandle handle) Remove the link corresponding to a given handle.
void	shutdown() Stops the storage engine.
void	startup(HGStore store, HGConfiguration configuration) Starts the storage engine.
HGPersistentHandle	store(HGPersistentHandle handle, byte[] data) Store a raw data buffer and return its handle.
HGPersistentHandle	store(HGPersistentHandle handle, HGPersistentHandle[] link) Store a primitive link and return its handle.

Method Detail

getConfiguration

Object getConfiguration()

Each different storage mechanism provides its own configuration object with parameters that can be set before storage is initialized. This method returns the storage specific configuration object that must be cast to be appropriate concrete type.

startup

void startup(HGStore store,
           HGConfiguration configuration)

Starts the storage engine.

This method is invoked after storage configuration parameters have been set and its purpose is to perform complete initialization for the underlying storage layer, possibly creating a new database instance. When this method returns, the storage should be ready for use.

shutdown

void shutdown()

Stops the storage engine.

This method is invoked when the database instance is closed. It is expected to perform all necessary cleanup and closing of resources of the storage layer.

getTransactionFactory

HGTransactionFactory getTransactionFactory()

Return the transaction factory associated with this storage instance. Storage implementations in HyperGraphDB are expected to be transactional and support snapshot isolation semantics.

store

HGPersistentHandle store(HGPersistentHandle handle,
                       HGPersistentHandle[] link)

Store a primitive link and return its handle.

Parameters:

handle - The handle to use as the identifier of the link.

link - The primitive link. Neither the array nor any of its element can be null.

Returns:

The handle argument.

getLink

HGPersistentHandle[] getLink(HGPersistentHandle handle)

Return the link corresponding to a given handle or null if it is not found.

removeLink

void removeLink(HGPersistentHandle handle)

Remove the link corresponding to a given handle.

containsLink

boolean containsLink(HGPersistentHandle handle)

Return true if there is a primitive link for the given handle.

store

HGPersistentHandle store(HGPersistentHandle handle,
                       byte[] data)

Store a raw data buffer and return its handle.

Parameters:

handle - The handle to use as identifier within the data space.

data - The buffer to store. There is no limit to the size of this buffer, but it can't be null.

Returns:

The handle argument.

getData

byte[] getData(HGPersistentHandle handle)

Return the data corresponding to a given handle or null if it is not found.

removeData

void removeData(HGPersistentHandle handle)

Remove the data corresponding to a given handle.

containsData

boolean containsData(HGPersistentHandle handle)

Return true if the data space contains data with the given handle and false otherwise.

getIncidenceResultSet

HGRandomAccessResult<HGPersistentHandle> getIncidenceResultSet(HGPersistentHandle handle)

Return the incidence set associate with the given handle. The result set should be empty if there is no incidence set for that handle.

removeIncidenceSet

void removeIncidenceSet(HGPersistentHandle handle)

Remove the incidence set associated with the given handle. Do nothing if there is no such set.

getIncidenceSetCardinality

long getIncidenceSetCardinality(HGPersistentHandle handle)

Return the number of elements of the incidence set for the given handle or 0 if no such set exists.

addIncidenceLink

void addIncidenceLink(HGPersistentHandle handle,
                    HGPersistentHandle newLink)

And an element to the incidence set of a given atom (as identified by the handle parameter).

removeIncidenceLink

void removeIncidenceLink(HGPersistentHandle handle,
                       HGPersistentHandle oldLink)

Remove a specifiec element from the incidence set of a given atom (as identified by the handle parameter).

getIndex

<KeyType,ValueType> HGIndex<KeyType,ValueType> getIndex(String name)

Get the HyperGraphDB index with the given name. Return null if no index with that name exists.

getIndex

<KeyType,ValueType> HGIndex<KeyType,ValueType> getIndex(String name,
                                                      ByteArrayConverter<KeyType> keyConverter,
                                                      ByteArrayConverter<ValueType> valueConverter,
                                                      Comparator<?> comparator,
                                                      boolean isBidirectional,
                                                      boolean createIfNecessary)

Retrieve the index with the given name, or create a new index if no index with that name exists.

Parameters:

name - The name of the index. It must be unique for the storage layer.

keyConverter - Converter to byte [] for the keys in this index. Necessary when creating a new index. If null, a default converter should be used.

valueConverter - Converter to byte [] for the values in this index. Necessary when creating a new index. If null, a default converter should be used.

removeIndex

void removeIndex(String name)

Remove the index with the given name. Do nothing if not such index exists.