org.mozilla.mentat

Class Mentat

java.lang.Object

org.mozilla.mentat.Mentat

All Implemented Interfaces:

AutoCloseable

public class Mentat
extends Object

The primary class for accessing Mentat's API.
This class provides all of the basic API that can be found in Mentat's Store struct.
The raw pointer it holds is a pointer to a Store.

Constructor Summary

Constructors

Constructor and Description
Mentat() Open a connection to an in-memory Store.
Mentat(JNA.Store rawPointer) Create a new Mentat with the provided pointer to a Mentat Store
Mentat(String dbPath) Open a connection to a Store in a given location. If the store does not already exist, one will be created.

Method Summary

Modifier and Type	Method and Description
InProgress	beginTransaction() Start a new transaction TODO: Throw an exception if the result contains an error.
void	cache(String attribute, CacheDirection direction) Add an attribute to the cache.
void	close()
protected void	destroyPointer(JNA.Store p)
long	entIdForAttribute(String attribute) Get the the `Entid` of the attribute
InProgressBuilder	entityBuilder() Creates a new transaction (InProgress) and returns an InProgressBuilder for that transaction.
EntityBuilder	entityBuilder(long entid) Creates a new transaction (InProgress) and returns an EntityBuilder for the entity with `entid` for that transaction.
EntityBuilder	entityBuilder(String tempId) Creates a new transaction (InProgress) and returns an EntityBuilder for a new entity with `tempId` for that transaction.
protected void	finalize()
Query	query(String query) Start a query.
void	registerObserver(String key, String[] attributes, TxObserverCallback callback) Register an callback and a set of attributes to observer for transaction observation.
TxReport	transact(String transaction) Simple transact of an EDN string.
void	unregisterObserver(String key) Unregister the observer that was registered with the provided key such that it will no longer be called if a transaction occurs that affects the attributes that the observer was registered to observe.
TypedValue	valueForAttributeOfEntity(String attribute, long entid) Retrieve a single value of an attribute for an Entity TODO: Throw an exception if the result contains an error.

Methods inherited from class java.lang.Object

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

Constructor Detail

Mentat

public Mentat(String dbPath)

Open a connection to a Store in a given location.
If the store does not already exist, one will be created.

Parameters:

dbPath - The URI as a String of the store to open.

Mentat

public Mentat()

Open a connection to an in-memory Store.

Mentat

public Mentat(JNA.Store rawPointer)

Create a new Mentat with the provided pointer to a Mentat Store

Parameters:

rawPointer - A pointer to a Mentat Store.

Method Detail

cache

public void cache(String attribute,
                  CacheDirection direction)

Add an attribute to the cache. The CacheDirection determines how that attribute can be looked up. TODO: Throw an exception if cache action fails. https://github.com/mozilla/mentat/issues/700

Parameters:

attribute - The attribute to cache

direction - The direction the attribute should be keyed. FORWARD caches values for an attribute keyed by entity (i.e. find values and entities that have this attribute, or find values of attribute for an entity) REVERSE caches entities for an attribute keyed by value. (i.e. find entities that have a particular value for an attribute). BOTH adds an attribute such that it is cached in both directions.

transact

public TxReport transact(String transaction)

Simple transact of an EDN string. TODO: Throw an exception if the transact fails. https://github.com/mozilla/mentat/issues/700

Parameters:

transaction - The string, as EDN, to be transacted.

Returns:

The TxReport of the completed transaction

entIdForAttribute

public long entIdForAttribute(String attribute)

Get the the `Entid` of the attribute

Parameters:

attribute - The string represeting the attribute whose `Entid` we are after. The string is represented as `:namespace/name`.

Returns:

The `Entid` associated with the attribute.

query

public Query query(String query)

Start a query.

Parameters:

query - The string represeting the the query to be executed.

Returns:

The Query representing the query that can be executed.

valueForAttributeOfEntity

public TypedValue valueForAttributeOfEntity(String attribute,
                                            long entid)

Retrieve a single value of an attribute for an Entity TODO: Throw an exception if the result contains an error. https://github.com/mozilla/mentat/issues/700

Parameters:

attribute - The string the attribute whose value is to be returned. The string is represented as `:namespace/name`.

entid - The `Entid` of the entity we want the value from.

Returns:

The TypedValue containing the value of the attribute for the entity.

registerObserver

public void registerObserver(String key,
                             String[] attributes,
                             TxObserverCallback callback)

Register an callback and a set of attributes to observer for transaction observation. The callback function is called when a transaction occurs in the `Store` that this `Mentat` is connected to that affects the attributes that an observer has registered for.

Parameters:

key - `String` representing an identifier for the observer.

attributes - An array of Strings representing the attributes that the observer wishes to be notified about if they are referenced in a transaction.

callback - the function to call when an observer notice is fired.

unregisterObserver

public void unregisterObserver(String key)

Unregister the observer that was registered with the provided key such that it will no longer be called if a transaction occurs that affects the attributes that the observer was registered to observe.

The observer will need to re-register if it wants to start observing again.

Parameters:

key - String representing an identifier for the observer.

beginTransaction

public InProgress beginTransaction()

Start a new transaction TODO: Throw an exception if the result contains an error. https://github.com/mozilla/mentat/issues/700

Returns:

The InProgress used to manage the transaction

entityBuilder

public InProgressBuilder entityBuilder()

Creates a new transaction (InProgress) and returns an InProgressBuilder for that transaction. TODO: Throw an exception if the result contains an error. https://github.com/mozilla/mentat/issues/700

Returns:

an InProgressBuilder for a new transaction.

entityBuilder

public EntityBuilder entityBuilder(long entid)

Creates a new transaction (InProgress) and returns an EntityBuilder for the entity with `entid` for that transaction. TODO: Throw an exception if the result contains an error. https://github.com/mozilla/mentat/issues/700

Parameters:

entid - The `Entid` for this entity.

Returns:

an EntityBuilder for a new transaction.

entityBuilder

public EntityBuilder entityBuilder(String tempId)

Creates a new transaction (InProgress) and returns an EntityBuilder for a new entity with `tempId` for that transaction. TODO: Throw an exception if the result contains an error. https://github.com/mozilla/mentat/issues/700

Parameters:

tempId - The temporary identifier for this entity.

Returns:

an EntityBuilder for a new transaction.

destroyPointer

protected void destroyPointer(JNA.Store p)

close

public void close()

Specified by:

close in interface AutoCloseable

finalize

protected void finalize()

Overrides:

finalize in class Object