com.hazelcast.mapreduce.impl

Class MapKeyValueSource<K,V>

java.lang.Object

com.hazelcast.mapreduce.KeyValueSource<K,V>

com.hazelcast.mapreduce.impl.MapKeyValueSource<K,V>

Type Parameters:

K - type of the key of the IMap

V - type of the value of the IMap

All Implemented Interfaces:

PartitionIdAware, DataSerializable, IdentifiedDataSerializable, Closeable, AutoCloseable

public class MapKeyValueSource<K,V>
extends KeyValueSource<K,V>
implements IdentifiedDataSerializable, PartitionIdAware

This KeyValueSource implementation is used in KeyValueSource.fromMap(com.hazelcast.core.IMap) to generate a default implementation based on a Hazelcast IMap.

Constructor Summary

Constructors

Constructor and Description
MapKeyValueSource(String mapName)

Method Summary

Modifier and Type	Method and Description
void	close()
Map.Entry<K,V>	element() Returns the current index element Calls to this method won't change state.
int	getFactoryId() Returns DataSerializableFactory factory ID for this class.
int	getId() Returns type identifier for this class.
String	getMapName()
boolean	hasNext() Called to request if at least one more key-value pair is available from this data source.
K	key() Returns the current index key for KeyPredicate analysis.
boolean	open(NodeEngine nodeEngine) This method is called before accessing the key-value pairs of this KeyValueSource.
void	readData(ObjectDataInput in) Reads fields from the input stream
boolean	reset() This method resets all internal state to be a new instance.
void	setPartitionId(int partitionId) Sets the partition ID to the implementing instance it is executed against
void	writeData(ObjectDataOutput out) Writes object fields to output stream

Methods inherited from class com.hazelcast.mapreduce.KeyValueSource

fromList, fromMap, fromMultiMap, fromSet, getAllKeys, getAllKeys0, isAllKeysSupported

Methods inherited from class java.lang.Object

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

Constructor Detail

MapKeyValueSource

public MapKeyValueSource(String mapName)

Method Detail

getMapName

public String getMapName()

open

public boolean open(NodeEngine nodeEngine)

Description copied from class: KeyValueSource

This method is called before accessing the key-value pairs of this KeyValueSource.

Specified by:

open in class KeyValueSource<K,V>

Parameters:

nodeEngine - nodeEngine of this cluster node

Returns:

true if the operation succeeded, false otherwise

close

public void close()
           throws IOException

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Throws:

IOException

hasNext

public boolean hasNext()

Description copied from class: KeyValueSource

Called to request if at least one more key-value pair is available from this data source. If so, this method returns true, otherwise it returns false. Calls to this method will change the state, more specifically if an element is found, the index will be set to the found element. Subsequent calls to the key() and element() methods will return that element.

Specified by:

hasNext in class KeyValueSource<K,V>

Returns:

true if at least one more key-value pair is available from this data source, false otherwise.

key

public K key()

Description copied from class: KeyValueSource

Returns the current index key for KeyPredicate analysis. This is called to prevent a possible deserialization of unneeded values because the key is not interesting for the running mapreduce algorithm. Calls to this method won't change state.

Specified by:

key in class KeyValueSource<K,V>

Returns:

the current index key for KeyPredicate analysis

element

public Map.Entry<K,V> element()

Description copied from class: KeyValueSource

Returns the current index element Calls to this method won't change state.

Specified by:

element in class KeyValueSource<K,V>

Returns:

the current index element

reset

public boolean reset()

Description copied from class: KeyValueSource

This method resets all internal state to be a new instance. The same instance of the KeyValueSource may be used multiple times in a row depending on the internal implementation, especially when the KeyValueSource implements PartitionIdAware.
If the instance is reused, a sequence of reset(), KeyValueSource.open(com.hazelcast.spi.NodeEngine) and Closeable.close() is called multiple times with the other methods between open(...) and close().

Specified by:

reset in class KeyValueSource<K,V>

Returns:

true if reset was successful, false otherwise

setPartitionId

public void setPartitionId(int partitionId)

Description copied from interface: PartitionIdAware

Sets the partition ID to the implementing instance it is executed against

Specified by:

setPartitionId in interface PartitionIdAware

Parameters:

partitionId - current partition ID

writeData

public void writeData(ObjectDataOutput out)
               throws IOException

Description copied from interface: DataSerializable

Writes object fields to output stream

Specified by:

writeData in interface DataSerializable

Parameters:

out - output

Throws:

IOException - if an I/O error occurs. In particular, an IOException may be thrown if the output stream has been closed.

readData

public void readData(ObjectDataInput in)
              throws IOException

Description copied from interface: DataSerializable

Reads fields from the input stream

Specified by:

readData in interface DataSerializable

Parameters:

in - input

Throws:

IOException - if an I/O error occurs. In particular, an IOException may be thrown if the input stream has been closed.

getFactoryId

public int getFactoryId()

Description copied from interface: IdentifiedDataSerializable

Returns DataSerializableFactory factory ID for this class.

Specified by:

getFactoryId in interface IdentifiedDataSerializable

Returns:

factory ID

getId

public int getId()

Description copied from interface: IdentifiedDataSerializable

Returns type identifier for this class. It should be unique per DataSerializableFactory.

Specified by:

getId in interface IdentifiedDataSerializable

Returns:

type ID