Class GenericMapLoader<K,V>
- Type Parameters:
K
- type of the keyV
- type of the value
- All Implemented Interfaces:
MapLoader<K,
,V> MapLoaderLifecycleSupport
- Direct Known Subclasses:
GenericMapStore
MapLoader
built
on top of Hazelcast SQL engine.
It works with any SQL connector supporting SELECT statements.
Usage:
First define data connection, e.g. for JDBC use JdbcDataConnection
:
Config config = new Config();
config.addDataConnectionConfig(
new DataConnectionConfig("mysql-ref")
.setType("Jdbc")
.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(GenericMapLoader.DATA_CONNECTION_REF_PROPERTY, "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.
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Field Summary
Modifier and TypeFieldDescriptionprotected List<SqlColumnMetadata>
static final String
Property key to define column names in databasestatic final String
Property key to define data connectionstatic final String
Property key to define external name of the tablestatic final String
Property key to define id column name in databasestatic final String
Property key to control loading of all keys when IMap is first createdstatic final HazelcastProperty
Timeout for initialization of GenericMapLoaderstatic final String
Property key to decide on getting a single column as the valueprotected SqlService
static final String
Property key to data connection type name -
Constructor Summary
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Method Summary
Modifier and TypeMethodDescriptionprotected void
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.Loads the value of a given key.loadAll
(Collection<K> keys) Size of thekeys
collection is limited byClusterProperty.MAP_LOAD_CHUNK_SIZE
Loads all of the keys from the store.
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Field Details
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DATA_CONNECTION_REF_PROPERTY
Property key to define data connection- See Also:
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EXTERNAL_NAME_PROPERTY
Property key to define external name of the table- See Also:
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ID_COLUMN_PROPERTY
Property key to define id column name in database- See Also:
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COLUMNS_PROPERTY
Property key to define column names in database- See Also:
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TYPE_NAME_PROPERTY
Property key to data connection type name- See Also:
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LOAD_ALL_KEYS_PROPERTY
Property key to control loading of all keys when IMap is first created- See Also:
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SINGLE_COLUMN_AS_VALUE
Property key to decide on getting a single column as the value- See Also:
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MAPSTORE_INIT_TIMEOUT
Timeout for initialization of GenericMapLoader -
sqlService
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columnMetadataList
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Constructor Details
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GenericMapLoader
public GenericMapLoader()
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Method Details
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init
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 thisMapLoader
is configured, can be obtained from thehazelcastInstance
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 theMapLoader
, consider deferring them with a lazy initialization scheme.- Specified by:
init
in interfaceMapLoaderLifecycleSupport
- Parameters:
instance
- HazelcastInstance of this mapLoader.properties
- Properties set for this mapStore. see MapStoreConfigmapName
- name of the map.
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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 interfaceMapLoaderLifecycleSupport
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load
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. -
loadAll
Size of thekeys
collection is limited byClusterProperty.MAP_LOAD_CHUNK_SIZE
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loadAllKeys
Description copied from interface:MapLoader
Loads all of the keys from the store. The returnedIterable
may return the keys lazily by loading them in batches. TheIterator
of thisIterable
may implement theCloseable
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 interfaceMapLoader<K,
V> - Returns:
- all the keys. Keys inside the Iterable cannot be
null
.
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awaitSuccessfulInit
protected void awaitSuccessfulInit()Awaits successful initialization; if the initialization fails, throws an exception.
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