Package org.apache.storm.state

Class InMemoryKeyValueState<K,V>

java.lang.Object

org.apache.storm.state.InMemoryKeyValueState<K,V>

All Implemented Interfaces:

Iterable<Map.Entry<K,V>>, KeyValueState<K,V>, State

public class InMemoryKeyValueState<K,V>
extends Object
implements KeyValueState<K,V>

An in-memory implementation of the State.

Constructor Summary

Constructors

Constructor	Description
InMemoryKeyValueState()

Method Summary

Modifier and Type	Method	Description
void	commit()	Persist the current state.
void	commit(long txid)	Commit a previously prepared transaction.
V	delete(K key)	Deletes the value mapped to the key, if there is any.
V	get(K key)	Returns the value mapped to the key.
V	get(K key, V defaultValue)	Returns the value mapped to the key or defaultValue if no mapping is found.
Iterator<Map.Entry<K,V>>	iterator()
void	prepareCommit(long txid)	Invoked by the framework to prepare a transaction for commit.
void	put(K key, V value)	Maps the value with the key.
void	rollback()	Rollback a prepared transaction to the previously committed state.
String	toString()

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Constructor Detail

InMemoryKeyValueState

public InMemoryKeyValueState()

Method Detail

put

public void put(K key,
                V value)

Description copied from interface: KeyValueState

Maps the value with the key.

Specified by:

put in interface KeyValueState<K,V>

Parameters:

key - the key

value - the value

get

public V get(K key)

Description copied from interface: KeyValueState

Returns the value mapped to the key.

Specified by:

get in interface KeyValueState<K,V>

Parameters:

key - the key

Returns:

the value or null if no mapping is found

get

public V get(K key,
             V defaultValue)

Description copied from interface: KeyValueState

Returns the value mapped to the key or defaultValue if no mapping is found.

Specified by:

get in interface KeyValueState<K,V>

Parameters:

key - the key

defaultValue - the value to return if no mapping is found

Returns:

the value or defaultValue if no mapping is found

delete

public V delete(K key)

Description copied from interface: KeyValueState

Deletes the value mapped to the key, if there is any.

Specified by:

delete in interface KeyValueState<K,V>

Parameters:

key - the key

iterator

public Iterator<Map.Entry<K,V>> iterator()

Specified by:

iterator in interface Iterable<K>

commit

public void commit()

Description copied from interface: State

Persist the current state. This is used when the component manages the state.

Specified by:

commit in interface State

commit

public void commit(long txid)

Description copied from interface: State

Commit a previously prepared transaction. It should be possible to retrieve a committed state later.

Specified by:

commit in interface State

Parameters:

txid - the transaction id

prepareCommit

public void prepareCommit(long txid)

Description copied from interface: State

Invoked by the framework to prepare a transaction for commit. It should be possible to commit the prepared state later.

The same txid can be prepared again, but the next txid cannot be prepared when previous one is not yet committed.

Specified by:

prepareCommit in interface State

Parameters:

txid - the transaction id

rollback

public void rollback()

Description copied from interface: State

Rollback a prepared transaction to the previously committed state.

Specified by:

rollback in interface State

toString

public String toString()

Overrides:

toString in class Object