com.hazelcast.mapstore

Class GenericMapLoader<K>

java.lang.Object

com.hazelcast.mapstore.GenericMapLoader<K>

Type Parameters:

K -

All Implemented Interfaces:

MapLoader<K,GenericRecord>, MapLoaderLifecycleSupport

Direct Known Subclasses:

GenericMapStore

public class GenericMapLoader<K>
extends Object
implements MapLoader<K,GenericRecord>, MapLoaderLifecycleSupport

GenericMapLoader is an implementation of MapLoader built on top of Hazelcast SQL engine.

It works with any SQL connector supporting SELECT statements.

Usage:

First define data link, e.g. for JDBC use JdbcDataLink:

 Config config = new Config();
 config.addDataLinkConfig(
   new DataLinkConfig("mysql-ref")
     .setClassName(JdbcDataLink.class.getName())
     .setProperty("jdbcUrl", dbConnectionUrl)
 );

Then create a Map with MapLoader using the GenericMapLoader implementation:

 MapConfig mapConfig = new MapConfig(mapName);
 MapStoreConfig mapStoreConfig = new MapStoreConfig();
 mapStoreConfig.setClassName(GenericMapLoader.class.getName());
 mapStoreConfig.setProperty(JdbcSqlConnector.OPTION_DATA_LINK_REF, "mysql-ref");
 mapConfig.setMapStoreConfig(mapStoreConfig);
 instance().getConfig().addMapConfig(mapConfig);

The GenericMapLoader creates a SQL mapping with name "__map-store." + mapName. This mapping is removed when the map is destroyed.

Field Summary

Fields

Modifier and Type	Field and Description
protected List<SqlColumnMetadata>	columnMetadataList
protected com.hazelcast.mapstore.GenericMapStoreProperties	genericMapStoreProperties
static HazelcastProperty	MAPSTORE_INIT_TIMEOUT Timeout for initialization of GenericMapLoader
protected com.hazelcast.mapstore.Queries	queries
protected SqlService	sqlService

Constructor Summary

Constructors

Constructor and Description
GenericMapLoader()

Method Summary

Modifier and Type	Method and Description
protected void	awaitSuccessfulInit() Awaits successful initialization; if the initialization fails, throws an exception.
void	destroy() Hazelcast will call this method before shutting down.
void	init(HazelcastInstance instance, Properties properties, String mapName) Initializes this MapLoader implementation.
GenericRecord	load(K key) Loads the value of a given key.
Map<K,GenericRecord>	loadAll(Collection<K> keys) Size of the keys collection is limited by ClusterProperty.MAP_LOAD_CHUNK_SIZE
Iterable<K>	loadAllKeys() Loads all of the keys from the store.

Methods inherited from class java.lang.Object

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

Field Detail

MAPSTORE_INIT_TIMEOUT

public static final HazelcastProperty MAPSTORE_INIT_TIMEOUT

Timeout for initialization of GenericMapLoader

sqlService

protected SqlService sqlService

genericMapStoreProperties

protected com.hazelcast.mapstore.GenericMapStoreProperties genericMapStoreProperties

queries

protected com.hazelcast.mapstore.Queries queries

columnMetadataList

protected List<SqlColumnMetadata> columnMetadataList

Constructor Detail

GenericMapLoader

public GenericMapLoader()

Method Detail

init

public void init(HazelcastInstance instance,
                 Properties properties,
                 String mapName)

Description copied from interface: MapLoaderLifecycleSupport

Initializes this MapLoader implementation. Hazelcast will call this method when the map is first used on the HazelcastInstance. Implementation can initialize required resources for the implementing mapLoader, such as reading a config file and/or creating a database connection. References to maps, other than the one on which this MapLoader is configured, can be obtained from the hazelcastInstance in this method's implementation.

On members joining a cluster, this method is executed during finalization of the join operation, therefore care should be taken to adhere to the rules for PostJoinAwareService.getPostJoinOperation(). If the implementation executes operations which may wait on locks or otherwise block (e.g. waiting for network operations), this may result in a time-out and obstruct the new member from joining the cluster. If blocking operations are required for initialization of the MapLoader, consider deferring them with a lazy initialization scheme.

Specified by:

init in interface MapLoaderLifecycleSupport

Parameters:

instance - HazelcastInstance of this mapLoader.

properties - Properties set for this mapStore. see MapStoreConfig

mapName - name of the map.

destroy

public void destroy()

Description copied from interface: MapLoaderLifecycleSupport

Hazelcast will call this method before shutting down. This method can be overridden to clean up the resources held by this map loader implementation, such as closing the database connections, etc.

Specified by:

destroy in interface MapLoaderLifecycleSupport

load

public GenericRecord load(K key)

Description copied from interface: MapLoader

Loads the value of a given key. If distributed map doesn't contain the value for the given key then Hazelcast will call implementation's load (key) method to obtain the value. Implementation can use any means of loading the given key; such as an O/R mapping tool, simple SQL or reading a file etc.

Specified by:

load in interface MapLoader<K,GenericRecord>

Returns:

value of the key; returning null value signals value missing in the underlying store

loadAll

public Map<K,GenericRecord> loadAll(Collection<K> keys)

Size of the keys collection is limited by ClusterProperty.MAP_LOAD_CHUNK_SIZE

Specified by:

loadAll in interface MapLoader<K,GenericRecord>

Parameters:

keys - keys of the values entries to load

Returns:

map of loaded key-value pairs.

loadAllKeys

public Iterable<K> loadAllKeys()

Description copied from interface: MapLoader

Loads all of the keys from the store. The returned Iterable may return the keys lazily by loading them in batches. The Iterator of this Iterable may implement the Closeable interface in which case it will be closed once iteration is over. This is intended for releasing resources such as closing a JDBC result set.

The returned Iterable should not contain any null keys.

Specified by:

loadAllKeys in interface MapLoader<K,GenericRecord>

Returns:

all the keys. Keys inside the Iterable cannot be null.

awaitSuccessfulInit

protected void awaitSuccessfulInit()

Awaits successful initialization; if the initialization fails, throws an exception.