ai.grakn.kb.internal.cache

Class Cache<V>

java.lang.Object

ai.grakn.kb.internal.cache.Cache<V>

Type Parameters:

V - The object it is caching

public class Cache<V>
extends Object

An internal cached element

An internal cached object which hits the database only when it needs to. This is used to cache the components of ontological concepts. i.e. the fields of Type, RelationshipType, and Role.

Author:

fppt

Method Summary

Modifier and Type	Method and Description
void	clear() Clears the cache.
static Cache	createPersistentCache(CacheOwner owner, Cacheable cacheable, java.util.function.Supplier databaseReader) Creates a session level Cache which cannot be cleared.
static Cache	createSessionCache(CacheOwner owner, Cacheable cacheable, java.util.function.Supplier databaseReader) Creates a Cache that will only flush to a central shared cache then the Transaction is disposed off
static Cache	createTxCache(CacheOwner owner, Cacheable cacheable, java.util.function.Supplier databaseReader) Creates a Cache that will only exist within the context of a Transaction
void	flush() Takes the current value in the transaction cache if it is present and puts it in the valueGlobal reference so that it can be accessed via all transactions.
V	get() Retrieves the object in the cache.
void	ifPresent(java.util.function.Consumer<V> modifier) Mutates the cached value if something is cached.
boolean	isPresent()
void	set(V value) Explicitly set the cache to a provided value

Methods inherited from class java.lang.Object

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

Method Detail

createTxCache

public static Cache createTxCache(CacheOwner owner,
                                  Cacheable cacheable,
                                  java.util.function.Supplier databaseReader)

Creates a Cache that will only exist within the context of a Transaction

createSessionCache

public static Cache createSessionCache(CacheOwner owner,
                                       Cacheable cacheable,
                                       java.util.function.Supplier databaseReader)

Creates a Cache that will only flush to a central shared cache then the Transaction is disposed off

createPersistentCache

public static Cache createPersistentCache(CacheOwner owner,
                                          Cacheable cacheable,
                                          java.util.function.Supplier databaseReader)

Creates a session level Cache which cannot be cleared. When creating these types of Caches the only way to get rid of them is to remove the owner ConceptImpl

get

@Nullable
public V get()

Retrieves the object in the cache. If nothing is cached the database is read.

Returns:

The cached object.

clear

public void clear()

Clears the cache.

set

public void set(@Nullable
                V value)

Explicitly set the cache to a provided value

Parameters:

value - the value to be cached

isPresent

public boolean isPresent()

Returns:

true if there is anything stored in the cache

ifPresent

public void ifPresent(java.util.function.Consumer<V> modifier)

Mutates the cached value if something is cached. Otherwise does nothing.

Parameters:

modifier - the mutator function.

flush

public void flush()

Takes the current value in the transaction cache if it is present and puts it in the valueGlobal reference so that it can be accessed via all transactions.