ai.grakn.factory

Class SystemKeyspace

java.lang.Object

ai.grakn.factory.SystemKeyspace

public class SystemKeyspace
extends Object

Manages the system keyspace.

Used to populate the system ontology the first time the system keyspace is created.

Used to populate the system keyspace with all newly create keyspaces as a user opens them. We have no way to determining whether a keyspace with a given name already exists or not. We maintain the list in our Grakn system keyspace. An element is added to that list when there is an attempt to create a graph from a factory bound to the keyspace name. The list is simply the instances of the system entity type 'keyspace'. Nothing is ever removed from that list. The set of known keyspaces is maintained in a static map so we don't connect to the system keyspace every time a factory produces a new graph. That means that we can't have several different factories (e.g. Titan and in-memory Tinkerpop) at the same time sharing keyspace names. We can't identify the factory builder by engineUrl and config because we don't know what's inside the config, which is residing remotely at the engine!

Author:

borislav, fppt

Field Summary

Fields

Modifier and Type	Field and Description
static TypeLabel	KEYSPACE_ENTITY
static TypeLabel	KEYSPACE_RESOURCE
protected static org.slf4j.Logger	LOG
static String	SYSTEM_GRAPH_NAME

Method Summary

Modifier and Type	Method and Description
static void	close() Closes the system keyspace if there are no pending transactions on it.
static boolean	containsKeyspace(String keyspace) Checks if the keyspace exists in the system.
static void	deleteKeyspace(String keyspace) This is called when a graph is deleted via GraknAdmin.delete().
static void	initialise(String engineUrl, Properties properties) Initialises the system keyspace for a specific running instance of engine

Methods inherited from class java.lang.Object

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

Field Detail

SYSTEM_GRAPH_NAME

public static final String SYSTEM_GRAPH_NAME

See Also:

Constant Field Values

KEYSPACE_ENTITY

public static final TypeLabel KEYSPACE_ENTITY

KEYSPACE_RESOURCE

public static final TypeLabel KEYSPACE_RESOURCE

LOG

protected static final org.slf4j.Logger LOG

Method Detail

initialise

public static void initialise(String engineUrl,
                              Properties properties)

Initialises the system keyspace for a specific running instance of engine

Parameters:

engineUrl - the url of engine to get the config from

properties - the properties used to initialise the keyspace

close

public static void close()

Closes the system keyspace if there are no pending transactions on it.

containsKeyspace

public static boolean containsKeyspace(String keyspace)

Checks if the keyspace exists in the system. The persisted graph is checked each time because the graph may have been deleted in another JVM.

Parameters:

keyspace - The keyspace which might be in the system

Returns:

true if the keyspace is in the system

deleteKeyspace

public static void deleteKeyspace(String keyspace)

This is called when a graph is deleted via GraknAdmin.delete(). This removes the keyspace of the deleted graph from the system graph

Parameters:

keyspace - the keyspace to be removed from the system graph